The orientation of a single-crystal material is known to affect the strength and life of structural component parts. Results are presented of an investigation of the effects of secondary axis orientation angles on the failure of the first-stage of the space shuttle main engine alternate turbopump development of the high-pressure fuel turbopump. First, the correlation of different failure models with low-cycle fatigue data for nickel-base single-crystal test specimens was analyzed. Then the models with the highest correlation coefficients were used to study the actual single-crystal blade structure. Based on the results obtained, a new failure model was proposed. A detailed finite element model for the first-stage blade was used to calculate the stresses and strains at all blade nodes for different material orientations. Results of the analysis showed that the critical value of the failure model could vary by up to a factor of 3 by changing the primary and secondary material orientations. A comparison between analytical results and engine test results showed good correlation and also demonstrated the dependence of cracking location on crystal orientation. References: 19
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