Monitoring and Prediction of Damage in Filament Wound Composite Pipes Under Pressure Loading

A number of pressure loading tests were conducted on large-scale filament wound composite pipes. The objective of the program was to assess the effectiveness of existing failure criteria in predicting several limit states and to develop methods based on nondestructive evaluation techniques to monitor damage growth and predict residual capacity of composite pipes. The program consisted of internal pressure tests under static and fatigue pressure loading on specimens constructed following the ASME RTP-1 specifications for pressure vessels for corrosive or hazardous fluids. An external pressure test on a full-scale specimen constructed of carbon fiber was also part of the program. Finally, a series of impact tests on fiberglass pipe specimens were also performed. Acoustic emission (AE) and other nondestructive evaluation (NDE) monitoring techniques were used as part of the program. The AE method was selected for further study because of its applicability to existing structures and relative economy in its use. Results of the program indicated that AE may be used as a tool for predicting fatigue endurance of pressure vessels under internal loading. In addition, acoustic emission showed promising results as a tool for predicting residual capacity on impact damaged fiberglass pipes. In the external pressure (collapse) portion of the test program, AE monitoring presented with supporting and additional information for the interpretation of other measured data during a test where visual inspection at the time of loading was not possible. An analytical phase followed the experimental tests, in an effort to evaluate existing tools and their accuracy in predicting measured behavior. Results of the analysis are compared to the measured responses and limiting factor in their applicability are enumerated.