Estimated Maximum Mesh Error
The mesh stress error indicator output provides valuable information about the accuracy of a shell finite element analysis. Sumo and Frame analysis calculates the maximum estimated error by comparing smoothed and raw stresses throughout the model. The error level is displayed across the model as contours, with the 100% level indicating the maximum estimated error. For instance, if the estimated maximum error is 20%, the 50% contour would suggest an estimated error of 10% at the point being analysed.
Although large estimated errors can indicate issues, they do not necessarily mean that all stress values in the model are inaccurate. Instead, they help identify areas where the finite element mesh refinement may improve analysis accuracy. It is important to consider the following factors:
Error distribution: If estimated errors are concentrated in specific areas of the model, it suggests that the basic mesh layout is sound, but refinement may be necessary for those zones where the estimated errors are significant.
Error location: Small stress differences in critical areas of the model may be significant, whereas large stress differences in remote portions of the model may have no significant effect on the part being analysed.
Stress smoothing: While stress smoothing can improve accuracy in some cases by balancing out errors, it should not be used to hide real problems in the model.
In most cases, improving the accuracy of the analysis requires optimizing the finite element mesh, such as using smaller elements in areas of stress concentration. When making this decision, it is crucial to consider both the local and global characteristics of the model.