A four-point bend test was performed on 20 percent cold-prestrained Ni-Fe-Cr alloy tubes at 1100 F (593 C) to verify that creep rupture damage can be used to predict failure in a nonuniform stress field. Deflection control and acoustic emission techniques were used to detect crack initiation, strain gages were employed to record the strain history in the specimen, and a scanning electron microscrope was utilized to check crack initiation and propagation. Stress analyses were made using simplified and finite element methods. Comparison of test results and analyses concluded that creep rupture damage can be used to predict local material failure for structural components under multiaxial nonuniform loading conditions.

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