Professor Andrew Crocombe

Professor of Structural Mechanics

Qualifications: BSc, PhD, FIMechE, CEng

Email:
Phone: Work: 01483 68 9194
Room no: 13 AA 03

Further information

Research Interests

  • Adhesive bonding
  • Composite Materials
  • Biomechanics
  • Damage Modelling

Publications

Highlights

Journal articles

  • Han X, Hu P, Crocombe AD, Anwar SNR. (2014) 'The strength prediction of adhesive single lap joints exposed to long term loading in a hostile environment'. International Journal of Adhesion and Adhesives, 55, pp. 1-11.

    Abstract

    This work is concerned with investigating the residual static strength of adhesively bonded joints after long-term exposure to a combined mechanical-hygro-thermal environment. Associated experimental data are also reported. The degradation process of the joints was modelled using a fully-coupled approach, with the moisture concentration affecting the stress distribution and the stress state affecting the moisture diffusion analyses simultaneously. A bilinear cohesive zone model was then used to implement the progressive damage FE analysis of the quasi-statically loaded joints following the ageing phase. This model is degraded using the damage factors (creep strain and moisture uptake) accumulated over the ageing process and calibrated against the experimental results from static tests on the bulk adhesive. Predicted and experimentally-measured quasi-static responses for the aged adhesive joints were found to be in good agreement. © 2014 Elsevier Ltd.

  • Ahmad H, Crocombe AD, Smith PA. (2014) 'Strength prediction in CFRP woven laminate bolted single-lap joints under quasi-static loading using XFEM'. Composites Part A: Applied Science and Manufacturing, 66, pp. 82-93.

    Abstract

    This paper is concerned with modelling damage and fracture in woven fabric CFRP single-lap bolted joints that fail by net-tension. The approach is based on the assumption that damage (matrix cracking, delamination and fibre tow fracture) initiates and propagates from the hole in a self-similar fashion. A traction-separation law (based on physically meaningful material parameters) is implemented within an Extended Finite Element Method (XFEM) framework and used to predict the joint strength. Reasonable agreement between model and experiment was obtained for test configurations covering different weave types and lay-ups, a range of joint geometries (two hole diameters and a range of normalised joint widths) and finger-tight and fully torqued clamp-up conditions. The greatest discrepancies were for situations where the tensile fracture mechanisms were more complex, and hence not captured fully in the model or when bearing failure occurred. © 2014 Elsevier Ltd. All rights reserved.

  • Crocombe AD, Puigvert F, Gil L. (2014) 'Fatigue and creep analyses of adhesively bonded anchorages for CFRP tendons'. International Journal of Adhesion and Adhesives, 54, pp. 143-154.

    Abstract

    A bonded anchorage was investigated where a CFRP tendon was potted in a steel tube using an epoxy adhesive. Experimental creep tests on single lap joints and fatigue tests on anchorages, both with different adhesive thickness, were undertaken with failure occurring in the bond, close to the CFRP interface in cases. The creep and fatigue response of the adhesively bonded CFRP tendon anchors were separately predicted using Finite Element analysis. A visco-plastic material model was used to predict the time to failure of the anchors in creep. The effect of creep damage was modelled by degrading the yield stress of the adhesive. Moreover, a bi-linear traction-separation cohesive zone model was incorporated at the adhesive-tendon interface when simulating the fatigue loading of the anchorages. A fatigue damage model based on the degradation of the cohesive elements was implemented to take into account the fatigue damage evolution. The predicted results were found to be in good agreement with the experimentally recorded data. © 2014 Elsevier Ltd.

  • Frehill B, Crocombe AD, Agarwal Y, Bradley WN. (2014) 'Finite element assessment of block-augmented total knee arthroplasty.'. Comput Methods Biomech Biomed Engin, , pp. 1-11.

    Abstract

    Loosening and migration of tibial prostheses have been identified as causes of early total knee replacement (TKR) failure. The problem is made more complex when defects occur in the proximal tibia compromising fixation and alignment. Clinical studies using metal augments have shown these to be an alternative to other means of defect treatment. Finite element (FE) analysis can be used to identify regions that may be prone to loosening and migration. In the current work, 3D FE models of TKR uncontained type-2 defects treated with block augments have been constructed and analysed. It has been shown that a metal augment is the most suitable. The use of bone cement (PMMA) to fill proximal defects is not considered suitable as stresses carried by the cement block exceed those of the fatigue limit of bone cement. It has been shown that the stresses in the proximal cancellous bone of block-augmented models are significantly below levels likely to cause damage due to overloading. Furthermore, the use of stem extensions has been shown to reduce the cancellous bone stresses in the proximal region thus increasing the likelihood of bone resorption. Given this, it is recommended that stem extensions are not required unless necessary to mitigate some other problem.

  • Mubashar A, Ashcroft IA, Crocombe AD. (2014) 'Modelling damage and failure in adhesive joints using a combined XFEM-cohesive element methodology'. Journal of Adhesion, 90 (8), pp. 682-697.

    Abstract

    In recent years, cohesive elements based on the cohesive zone model (CZM) have been increasingly used within finite element analyses of adhesively bonded joints to predict failure. The cohesive element approach has advantages over fracture mechanics methods in that an initial crack does not have to be incorporated within the model. It is also capable of modelling crack propagation and representing material damage in a process zone ahead of the crack tip. However, the cohesive element approach requires the placement of special elements along the crack path and is, hence, less suited to situations where the exact crack path is not known a priori. The extended finite element method (XFEM) can be used to represent cracking within a finite element and hence removes the requirement to define crack paths or have an initial crack in the structure. In this article, a hybrid XFEM-cohesive element approach is used to model cracking in the fillet area using XFEM where the crack path is not known and then using cohesive elements to model crack and damage progression along the interface. The approach is applied to the case of an aluminium-epoxy single lap joint and is shown to be highly effective. © 2014 Copyright Taylor & Francis Group, LLC.

  • Vicentini D, Barroso A, París F, Mantič V, Crocombe A. (2014) 'Fatigue crack initiation and damage characterization in Brazilian test specimens for adhesive joints'. Journal of Adhesion Science and Technology, 28 (14-15), pp. 1418-1431.

    Abstract

    The present study is focused on the fatigue failure initiation at bimaterial corners by means of a configuration based on the Brazilian disc specimens. These specimens were previously used for the generalized fracture toughness determination and prediction of failure in adhesive joints, carried out under static compressive loading. Under static loading, local yielding effects might affect the asymptotic two-dimensional linear elastic stress representation under consideration. Fatigue loading avoids this fact due to the lower load levels used. The present tests were performed using load control; video microscopy and still cameras were used for monitoring initiation and crack growth. The fatigue tests were halted periodically and images of the corner were taken where fatigue damage was anticipated. Damage initiation and subsequent crack growth were observed in some specimens, especially in those which presented brittle failure under static and fatigue tests. These analyses allowed the characterization of damage initiation for a typical bimaterial corner that can be found in composite to aluminium adhesive lap joints. © 2012 © 2012 Taylor & Francis.

  • Puigvert F, Gil L, Crocombe AD. (2014) 'Static analysis of adhesively bonded anchorages for CFRP tendons'. Construction and Building Materials, 61, pp. 206-215.

    Abstract

    In pre-stressed concrete structures, consideration is being given to replacing the steel tendons with CFRP rods. One of the challenges associated with this is to develop a suitable anchorage for the CFRP rods. A bonded anchorage was investigated, where the CFRP is potted in a steel tube using epoxy adhesive. Experimental static tests of different configurations were undertaken with failure occurring in the bond. A set of numerical simulations were carried out with different adhesive material models to investigate the static response of the bonded anchorage and its failure mechanism. The adhesive was modelled with linear elastic properties, von Mises plasticity, Drucker-Prager plasticity and progressive damage. A cohesive zone model with progressive damage in the bonded joint was found to be in reasonable agreement with the experimentally recorded data. Also, an analytical formulation was developed (and validated) in order to provide an approximate distribution of shear stress in the bonded joint for circular anchors for adhesives with mainly elastic behaviour. © 2014 Elsevier Ltd. All rights reserved.

  • Han X, Crocombe AD, Anwar SNR, Hu P, Li WD. (2014) 'The effect of a hot-wet environment on adhesively bonded joints under a sustained load'. Journal of Adhesion, 90 (5-6), pp. 420-436.

