u2.06.13 General tips for using the DYNA_NON_LINE operator

Summary:

This document introduces the use of transient resolution methods (implicit or explicit) for the numerical simulation of nonlinear dynamic problems on a physical basis.

The general reference operator for this type of calculation is called DYNA_NON_LINE and its correct use will be facilitated by compliance with a few rules of good practice described in this document.

These usage tips cover:

• the correct definition of the model in a dynamic sense (including the initial conditions and

  limits),

• the definition of discretization including the choice of the time scheme

  ([R5.05.05], and also see Bibliography),

• the choice of amortization models,

• some post-treatment tips.

Given the great diversity of non-linear problems, the user will be able to very usefully complete your reading with other more specific references:

• [U2.06.03]: on amortization modeling,

• [U2.06.05]: for soil-structure interaction (linear and non-linear),

• [U2.06.09]: for single and multi-support in seismic calculation of equipment

  in particular,

• [U2.06.10]: on the specificities of studies such as civil engineering under seismic loading,

• [U2.06.11]: for the use of fluid-structure models coupled with DYNA_NON_LINE,

• [U2.04.07]: use of DYNA_NON_LINE to solve slowly evolving but highly non-linear problems that have difficulty converging with STAT_NON_LINE (see bibliography),

• [U2.07.04]: for the non-linear transient dynamics of a model partially reduced by dynamic condensation with DYNA_NON_LINE,

• [U2.06.32]: for modeling rotating machines.

Reading the documentation [U2.04.01], which gives advice on how to use the STAT_NON_LINE operator, is also highly recommended because here you will especially deepen the specificities related to dynamics. All the aspects common to STAT_NON_LINE and DYNA_NON_LINE and which are detailed in the documentation [U2.04.01], such as the choice of parameters for the Newton algorithm, remain valid in dynamics and are therefore not included here.

• 1. Introduction
• 2. Definition of a problem adapted to transitory dynamics
  • 2.1. Model
  • 2.2. Boundary conditions and excitations
  • 2.3. Initial conditions
• 3. Discretization of the ongoing problem
  • 3.1. Meshing
  • 3.2. Time integration diagram
  • 3.3. Initial conditions
  • 3.4. Depreciation modeling
  • 3.5. Modifying the mass matrix
  • 3.6. Instability and updated modal analysis
  • 3.7. Archiving and post-processing
  • 3.8. Energy balance
  • 3.9. Features available in STAT_NON_LINE and not in DYNA_NON_LINE
• 4. Specificities of coupled fluid-structure problems
• 5. Optimizing performance
  • 5.1. Model reduction and dynamic condensation by substructuring
  • 5.2. Parallelism
• 6. Conclusion
• 7. Bibliography