[Feature] A generalized way to define stress conditions and boundary controls disregarding domain geometry

[jhuang2601]

What is the requested feature? A generalized way to define in-situ stresses (tensor) and boundary controls (traction or displacement) disregarding domain geometry.

Is your request related to a specific problem? As of now, all external boundaries (box geometry) should be aligned with Cartesian system (either normal or parallel to x,y,z axis), which are determined by the orientations of principal stresses. This is required for initializing in-situ stresses (normal components) and assigning boundary controls (normal traction or roller constrains). This constrain should be relaxed for cases with complex geometry and boundary conditions.

Describe the solution you'd like

1. Domain geometry should not depend on in-situ stress orientations.
2. Tensor rotation should be functional to initialize in-situ stresses, whose orientations are not aligned with the global structure (x,y,z axis).
3. Roller constrains (zero normal displacement) and traction loading (both normal and shear components) can be applied to surfaces, which are not perfectly normal or parallel to x,y,z axis.