Long Term Behavior, Failure Analysis & In-Service Testing of Composite Cylinders

TRI proposes to develop reliable methodology and protocols for in-service inspection,recertifying and retiring DOT COPVs to maximize service life while ensuring personnel safety. This method must be sufficiently robust to prevent in-service failures, while being straightforward and affordable enough to be conducted at cylinder recertification facilities. To accomplish this with a high degree of confidence, TRI/Austin will break the problem down into two parts. The first, for Phase I, will involve diagnostic investigations of existing, field aged COPVs to identify and quantify principal failure modes. This part of the work will involve a limited rupture testing of sample COPVs. The second, for Phase II, will implement a larger-scale experimental design to vary several performance factors and quantify life characteristics of COPVs to obtain robust lifetime prediction distributions. Phase I work includes: a comprehensive information search to establish the baseline of knowledge about lifetime damage accumulation and failure mechanisms; collect retired cylinders to assess how damage occurs in field usage; develop initial reliability knowledge by burst testing several cylinders; and use the Phase I knowledge to (a)develop a comprehensive life prediction Design of Experiments for Phase II, and (b)provide an initial assessment of applicable inspection methods for recertification.