u2.07.04 Dynamic model condensation by static substructuring

Summary:

This document describes a method of using Code_Aster to allow transient calculation by the nonlinear transient dynamics operator DYNA_NON_LINE on a model reduced strictly to non-linear sub-domains, the linear sub-domains being taken into account once and for all by dynamic condensation by means of static macro-elements on the interfaces.

The condensation method is applied to all interface degrees of freedom common to condensed subdomains and to subdomains calculated by nonlinear finite element analysis. A complete general method requires the calculation of all the static constrained interface modes, each associated with a response to a unit displacement imposed for each degree of interface freedom. An alternative method makes it possible to use a reduced base of interface modes that are fewer in number but representative of the movements of all the degrees of interface freedom, in the expected frequency range.

• 1. Introduction
• 2. Classical condensation problem and principle of the method
• 3. Dynamic condensation methods using a complete or reduced basis of movements on the interfaces
  • 3.1. The calculation method using a complete base of movements at the interface
  • 3.2. The calculation method by modal reduction at the interface
  • 3.3. Validation of the use of dynamic condensation methods
  • 3.4. Respective interests of using dynamic condensation methods
• 4. Summary of the calculation of the « mixed » reduced model with dynamic condensation
• 5. Bibliography