Effect of Shear Stresses on Failure of Fibrous Composite Materials Accounting for Nonlinear Material Behavior

Variation of shear stresses  xy on failure behavior of different composite materials was investigated for two types of composites; Boron-Epoxy Narmco 5505 and Carbon-Epoxy AS4 (3501-6). The effect of material nonlinearity on failure behavior of unidirectional fibrous composite laminates was considered for several fiber-orientation angles; ϴ=15, 30, 45, 60 and 75 degrees. An energy-based nonlinear material model was adopted to predict the mechanical properties of a unidirectional composite lamina. A compatible failure criterion for nonlinear composite materials was utilized which incorporates the material model into the failure criterion. The resulting failure envelopes were compared for all the cases.