A multidirectional damage model for fiber-reinforced plastic laminates under static load

Abstract

A multidirectional damage model based on continuum damage mechanics for fiber-reinforced composite laminates is proposed in this paper. The influence of three main damage mechanisms, including transverse matrix cracking, local delamination, and fiber breakage, on the multidirectional stiffness properties of composite laminates is analyzed by introducing macro phenomenological damage variables. Then the mechanical behavior of elementary ply in laminates is modeled based on these damage variables. Besides, relations between micro-level damage variables and macro-level damage variables are established. Damage evolution laws of the three damage mechanisms are proposed to predict the degradation of multidirectional stiffness and failure strength of composite laminates under quasi-static loading. The experiment of cross-ply glass fiber-reinforced plastic laminates is carried out, and the prediction results show good agreement with the experimental results.

A Micro–macro Damage Mechanics-based Model for Fatigue Damage and Life Prediction of Fiber-reinforced Composite Laminates

“…In the previous work [28], the consistency of damage characterization model under quasi-static loading and fatigue loading was discussed and proven valid both under quasi-static and fatigue loading. Hence, the damaged strain energy density of elementary ply in composite laminates under fatigue loading was defined as follow with the assumption of plane-stress state [27],…”

“…Fig. 2 Damage evolution in composites under fatigue loading [26,27] Based on the above equations, the influence of the forementioned three damage modes is modelled, and accordingly, the damaged stiffness properties could be calculated based on Eq. ( 3).…”

“…Based on the matrix cracking evolution law, the increase of matrix crack density was predicted, as described in the previous work [28], then the damaged stiffness matrix of cracked plies could be obtained based on the COD theory in micromechanics [27],…”

“…( 1) and damaged elastic modulus at micro level in Eq. ( 8), a macro-micro relationship could be obtained [27],…”

“…, N denotes the cycle number of fatigue loading, ∆Y is the range of damage evolution variable. Taking the coupling between transverse and shear stress into consideration, the damage evolution variable Y is defined as follow [27],…”