Delaminations induced by constrained transverse cracking in symmetric composite laminates

Transverse ply cracking and its induced delaminations at the f:89> interfaces in [ [ [ :8i:fm:89n s laminates are theoretically investigated[ Three cracked and delaminated model laminates\ one _ve!layer model "FLM# laminate SL:fm:891n:fm:SR T and two three!layer model "TLM# laminates I and II\ fm:891n:fm T and S?L:891n:S?R T\ are designed to examine constraining mechanisms of the constraining plies of the center 89>! ply group on transverse crack induced delaminations\ where SL\ SR\ S?L and S?R are sublaminates [ [ [:8i T 8i:[ [ [ T\ [ [ [:8i:fm T and fm:8i:[ [ [ T\ respectively[ A sublaminate!wise _rst!order shear laminate theory is used to analyze stress and strain _elds in the three cracked and delaminated laminates loaded in tension[ The extension sti}ness reduction of the constrained 89>!plies and the strain energy release rate for a local delamination normalized by the square of the laminate strain are calculated as a function of delamination length and transverse crack spacing[ The constraining e}ects of the immediate neighboring plies and the remote plies are identi_ed by conducting comparisons between the three model laminates[ It is seen for the examined laminates that the nearest neighboring ply group of the 89>!plies primarily a}ects the sti}ness reduction and also the normalized strain energy release rate\ whereas the in~uences of the remote constraining layers are negligible