Either the Stiffness Tensor for the structure, or the effective stiffness for a selected direction can be computed (Stiffness X-Direction, …).

The stiffness tensor contains more information and allows to understand the properties of the structure more thoroughly. Nevertheless, if only the information for one direction is needed, the option to compute only a selected direction is much faster.

Choose whether the load applied to the material should be Strain or Stress from the pull-down menu. Choosing Strain is favorable for the solver and is often faster, but the choice has no effect on the quality of the solution.

Depending on the selected Load Type, a Strain or Stress Increment must be set. Generally, it is recommended to keep the default settings. Since the equation solved in ElastoDict-Effective Stiffness is linear, scaling the input increment (Strain respectively Stress) by a factor also scales the output (Stress respectively Strain) by the same factor. In conclusion, changing the input increment does not change the computed stiffness tensors.

Choose the Load Directions in which the effective stiffness should be calculated. The complete stiffness tensor can only be computed if all six load case directions are simulated (See Effective Elastic Properties for an exemplary analysis of ElastoDict-Effective Stiffness results). Otherwise, only part of the stiffness tensor is calculated. If only parts of the stiffness tensor are computed, the results might be inaccurate, especially if the structure is highly anisotropic. Therefore, we recommend using the option to compute the stiffness in selected directions (see Stiffness Tensor,) instead of computing only parts of the stiffness tensor.

For the strain equivalence principle (see the Solver tab), each load case adds one column to the stiffness tensor. For the energy equivalence principle, only the entries of the stiffness tensor can be calculated, for which both the load case belonging to the column-number and the load case belonging to the row-number, have been solved.

When thermal expansion is chosen, the tensor with the thermal expansion coefficients is computed for the current structure. Thermal expansion is a separate load case independent from the strain or stress loads. The temperature change is then specified as Temperature Increment [K].

Here, the domain boundary conditions can be set. In general, periodic boundary conditions should be used for periodic structures, whereas otherwise symmetric boundary conditions should be applied. For further explanations, see the corresponding paragraph in the ElastoDict-Deformations section.

For the FeelMath solver (explained under Solver below), periodic boundary conditions are usually much faster and need less memory than symmetric boundary conditions. In many cases, for example for composite structures with low fiber percentage, the results for periodic boundary conditions are comparable with the results for symmetric boundary conditions even if the analyzed structure is not periodic.

The LIR solver is less affected by the choice of the boundary conditions. Usually, it is slightly faster with symmetric boundary conditions than with periodic boundary conditions.

If the Stiffness Mode is set to Stiffness Tensor, only Periodic or Symmetric boundary conditions are available. For Stiffness in X,Y or Z-Direction, also Mixed boundary conditions can be set. Mixed boundary conditions are symmetric in the load direction and periodic in the tangential directions. They are usually faster to calculate than symmetric boundary conditions.