Three-dimensional stress and progressive failure analysis of ultra thick laminates and experimental validation

Test methods and analysis capabilities for fibre reinforced composites are generally limited to thin laminates. However, extending the range of application of composite materials to thick laminates is essential for a multitude of possible composite structures. This paper presents an adapted three-point bending test for a new quasi isotropic stacking sequence for non crimped fabrics for the application in ultra thick laminates (UTL). In addition, numerical simulation capabilities for thick laminates using a multiscale analysis are shown. The three-point bending test setup is developed to examine the failure behaviour of 30–60 mm thick coupons. The presented numerical analysis features a ply based mesh, stacked continuum elements as well as a multiscale approach with meso scale unit cells in order to refine initial assumptions for 3D material properties. Initial stress calculations are performed on macro level using material properties from 2D tests. Extending the analysis by a multiscale approach, material properties are generated on meso level using unit cells models. Progressive failure is subsequently modelled on macro level, using the previously obtained material properties and the Juhasz failure criterion. The failure load is compared to experimental findings.