Incorporation of Analysis Enhancements of a p-Element Analysis Code Required for Implementing the Strain Invariant Failure Theory

Historically, the correlation between predicted failure and actual failure of composite aircraft structures has left much to be desired. Current analytical prediction methods often over estimate or under estimate the failure load by 25% or more. Compounding the problem is that the failure of composite structure has led to a lengthy and costly, test-based certification process. A relatively new failure theory for composites, the Strain Invariant Failure Theory (SIFT), is proving to be far more accurate at predicting failure. SIFT in conjunction with a robust finite element analysis (FEA) tool offer an efficient method aimed at streamlining the design certification process for laminated composite structures. Phase 1 activities demonstrated proof of concept that the following features can be implemented into a p-element FEA code. - General Shell element with a transition to a 3D solid element - Laminated orthotropic material properties that follow a general curvature. - 2D & 3D Contact element and a 3D Fastener element. Phase 2 activities will fully develop these features and enable their use in a production environment.