The influence of interlaminar microstructure on micro-cracking at laminate free edge

To investigate the influence of interlaminar microstructure on micro-cracking at the free edge of a laminate, a two-scale finite element modelling approach has been developed and used to examine the 90/90 interface in [25(N)/-25(N)/90(N)](s) laminates. The current paper extends the analysis to the -25/90 interface. The results are compared with that of the 90/90 interface. The results show that, like the 90/90 interface, the micro-scale matrix stress at the free edge is sensitive to the interlaminar microstructure. Increasing the resin content resulted in the matrix stress increasing during thermal cooldown, but reducing under tensile loading. However, the site of the maximum matrix stress was different. The results suggest that manufacturing induced pre-cracks may not coincide with the sites of progressive cracking under service loadings. The analysis provides new insights into the micro-cracking and damage evolution observed in experiments.