Fatigue as monitored by the torsion pendulum

This paper describes the use of a new air‐bearing torsion pendulum as a nondestructive monitor of torsional fatigue in epoxy resin castings. Results indicate that both G′ and tan δ undergo significant changes as fatigue is induced in the specimen. In those specimens that have not been sufficiently post‐cured, cyclic fatiguing induces further crosslinking. However, this is accompanied by a competing reaction of crack formation and propagation leading ultimately to failure.