FEM subsystem replacement techniques for strength problems in variable geometry trusses

This work presents the application of a procedure for replacing FEM subsystems with a high number of dofs (possibility of including mobile internal parts) using equivalent parametric macroelements (EPMs) with a much reduced number of elements to decrease significantly the analysis time with an acceptable error. This procedure is applied to the replacement of variable geometry truss (VGT) mobile joints. The equivalence criterion proposed is based on elastic strain energies absorbed by both bodies. Said replacement involves resolution of a redundant nonlinear equation system, iteratively focused via linearization and subsequent resolution via the least squares method. The search for initial approximation is supported by genetic algorithm techniques.