Title: Failure prediction of glass/epoxy specimens using NOL ring test and acoustic emission technique

Authors: R. Joselin; T. Chelladurai; K.M. Usha; E.S. Vasudev

Addresses: JNTU Hyderabad, Hyderabad – 500085, A.P., India ' Gnanamani College of Technology, Namakkal – 637 018, Tamilnadu, India ' CCTD/CCQG/CMSE, VSSC/ISRO, Thiruvananthapuram – 695 013, India ' CMSE, VSSC/ISRO, Thiruvananthapuram – 695 013, India

Abstract: Methods have been evolved for the evaluation of filament wound composite structures making use of Naval Ordnance Laboratory (NOL) ring specimens. Internal pressure could be applied to the ring shaped specimens similar to hydro burst test of actual pressure vessels. In this investigation, suitable testing technique to estimate the tensile strength of NOL rings is presented. Also, in order to demonstrate the advantages of burst test, appropriate testing and evaluation of glass/epoxy rings under defect free as well as adverse conditions is carried out through acoustic emission (AE) monitoring. Thus, the degradation on the strength of glass/epoxy rings is understood through AE technique. Moreover, a mathematical approach is developed to predict the failure load of glass/epoxy rings at relatively lower load level itself with a reasonable error margin. Due to simplicity of this technique, a number of ring tests could be repeated easily as against the burst test of actual pressure vessels.

Keywords: glass-epoxy NOL rings; burst pressure; acoustic emission; pressure vessels; failure prediction; filament wound composites; tensile strength; ring tests.

DOI: 10.1504/IJMPT.2015.067832

International Journal of Materials and Product Technology, 2015 Vol.50 No.2, pp.180 - 192

Accepted: 07 Nov 2014
Published online: 05 Mar 2015 *

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