Comparison of Damage Prediction in a Laminated Composite Plate Using Associative and Non-associative Damage Flow Rules

Continuum damage mechanics is used to predict the stiffness degradation in materials. In this article, tensorial damage variables in their principal direction represent the assumed orthotropic nature of damage surfaces. The thermodynamics of internal variables is used to arrive at a non-associative damage flow rule in which the loading criteria and damage flow potential function are different. The finite element method is adopted to arrive at nonlinear algebraic equations solved using the Newton–Raphson iterative procedure. The damage evolution equations are solved by satisfying loading criteria at each Gauss point. The comparison of damage prediction for cross-ply laminate depicts greater damage values based on non-associative damage flow rule compared to associative damage flow rule.