A Combined Asymptotic-multi-scale Approach for Compressive Failure Analysis of Composites
Researcher: Nabeel Safdar
Institute of Structural Analysis
Principal Investigator: Prof. Raimund Rolfes
French Co-Advisor in Cachan: Prof. Olivier Allix
The strength of composites under compression is to an important extent determined by phenomena occurring at the micro-level. The relatively low compressive strength of unidirectional laminates as compared with the tensile strength is related with the formation of kink bands, and the compressive failure of composites corresponds to an interaction of four failure mechanisms: fiber kinking, splitting, matrix cracking and delamination. This interaction is responsible for the final failure of the laminate at the meso- and the macro-level. Recent multi-scale investigations have made it possible to predict the essential phenomena associated with compressive failure numerically using accurate but time-consuming finite element analysis.
In order to gain a further understanding of the complex failure behavior on the one hand, and to establish design tools that are computationally efficient on the other hand, asymptotic methods (perturbation-type approaches) will be combined with the multi-scale finite element analysis. In particular, the instability phenomena and geometrically nonlinear behavior of the fiber will be analyzed using accurate asymptotic procedures, which have been integrated in the multi-scale analysis.