Modeling of mechanical properties at high temperature and creep fatigue analysis for niobium alloy based on damage mechanics

Abstract

The elasto-plastic constitutive equation based on the concept of continuum damage mechanics was formulated for the niobium alloy (C103) which is used as a chamber material in a satellite's thruster. The existing theory was extended to deal with the creep fatigue behavior at the high temperature of 1500°C. Creep, tensile and creep fatigue tests (stress-controlled) were conducted with plate bar specimens made of the niobium alloy. The tests were conducted at 1500°C and obtained data were used to determine the material parameters employed in the constitutive equation. Time-strain curves and damage-evolution curves were also simulated and the validity of material parameters was confirmed by comparing calculated values with test results. Creep fatigue life analyses were also conducted and the results were compared with the experimental values. From the results, it is expected that the used constitutive equations and determined material parameters can predict the mechanical features and creep fatigue life for the niobium alloy at the high temperature.

Keywords

• damage mechanics
• niobium alloy
• high temperature
• creep
• fatigue