    Abstract

    The aim of this research was to develop numerical modelling techniques for simulating the simultaneous effects of moisture, elevated temperature, and applied load on the performance of adhesively bonded joints. Associated experimental data are also reported. The degradation process of the joints was modelled using a fully-coupled approach, with the moisture concentration affecting the stress distribution and the stress state affecting the moisture diffusion analyses simultaneously. Further, the stress analysis contains a moisture-dependent creep model to accommodate viscous effects, and both swelling and thermal strains were included in the simulation. The governing parameters adopted in the modelling procedure were determined from experimental work based on the bulk adhesive. The joint response was monitored throughout the ageing process and good correlation was found between the experimental and numerical results. Copyright © 2014 Taylor & Francis Group, LLC.

  • Ahmad H, Crocombe AD, Smith PA. (2014) 'Strength prediction in CFRP woven laminate bolted double-lap joints under quasi-static loading using XFEM'. Composites Part A: Applied Science and Manufacturing, 56, pp. 192-202.

    Abstract

    The current paper is concerned with modelling damage and fracture in woven fabric composite double-lap bolted joints that fail by net-tension. A 3-D finite element model is used, which incorporates bolt clamp-up, to model a range of CFRP bolted joints, which were also tested experimentally. The effects of laminate lay-up, joint geometry, hole size and bolt clamp-up torque were considered. An Extended Finite Element (XFEM) approach is used to simulate damage growth, with traction-separation parameters that are based on previously reported, independent experimental measurements for the strength and toughness of the woven fabric materials under investigation. Good agreement between the predicted and measured bearing stress at failure was obtained. © 2013 Elsevier Ltd. All rights reserved.

  • Ahmad H, Crocombe AD, Smith PA. (2014) 'Strength prediction of notched woven composite plates using a cohesive zone approach'. Advanced Materials Research, 845, pp. 199-203.

    Abstract

    The present paper is concerned with modelling damage and fracture in notched woven fabric composites. Previous experimental work has shown that damage at a notch in a variety of GFRP and CFRP composites based on woven fabric reinforcement comprises matrix damage and fibre tow fracture along the plane of maximum stress. It is these experimental observations that inform the failure modelling developed here, in which a cohesive zone approach is used within a 2- D finite element framework. The cohesive zone parameters are based on previously reported experimental measurements for the strength and toughness of the woven fabric materials under investigation. The approach is shown to provide predictions of notched strength that are in very good agreement (less than 11% discrepancy) with experimental results from the literature for a range of GFRP and CFRP woven fabric systems. © (2014) Trans Tech Publications, Switzerland.

  • Ahmad H, Crocombe AD, Smith PA. (2013) 'Physically based finite element strength prediction in notched woven laminates under quasi-static loading'. Plastics, Rubber and Composites, 42 (3), pp. 93-100.

    Abstract

    The present paper is concerned with modelling damage and fracture in notched woven fabric composites. Previous experimental work has shown that, under tensile loading, damage at a notch in a variety of glass fibre reinforced plastic (GFRP) and carbon fibre reinforced plastic (CFRP) composites based on woven fabric reinforcement comprises matrix damage and fibre tow fracture along the plane of maximum stress. It is these experimental observations that inform the failure modelling developed here, in which a cohesive zone approach is used within a two-dimensional extended finite element method framework. The traction-separation parameters used in the extended finite element method implementation are based on previously reported experimental measurements for the strength and toughness of the woven fabric materials under investigation. The approach is shown to provide predictions of notched strength that are in very good agreement with experimental results from the literature for a range of glass fibre reinforced plastic and carbon fibre reinforced plastic woven fabric systems and also agree well with results obtained from closed form analytical models, which require calibration. © Institute of Materials, Minerals and Mining 2013.

  • Kimpton CI, Crocombe AD, Bradley WN, Gavin Huw Owen B. (2013) 'Analysis of Stem Tip Pain in Revision Total Knee Arthroplasty.'. J Arthroplasty, 28 (6), pp. 971-977.

    Abstract

    Stem tip pain following revision total knee arthroplasty is a significant cause of patient dissatisfaction, which in the presence of an aseptic well-fixed component has no widely accepted surgical solution. A definitive cause of stem tip pain remains elusive, however it has been suggested that high stress concentrations within the region of the stem tip may play a role. This paper reports a finite element study of a novel clinical technique where a plate is attached to the tibia within the region of the stem tip to reduce stem tip pain. The results demonstrate that the plate reduces stress concentrations in the bone at the stem tip of the implant. The magnitude of stress reduction is dependent upon plate location, material and attachment method.

  • Sugiman S, Crocombe AD, Aschroft IA. (2013) 'The fatigue response of environmentally degraded adhesively bonded aluminium structures'. International Journal of Adhesion and Adhesives, 41, pp. 80-91.

    Abstract

    Experimental studies have been undertaken investigating the effect of moisture on the fatigue response of adhesively bonded monolithic single lap joints and laminated doublers loaded in bending, both made of the same materials. The joints were aged in deionised water at a temperature of 50 °C for up to 2 years exposure. The backface strain technique was employed to monitor damage initiation and propagation in the joints. The test results show that the fatigue life degraded with increasing moisture content and tended to level off when approaching saturation. The failure surfaces were cohesive in the adhesive. Numerical fatigue modelling has been undertaken to predict the fatigue response of these joints utilising a strain-based fatigue damage law integrated with a bilinear traction-separation cohesive zone model. The residual stresses due to thermal and swelling strain were included in the model. Good agreement was found between the predicted fatigue response and the experimental results. © 2012 Elsevier Ltd. All rights reserved.

  • Sugiman S, Crocombe AD, Aschroft IA. (2013) 'Experimental and numerical investigation of the static response of environmentally aged adhesively bonded joints'. International Journal of Adhesion and Adhesives, 40, pp. 224-237.

    Abstract

    The aim of this research is to investigate the effect of moisture on the static response of adhesively bonded monolithic single lap joints and laminated doublers loaded in bending. All joints were made of aluminium alloy Al 2024-T3 bonded using epoxy film adhesive FM 73M OST. The joints were aged in deionised water at a temperature of 50°C for up to 2 years exposure. The use of different widths of specimen (5 mm for monolithic single lap joints and 15 mm for laminated doublers) allowed both full and partial saturation of the adhesive layer. The bulk adhesive has been characterised to obtain the coefficient of moisture diffusion, the coefficient of thermal and moisture expansion and the moisture dependent mechanical properties. The testing results showed that the mechanical properties degraded in a linear way with the moisture content. The residual strength after exposure decreased with increasing moisture content (exposure time) and tended to level off towards saturation. The damage evolution and failure of the joint has been successfully monitored using the backface strain technique and in-situ video microscopy. Progressive damage finite element modelling using a moisture dependent, bilinear traction-separation law has been undertaken to predict the residual strength. Residual stresses due to thermal and swelling strains in the adhesive layer have been included; however their effect on the predicted static strength was not significant. Good agreement was found between the predicted residual strength and the experimental result. © 2012 Elsevier Ltd.

  • Hafiz TA, Crocombe AD, Smith PA, Abdel-Wahab MM. (2013) 'Mixed-mode fatigue crack growth in FM73 bonded joints'. International Journal of Adhesion and Adhesives, 40, pp. 188-196.

    Abstract

    Fatigue tests have been carried out to investigate mixed mode fatigue crack growth behaviour in FM73 epoxy adhesive using double cantilever beam (DCB) specimens. The DCB configuration used consisted of equal thickness mild steel adherends bonded with FM73 adhesive. The joints were tested under pure mode I and a range of fatigue mixed-mode conditions using a relatively simple, variable-mode loading fixture developed in previous work [1]. The fatigue testing was carried out in displacement control, with an initial load ratio (R) of 0.1. The fatigue load decreased as the fatigue crack grew and this load was recorded. Crack growth was monitored and measured using a video microscope. The results suggest that crack initiation in the test specimens is controlled by the mode I strain energy release rate, G component. The fatigue crack growth rates were characterised using a Paris law approach, from which it appears that the total strain energy release rate range, ΔG , is a more dominant factor in controlling crack growth than the mode I component of strain energy release rate range, ΔG. For a quantitative description of the mixed-mode fatigue crack growth, generalised forms of the Paris relation are developed. © 2012 Elsevier Ltd.

  • Sanderson AR, Ogin SL, Crocombe AD, Gower MRL, Lee RJ. (2012) 'Use of a surface-mounted chirped fibre Bragg grating sensor to monitor delamination growth in a double-cantilever beam test'. Composites Science and Technology, 72 (10), pp. 1121-1126.

