Impact bending fatigue and impact response behavior of a nuclear-grade graphite beam

Abstract Repeated impact bending tests have been carried out on a fine-grained Isotropic graphite for HTTR under constant energy condition. Each specimen whose length differed was centrally impacted by an instrumented pendulum. The simple one-dimensional model taking the Hertzian contact stiffnesss into consideration has been applied to evaluate the relationship between the maximum stress of specimen generated by impact, the impact force, and the impact energy. It has been confirmed that the endurance curves in terms of impact energy are dependent on the length of the specimen, but the one in terms of the evaluated maximum stress is independent of that, and the strength of graphite is lower in impact fatigue than in nonimpact fatigue.