Optimization of the Specimen Geometry of Unidirectional Reinforced Composites with a Fibre Orientation of 90° for Tensile, Quasi-Static and Fatigue Tests

摘要

When testing unidirectional reinforced composites with a fiber orientation of 90° in tensile tests with rectangular specimens, the influence of the clamping often causes a failure in their vicinity and therefore the test cannot be regarded as valid. In this paper, a test specimen design was determined which is well suited for testing the material properties transverse to the fiber direction by calculating the influence of geometric details of shoulder bar specimens with the help of finite element simulation. The particularly critical clamping and shoulder areas were examined more closely to ensure failure mainly in the test field. In the clamping area the design of the glued-on tabs was investigated and in the shoulder area an optimization of the shoulder geometry was done. Based on the two optimized design proposals, test specimens were produced and evaluated by monotonous tensile tests. Subsequently, Wohler tests were carried out at different R-ratios and load levels and compared with results of rectangular specimens.