    Abstract

    A surface-mounted chirped fibre Bragg grating (CFBG) sensor has been used for the first time to monitor delamination growth within a composite material (a transparent, unidirectionally reinforced glass fibre/epoxy resin double-cantilever beam (DCB) specimen). The specimens were tested using a constant displacement rate, with the delamination length being measured using complementary techniques: (i) in situ photography, (ii) surface-mounted strain gauges, and (iii) the surface-mounted CFBG sensors. The unidirectionally reinforced DCB specimens showed characteristics typical of such material which complicate the curvature of the beams, i.e. the development of extensive fibre bridging and pronounced R-curve behaviour. To validate the interpretation of the CFBG reflected spectrum, the experimentally determined strains from the surface-mounted strain gauges have been used, together with in situ photographs of the position of the delamination front. Using the CFBG sensor technique, the delamination length was measured to within about 4 mm over the 60 mm sensor length.

  • Gruber P, Sharp RS, Crocombe AD. (2012) 'Normal and shear forces in the contact patch of a braked racing tyre Part 2: Development of a physical tyre model'. Vehicle System Dynamics: international journal of vehicle mechanics and mobility, 50 (3), pp. 339-356.

    Abstract

    This article is the second part of a two-part article looking at carcass deflections, contact pressure and shear stress distributions for a steady-rolling, slipping and cambered tyre. In the first part, a previously described and validated finite-element (FE) model of a racing-car tyre is developed further to extract detailed results which are not easily obtainable through measurements on an actual tyre. Generally, these results aid in the understanding of contact patch characteristics. In particular, they form a basis for the development of a simpler physical tyre model, which forms the focus of this part of the article. The created simpler tyre model has the following three purposes: (i) to reduce computational demand while retaining accuracy, (ii) to allow identification of tyre model features that are fundamental to an accurate representation of the contact stresses and (iii) to create a facility for better understanding of tyre wear mechanisms and thermal effects. Results generated agree well with the physically realistic rolling-tyre behaviour demonstrated by the FE model. Also, the model results indicate that an accurate simulation of the contact stresses requires a detailed understanding of carcass deformation behaviour.

  • Gruber P, Sharp RS, Crocombe AD. (2012) 'Normal and shear forces in the contact patch of a braked racing tyre Part 1: Results from a Finite Element model'. Vehicle System Dynamics: international journal of vehicle mechanics and mobility, 50 (2), pp. 323-337.
  • Sugiman S, Crocombe AD. (2012) 'The static and fatigue response of metal laminate and hybrid fibre-metal laminate doublers joints under tension loading'. Composite Structures, 94 (9), pp. 2937-2951.

    Abstract

    Experimental and numerical studies have been undertaken on metal laminate (ML) doublers and hybrid fibre-metal (aluminium-Glare) laminate (FML) doublers to investigate their static and fatigue response under tension loading. Inevitably sheets in these laminates butt together and these butts can affect the joint strength. Progressive damage modelling, including the damage in the adhesive bondline, the butt, the metal and the fibre has been undertaken in both static and fatigue loading. This modelling was found to be in good agreement with the experiment data in terms both of the strength and the failure mechanisms. In ML, the butt influenced the static and fatigue response. In hybrid FML, the specimens either have the fibres parallel to the loading direction (spanwise) or perpendicular to the loading direction (chordwise). The spanwise specimen was found to have the highest strength followed by chordwise specimens without butts and finally chordwise specimens with butts. The most critical position for a butt was found to be adjacent to the doubler end. Without butts the static strength for spanwise and chordwise specimens was controlled by the failure in the Glare layer whilst the fatigue failure was precipitated by failure in the aluminium sheet. © 2012 Elsevier Ltd.

  • Adediran OA, Xu W, Crocombe AD, Abdel Wahab MM. (2012) 'Application of FE model updating for damage assessment of FRP composite beam structure'. Conference Proceedings of the Society for Experimental Mechanics Series, 6, pp. 385-398.

    Abstract

    The FRP composite beam structure that is intended to represent deck prototype used in civil engineering construction is investigated. FRP composite material may have possible damage, which affect vibration structural integrity and reliability. To overcome this problem, vibration data from experiments can be used to assess such damage accurately. The FE mode updating process is demonstrated in parameter identification as well as structural damage identification. It is used to minimise the difference between experimental and numerical data. The updated parameters are the modified parameters selected in the FE model with aim of correcting modelling errors and/or damage detection. In this FE model updating procedure, model physical characteristics are changed so that the differences between experimental and numerical dynamic properties are reduced. The FE model updating is carried out using optimisation tools in ANSYS software. Only the first three natural frequencies will be considered in this work. The FE model updating procedure brings the numerical results of the FRP structure in proper correlation to the experimental results, according to an objective function, by changing the FE model parameters. The test results of the structure under intact and damage states are presented. It is suggested that there is damage at the unbounded joint when there is significant change in fixed parameters of the structure beyond acceptable degree. © The Society for Experimental Mechanics, Inc. 2012.

  • Sugiman S, Crocombe AD, Aschroft IA. (2012) 'Modelling the static response of unaged adhesively bonded structures'. ENGINEERING FRACTURE MECHANICS, 98, pp. 296-314.
  • Sugiman S, Crocombe AD, Katnam KB. (2011) 'Investigating the static response of hybrid fibre-metal laminate doublers loaded in tension'. COMPOSITES PART B-ENGINEERING, 42 (7), pp. 1867-1884.
  • Woodland S, Crocombe AD, Chew JW, Mills SJ. (2011) 'A New Method for Measuring Thermal Contact Conductance-Experimental Technique and Results'. JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME, 133 (7) Article number ARTN 071601
  • Wahab MMA, Hilmy I, Ashcroft IA, Crocombe AD. (2011) 'Damage Parameters of Adhesive Joints with General Triaxiality Part I: Finite Element Analysis'. JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY, 25 (9), pp. 903-923.
  • Mubashar A, Ashcroft IA, Critchlow GW, Crocombe AD. (2011) 'Strength prediction of adhesive joints after cyclic moisture conditioning using a cohesive zone model'. Engineering Fracture Mechanics, 78 (16), pp. 2746-2760.

    Abstract

    This paper presents a methodology to predict the strength of adhesive joints under variable moisture conditions. The moisture uptake in adhesive joints was determined using a history dependent moisture prediction methodology where diffusion coefficients were based on experimental cyclic moisture uptake of bulk adhesive samples. The predicted moisture concentrations and moisture diffusion history were used in a structural analysis with a cohesive zone model to predict damage and failure of the joints. A moisture concentration and moisture history dependent bilinear cohesive zone law was used. The methodology was used to determine the damage and failure in aluminium alloy - epoxy adhesive single lap joints, conditioned at 50 °C and good predictions of failure load were observed. The damage in the adhesive joints decreased the load carrying capacity before reaching the failure load and a nonlinear relationship between the load and displacement was observed. Changes in crack initiation and crack propagation were also observed between different types of joints. The presented methodology is generic and may be applied to different types of adhesive joint and adhesive. © 2011 Elsevier Ltd.

  • Khoramishad H, Crocombe AD, Katnam KB, Ashcroft IA. (2011) 'Fatigue damage modelling of adhesively bonded joints under variable amplitude loading using a cohesive zone model'. ENGINEERING FRACTURE MECHANICS, 78 (18), pp. 3212-3225.
  • Wahab MMA, Hilmy I, Ashcroft IA, Crocombe AD. (2011) 'Damage Parameters of Adhesive Joints with General Triaxiality, Part 2: Scarf Joint Analysis'. JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY, 25 (9), pp. 925-947.
  • Capell TF, Ogin SL, Crocombe AD, Peres P, Barnoncel D. (2011) 'Detection of disbonding in bonded joints with a spatially displaced CFBG sensor'. ICCM International Conferences on Composite Materials,
  • Ahmad H, Crocombe AD, Smith PA. (2011) 'Failure modelling of woven GFRP bolted joints under quasi-static loading'. ICCM International Conferences on Composite Materials,

    Abstract

    A 2-D finite element model has been developed to simulate crack growth (net-tension and shear-out failures) in composite bolted joints. Results from the model have been compared with a similar approach from the literature and experimental data for a woven fabric system. Agreement is reasonable in each case.

