High Performance Tools for Failure, Damage Tolerance and Stability Analysis of Composite Structures

Abstract

The paper is aiming at high performance tools which reconcile the contradiction objectives of accuracy and speed and therefore are suited for application already in the design phase of composite structures. By that means they will contribute significantly to a modern Concurrent/Integrated Engineering Process. TRAVEST is a pre- and postprocessing program for finite element solvers which computes the full three-dimensional state of stress from results of a simple shell analysis using a formulation of the extended 2D-method for FE-discretisations with eight- and six-noded elements, respectively. A new theory has been developed, which allows for using the extended 2D-method in conjunction with fournoded elements. This would allow for much wider application in industry. For thick-walled composite structures a hierarchical 3D composite element has been developed, implemented into B2000 and compared to existing elements. All transverse stress components show very much improved quality. For 3D reinforced composites a new failure model has been developed. It is an extension of a physically based criterion which is applicable to unidirectional layers only. The model is implemented into TRAVEST and is also suited for use in B2000 in conjunction with the 3D composite element. The composite damage tolerance analysis code CODAC was improved by implementing a Rayleigh- Ritz procedure for residual strength analysis. Comparison with in-house experiments revealed good quality of the results. The postbuckling behaviour of composite panels was simulated using commercial finite element software and compared to in-house tests. The verified model constitutes the basis for development of a fast postbuckling algorithm which will be based on a hybrid reduced basis technique.