Composite tank permeation prediction and verification

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Composite tank permeation prediction and verification

Abdi, F. / Israeli, L. / Johnson, S. / Aggarwal, P. / Rayburn, J. / Fox, D.

This paper covers the verification process of commercially available life prediction software "GENOA" to predict permeation (leak rate) versus strain, critical damage events, and the contributing failure mechanism associated with permeation. This prediction model seeks to reduce the required amount of testing by predicting the permeability at any given point in the tank life cycle. The software verification process include: 1) a comparison of commercialized FE large displacement solutions using an 18 and 21 inch quasi-isotropic composite disk under normal pressure. GENOA large displacement simulations compared well with the stress and displacements of ANSYS and NASTRAN; 2) permeability verification of Southwest Research Institute (SRI) preconditioned damaged test panels, where the GENOA software was used to predict the damages created in the panel and associate the damage data obtained to the permeability level. A composite test panel of 10 ply IM7-5250 was subjected to a series of sequential tests to determine the accumulation of matrix damage. Cryogenic (-423 degree F) and controlled cyclic strain testing were simulated by the GENOA code which showed matrix surface cracking and through the thickness cracks which were close to the permeability test; 3) prediction of critical damage events: damage initiation, damage propagation, fracture initiation, fracture propagation, residual strength, and 4) Permeation (leak rate) analysis of a 21 inches composite disk, revealed the change in damage mechanisms was due to scaling effect.