  • Katnam KB, Crocombe AD, Khoramishad H, Ashcroft IA. (2011) 'The Static Failure of Adhesively Bonded Metal Laminate Structures: A Cohesive Zone Approach'. JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY, 25 (10), pp. 1131-1157.
  • Katnam KB, Crocombe AD, Sugiman H, Khoramishad H, Ashcroft IA. (2011) 'Static and fatigue failures of adhesively bonded laminate joints in moist environments'. International Journal of Damage Mechanics, 20 (8), pp. 1217-1226.

    Abstract

    Advanced structural adhesives are now an important joining technique in automobile and aerospace applications. The perceived uncertainty in the long-term structural performance of bonded members when subjected to static/fatigue loads in aggressive environments is probably restricting an even more widespread use of this joining technology. In this article, the effect of moisture on the static and fatigue resistances of adhesively bonded laminate joints was investigated. Experimental tests were performed on both aged and unaged adhesively bonded laminate joints for static and fatigue responses. Further, using a cohesive zone approach for the adhesive bondlines, a combined diffusion–stress analysis was developed to predict the progressive damage observed in the joints tested experimentally. The numerical predictions were found to be in good agreement with the experimental test results.

  • Mubashar A, Ashcroft IA, Critchlow GW, Crocombe AD. (2011) 'A method of predicting the stresses in adhesive joints after cyclic moisture conditioning'. Journal of Adhesion, 87 (9), pp. 926-950.

    Abstract

    The durability of adhesive joints is of special concern in structural applications and moisture has been identified as one of the major factors affecting joint durability. This is especially important in applications where joints are exposed to varying environmental conditions throughout their life. This paper presents a methodology to predict the stresses in adhesive joints under cyclic moisture conditioning. The single lap joints were manufactured from aluminium alloy 2024 T3 and the FM73-BR127 adhesive-primer system. Experimental determination of the mechanical properties of the adhesive was carried out to measure the effect of moisture uptake on the strength of the adhesive. The experimental results revealed that the tensile strength of the adhesive decreased with increasing moisture content. The failure strength of the single lap joints also progressively degraded with time when conditioned at 50C, immersed in water; however, most of the joint strength recovered after drying the joints. A novel finite element based methodology, which incorporated moisture history effects, was adopted to determine the stresses in the single lap joints after curing, conditioning, and tensile testing. A significant amount of thermal residual stress was present in the adhesive layer after curing the joints; however, hygroscopic expansion after the absorption of moisture provided some relief from the curing stresses. The finite element model used moisture history dependent mechanical properties to predict the stresses after application of tensile load on the joints. The maximum stresses were observed in the fillet areas in both the conditioned and the dried joints. Study of the stresses revealed that degradation in the strength of the adhesive was the major contributor in the strength loss of the adhesive joints and adhesive strength recovery also resulted in recovered joint strength. The presented methodology is generic in nature and may be used for various joint configurations as well as for other polymers and polymer matrix composites. © 2011 Taylor & Francis Group, LLC.

  • Jumbo FS, Ashcroft IA, Crocombe AD, Wahab MMA. (2010) 'Thermal residual stress analysis of epoxy bi-material laminates and bonded joints'. INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES, 30 (7), pp. 523-538.
  • Shenoy V, Ashcroft IA, Critchlow GW, Crocombe AD. (2010) 'Unified methodology for the prediction of the fatigue behaviour of adhesively bonded joints'. International Journal of Fatigue, 32 (8), pp. 1278-1288.

    Abstract

    A unified model is proposed to predict the fatigue behaviour of adhesively bonded joints. The model is based on a damage mechanics approach, wherein the evolution of fatigue damage in the adhesive is defined as a power law function of the micro-plastic strain. The model is implemented as an external subroutine for commercial finite element analysis software. Three dimensional damage evolution and crack propagation were simulated using this method and an element deletion technique was employed to represent crack propagation. The model was able to predict the damage evolution, crack initiation and propagation lives, strength and stiffness degradation and the backface strain during fatigue loading. Hence the model is able to unify previous approaches based on total life, strength or stiffness wearout, backface strain monitoring and crack initiation and propagation modelling. A comparison was made with experimental results for an epoxy bonded aluminium single lap joint and a good match was found. © 2010 Elsevier Ltd. All rights reserved.

  • Khoramishad H, Crocombe AD, Katnam KB, Ashcroft IA. (2010) 'Predicting fatigue damage in adhesively bonded joints using a cohesive zone model'. INTERNATIONAL JOURNAL OF FATIGUE, 32 (7), pp. 1146-1158.
  • Shenoy V, Ashcroft IA, Critchlow GW, Crocombe AD. (2010) 'Fracture mechanics and damage mechanics based fatigue lifetime prediction of adhesively bonded joints subjected to variable amplitude fatigue'. Engineering Fracture Mechanics, 77 (7), pp. 1073-1090.

    Abstract

    The first part of the paper describes an investigation into the behaviour of adhesively bonded single lap joints (SLJs) subjected to various types of variable amplitude fatigue (VAF) loading. It was seen that a small proportion of fatigue cycles at higher fatigue loads could result in a significant reduction in the fatigue life. Palmgren-Miner's damage sum tended to be less than 1, indicating damage accelerative load interaction effects. In the second part of the paper, fracture mechanics (FM) and damage mechanics (DM) approaches are used to predict the fatigue lifetime for these joints. Two FM based approaches were investigated, which differed with respect to the cycle counting procedure, however, both approaches were found to under-predict the fatigue lifetime for all the types of spectra used. This was attributed to the inability of the FM based models to simulate the crack initiation phase. A DM based approach was then used with a power law relationship between equivalent plastic strain and the damage rate. Good predictions were found for most of the spectra, with a tendency to over-predict the fatigue life. © 2010 Elsevier Ltd.

  • Hafiz TA, Crocombe AD, Smith PA, Abdel Wahab MM. (2010) 'Mixed-mode fracture of adhesively bonded metallic joints under quasi-static loading'. Engineering Fracture Mechanics, 77 (17), pp. 3434-3445.

    Abstract

    Quasi-static tests have been carried out to characterise mixed-mode fracture using a Double Cantilever Beam (DCB) specimen. The DCB consists of equal thickness mild steel adherends bonded with FM-73M epoxy adhesive and is tested under pure mode I, pure mode II and a range of mode-mixity conditions, using a relatively simple loading fixture. The test method is analysed using closed-form and finite element methods, which agree well provided that the adhesive deformation is considered. The strain energy release rate components at fracture are presented in a conventional G (mode I)-G (mode II) failure plot using closed-form Linear Elastic Fracture Mechanics (LEFM) methods reported previously in the literature. The results showed that the strain energy release rate is enhanced in the situation of the mode II (in-plane shearing) dominated mixed mode condition as compared to the mode I (opening mode) dominated mixed mode. © 2010 Elsevier Ltd.

  • Arastu MH, Partridge R, Crocombe A, Solan M. (2010) 'Determination of optimal screw positioning in flexor hallucis longus tendon transfer for chronic tendoachilles rupture'. Foot and Ankle Surgery, 17 (2), pp. 74-78.
  • Wahab MMA, Hilmy I, Crocombe AD, Ashcroft IA. (2010) 'Evaluation of fatigue damage in adhesive bonding: Part 1: Bulk adhesive'. Journal of Adhesion Science and Technology, 24 (2), pp. 305-324.

    Abstract

    The measurement of fatigue damage in adhesive bonding has been investigated. Bulk adhesive was used in this study for two reasons: the stress distribution of adhesives in bulk is simpler to investigate than adhesives in joints; and the specimen dimensions met fatigue test standards. Bulk adhesive was made from a film type of epoxy resin. In general, the characteristics and the behaviour of bulk adhesive may differ from adhesive in joint because of the presence of voids and the constraints imposed by the substrates. Low cycle fatigue tests with a load amplitude ratio of 0.1 at a frequency of 5 Hz were performed to determine the damage as a function of the number of cycles. Damage curves, i.e., the evolution of the damage variable as a function of number of cycles, were derived and plotted using an isotropic damage equation. Damage was evaluated using the decrease of stress range during the lifecycles of a constant displacement amplitude test. It was found that the damage curves were well fitted by a low cycle, fatigue damage evolution law equation. This equation was derived from a dissipation potential function. Curve fitting was performed using the robust least square technique rather than ordinary linear least square technique because damage curves have extreme points (usually near the failure point). It was found that the fitting process would not converge for adhesive fractures at high cycle values (N > 9000). Two damage constants A and β were found from the fitting process. Each fatigue set of data, at a certain level of von-Mises stress range for the undamaged state or at the stabilized hardened state, (Δσ), had a different set of damage parameters A and β. Linear regression of these points was used to express A and β as a function of Δσ . Using these expressions, damage curves for different levels of Δσ could be predicted. © Koninklijke Brill NV, Leiden, 2010.

