Products: Abaqus/Standard Abaqus/AMS
Benefits: A new innovative algorithm generating a free-interface or mixed-interface substructure using the AMS eigensolver significantly improves the performance of a substructure generation procedure. This new algorithm allows for partial recovery of eigenmodes at the user-defined node set, which allows you to avoid computationally expensive full eigenmodes recovery and to reduce the overall data storage requirement for substructure generation. In addition, the performance of conventional substructure generation for free-interface or mixed-interface substructures is improved.
Description: A new fast substructure generation capability using the AMS eigensolver was first introduced in Abaqus 6.12 for fixed-interface substructures (Craig-Bampton substructures). In Abaqus 6.13 the new fast substructure generation capability also supports the generation of free-interface substructures (Craig-Chang substructures), general mixed-interface substructures, and substructures with partially retained nodes. In addition, the performance of conventional free-/mixed-interface substructure generation is improved by the enhanced orthogonalization for dynamic mode computation.
Table 5–1 illustrates the improved substructure generation performance, which includes the AMS frequency extraction step and the subsequent substructure generation step on a system with Intel Westmere processors (12 cores) and 96 GB physical memory for three industrial models:
Model 1 is a 13 million degree-of-freedom powertrain model with no substructure matrix recovery.
Model 2 is a 4.5 million degree-of-freedom powertrain model with selective substructure matrix recovery.
Model 3 is a 10 million degree-of-freedom automotive vehicle body model with full substructure matrix recovery.
Table 5–1 Performance improvement of free-interface substructure generation procedure due to a new fast substructure generation capability of the AMS eigensolver.
| Model | Degrees of Freedom (Millions) | Number of Retained Degrees of Freedom | Number of Modes | Abaqus 6.12 Elapsed Time (hh:mm) | Abaqus 6.13 Elapsed Time (hh:mm) | |
|---|---|---|---|---|---|---|
| Conventional | Enhanced Conventional | AMS-based | ||||
| Model 1 | 13.0 | 1188 | 150 | 43:10 | 34:54 | 2:43 |
| Model 2 | 4.5 | 4488 | 154 | 10:13 | 7:59 | 0:13 |
| Model 3 | 10.0 | 336 | 571 | 45:26 | 5:52 | 1:30 |
The heading AMS-based indicates the new fast substructure generation functionality using the AMS eigensolver, and Enhanced Conventional indicates the conventional substructure generation functionality with enhanced orthogonalization in the substructure generation step. As shown in the table, a significant performance improvement can be achieved by the fast substructure generation functionality compared to the conventional and enhanced conventional approaches. The level of performance improvement varies depending on the number of dynamic modes. As the number of dynamic modes increases, more performance improvement can be achieved in Abaqus 6.13 with both new approaches.
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 6.12 versus Abaqus 6.13. These differences are expected since 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 6.12 and previous releases.
The new fast substructure generation capability does not support the following features (the conventional algorithm is used for these cases):
Gravity load and substructure load cases
Coupled acoustic-structural substructures
Unsymmetric substructures