An Energy-based Life Prediction Method of Copper Alloy for Liquid Rocket Engine of Reusable Launch Vehicle

Thermal-mechanical load is generated by resulting from multiple use of a liquid rocket engine for the development of a reusable launch vehicle. A regenerative cooling channel of thrust chamber of rocket engine can be failed by thermal fatigue generated by the cyclic thermal-mechanical load at high temperature. In this study, tensile test data and fatigue life data of various kinds of copper alloys for developing space shuttle from NASA and for developing Korea Space Launch Vehicle from KARI have been used to analyze fatigue life of regenerated cooling channel. Life prediction equations based on strain suggested by Manson, Muralidharan, Mitchell, Lee, Ong, Baumel and Seeger were compared as applied to various copper alloy cases to predict fatigue lives from tensile test data. The present study has revealed that among the presently considered strain-based life prediction methods, universal slopes method provides the best life prediction result for the copper alloys, and the modified Mitchell’s method provides the best life prediction result for oxygen free high conductivity (OFHC) copper. However, the strain based life prediction methods were predicted less than 65% data within 3X scatter band. An energy-based equation was suggested to predict life better, and the suggested equation predicted the lives of copper alloys well within 3X scatterband.