Identifying Problem Areas for Poorly Converging Implicit Solutions

For non or poorly converging implicit solutions, the parameter D3ITCTL parameter in *CONTROL_IMPLICIT_SOLUTION may come handy to isolate regions of interest. When D3ITCTL is non-zero, LS-DYNA outputs the model information at each Iterative step into a binary file named D3ITER which is in the same format as D3PLOT. The number of steps for which the iterative plots are to be stored is limited by the value of D3ITCTL. To save disk space, it is recommended to set D3ITCTL = 1, which indicates LS-DYNA to dump the iterative plots for every step with a maximum number of just 1 step stored into the database. With this definition, if LS-DYNA terminates abruptly without finding a converged solution, we can view the D3ITER files in LS-PREPOST to identify the problem areas. It may be necessary to scale the nodal displacements in order to visualize the movements of the nodes.

Note: There may be significant I/O issues when setting a non-zero D3ITCTL and is recommended only for debugging or when running implicit simulations with immature models.

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d3itctl flow

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