PreVABS 1.6.0 · .sg output
Description
For meshes containing higher-order triangles (TRI6), PreVABS writes the first midside node into the N4 column instead of N5. Per VABS manual, N4 must be zero for triangles. VABS interprets the misplaced node as a degenerate quad corner and aborts:
Something wrong with the mesh. The Jacobian of element 1 is less than zero.
Expected vs actual
Expected: ElemID N1 N2 N3 0 N5mid N6mid N7mid 0 0
Actual: ElemID N1 N2 N3 N4mid 0 N5mid N6mid 0 0
Workaround
Swap N4 and N5 for all triangular elements in the generated .sg file. Confirmed to resolve the Jacobian error.
Environment
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PreVABS 1.6.0, Windows
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Reproduces with tutorial: https://wenbinyugroup.github.io/ivabs/ref/prevabs/contents/tutorial.html