The ElastoDict-Effective Stiffness FeelMath solver options are mostly the same as for the ElastoDict-Deformations. Here, the Equivalence Principle can be chosen additionally, which is not available for ElastoDict-Deformations.

Equivalence Principle

The Equivalence principle defines the equations which are solved for the computation of the effective properties of the structure. In principle, the effective properties are the properties of a homogeneous material with the same properties as the given structure. There are two approaches to compute these properties:

• Based on Strain Equivalence: the stress caused by a given strain is the same for the homogeneous and non-homogeneous material.
• Based on Energy and Strain Equivalence: the elastic energy stored in the material caused by a given strain is the same in the homogeneous and non-homogeneous material. The strain equivalence is calculated additionally to the energy equivalence if this option is chosen.

In ElastoDict-Effective Stiffness, either Strain Equivalence or Energy and Strain Equivalence can be chosen. By computing the latter, also the deviation in the results of both methods is evaluated in the result file and provides a measure for the quality of the solution. Depending on the structure, both methods might lead to slightly different results.