ADINA Structures and appropriate model fidelity for dynamic analysis

ADINA Structures and Appropriate Model Fidelity for Dynamic Analysis

What is ADINA Structures?

ADINA (Automatic Dynamic Incremental Nonlinear Analysis) Structures is a finite element solver that provides state-of-the-art stress capabilities for the analysis of solids and structures.  The analysis can be linear or highly nonlinear, static or dynamic, and may include geometric nonlinearities, large deformations, severe material nonlinearities, load nonlinearities, and contact conditions.

ADINA Structures may be used as a standalone program for structural-only analyses, or it may be used in conjunction with other modules in the ADINA product suite for multiphysics applications, such as thermo-mechanical coupling or fluid-structure interaction analyses.


What is Dynamic Analysis?

Any analysis where the load is time varying and inertia forces may be present.


What Model Fidelity is Appropriate for Dynamic Analysis?

The appropriate model fidelity depends on the objectives of the dynamic analysis and the physical behavior that needs to be captured.  The answer is problem specific, but some general considerations are listed below.

  1. Maintain simplicity for conceptual and preliminary design models.
    1. Limit the total number of degrees of freedom.
    2. Utilize 1-D and 2-D elements when possible.
    3. Avoid solid elements which use more degrees of freedom.
    4. Maintain good element quality and avoid small element edges.
    5. Utilize RBE2 elements to simplify connections.
    6. Only model primary load paths with structural elements.
    7. Simplify secondary load paths and non-structural components with RBE and mass elements.
  1. Check the behavior and sensitivity of your simplified dynamic model.
    1. Maintain an accurate mass distribution
    2. Check the model CG and mass inertia against a detailed finite element model or a detailed weights and balance model.
    3. The structural modes of a simplified model should match the structural modes of a more detailed model within a reasonable tolerance.
    4. If a complete detailed model does not exist, then add individual details to the simplified model and check the sensitivity of the structural modes.
  1. Steps for the Method of Equivalent Static Loads Analysis
    1. Dynamic analysis of a simplified finite element model
    2. Identify critical stress and strain states from the dynamic solution
    3. Equivalent static loads can be defined using forces or displacements that are extracted from the dynamic solution at part interfaces.
    4. Apply the forces or enforce the displacements in static analysis of a detailed part finite element model.
    5. Equivalent static loads are intended to create an approximately “equivalent” stress-strain state using static analysis.
    6. This can be much more time efficient to evaluate detailed stress margins for final part analysis than adding more and more fidelity to a dynamic model.

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