Probabilistic FMECA

In this paper, a probabilistic failure mode, effect and criticality analysis (FMECA) approach is presented that combines concepts of load (stress) and capability (strength) analysis with other variables, such as material, pressure, temperature, etc. for conducting a FMECA. This analysis helps the design team to predict the probability of success with a high level of confidence. The analysis was performed on a major component of a solid propulsion system (SPS), namely the insulation, to illustrate how the method could be utilized to improve the design. The results of the probabilistic reliability analysis of the insulation, provide a reliability value of 0.999999514, based on the model used to represent the insulation characteristics. In addition, a sensitivity analysis was conducted to determine the relative contribution of each of the variables in the insulation model to the overall reliability of the system. Comparison of the changes to the base solution indicate that many of the causal variables with ±3 standard deviations (±3σ), namely the propellant web (3+), propellant burn rate (3±), insulation thickness (3-), erosion rate (3+), and the motor burn time (3-), provide a larger reliability value than the base