Failure mode effect analysis for a better functional composite rocket motor casing

Abstract

Composite Rocket Motor Casing (CRMC) is one of the highly critical elements of Solid Rocket Motor (SRM) and Launch Vehicle (LV). Being a single shot device and designed with a marginal Factor of Safety (FOS), it calls for a robust design with a high order of reliability. Composites are strongly influenced by the manufacturing process and are susceptible to flaws. To, take care of the manufacturing process variability, it demands stringent process and quality control. Any design or process non-conformity and defects in composites may have a functional influence resulting in a calamitous effect and total mission failure. In this present study, as part of a systematic risk assessment framework, Failure Mode Effect Analysis (FMEA) and Failure Mode Effect and Criticality Analysis (FMECA) are performed on a typical CRMC to study all potential failure modes and their severity. For a typical configuration of CRMC, qualitative analysis in line with MIL-STD-1629A and quantitative FMECA using Risk Priority Number (RPN) is performed. The results are studied in-depth and the most critical and high-risk failure modes are identified using the RPN method. The results of the FMEA and FMECA are also supported by our experiences in the development of CRMCs of various configurations and experimental test data obtained during qualification testing. Based on our experiences on more than 100 CRMCs, an action plan is developed to mitigate risk and improve design and process robustness. The preventive and corrective actions successfully developed CRMCs and were successfully used in multiple LV without a single failure with expected performance. The results of the FMEA, FMECA analysis, as well as the robustness of the recommendations mentioned in this paper, can form effective and well-established guidelines for CRMC designers and engineering practitioners boosting the overall reliability and lowering overall life cycle program costs.