Dynamic residual property predictions for laminated composite structures: FE-based internal state variable approach

Abstract

An incremental dynamic response finite element (FE) based formulation serves to model the initiation and progression of damage in laminated composite structures. A direct integration algorithm is utilized and equilibrium iterations are performed on a ply-by-ply basis. An internal state variable approach (ISV) provides the means to represent intralaminar crack distributions. The numerical approach presented here provides a representation of stiffness variation that compares more favorably with experiment than does the more commonly utilized ply discount method. This approach is combined with stress based criteria to account for interior delaminations and fiber fracture failure modes. A shear deformable finite element formulation is used to obtain results. In-plane stresses are obtained from the constitutive equations while solution of the equilibrium equations yields the transverse stress variation. Results are obtained for a number of beam/plate geometries subjected to transient dynamic loading conditions.