Many analysis problems are generally meshed with hexahedron-dominant (hex-dom) elements. The elements comprise pure hexahedron as well as degenerate tetrahedron, wedge, and pyramid topologies, collectively referred to as hexahedron-dominant meshes.

Hex-dom elements are preferred in many applications because of the greater accuracy they offer over tetrahedral elements (of the same order), even though meshing complex geometries with tetrahedrons is easier. For large-deformation problems, as with any mesh, hex-dom meshes can deform excessively and the problem may fail to converge. Also, in both large- and small-deformation problems, the size, quality, and gradation of the initial mesh may be insufficient to provide reliable solutions with the necessary accuracy.

Automatic nonlinear mesh adaptivity via NLAD-ETCHG offers an efficient way to alleviate mesh distortion and/or improve local-mesh density-dependent solution accuracy. Because efficient hex-dom remeshing techniques are unavailable, NLAD-ETCHG converts a hex-dom mesh to a tetrahedral mesh using efficient tetrahedral-remeshing algorithms in a mechanistically consistent manner.