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Discontinuities between elements when using contours

Although nodal and element equilibrium is achieved in a general finite element analysis, differential equilibrium (e.g. stress equilibrium) is not necessarily achieved at all points of the continuum considered – most notably at the shared boundaries of elements. The reason is given fully in finite element equilibrium.

If such step changes are found between elements in a contour display, the remedy is mesh refinement. It suggests that interpolation from the gauss points (where solution is carried out) to the nodes (where load effects are reported) is great, i.e. the change of load effect between one gauss point and the next is large and the assumed shape function of the element is not able to interpolate with sufficient accuracy. These effects are often most apparent if "unsmoothed" contours are used.

If the results are not required at the locations in the mesh producing these discontinuities, the effect may normally be ignored since the load path will be correctly simulated in the general case.

More detailed information on finite element equilibrium

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