* new mortar segmentation tests which are failing
* test_problems_mortar_3d.jl: first test (Tet4) pass
* solvers.jl: diagonal of A is now properly filled, if that option is used. Another option is to remove zero rows from matrix system, which is on by default
* problems_mortar.jl: added new function diagnose_interface to calculate quantities from interface hopefully revealing bugs in calculation
* problems_mortar_3d.jl: added docstring for check_orientation! and removed flooding debug messages not helping to debug anything
* solvers.jl: Another way to solve Ax = b
* Refactored code to make implementation of Tri6 assemble! easier
* Patch test with linear Tet4 elements and quadratic Tet10 elements pass
When using quadratic elements, in polygon clipping algorithm element is divided to linear sub-elements as proposed in [Puso2008]. Interpolation of Lagrange multiplier space is done using quadratic shape functions.
References
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[Puso2008] Puso, Michael A., T. A. Laursen, and Jerome Solberg. "A segment-to-segment mortar contact method for quadratic elements and large deformations." Computer Methods in Applied Mechanics and Engineering 197.6 (2008): 555-566.
* increased coverage by adding diagnose_interface
* test using dual basis, failing for unknown reason
* Fixed dual basis construction for Mortar/Tet4
The coefficient matrix Ae for one particular slave element e is the result performing numerical integration on *all* integration cells associated with this element [Popp2013]. Ae cannot be calculated "cell-wise" like it was done before. Now patch test will pass also using `interface.properties.dual_basis = true` option. Partially integrated slave elements are supported as well.
References
----------
[Popp2013] Popp, Alexander, et al. "Improved robustness and consistency of 3D contact algorithms based on a dual mortar approach." Computer Methods in Applied Mechanics and Engineering 264 (2013): 67-80.
* Minor modifications to preprocess.jl
- removed two functions which are unimplemented (but maybe planned in future)
- added function create_node_set_from_element_set!, which can be used, like name suggests, to create a node set from nodes belonging to some set of elements.
* solvers.jl: now prints a list of overconstrained nodes which can be easily copy-pasted to problem.assembly.removed_dofs list to solver overconstrained situation manually
* Increase code coverage
Added a new test which tests dual basis 3d mortar + adjust option when using Tet4 in elasticity problem.
* Tet10 + Dual basis still failing, others are working
* mortar 3d low level tests
* linear surface element projection tests pass
* Introduced basis transform constant alpha
Tet10 + dual basis patch test still failing, but single element low level routine tests gives expected results with alpha=0.2
* added new integration rule FPG12 for triangular elements
* added drop_tolerance option to remove very small values from constraint matrices
* Introduced a basis transform matrix T
Constructing bi-orthogonal basis for quadratic surfaces is ill-conditioned. By doing a basis transform N' = N*T for slave side displacement vector it's possible to construct a bi-orthogonal basis in a same way than with linear elements. Setting alpha=0.2 ensures that quadratic basis functions are strictly positive in practical cases.
* fix 3d clipping test routine, accepts only 3d vertices
* dropped number of integration poitns from 12 to 7 in quadratic mortar surfaces intrestingly gives more accurate results, maybe something numerical error in FPG12 integration rule..?
* added two displacement patch tests + output writing for all cases
* %s/Int64/Int/g
* Changed test data location
* Fine tuning of logging levels
Andreas Dörfler