چكيده به لاتين
In this thesis, the damage condition of symmetric cross-ply laminated composites under uniaxial tensile loading has been studied. matrix cracking, is the first mode of damage in composite laminate. For analyze cracked laminates a Formulation has been developed to predict damage condition and reducing mechanical properties. In order to predict damage condition, firstly, an optimal stress field is proposed using micromechanic criteria and vibrational approach on the unit cell. After about 30 years of the Hashin's variational model, this method has been extended for symmetrical and staggered crack form in symmetric cross-ply laminates, as well as laminates with more than two cracked layers. Then, based on the finite fracture mechanic, the energy release rate of crack initiation and matrix crack growth are calculated. The critical energy release rate (as a criterion for predicting growth, saturation of matrix cracks and initiation other fracture modes, such as delamination), are determined by using experimental data and finite fracture mechanic criteria. In addition to the above studies, matrix cracking has been analyzed by homogenization method. Also validation of analytical results with numerical results obtained from finite element software and experimental results has been carried out.
