The SPECTROM-31 Compliant Joint Model: A preliminary description and feasibility study: Nevada Nuclear Waste Storage Investigations project

A deformable continuum joint model, the Compliant Joint Model, has been incorporated into the two-dimensional finite-element computer program SPECTROM-31. The stress-deformation response of a joint set normal to its plane of orientation is elastic and hyperbolic in form. The shear stress-deformation response of the joint set tangent to its plane of orientation is linear elastic. The response of up to four arbitrarily oriented joint sets is combined with the linear elastic response of the matrix component of the model to form an anisotropic nonlinear elastic composite material. The inherent numerical difficulties associated with the iterative solution of complex problems with such nonlinear models led to a preliminary investigation of the feasibility of employing the Compliant Joint Model in large finite-element models. Primary factors affecting the degree of difficulty in obtaining the numerical solution were identified as the initial stress state and loading history, joint orientation and degree of dispersion, and degrees of freedom in the model. The collective importance of these factors focuses on their effect on the composite stiffness of the material and the associated potential for an ill-conditioning of the stiffness matrix. 6 refs., 6 figs., 9 tabs