A fracture mechanics study of the turbine wheel in the space shuttle auxiliary power unit

Abstract A review of fracture mechanics concepts relevant to safe life analysis of fatigue loaded parts was given. For the fracture control on the Shuttle APU turbine wheel, an environmental crack growth test program was conducted on candidate wheel materials exposed to decomposed hydrazine. The decomposed hydrazine was found to be no more severe in causing crack growth than an environment of high temperature air. A fatigue crack growth experimental and analytical study was conducted on the final design of the wheel, and the results indicated that special NDE was required for the wheel to have adequate safe life.