  • Katnam KB, Crocombe AD, Khoramishad H, Ashcroft IA. (2010) 'Load Ratio Effect on the Fatigue Behaviour of Adhesively Bonded Joints: An Enhanced Damage Model'. JOURNAL OF ADHESION, 86 (3), pp. 257-272.
  • Solana AG, Crocombe AD, Ashcroft IA. (2010) 'Fatigue life and backface strain predictions in adhesively bonded joints'. INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES, 30 (1), pp. 36-42.
  • Ashcroft IA, Shenoy V, Critchlow GW, Crocombe AD. (2010) 'A comparison of the prediction of fatigue damage and crack growth in adhesively bonded joints using fracture mechanics and damage mechanics progressive damage methods'. Journal of Adhesion, 86 (12), pp. 1203-1230.
  • Wahab MMA, Hilmy I, Crocombe AD, Ashcroft IA. (2010) 'Evaluation of fatigue damage in adhesive bonding: Part 2: Single lap joint'. Journal of Adhesion Science and Technology, 24 (2), pp. 325-345.

    Abstract

    The damage parameters for crack initiation in a single lap joint (SLJ) are determined by combining continuous damage mechanics, finite element analysis (FEA) and experimental fatigue data. Even though a SLJ has a simple configuration, the stresses in the adhesive region are quite complex and exhibit multi-axial states. Such a condition leads to the need to introduce a general value for the triaxiality function in the damage evolution law rather than using a triaxiality function which equals unity, as in the case of a uni-axial stress state, e.g., the bulk adhesive test specimen presented in Part 1 of this paper. The effect of stress singularity, due to the presence of corners at edges, also contributes to the complex state of stress and to the variability of the triaxiality function along the adhesive layer in a SLJ. The damage parameters A and β determined in Part 1 for bulk adhesive are now extended to take into account the multi-axial stress state in the adhesive layer, as calculated from FEA. © Koninklijke Brill NV, Leiden, 2010.

  • Katnam KB, Sargent JP, Crocombe AD, Khoramishad H, Ashcroft IA. (2010) 'Characterisation of moisture-dependent cohesive zone properties for adhesively bonded joints'. Engineering Fracture Mechanics, 77 (16), pp. 3105-3119.
  • Frehill B, Crocombe A, Cirovic S, Agarwal Y, Bradley N. (2010) 'Initial stability of type-2 tibial defect treatments'. PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART H-JOURNAL OF ENGINEERING IN MEDICINE, 224 (H1), pp. 77-85.
  • Khoramishad H, Crocombe AD, Katnam KB, Ashcroft IA. (2010) 'A generalised damage model for constant amplitude fatigue loading of adhesively bonded joints'. International Journal of Adhesion and Adhesives, 30 (6), pp. 513-521.
  • Wenman MR, Price AJ, Steuwer A, Chard-Tuckey PR, Crocombe A. (2009) 'Modelling and experimental characterisation of a residual stress field in a ferritic compact tension specimen'. INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING, 86 (12), pp. 830-837.
  • Mubashar A, Ashcroft IA, Critchlow GW, Crocombe AD. (2009) 'Moisture absorption-desorption effects in adhesive joints'. International Journal of Adhesion and Adhesives, 29 (8), pp. 751-760.

    Abstract

    This paper presents a study of moisture absorption-desorption effects in single lap adhesive joints. Experiments were carried out to characterise the moisture uptake of the single part epoxide adhesive, FM73. Tensile testing of single lap joints manufactured from aluminium alloy 2024 T3 and O and FM73 adhesive was carried out after the joints were exposed to different conditioning environments. The experimental results revealed that the failure strength of the single lap joints with 2024 T3 adherends progressively degraded with time when conditioned at 50 °C, immersed in water. However, the joint strength almost completely recovered after moisture was desorbed. The single lap joints with 2024 O adherends showed decreased strength for 28 days of conditioning, after which strength recovered, reaching a plateau after 56 days. Again, strength almost completely recovered on desorption of moisture. The strength recovery of the joints, after desorption of moisture, showed that the degradation of the adhesive was largely reversible. Analysis of the failure surfaces revealed that the dry joints failed cohesively in the adhesive layer and that the failure path moved towards the interface after conditioning. The failure mode then reverted back to cohesive failure after moisture desorption. © 2009 Elsevier Ltd. All rights reserved.

  • Shenoy V, Ashcroft IA, Critchlow GW, Crocombe AD, Abdel Wahab MM. (2009) 'An evaluation of strength wearout models for the lifetime prediction of adhesive joints subjected to variable amplitude fatigue'. International Journal of Adhesion and Adhesives, 29 (6), pp. 639-649.

    Abstract

    Almost all structural applications of adhesive joints will experience cyclic loading and in most cases this is irregular in nature, a form of loading commonly known as variable amplitude fatigue (VAF). This paper is concerned with the VAF of adhesively bonded joints and has two main parts. In the first part, results from the experimental testing of adhesively bonded single lap joints subjected to constant and variable amplitude fatigue are presented. It is seen that strength wearout of bonded joints under fatigue is non-linear and that the addition of a small number of overloads to a fatigue spectrum can greatly reduce the fatigue life. The second part of the paper looks at methods of predicting VAF. It was found that methods of predicting VAF in bonded joints based on linear damage accumulation, such as the Palmgren-Miner rule, are not appropriate and tend to over-predict fatigue life. Improved predictions of fatigue life can be made by the application of non-linear strength wearout methods with cycle mix parameters to account for load interaction effects. © 2009 Elsevier Ltd. All rights reserved.

  • Liljedahl CDM, Crocombe AD, Gauntlett FE, Rihawy MS, Clough AS. (2009) 'Characterising moisture ingress in adhesively bonded joints using nuclear reaction analysis'. INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES, 29 (4), pp. 356-360.
  • Shenoy V, Ashcroft IA, Critchlow GW, Crocombe AD, Abdel Wahab MM. (2009) 'An investigation into the crack initiation and propagation behaviour of bonded single-lap joints using backface strain'. International Journal of Adhesion and Adhesives, 29 (4), pp. 361-371.

    Abstract

    In this paper, the backface strain (BFS) measurement technique is used to characterise fatigue damage in single-lap adhesive joints subjected to constant amplitude fatigue loading. Different regions in the BFS plots are correlated with damage in the joints through microscopic characterisation of damage and cracking in partially fatigued joints and comparison with 3D finite element analysis (FEA) of various crack growth scenarios. Crack initiation domination was found at lower fatigue loads whereas crack propagation dominated at higher fatigue loads. Using the BFS and fatigue life measurement results, a simple predictive model is proposed which divides the fatigue lifetime into different regions depending upon the fatigue load. The model can be used with experimental BFS measurements to determine the residual life of the joint in different regions of damage progression during the fatigue life. © 2008 Elsevier Ltd. All rights reserved.

  • Shenoy V, Ashcroft IA, Critchlow GW, Crocombe AD, Abdel Wahab MM. (2009) 'Strength wearout of adhesively bonded joints under constant amplitude fatigue'. International Journal of Fatigue, 31 (5), pp. 820-830.

    Abstract

    The behaviour of adhesively bonded lap joints subjected to fatigue loading is still not well understood. In this paper strength degradation of joints during fatigue cycling is measured experimentally and related to damage evolution. Strength wearout (SW) measurements carried out under constant amplitude fatigue loading of single lap joints are presented and correlated with in situ measurements of back-face strain (BFS) and estimations of damage progression from fracture surfaces and sectioning of partially fatigued samples. Residual strength was found to decrease non-linearly with respect to the number of fatigue cycles and this corresponded to non-linear increases in the BFS and damage measurements. In particular it was noted that fatigue damage accelerated very quickly towards the end of the fatigue life of a joint. A non-linear SW model is proposed and was found to agree well with the experimental results. This model can be used to predict the residual strength of a joint after a period of fatigue loading once a single empirical constant has been determined. © 2008 Elsevier Ltd. All rights reserved.

