OS-E: 0125 Diagnose Non-converged Solution using NLMON

Modeled using solid and shell elements and when the solution is not converged, run diagnostics modeling errors using NLMON.

Figure 1. FE Model

Model Files

Refer to Access the Model Files to download the required model file(s).

The model file used in this example includes:


Model Description

The cantilever beam model is shown in Figure 1, and both the elements joined by merging the common nodes. This example simulation is with nonlinear static solution with large displacement.
FE Model
Element Types
Young’s Modulus
2.1E5 MPA
Poisson's Ratio


Note: NLMON toolkit is for nonlinear convergence monitoring and debugging (load NLMON_NL.h3d file). Import the Tcl script from HyperView to launch NLMON utility tool from this location in the Altair Simulation installation: <Altair_Home>\hwsolvers\scripts\ os_out_file_parser.tcl and load the .out file in this utility to sync it with HyperView. NLMON works with large and small displacement problems.
In the .out file, notice the max displacement increment and correction is at node 13 (Figure 2). Load the NLMON_nl.h3d file and the .out file using NLMON utility tool to sync. Click on the maximum displacement increment or maximum displacement correction on the NLMON utility (Figure 4) and notice that elements (shell elements rotations) are not clamped correctly (animate for better visualization) in HyperView page, as shown in Figure 3.
Tip: To improve convergence, use TIE or FREEZE contact to connect shell and solid elements.

Figure 2. OUT File and Correction Results

Figure 3. Non-Converge Results of Maximum Displacement Increment . and Correction Results in NLMON Utility Page

Figure 4. Non-Converge Results of Maximum Displacement Increment