New combined shear and compression test method

A new test method was developed to determine shear/compression properties of composite insulation systems used in superconducting magnets. It was developed specifically to enable in-situ testing (without warm-up) of insulation systems in a high flux neutron radiation and cryogenic (4 K) temperature environment at the Munich Research Reactor (FRM - Forschungsreaktor Munchen). The new shear/compression specimen consists of two sections of composite insulation bonded at a specific angle between three pieces of 316 stainless steel. During the test, the specimen is compressed between two loading platens. By varying the angle of the test specimen, different shear/compression ratios can be evaluated and a shear/compression envelope for various materials can be produced. This test method produces the same shear and compressive strengths found in other shear/compression tests, but the test fixture is smaller, and multiple test specimens are not required. The composite insulation systems were tested at 45 degrees to demonstrate the feasibility of the test. Specimens were produced from a vacuum pressure impregnation (VPI) resin system and a prepreg resin system. Design and fabrication of the test specimens and their shear and compressive properties are presented