I would like to ask for some plots regarding mesh information which can be seen in the Results tab or the Color annotations. These plots are useful to see the mesh quality, discontinuities, and useful data of refinements in a very elegant way. The images I show here are from PyNastranGUI, which is an open-source post-processor for Nastran-based files. Some of the available plots are:
Node ID
Element ID
Element orientation
Area
Min/max edge length
Min/max interior angle
Deviation from the ideal angle (90° for quads, 120° for trias, and so on…)
Aspect ratio
Taper ratio
Shell offset
I think that along with the current increasing mesh capabilities of PrePoMax, this can be useful for the user to identify regions to improve the meshing definitions.
it seems quadratic element has it robustness to deal with distorted element, highly aspect ratio, etc. Quality check can be inappropriate or unnecessary for this element type.
if i can understand properly, unaccepted Jacobian ratios by the solver is related to bad element shapes due to some node corners lied on a straight line. Distorted element have different meaning and still can be solvable, but less accurate. These condition can be significantly different between linear and quadratic element type.
Basically, it measures the element distortion due to midside nodes of quadratic elements moving away from between the corner nodes. With some complex geometries (midside nodes trying to follow the curvature of the geometry) or large deformations, it might even become negative meaning that the element is inverted and thus useless.
However, Jacobian measure is defined differently in some software. For example, the upper limit is sometimes 1 while in other software there’s no upper limit:
But 1 means perfect shape with midside nodes in the middle between corner nodes.
well, that’s some exception. Midside nodes always kept when doing comparison between linear and quadratic element type. Distortion is related to stretching, pressing or shearing, not bending/curving or twisting.
