Predicting joint sealant performance of elastomers by computer simulation. II. Results in simple extension and compression

摘要

AbstractStress computations have been performed by a technique based on the subdivision of a body into many quasi‐homogeneous elements of a material having separable time‐dependent and strain‐dependent mechanical properties. For several sealant materials and joint seal shapes, under simple tension and/or compression movements, results are compared to experimental data on model sealed joints. There is reasonable agreement between the predicted and experimental total stress in joint seals of all the sealants tested up to nominal joint deformations of about 20–40. Furthermore it has been shown that the strain distribution in the outer layer of the sealant is nonuniform and the deformed shape is nonparabolic, which disagrees with the assumptions of the joint seal analysis proposed by E. Tons. The nonparabolic deformations have been experimentally confirmed using a resin‐casting technique to “freeze” the deformed joint seal to permit measurement of its shape. The computed stress and strain distributions show that the stresses are highest near the corners of the joint seal and are directed at an acute angle to the substrate, indicating that the peel strength of the sealant plays a major role in determining the overall joint strength. It has been shown how the computational technique can be applied to alternate compression and tension cycles to predict some effects of polymer stress relaxation characteristics on the stress distributions. Although the computational method has only been applied to a few representative isothermal sealed‐joint systems under relatively simple loading conditions, the technique certainly has been shown to be feasible for predicting stresses within a seal over a reasonable range of nominal joint deformations. It is expected that the technique can be extended to more complex joint motions by modification of the computer programs and the input of additional data on actual joint movements. Work is in progress to extend the method in this direction and should lead to a more rational approach to sealant specifications and selection as well as improvements in joi