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Dr Lynn Boniface


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+44 (0)1483 682359
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Academic and research departments

Department of Mechanical Engineering Sciences.

My publications

Publications

Boniface L, Ogin SL, Smith PA (1993)Change in thermal expansion coefficient as a damage parameter during thermal cycling of crossply laminates, In: ASTM Special Technical Publication(1156)pp. 139-160
An experimental and theoretical study of the effects of 90° ply cracking on the thermal expansion coefficients of crossply laminates has been carried out. It has been found experimentally that reductions in the coefficient of thermal expansion of up to 50% are caused by 90° ply cracks induced mechanically, although considerable care is needed in the experimentation. This behavior was modeled using a simple shear-lag analysis, and the resulting analytical expressions are compared with other approaches available in the literature. The growth of matrix cracks in a model GFRP system under severe thermal cycling (77 to 373 K) is investigated. The changes in expansion coefficient are affected by the growth of 0° ply cracks in addition to the 90° ply cracks. The crack growth rate/cyclic strain energy release rate range data are compared with those reported previously for mechanical fatigue cycling of similar material. The two data sets are consistent if plotted in terms of a fracture mechanics parameter which aims to account for the temperature dependence of material properties.
Boniface L, Ogin SL, Smith PA (1991)Fracture mechanics approaches to transverse ply cracking in composite laminates, In: ASTM Special Technical Publication(1110)pp. 9-29
The growth of transverse ply cracks in composite laminates has been investigated both theoretically and experimentally. Some of the closed-form strain energy release rate based analyses of this problem in the literature have been compared and extensions to these approaches are presented. These models have been shown to be consistent with an alternative approach based on an approximate expression for the stress intensity factor at the tip of a growing transverse ply crack. An experimental study of transverse ply crack growth has been carried out using a simple model array of transverse ply cracks in a glass/epoxy laminate. By making the transverse ply sufficiently thick, the specimen compliance was found to change measurably as individual cracks grow. Hence, the strain energy release rate could be determined experimentally (via the compliance relationship) and compared with analytical predictions. Agreement was found to be satisfactory.
Boniface L, Foreman A, Hitchen S (1998)Comparative evaluation of solid and hollow S2 glass fibre epoxy laminates, In: PLASTICS RUBBER AND COMPOSITES PROCESSING AND APPLICATIONS27(5)pp. 234-239 INST MATERIALS
The tensile and compressive mechanical performance of a range of unidirectional and +/-45 degrees/0 degrees laminates, based on solid and hollow glass fibres, has been compared in terms of absolute and specific values (i.e. property normalised by the laminate density). The damage tolerance of both systems during impact loading has also been established. The use of hollow glass fibres lends to reductions in laminate density of up to 23% compared with solid fibre constructions. Although the absolute values of mechanical properties are lower for the hollow fibre materials (with the exception of compressive failure strain), normalised properties compare more favourably, especially in compression. It is confirmed that materials utilising hollow fibres for reinforcement have considerable potential for applications in which weight saving is important, without significant reduction in mechanical properties relative to solid fibre materials.
Ogin SL, Boniface L, Bader MG (1986)FATIGUE GROWTH OF TRANSVERSE PLY CRACKS IN (0/90//2)S GLASS FIBRE REINFORCED AND (0/90//3)S CARBON FIBRE REINFORCED PLASTIC LAMINATES., In: I Mech E Conference Publications (Institution of Mechanical Engineers)pp. 173-178
The growth of individual transverse ply cracks during tension-tension fatigue of (0/90//2)s GFRP and (0/90//3)s CFRP has been observed using transmitted light and penetrant enhanced X-radiography, respectively. The growth rate of cracks in both laminates is independent of crack length but depends on the spacing between the cracks. Very low growth rates occur for small crack spacings or if crack branching occurs. The results are interpreted using a stress intensity factor approach.
Gao F, Boniface L, Ogin SL, Smith PA, Greaves RP (1999)Damage accumulation in woven-fabric CFRP laminates under tensile loading: Part 1. Observations of damage accumulation, In: COMPOSITES SCIENCE AND TECHNOLOGY59(1)pp. 123-136 ELSEVIER SCI LTD
Vickers PE, Boniface L, Pricket A, Watts JF (2000)The effect of siloxane-type molecules on the interlaminar toughness of CFRP, In: COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING31(6)pp. 559-569 ELSEVIER SCI LTD
Gao F, Boniface L, Ogin SL, Smith PA, Greaves RP (1999)Damage accumulation in woven-fabric CFRP laminates under tensile loading: 2. Modelling the effect of damage on macro-mechanical properties, In: COMPOSITES SCIENCE AND TECHNOLOGY59(1)pp. 137-145 ELSEVIER SCI LTD
Bassam F, Boniface L, Jones K, Ogin SL (1998)On the behaviour of the residual strain produced by matrix cracking in cross-ply laminates, In: COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING29(11)pp. 1425-1432 ELSEVIER SCI LTD
Vickers PE, Fitzpatrick MF, Boniface L, Watts JF (2001)A small area XPS study of the fracture surface of a thermoplastic-modified CFRP, In: JOURNAL OF MATERIALS SCIENCE36(9)pp. 2323-2327 KLUWER ACADEMIC PUBL
SMITH PA, BONIFACE L, OGIN SL (1990)COMPLIANCE CRACK LENGTH MEASUREMENTS FOR INDIVIDUAL TRANSVERSE PLY CRACKS IN MODEL ARRAYS, In: FULLER J, GRUNNINGER G, SCHULTE K, BUNSELL AR, MASSIAH A, (eds.), DEVELOPMENTS IN THE SCIENCE AND TECHNOLOGY OF COMPOSITE MATERIALSpp. 913-918
Boniface L, Smith PA, Bader MG, Rezaifard AH (1997)Transverse ply cracking in cross-ply CFRP laminates - Initiation or propagation controlled?, In: JOURNAL OF COMPOSITE MATERIALS31(11)pp. 1080-1112 TECHNOMIC PUBL CO INC
Smith PA, Boniface L, Glass NFC (1998)A comparison of transverse cracking phenomena in (0/90)(s) and (90/0)(s) CFRP laminates, In: APPLIED COMPOSITE MATERIALS5(1)pp. 11-23 KLUWER ACADEMIC PUBL
BONIFACE L, OGIN SL, SMITH PA (1991)EFFECT OF TRANSVERSE CRACKS ON LOCAL STRAIN DISTRIBUTION IN CROSSPLY COMPOSITE LAMINATES, In: FIRST INTERNATIONAL CONFERENCE ON DEFORMATION AND FRACTURE OF COMPOSITESpp. 160-165
BONIFACE L, OGIN SL, SMITH PA (1991)STRAIN-ENERGY RELEASE RATES AND THE FATIGUE GROWTH OF MATRIX CRACKS IN MODEL ARRAYS IN COMPOSITE LAMINATES, In: PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES432(1886)pp. 427-444 ROYAL SOC LONDON
BONIFACE L, OGIN SL (1989)APPLICATION OF THE PARIS EQUATION TO THE FATIGUE GROWTH OF TRANSVERSE PLY CRACKS, In: JOURNAL OF COMPOSITE MATERIALS23(7)pp. 735-754 TECHNOMIC PUBL CO INC