A Reduced Order Constitutive Modeling Approach for a Material Subjected to Combined Cycle Fatigue

Abstract

Material selection for key components is a critical step in the design process where high temperature and large loads are involved. Service conditions, however, may be more aggressive than those to which many materials have been exposed to in laboratory conditions. For example, key combustion equipment will experience super-imposed thermal, mechanical, and vibratory loading. Despite the more recent efforts to characterize materials under these so-called combined extreme environments (CEEs), the temperature- and rate-dependent cyclic hardening/softening responses are still relatively under-characterized. A method to develop first approximations of constitutive model/parameters for materials under extreme service conditions is presented. The method is exercised on IN617 a Ni-base alloy often employed for high temperature applications. The approach shows that a minimal collection of tensile, creep, and LCF data are needed to develop predictions of materials under thermomechanical fatigue with vibratory loading.

High temperature low cycle fatigue characterization of equiaxed MAR-M-247

“…Some serrated yielding behavior was also observed where load reversal occurred, which demonstrates a dynamic strain ageing phenomena. This has been previously observed by van den Beukel and Gordon [17,18].…”