  • Mubashar A, Ashcroft IA, Critchlow GW, Crocombe AD. (2009) 'Modelling cyclic moisture uptake in an epoxy adhesive'. Journal of Adhesion, 85 (10), pp. 711-735.

    Abstract

    This paper presents a methodology for predicting moisture concentration in an epoxy adhesive under cyclic moisture absorption-desorption conditions. The diffusion characteristics of the adhesive were determined by gravimetric experiments under cyclic moisture conditions and the dependence of diffusion coefficient and saturated mass uptake on moisture history was determined. Non-Fickian moisture absorption was observed during absorption cycles while moisture desorption remained Fickian. The diffusion coefficient and saturated moisture content showed variation with absorption-desorption cycling. A finite element-based methodology incorporating moisture history was developed to predict the cyclic moisture concentration. A comparison is made between the new modelling methodology and a similar method that neglects the moisture history dependence. It was seen that the concentration predictions based on non-history dependent diffusion characteristics resulted in over-prediction of the moisture concentration in cyclic conditioning of adhesive joints. The proposed method serves as the first step in the formulation of a general methodology to predict the moisture dependent degradation and failure in adhesives.

  • Gruber P, Sharp RS, Crocombe AD. (2008) 'Friction and camber influences on the static stiffness properties of a racing tyre'. PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART D-JOURNAL OF AUTOMOBILE ENGINEERING, 222 (D11), pp. 1965-1976.
  • Hua Y, Crocombe AD, Wahab MA, Ashcroft IA. (2008) 'Continuum damage modelling of environmental degradation in joints bonded with EA9321 epoxy adhesive'. INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES, 28 (6), pp. 302-313.
  • Palaniappan J, Ogin SL, Thorne AM, Reed GT, Crocombe AD, Capell TF, Tjin SC, Mohanty L. (2008) 'Disbond growth detection in composite-composite single-lap joints using chirped FBG sensors'. COMPOSITES SCIENCE AND TECHNOLOGY, 68 (12), pp. 2410-2417.
  • Wang R, Crocombe AD, Richardson G, Underwood CI. (2008) 'Energy dissipation in spacecraft structures incorporating bolted joints with viscoelastic layers'. PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING, 222 (G2), pp. 201-211.
  • Wang R, Crocombe AD, Richardson G, Underwood CI. (2008) 'Energy dissipation in spacecraft structures incorporating bolted joints operating in macroslip'. JOURNAL OF AEROSPACE ENGINEERING, 21 (1), pp. 19-26.
  • Crocombe AD. (2008) 'Incorporating environmental degradation in closed form adhesive joint stress analyses'. JOURNAL OF ADHESION, 84 (3), pp. 212-230.
  • Thozhur SM, Crocombe AD, Smith PA, Cowley K, Mullier M. (2007) 'Cutting characteristics of beard hair'. JOURNAL OF MATERIALS SCIENCE, 42 (20), pp. 8725-8737.
  • Solana AG, Crocombe AD, Wahab MMA, Ashcroft IA. (2007) 'Fatigue initiation in adhesively-bonded single-lap joints'. JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY, 21 (14), pp. 1343-1357.
  • Palaniappan J, Wang H, Ogin SL, Thorne AM, Reed GT, Crocombe AD, Rech Y, Tjin SC. (2007) 'Changes in the reflected spectra of embedded chirped fibre Bragg gratings used to monitor disbonding in bonded composite joints'. COMPOSITES SCIENCE AND TECHNOLOGY, 67 (13), pp. 2847-2853.
  • Lijedahl CDM, Crocombe AD, Wahab MA, Ashcroft IA. (2007) 'Modelling the environmental degradation of adhesively bonded aluminium and composite joints using a CZM approach'. INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES, 27 (6), pp. 505-518.
  • Shao F, Xu W, Crocombe A, Ewins D. (2007) 'Natural frequency analysis of osseointegration for trans-femoral implant'. ANNALS OF BIOMEDICAL ENGINEERING, 35 (5), pp. 817-824.
  • Hua Y, Crocombe AD, Wahab MA, Ashcroft IA. (2007) 'Continuum damage modelling of environmental degradation in joints bonded with E32 epoxy adhesive'. JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY, 21 (2), pp. 179-195.
  • Palaniappan J, Ogin SL, Capell TF, Thorne AM, Crocombe AD, Reed GT, Tjin SC, Mohanty L. (2007) 'Reflected spectra predictions for chirped fibre bragg gratings used for disbond detection in composite/composite joints'. ICCM International Conferences on Composite Materials,

    Abstract

    In this paper it is shown that a chirped fibre Bragg grating sensor embedded within a composite adherend can be used to monitor disbond initiation and propagation in an adhesively bonded single lap-joint. Characteristic changes in the reflected spectra from the sensor indicate both disbond initiation and the current position of the disbond front to within about 2 mm (a distance which depends on adherend material and sensor position in relation to the adhesive bondline). When the sensor extends the full overlap length, disbond initiation from either end of the overlap can be monitored. The results have been modelled using a combination of finite-element analysis and commercial software for predicting FBG spectra; the predicted spectra are in very good agreement with experiment. The CFBG sensor technique could provide the basis for monitoring a wide range of bonded joints and structures where one adherend is a composite material.

  • Liljedahl CDM, Crocombe AD, Wahab MA, Ashcroft IA. (2006) 'Modelling the environmental degradation of the interface in adhesively bonded joints using a cohesive zone approach'. JOURNAL OF ADHESION, 82 (11), pp. 1061-1089.
  • Liljedahl CDM, Crocombe AD, Wahab MA, Ashcroft IA. (2006) 'Damage modelling of adhesively bonded joints'. INTERNATIONAL JOURNAL OF FRACTURE, 141 (1-2), pp. 147-161.
  • Crocombe AD, Hua YX, Loh WK, Wahab MA, Ashcroft IA. (2006) 'Predicting the residual strength for environmentally degraded adhesive lap joints'. INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES, 26 (5), pp. 325-336.
  • Xu W, Xu DH, Crocombe AD. (2006) 'Three-dimensional finite element stress and strain analysis of a transfemoral osseointegration implant'. PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART H-JOURNAL OF ENGINEERING IN MEDICINE, 220 (H6), pp. 661-670.
  • Hua Y, Crocombe AD, Wahab MA, Ashcroft IA. (2006) 'Modelling environmental degradation in EA9321-bonded joints using a progressive damage failure model'. JOURNAL OF ADHESION, 82 (2), pp. 135-160.
  • Thozhur SM, Crocombe AD, Smith PA, Cowley K, Mullier N. (2006) 'Structural characteristics and mechanical behaviour of beard hair'. JOURNAL OF MATERIALS SCIENCE, 41 (4), pp. 1109-1121.
  • Crocombe AD, Wang R, Richardson G, Underwood CI. (2006) 'Estimating the energy dissipated in a bolted spacecraft at resonance'. COMPUTERS & STRUCTURES, 84 (5-6), pp. 340-350.
  • Palaniappan J, Wang H, Ogin SL, Thorne A, Reed GT, Crocombe AD, Tjin SC. (2005) 'Structural health monitoring of bonded composite joints using embedded chirped fibre Bragg gratings'. ADVANCED COMPOSITES LETTERS, 14 (6), pp. 185-192.

Conference papers

  • Sanderson AR, Ogin SL, Capell TF, Crocombe AD, Gower MRL, Barton E, Lee RJ, Hawker J. (2012) 'Monitoring the disbonding of a CFRP plate-bonded reinforcement of a structural beam using a chirped FBG sensor'. ECCM 2012 - Composites at Venice, Proceedings of the 15th European Conference on Composite Materials,

    Abstract

    A surface-mounted CFBG sensor has been used to monitor disbond growth of a CFRP platebonded reinforcement of a structural box-section beam, bonded using a room-temperature cure structural adhesive. These tests are part of a programme to determine whether disbonding of such a plate could be monitored by ambient thermal fluctuations alone with the aid of thermal mismatch strains. Disbonds were introduced by physically cutting the structural adhesive and a range of different disbond lengths and temperatures have been investigated. When monitoring the disbond growth using the CFBG sensors, a distinct peaktrough perturbation in the reflected spectra was indicative of the location of the disbond front during the test. A prediction of the reflected spectrum was in good agreement with the experimentally-determined results, enabling the disbond lengths to be measured using the CFBG sensor technique to within about 3 mm.

