Creep-fatigue life prediction of perforated copper-alloy plate by using Digital Image Correlation Method

Abstract

LE-9 rocket engine for next-generation launch vehicle H3 is being developed for realizing high performance, low cost and high reliability. Thermal fatigue life prediction on a combustion chamber structure with multiple cooling holes is important for design of rocket engine. In this paper, strain-controlled fatigue and creep-fatigue tests have been conducted at 558°C, using perforated copper-alloy plate specimens simulating cooling holes of combustion chamber for a rocket engine. Strain measurement using digital image correlation method was performed during fatigue tests for confirming strain distribution in the test specimen. Strain distribution from inelastic FEM almost agreed with that from the measurement. Creep-fatigue life prediction was carried out for perforated plate specimen, combining inelastic FEM with both the linear damage rule based on creep rupture time fraction and the strain range partitioning method. Creep-fatigue life prediction by the strain range partitioning was found to have accuracy within a factor of 2.