Influence of sample and test geometry on the interlaminar shear strength of fiber reinforced plastics under static and dynamic loading at RT and 77 K

Fiber reinforced plastics are employed as insulation system for the superconducting magnet coils in fusion devices. In view of this application the material performance especially under interlaminar shear loading has to be assessed under conditions including the appropriate radiation environment at the magnet location. The established standards for their mechanical characterization involve sample sizes that are by far too large for reactor irradiation. As a consequence, the short-beam-shear (SBS) and the double-lap-shear (DLS) geometry were chosen for static and dynamic tests of the interlaminar shear strength at room temperature and at 77 K. Scaling experiments were made to investigate the influence of the sample and test geometry on the shear strength. In addition, finite element calculations were made for both geometries, in order to assess the stress distribution and the failure criteria of the specimens and to compare the theoretical results with the experimental data.