Effect of long-seam mismatch on the burst pressure of maraging steel rocket motor cases

This paper examines the failure bahaviour of maraging steel rocket motor cases to understand the combined stress theories of failure and their use in design. Effects of weld-mismatches on the load bearing capacity of the motor case, failure pressure estimates and their validation through burst pressure testing of the motor case, are discussed. A simplified procedure, which can be easily programmed on a digital computer, is presented for experimental stress analysis through strain gauge measurements on the surface of the casing during test. A simple expression useful for failure pressure estimates of rocket motor cases having weld mismatch, is presented. The failure pressure estimates are found to be in good agreement with the burst pressure test results of maraging steel motor cases.