Modelling FRP open-hole tensile tests in Abaqus

Abstract

The use of fibre reinforced polymers (FRP) are stimulated in the construction industry for their remarkable corrosion resistance, good thermo-mechanical properties, high strength-to-weight ratio and high stiffness-to-weight ratio. The open-hole strength of FRP is an important parameter in a composite design because it can be representative in simple features of composite components leading to stress concentrations such as cutouts, fastener holes or a flaw in the material. Therefore, an open-hole tension test is simulated in the finite element program ABAQUS to determine the failure load of an [45°/−45°] lay-up using the material AS4/PEEK. In ABAQUS, both static implicit and dynamic explicit analysis are performed. For both analyses, the failure loads, stability and failure mechanisms are examined. The geometry and material properties are chosen to match the properties used in van der Meer and Sluys in order to compare results. The model is build up of 8808 SC8R elements and the interface between the plies is modelled using the surface-based cohesive behaviour technique. The static and dynamic analysis revealed that there’s a large influence of non physical and time related variables on the simulated failure load of the laminate. The results of the dynamic target time step sensitivity analysis didn’t converge to a legitimate value for the failure loads. The same has been concluded for the mesh size sensitivity analysis. Based on the stability of the solutions a reasonable value has been chosen for these variables. Comparing the results of the static and dynamic analysis with the results of van der Meer and Sluys, illustrated that the failure loads differ largely. The failure mechanisms are different due to the homogenisation of the material that is fundamental to continuum models in ABAQUS. At the failure load in the static and dynamic analysis, the matrix fails under tension and shear through the whole thickness of the laminate in the same direction. This unrealistic event differs from the failure mechanism observed in van der Meer and Sluys. In order to overcome the unrealistic failure behaviour in the static and dynamic analyses, XFEM modelling techniques are recommended to bridge the problem with the damage propagation direction parallel to the fibre direction.