Fatigue test of epoxide resin at low temperature

This chapter attempts to obtain experimental data at liquid helium temperature (LHeT), to examine the temperature dependence of fatigue properties and to provide reference data for magnet design. Describes the flexural test and the fatigue test. Uses a cured Bisphenol-A resin, the basis of many commercially available epoxide resins, which is subjected to a repeating load and is investigated for fatigue properties at cryogenic temperatures. Finds a deformation rate dependence in the epoxide resin in the flexural test and that the breaking load at the first loading in the fatigue test is lower than the static breaking load at RT (room temperature), LNT (liquid nitrogen temperature) and LHeT. Concludes that temperature decrease reduces the specimen sensitivity to fatigue loading, even though the absolute breaking load level on the load-endurance diagram at LNT is always larger than at LHeT. Finds that the load-endurance diagram obtained at LNT is similar to that at LHeT if the load axis is normalized in terms of the static breaking load. Points out that the crack initiation process is the rate-determining process in fatigue at cryogenic temperatures