Stirling Engine - Approach for Long-Term Durability Assessment

This paper summarizes the approach being used by the NASA Lewis Research Center for the long-term durability assessment of the Stirling engine hot-section components. The approach consists of: (1) preliminary Structural assessment; (2) development of a viscoplastic constitutive model to accurately determine material behavior under high-temperature thermomechanical loads, such as creep and plasticity interaction, and creep-ratcheting; (3) an experimental program to characterize material constants for the viscoplastic constitutive model, and for the short-time verification of specific materials of interest; (4) finite-element thermal analysis, and structural analysis using a viscoplastic constitutive model to obtain stress/strain/temperature at the critical location of the hot-section components for life assessment; and (5) development of a life prediction model applicable for long-term durability assessment at high temperatures.