Constitutive model for thermomechanical fatigue conditions of an additively manufactured combustor alloy

Abstract

In this study, the mechanical response of an additively manufactured nickel-based combustor alloy, subjected to thermomechanical fatigue (TMF) loadings has been investigated and modelled. TMF tests were performed in both in-phase and out-of-phase conditions with different strain ranges and temperature ranges of 100 °C–450 °C and 100 °C–600 °C, respectively. The smooth specimens were manufactured in two different orientations to study the influence of anisotropy, and the specimens were machined to final dimensions with conventional techniques. A constitutive model with focus on describing the mid-life behaviour was developed where the total inelastic strain was divided into one plastic (rate-independent) and one creep (rate-dependent) part, to be able to describe both the rate-dependent effects from TMF conditions as well as rate-independent responses. A cycle jumping procedure was used, which enables to simulate the mid-life response of the material for TMF as well as low-cycle fatigue conditions within three simulated loading cycles.