Static and dynamic scaling experiments on double lap shear specimens at room temperature and at 77 K Original Research Article

In view of applications of fibre-reinforced plastics as insulating materials for the windings of the superconducting magnets in the ITER fusion device and because of its pulsed operation, the interlaminar shear strength (ILSS) of these materials has to be assessed at cryogenic temperatures in the static and in the fatigue mode. However, none of the existing test procedures for the assessment of the ILSS provides a pure and uniform shear stress over a sizable region of the test sample. Therefore, the results depend on the size of the shear area. A scaling programme of the double lap shear test specimen geometry was performed in the static and the fatigue mode on a glass-fibre-reinforced epoxy at room temperature and at 77 K. The results show an increase of the ILSS with decreasing length of the shear area, while the shear fatigue behaviour appears to be independent of sample geometry.