Damage Progression in Open-Hole Tension Composite Laminates by the Element-Failure Method

Abstract

Damage Propagation in composite laminates is traditionally modeled by the material property degradation method (MPDM), which assumes that a damaged material can be replaced by an equivalent material with degraded properties. In this thesis, a new damage-modeling technique known as the Element-failure method (EFM) is proposed, which assumes that the nodal forces of a finite element of a damaged composite can be modified to achieve the decrease of load-carrying capacity. The EFM is implemented to a 3D implicit finite element code to model the damage propagation in open-hole tension composites. Using a failure criterion called the strain invariant failure theory (SIFT) in conjunction with the fiber ultimate strain, the damage patterns and ultimate strengths of composites predicted by the EFM agree very well with the experimental observation. In addition, the hole size effect of open hole tension composites is also investigated by the EFM.