Matrix crack initiation and progression in compositelaminatessubjected to bending and extension

An experimental investigation of matrix crack initiation and progression in glass:epoxy laminates of di}erent stacking sequences is presented[ The laminates have been loaded in extension and bending\ and the degree of damage as function of the load has been recorded[ The changes in certain elastic properties caused by the damage were also measured\ and are compared to results from a previously developed approximate analytic model[ An energy release rate resistance curve is adopted in an attempt to describe the initiation and progression of matrix cracks in the laminates[ The amount of cracking is also viewed in relation to the strain transverse to the _bres in the ply under consideration\ and the ply stresses at the onset of cracking are calculated[ The di}erent damage evolution criteria are compared to the experimental results\ and their validity and reliability are discussed[ By use of the ply strain transverse to the _bres as a critical parameter for damage evolution\ the load deformation curves of the tested laminates are simulated taking damage progression into account