Lifetime assessment of anisotropic materials by the example short fibre reinforced plastic

Abstract

Lifetime assessment at an early stage of a development process is essential to ensure an optimal solution. Classical approaches are often limited to isotropic materials like metals. This paper presents an approach to deal with anisotropic materials using the example of short fibre reinforced plastics (sfr). Therefore, a given work flow, consisting the manufacturing process and the micro structure, is extended by the direction-depended non-linear material behaviour. Furthermore the crucial points of lifetime assessment are pointed out. Starting from a process simulation the influence of a manufacturing process on the local material properties is captured for an finite element analysis. In interaction with micro mechanical models an anisotropic stress field can be calculated which then can be used in the lifetime calculation. To characterize the material and adapt required material-models quasi static as well as cyclic tests were performed. Finally the lifetime can be calculated based on the concept of local S/N-curves. Following this enhanced method, a part equitable life time assessment can be performed independent of geometry. Compared to other methods the local material behaviour and local loads are captured over the whole structure. This provides a time and cost efficient life time prediction even on large structures. Since software tools are available for all simulation steps the presented method provides a time and cost efficient life time prediction even on big structures.