Modelling the effect of size on compressive strength of fibre composites with random waviness

A finite element analysis is developed to model the compressive strength of fibre composites containing randomly distributed waviness defects. The waviness is characterised by the standard deviation in the waviness amplitude and a typical defect size. The effects of the waviness amplitude and the specimen size, relative to the defect size are explored. There is a significant reduction in strength with increasing waviness amplitude, confirming predictions for idealised waviness distributions. A modest reduction in strength is predicted with increasing specimen size relative to the defect size. This dependence is sensitive to the details of the waviness distribution and can be interpreted using a Weibull model. The details of critical waviness defects are examined to understand what type of defect controls the strength with random waviness distributions. Practical implications of the findings are discussed, particularly emphasising the importance of characterising and modelling fibre waviness in large structures.