Cobham

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Calculate the deformation, stresses and strains of a body subject to external and internal forces. The forces calculated from electromagnetic fields can be used as input to the stress analysis.

STRESS/ST and STRESS/EV can be used for stress analysis. STRESS/ST calculates the deformation, stresses and strains of a body subject to external and internal forces. The forces calculated from electromagnetic fields can be used as inpu to the stress analysis. STRESS/EV calculates the modes, i.e. the eigenvalues and eigenvectors, of a body that is not subject any internal or external forces.

 

Data for STRESS/ST and STRESS/EV can only be created using the Modeller.

 

Material Properties

Stress analysis can analyse isotropic, orthotropic and fully anisotropic materials. It uses the following material properties:

  1. Young's modulus
  2. Poisson's ratio
  3. Shear modulus
  4. Elasticity matrix (fully anisotropic materials)
  5. Thermal expansion coefficients (STRESS/ST only)
  6. General expansion integrals (STRESS/ST only)
  7. Density (STRESS/ST only)

The material properties can be specified as numeric values or as expressions. For example, the thermal expansion coefficients could be functions of temperature or position.

 

Internal Forces

The model can be deformed by internal forces from 3 sources:

  1. a functional force density, which can use values calculated by the Post-Processor from an electromagnetic analysis, e.g. EFD, the element force density;
  2. rotational forces calculated from a constant rotational velocity about the global Z axis;
  3. gravity (any of the 6 major coordinate directions can be defined as 'down').

 

External Forces and Constraints

External forces and constraints can be applied globally or as boundary conditions on the surfaces of the model. The available forces are (only STRESS/ST):

  1. pressure, a force density normal to the surface, and
  2. traction, a force in any direction.

The available constraints that are available for both STRESS/ST and STRESS/EV:

  1. fixed:
    1. fixed in all 3 directions;
    2. fixed in tangential directions;
    3. fixed in the direction normal to the surface;

The available constraints that are only available for both STRESS/ST

  1. defined normal displacement;
  2. defined displacement in all 3 directions, and
  3. thermal expansion, with values for the reference and operating temperatures, which can be imported from thermal analysis.
  4. general expansion, which can be used to model magnetostriction, electrostriction and piezo effects, with the expansion integrals expressed as functions of magnetic or electric field vectors imported from electromagnetic analysis.

 

Eigenvalue Frequency Range

STRESS/EV finds a specified number of eigenvalues above a given frequency, or within a specified range. Multiple simulations are created in the analysis database allowing post-processing of each mode.

 

Post-Processing

STRESS/ST and STRESS/EV calculate displacement vectors and stress (σ) and strain (ε) tensors for display by the Post-Processor. In addition, the Post-Processor calculates the invariants and principals of the stress and strain tensors and the Von Mises stress.

 

 
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