  • Rito RL, Ogin SL, Crocombe AD, Capell TF, Sanderson AR, Guo Y, Tjin SC, Lin B. (2012) 'On the use of a CFBG sensor to monitor scarf repairs of composite panels'. Emerging Technologies in Non-Destructive Testing V - Proceedings of the 5th Conference on Emerging Technologies in NDT, , pp. 187-192.

    Abstract

    Scarf repairs are often used for damaged composite structures in order to recover the mechanical properties of the original structure. During service, there is the possibility that damage will occur in the repaired region and hence it would be useful to be able to monitor such repairs. This work investigates the use of chirped fibre Bragg grating (CFBG) sensors to monitor the development of damage initiation and growth in the repaired region. The experimental part of the work uses a model system consisting of a scarf-repaired, transparent GFRP beam. During fatigue loading, damage in the form of cracks initiate at the interface between the scarf-repair and the parent material on the tensile face of the beam, and grows within this region. The modulus reduction as a consequence of crack growth has been monitored and finite-element analysis (FEA) has been used to predict this reduction, with reasonable agreement between experiment and modelling. Using the FEA analysis, predictions have been made of the strain changes in the vicinity of the growing damage and the effect that these would have on reflected spectra recorded by a chirped fibre Bragg grating sensor bonded across the scarf repair. The predictions suggest that as the damage develops within the scarf repair, the strain changes will modify the reflected spectra in such a way that the initiation of damage can be detected and the growth of fatigue cracks associated with the scarf repair can be monitored. The predictions are in good qualitative agreement with experimental results. © 2012 Taylor & Francis Group, London.

  • Ogin SL, Crocombe AD, Capell TF, Sanderson AR, Rito RL, Guo Y, Tjin SC, Lin B. (2012) 'The use of chirped fibre Bragg grating sensors to monitor delaminations in composite materials and structures'. Emerging Technologies in Non-Destructive Testing V - Proceedings of the 5th Conference on Emerging Technologies in NDT, , pp. 163-168.

    Abstract

    Chirped fibre Bragg grating (CFBG) sensors embedded within composite materials have been shown to be able to monitor delamination growth in adhesively bonded single-lap joints, whether the sensors are embedded within a composite adherend or within the adhesive bondline itself. The relative ease of interpretation of CFBG reflected spectra with regard to delamination growth is a consequence of the relationship between the spectral bandwidth of the reflected spectrum (typically 20 nm) and physical locations along the sensor length (typically 60 mm). When the sensor is embedded in, or bonded to, a composite material subjected to a tensile uniform strain, all the grating spacings are increased and the entire spectrum shifts to higher wavelengths-just as for a uniform FBG sensor. However, if the strain field is perturbed by damage in the composite (such as a matrix crack or a delamination), so that the smooth linear increase in the grating spacing is disrupted, then a perturbation appears in the reflected spectrum that can be used to determine the physical location of the damage. In this paper, results on monitoring delamination/disbond growth will be discussed with regard to sensor location, together with the possibility of using the sensors to monitor repaired composite structures. © 2012 Taylor & Francis Group, London.

  • Ogin SL, Sanderson AR, Crocombe AD, Gower MRL, Lee RJ, Tjin SC, Lin B. (2011) 'Monitoring crack growth in a DCB test using a surface-bonded chirped FBG sensor'. Jeju, Korea,: 18TH INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS

    Abstract

    Delamination growth within transparent, unidirectionally reinforced glass fibre/epoxy doublecantilever beam (DCB) specimens has been monitored using a surface-mounted chirped fibre Bragg grating (CFBG) sensor. The specimens were tested using a constant displacement rate, with the delamination length being measured using (i) surface-mounted CFBG sensors, (ii) in situ photography, and (iii) surface-mounted strain gauges. The DCB specimens showed characteristics typical of such material, with the development of extensive fibre bridging and pronounced R-curve behaviour. A distinct perturbation in the reflected spectra, when monitoring the delamination growth using the CFBG sensors, was indicative of the location of the delamination front during the test. The in situ photographs and the surface strain measurements provided by the strain gauges were used to predict the experimentally determined CFBG reflected spectra, with good agreement between prediction and experiment. These results enabled the delamination length to be measured using the CFBG sensor technique to within 4 mm over the 60 mm sensor length.

  • Yang Y, Rahmanivahid P, Xu W, Crocombe AD. (2011) 'A finite element analysis and experimental study of human edentulous mandible'. Proceedings of the Third Annual Conference of the Biomedical Science and Engineering Center, Knoxville, USA: 3rd BSEC 2011

    Abstract

    By the means of finite element analysis (FEa), biomechanical behaviors of human mandible have been widely studied over decades. Many different types of simulation of muscle forces have been employed in studies to increase the reality of mastication environment. Among these studies, Cruz et al (2003)'s calculation of muscle forces was well accepted. However, these simulations have not been verified experimentally as seen in literatures. In this study, a three dimensional (3D) finite element model of human mandible was created from CT images of a cadaver mandible bone. 4 pairs of muscle forces was applied to this 3D model based on a calculation by using Cruz et al (2003)'s method. The exact cadaver bone was used in an experimental testing rig to evaluate strain distribution and, hence, to verify the results of FEa. A set of different sizes of loads which matches with the one used in FE study was applied to the cadaver bone. Strain gauges were employed to gain data of strain distribution on the bone. The experimental result shows that the trend of stress/strain during increase or decrease of muscle forces coincides with FE result. This verifies the masticator muscle force calculation of Cruz et al (2003) to be correct.

