Products: Abaqus/Standard Abaqus/AMS
Benefits: A new innovative algorithm generating a substructure using the AMS eigensolver significantly improves substructure generation performance. This new algorithm also eliminates the requirement of full eigenmodes recovery for the substructure generation step; therefore, disk space usage in the substructure generation step can be reduced significantly if eigenmodes are recovered only at the user-defined node set.
Description: A new substructure generation capability in the AMS eigensolver delivers significant performance improvement and reduces disk space requirements for substructure generation.
Table 5–1 illustrates the improved substructure generation performance. This example includes an AMS frequency extraction step and the subsequent substructure generation step on a system with Intel Westmere processors and 128 GB physical memory for three industrial models: Model 1 is an 10 million degree of freedom automotive body-in-white model with full substructure matrix recovery, Model 2 is a 9.6 million degree of freedom automotive vehicle body model with full substructure matrix recovery, and Model 3 is a 13 million degree of freedom powertrain model with no substructure matrix recovery. In the table “w/o NSET” indicates full eigenmodes recovery in the AMS frequency extraction step and “w/ NSET” indicates selective recovery of the eigenmodes at the user-specified node set in the AMS frequency extraction step.
Table 5–1 Performance improvement of the substructure generation procedure due to the new substructure generation capability of the AMS eigensolver.
| Model | Degrees of Freedom (Millions) | Number of Retained Degrees of Freedom | Abaqus 6.11 (16-core) | Abaqus 6.12 (16-core) | |||
|---|---|---|---|---|---|---|---|
| Number of Modes | Wall Clock Time w/o NSET (h:mm) | Number of Modes | Wall Clock Time w/o NSET (h:mm) | Wall Clock Time w/ NSET (h:mm) | |||
| Model 1 | 10.0 | 336 | 554 | 2:05 | 555 | 0:43 | N/A |
| Model 2 | 9.6 | 36 | 1317 | 3:00 | 1317 | 1:25 | N/A |
| Model 3 | 13.0 | 1188 | 955 | 17:39 | 955 | 3:55 | 1:45 |
In Abaqus 6.11 full eigenmode recovery in the AMS frequency extraction step is mandatory for subsequent substructure generation. However, in Abaqus 6.12 eigenmode recovery at the user-specified node set in the AMS frequency extraction step is now available with the substructure generation procedure. For substructures with no matrix recovery or selective matrix recovery, substructure generation performance is improved, and disk space requirements are reduced. As shown for Model 3 in Table 5–1, substructure generation with eigenmodes requested only at a small set of specified nodes runs 2.2 times faster than full recovery and uses approximately 500 GB less in disk space for the substructure generation step.
Due to the changes in the order of the system of equations regarding retained nodes, it is possible to observe slight differences in the number of eigenmodes extracted by AMS in Abaqus 6.11 compared to Abaqus 6.12. These differences are expected since the AMS eigenmodes close to the user-specified maximum frequency are generally less accurate and more sensitive to perturbations (e.g., changes in the order of the system of equations or parallel execution of the element operator generation procedure). However, the substructure usage-level results of the subsequent modal dynamic procedures are very close to the results in Abaqus 6.11 and previous releases.
The new substructure generation capability does not support the following features (the conventional algorithm will be used for these unsupported cases):
Free-interface or mixed-interface substructures
Partially retained nodes (with not all degrees of freedom retained)
Gravity load and substructure load cases
Coupled acoustic-structural substructure
Unsymmetric substructures