Failure analysis of M250 maraging steel stud used in Flex Nozzle Control actuator bracket of solid propulsion system

The unexpected in-service failure of a heavy-duty hydraulic cylinder motivated the present investigation. The combined use of fracture mechanics concepts and of the finite element method demonstrated that part failure was due to the specific weld joint solution between cylinder and end-cap and the fatigue life predictions correlated with the estimated service life before crack detection. Alternative designs involving modified end cap geometry were developed and demonstrated to achieve a considerably longer operational life.