Abstract

In the formulation of the Stiffness-Force method (SFM) are taken into account the equilibrium equations and the compatibility conditions. These are obtained from the principles of virtual work and complementary virtual work. The structure of the governing equation of this method is similar to that of stiffness-method (SM) as the principal unknows are the displacements. This method is equivalent to IFMD formulated by Patnaik and to the hybrid methods formulated by Pian.For the Stiffness-Force method finite element analysis, a user subroutine UEL for a four node quadrilateral element has been developed. This subroutine has been implemented in the commercial program Abaqus. The procedure followed for the analysis of the model has been:1. Analysis of the model using the program Abaqus that employs the SM in its formulation.2. Analysis of the same model using the user subroutine UEL employing the SFM.3. Comparison of the results of both analysis, using varying degrees of discretization, to those obtained by an analytical approach.This procedure has been used in the analysis of the open-hole tensile strength test of a unidirectional composite.