  • Crocombe AD, Frehill B, Agarwal Y, Bradley N. (2010) 'Stability of conical augments in the treatment of contained proximal tibial defects'. Davos: European Orthopaedics Research 18th European Conference on Orthopaedics
  • Crocombe AD, Agarwal Y, Frehill B, Bradley N. (2010) 'Stability of augmented total knee replacement'. Davos: European Orthopaedics Research 18th European Conference on Orthopaedics
  • Crocombe AD, Capell TF, Ogin SL, Thorne AM, Reed GT, Tjin SC, Lin B. (2010) 'Monitoring delaminations in enf specimens using chirped fibre bragg grating sensors, 56.1 – 56.9'. Hungary: 14th European Conference on Composite Materials (ECCM14)
  • Sampo' E, Sorniotti A, Crocombe AD. (2010) 'Chassis Torsional Stiffness: Analysis of the Influence on Vehicle Dynamics'. Tire and Wheel Technology and Vehicle Dynamics and Handling, 2010, Detroit: SAE 2010 World Congress
  • Crocombe AD, Frehill B, Cirovic S, Agarwal Y. (2009) 'Long-term stability analysis of augmented knee arthroplasty using bone remodelling algorithms'. Bertinoro (Forlì), Italy: 4th Int Conf on Computational Bioengineering
  • Crocombe AD, Hafiz TA, Smith PA, Abdel Wahab MM. (2009) 'The Development of an experimental technique to characterise mixed-mode fracture in adhesively bonded joints'. Islamabad, Pakistan: First International Conference on Aerospace Science & Engineering (ICASE-2009)
  • Crocombe AD, Reed GT, Ogin SL, Thorne AM, Palaniappan J, Capell TF, Tjin SC, Mohanty L. (2009) 'The use of chirped fibre Bragg grating sensors to monitor disbond growth'. Honolulu, Hawaii: ICCE-17
  • Capell TF, Palaniappan J, Ogin SL, Thorne AM, Reed GT, Crocombe AD, Tjin SC, Wang Y, Guo Y. (2009) 'Detection of defects in as manufactured GFRP-GFRP and CFRP-CFRP composite bonded joints using chirped fibre Bragg grating sensors'. MANEY PUBLISHING PLASTICS RUBBER AND COMPOSITES, KTH Campus, Stockholm, SWEDEN: 13th European Conference on Composite Materials (ECCM-13) 38 (2-4), pp. 138-145.
  • Crocombe AD, Agarwal Y, Frehill B, Cirovic S, Bradley N. (2009) 'Stability of Tibial Implants in Augmented Knee Arthroplasty'. IMechE, London: Knee Arthroplasty 2009
  • Crocombe AD, Katnam KB, Khoramishad H, Sugiman S, Ashcroft IA. (2009) 'Environmental-Fatigue Damage Model for Adhesively Bonded Laminated Joints'. Rome: ACE-X 2009
  • Crocombe AD, Mubashar A, Ashcroft IA, Critchlow GW. (2009) 'Strength Recovery in Epoxy Adhesive Joints under Cyclic Moisture Conditioning Environment'. Rome: ACE-X 2009
  • Crocombe AD, Khoramishad H, Katnam K, Ashcroft IA. (2009) 'Damage modelling of adhesively bonded joints subjected to fatigue loading at different load ratios'. Rome: ACE-X 2009
  • Crocombe AD, Khoramishad H, Katnam K, Abdel Wahab MM, Ashcroft IA. (2008) 'Fatigue damage study of adhesively bonded joints on thick laminated substrates'. Oxford: EURADH 2008
  • Crocombe AD, Frehill B, Cirovic S, Agarwal Y. (2008) 'Application of Bone Remodelling Algorithms to Knee Arthroplasty'. Prague: Human Biomechanics 2008
  • Crocombe AD, Graner Solana A, Abdel Wahab MM, Ashcroft IA. (2008) 'Fatigue behaviour in adhesively-bonded single lap joints'. Oxford: EURADH 2008
  • Crocombe AD, Jo SI, Onoufriou T. (2008) 'Effect of corrosion on the reliability of a bridge based on Response Surface Method'. Seoul Korea: IABMAS 08 (4th Intl Conf on Bridge Maintenance, Safety and Management)
  • Hilmy I, Wahab MMA, Ashcroft IA, Crocombe AD, Lee HS, Yoon IS, Aliabadi MH. (2008) 'A Finite Element Analysis of Scarf Joint for controlling the Triaxiality function in Adhesive Bonding.'. TRANS TECH PUBLICATIONS LTD ADVANCES IN FRACTURE AND DAMAGE MECHANICS VII, Seoul, SOUTH KOREA: 7th International Conference on Fracture and Damage Mechanics 385-387, pp. 17-20.
  • Woodland S, Crocombe AD, Chew JW, Mills SJ. (2008) 'A NEW METHOD FOR MEASURING THERMAL CONTACT CONDUCTANCE EXPERIMENTAL TECHNIQUE AND RESULTS'. AMER SOC MECHANICAL ENGINEERS PROCEEDINGS OF THE ASME TURBO EXPO 2008, VOL 4, PTS A AND B, Berlin, GERMANY: 53rd ASME Turbo Expo 2008, pp. 627-634.
  • Crocombe AD, Ashcroft IA, Jumbo F, Abdel Wahab MM. (2007) 'Modelling Environmental Ageing in Bonded Joints'. Portugal: International Conference on Advanced Computational Engineering and Experimenting 2007
  • Crocombe AD, Ashcroft IA, Shenoy V, Critchlow GW, Abdel Wahab MM. (2007) 'The Initiation and Propagation of Damage in Adhesively Bonded Joints Subjected to Constant and Variable Amplitude Fatigue'. Portugal: International Conference on Advanced Computational Engineering and Experimenting 2007
  • Crocombe AD, Capell T, Ogin SL, Reed GT, Thorne AM, Palaniappan J, Tjin SC, Mohanty L. (2007) 'The use of thermal mismatch stresses to detect disbond initiation and propagation in metal/composite bonded joints using a CFBG fibre optic sensor'. Kyoto: 16th Int Conf on Comp Matls
  • Crocombe AD, Palaniappan J, Ogin SL, Thorne AM, Reed GT, Tjin SC, Mohanty L. (2007) 'Disbond detection in composite-composite bonded joints using embedded chirped fibre bragg gratings'. Kyoto: 16th Int Conf on Comp Matls
  • Capell TF, Palaniappan J, Ogin SL, Crocombe AD, Reed GT, Thorne AM, Mohanty L, Tjin SC. (2007) 'The use of an embedded chirped fibre Bragg grating sensor to monitor disbond initiation and growth in adhesively bonded composite/metal single lap joints'. IOP PUBLISHING LTD JOURNAL OF OPTICS A-PURE AND APPLIED OPTICS, Univ Manchester, Manchester, ENGLAND: Photon 2006 Conference 9 (6), pp. S40-S44.
  • Crocombe AD, Xu DH, Xu W. (2007) 'A Study of Strain Related Bone Remodelling of the Osseointegrated Patient'. Davos Switzerland: 8th European Cells and Materials Meeting
  • Crocombe AD, Ogin SL, Reed GT, Thorne AM, Palaniappan J, Capell T, Wang H, Mohanty L, Tjin SC. (2007) 'An optical method, based on chirped fibre Bragg gratings, for the non-destructive evaluation of disbonding in bonded composite joints'. ICSAM 2007: Int Conf on Struct Analysis of Advanced Materials
  • Ali AM, Wahab MMA, Crocombe AD, Ashcroft IA, Garibaldi L, Surace C, Holford K, Ostachowicz WM. (2007) 'Damage assessment of adhesively bonded FRP Beams using modal parameters'. TRANS TECH PUBLICATIONS LTD Damage Assessment of Structures VII, Turin, ITALY: 7th International Conference on Damage Assessment of Structures (DAMAS 2007) 347, pp. 525-530.
  • Hilmy I, Wahab MMA, Crocombe AD, Ashcroft IA, Solana AG, Alfaiate J, Aliabadi MH, Guagliano M, Susmel L. (2007) 'Effect of triaxiality on damage parameters in adhesive'. TRANS TECH PUBLICATIONS LTD Advances in Fracture and Damage Mechanics VI, Madeira, PORTUGAL: 6th International Conference on Fracture and Damage Mechanics 348-349, pp. 37-40.
  • Crocombe AD, Sofocleous K, Ogin SL, Tsakiropoulos P, Le-Page BH. (2006) 'Controlled impact testing of shape memory alloy composites'. Biarritz: 12th European conference on Composite Materials
  • Crocombe AD, Palaniappan J, Wang H, Ogin SL, Thorne A, Reed GT, Tjin SC. (2006) 'Disbond growth detection in bonded composite joints using a fibre bragg grating'. Biarritz: 12th European Conference on Composite Materials
  • Gauntlett FE, Rihawy MS, Clough AS, Liljedahl CDM, Crocombe AD. (2006) 'Using a scanning microbeam and a CdZnTe array for nuclear reaction measurements of water diffusion into an adhesive resin'. ELSEVIER SCIENCE BV NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, Seville, SPAIN: 17th International Conference on Ion Beam Analysis 249, pp. 406-408.
  • Hilmy I, Wahab MMA, Ashcroft IA, Crocombe AD, Aliabadi MH, Li Q, Li L, Buchholz FG. (2006) 'Measuring of damage parameters in adhesive bonding'. TRANS TECH PUBLICATIONS LTD Fracture and Damage Mechanics V, Pts 1 and 2, Harbin, PEOPLES R CHINA: 5th International Conference on Fracture and Damage Mechanics 324-325, pp. 275-278.

Book chapters

  • Crocombe AD, Ashcroft IA. (2008) 'Modelling Fatigue in Adhesively Bonded Joints'. in Silva LFMD, Öchsner A (eds.) Modeling of Adhesively Bonded Joints Springer Verlag Article number 7 , pp. 183-223.

    Abstract

    The book proposed intends to provide the designer with the most advanced stress analyses techniques in adhesive joints to reinforce the use of this promising ...

  • Crocombe AD, Ashcroft IA. (2008) 'Simple Lap Joint Geometry'. in Silva LFMD, Öchsner A (eds.) Modeling of Adhesively Bonded Joints Springer Verlag Article number 1 , pp. 3-23.

    Abstract

    The book proposed intends to provide the designer with the most advanced stress analyses techniques in adhesive joints to reinforce the use of this promising ...

  • Crocombe AD, Ashcroft IA, Wahab MA. (2008) 'Environmental Degredation'. in Silva LFMD, Öchsner A (eds.) Modeling of Adhesively Bonded Joints Springer Verlag Article number 8 , pp. 225-241.

    Abstract

    The book proposed intends to provide the designer with the most advanced stress analyses techniques in adhesive joints to reinforce the use of this promising ...

Research Overview

The focus of this research is damage (assessment and modelling). In adhesive bonding this relates to fatigue damage and environmental degradation, in biomechanics this relates to bone remodelling around craniofacial and femoral implants whilst in composites this relates to fatigue and impact damage. In adhesive bonding my driving mission over recent years has been to extend the predictive modelling techniques developed for quasi-statically loaded structures to embrace loading conditions such as static and dynamic fatigue and environmental degradation that are more typical of actual service load conditions. Research funding to support these activities over the time at the University of Surrey is in excess £2M and has resulted in over 200 published journal and conference papers. A selection of recent papers are shown below.

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