Determination of the first ply failure load for a cross ply laminate subjected to uniaxial tension through computational micromechanics

• A method for determining the in situ strength of fiber-reinforced laminas is proposed.
• Matrix tensile stresses are responsible for the coalescence of matrix cracks.
• The unit cell with hardening matrix predicts realistically the location of plastic zone.
• The failure strain obtained from micromechanical model is larger than that from tests.

A method for determining the in situ strength of fiber-reinforced laminas for three types of transverse loading including compression, tension and shear is presented. In the framework of this method, an analysis of local stresses that are responsible for the coalescence of matrix cracks is carried out by using a multi-fiber unit cell model and finite element method. The random distribution of fibers, fiber–matrix decohesion and matrix plastic deformations are taken into account in the micromechanical simulations. The present study also shows that the nonlinear hardening behavior of matrix reflects more realistically the influence of plastic deformations on the in situ transverse strength of lamina than the perfectly plastic behavior of matrix. The prediction of the in situ transverse strength is verified against the experimental data for a cross ply laminate subjected to uniaxial tension.