1. Introduction

The objective of dynamic model condensation by static substructuration is to reduce the total number of degrees of freedom of a model made up of several sub-domains by condensing the resolution of the sub-domains of linear behavior onto the degrees of freedom of their interfaces with sub-domains of non-linear behavior, treated as finite elements.

The idea is then to represent each of these sub-domains by a macro-element of static type in order to be able to use it in a « mixed » reduced model also including finite elements for the non-condensed parts of non-linear behavior in order to carry out nonlinear analyses using the nonlinear calculation operators STAT_NON_LINE [U4.51.03] or DYNA_NON_LINE [U4.53.01].

In the condensation of each linear sub-domain, we also want to integrate the contribution of inertial forces, and therefore the dynamic part of its behavior obtained by modal analysis, and for this, we will therefore use dynamic macroelements such as the static macroelements necessary for static substructuring. This approach is known in the literature under the term: « System Equivalent Reduction-Expansion Process ». In linear mode, it preserves the natural pulsations of the initial system in the expected frequency range.

The principle of this condensation and its application are described in the documents [bib1, bib2, bib5].