RSS Feeds
Reader Rates New FEA Package
Automotive Engineer takes COSMOSWorks 2005 for a ride
Paris Altidis, Borg Warner Automotive -- Design News, February 28, 2005
Just because it is fully integrated into SolidWorks2005, don’t assume that COSMOSWorks’ (CW) analytical capabilities are less impressive than those in software dedicated for structural analysis. They are every bit as impressive.
CW capabilities span from the very basic FE analysis all the way into advanced studies in the nonlinear regime. These capabilities are divided in modules that fit the needs of a new, experienced or advanced user.
The CW module is integrated in SolidWorks as a manager tree next to the Feature, Property, and Configuration Manager trees. From there, an FE study can become part of a SolidWorks component or assembly. The study is nothing but a project folder where the FE entities are defined. The top level definition in every CW study is the type of the analysis that needs to be performed: Static, Frequency, Buckling and Thermal for basic module, and Optimization, Nonlinear, Drop Test, and fatigue in the advanced module. CW can only use solid and shell elements in the modeling of parts in SolidWorks. The lack of beam elements can be replaced with springs and pin connectors along with explicit definition of bolts. From a SolidWorks standpoint, a new FE study is associated with the active design configuration, thus allowing the user to create as many FE studies as the number of configurations.
The two other interesting tools in the definition stage are the ability to tabulate actual test results or reference data for comparison in the post-processing phase as well as the definition of nonlinear material curves for time and temperature-dependent properties as well as SN curves for fatigue analysis.
There is an improved user interface in all of the CW toolbars and a feature called QuickTips. Think of the latter as a context sensitive How-I-do type of help. The topics are related directly to the study type and the subtopic (restraints, materials, loads) in the menu structure you are trying to find an answer for.
The first step in the FE model definition is typically a material selection which in CW can be isotropic, orthotropic, including some nonlinear material models for rubber type (Mooney- Rivlin, Blatz-Ko, Ogden) or even Drucker-Prager for modeling plasticity in plastics. The built-in materials database over 46,000 materials that can be accessed from www.Matweb.com that is available with an inexpensive premium subscription. Overall, the material definition is very complete and detailed. The idea of units in CW is very open: Users can specify whatever units they prefer in all phases of their model building and post-processing. This is especially useful in the material definition where their sources can be limited to one unit system and conversions can be error prone at times.
The load and boundary conditions can be defined in a number of ways. The pin, bolt, spring ,or elastic supports make up for the lack of special types of elements. This version includes surface-to-surface radiation loads, along with other thermal loading including specifying a different initial temperature for each component.
Models that have a number of symmetry planes can take advantage of CW’s symmetry boundary conditions that help reduce the model size and if done correctly produce identical results to a full model. For those users with access to the Motion and Floworks modules of COSMOS, just transfer the loads directly into CW with no translation.
Part of the nonlinear features in CW is the extensive of use structural and thermal contact features. The advantage of using nonlinear materials like rubber or metals with plasticity in an analysis with contact is the closest one can get to a realistic representation of the underlying physics of the problem. My pet peeve about contact modeling in CW is the total lack of friction between parts along with its inability to address self-contact in parts like a collapsed seal or a rubber boot. Like in other areas of CW, any contact defined for a specific study becomes part of it and you can build different scenarios (studies) with different contact interfaces and internal setting from the same core model.
The highlight of this release is probably the ability to simulate a drop test. The time to solve such a type of analysis is compensated by its benefits in the design stage, as you can include all the material nonlinearities built into your models. Among other settings in defining the drop test in CW, a user can define the friction with the surface on which it drops, the drop angle and the direction of gravity. The drop test capability is a promising addition in CW that comes with some limitations: The surface on which the parts are dropped is assumed to be infinitely stiff with no damping properties. For assemblies used in a drop test, it is not possible to include any contact or interaction between mating parts.
I was surprised to encounter some problems in defining a response plot as a means to post-process the drop test results: The selected nodal locations are represented by a node number on the plot with no clear way to edit the location to something more meaningful to the user. Unlike other areas of CW, once the plot is customized and closed, its attributes are not retained and need to be redone once needed for replotting.
For the most part, the solver in CW can be invoked as soon as the meshing is complete. CW has a number of ways to not only set the mesh density but to improve it using a quality report that can be used as a diagnostics tool. In most cases, the benefit of using CW’s fast solver technology shows in the quick turnaround for results. The nonlinear models still rely on external solvers and depending on the complexity of the models it can take a considerable amount of time to converge to a correct solution. The postprocessing that takes place afterwards offer some tools to make the results more meaningful: Without going through the Design Check wizard, use of the yield Indicator will point to the location of failure in the structure. No need to plot your results one at a time since you can open multiple windows with different results – a nice overview in one big display.
From a hardware standpoint, CW now allows the use of multiprocessor support (if present) for the FFEPlus solver. It can also address up to 2 GB of RAM to support FE models of large assemblies.
Conclusion
As a CAE engineer who deals with FEA on a daily basis, I can say the transition of a new user into its advanced features will be almost transparent.
|
