Advances in Structural Integrity Evaluation and Residual Strenght Prediction of Pressure Vessels using Acoustic Emission Technique

摘要

Ever since the first application of Acoustic Emission (AE) technique to arocket motor case almost four decades ago, acoustic emission technology hasmade rapid strides in the integrity evaluation of pressure vessels made ofmetallic as well as composites. With the technological revolution that istaking place in electronics and software, the day is not far off whenacoustic emission can predict precisely the residual life of a pressurevessel. The authors experimented with a number of Ti-lined Kevlar-epoxycomposite pressure vessels slated for aerospace application with optimalnumber of AE channels. On the basis of the AE data acquired during the autofrettagingpressure cycle and the subsequent proof pressure cycle, it isfound possible to estimate the residual life of the hardware with itsattendant degradation represented by the 'felicity ratio' etc. Moreover, theemerging philosophy for the prediction of the left over life of a hardwareat a test pressure which is much lower than the maximum expected operatingpressure level is outlined in the paper. Besides, the possibility ofresidual life estimation for Ti-6Al-4V alloy pressure bottles of low marginis also discussed in the paper with reference to our in-house AE studiescarried out on a number of such aerospace hardware. At the Vikram SarabhaiSpace Centre, Trivandrum, the AE technique has also demonstrated to be anefficient tool for detecting and characterising the severity of defects likelack of fusion, which was, missed by conventional NDT techniques. By andlarge, the AE technique has made remarkable advances in the recent times toqualify itself as a unique mandatory tool for the acceptance of pressurisedsystems in whatever application calling for stringent quality requirements.