RESIDUAL-STRESSES IN CSM VINYL-ESTER RESIN LAMINATES DUE TO POSTCURE SHRINKAGE

In the design of glass reinforced plastic vessels for the chemical ind ustry it should be recognised that the matrix can undergo significant chemical shrinkage during elevated temperature post-curing. If this sh rinkage is restrained from occurring freely then residual stresses can be set up. These can quite easily exceed the levels of stress or stra in allowed for by accepted design codes and are sufficient to promote environmentally assisted cracking in certain operating environments. F urthermore, in many cases the residual stresses will be significantly larger than the stresses associated with mechanical and thermal loadin g. This work provides some experimental results for this important typ e of stress. Post-cure shrinkage strain results are presented for cast ings of two vinyl ester resin types, flat CSM laminates and for thick walled tubes. The results for the tubes are compared to values predict ed by commercial finite element software and by the use of the Rayleig h-Ritz method. Correlation between the predicted and measured values i s shown to be inconsistent and possible reasons for this are explored. (C) 1998 Elsevier Science Ltd. All rights reserved.