Some remarks about the CAE Process

The “CAE driven design process” has gained significant attraction in most industries such as aerospace, automotive, biomedical, consumer goods, defense, energy, electronics, heavy industry, and marine throughout the last years. The reasons for the overall acceptance of CAE are manifold as simulation has proven to help finding                                    

• New and inspiring designs
• Products with better quality
• Designs faster i.e. due to shortened development cycles
• Reduce number of prototypes by reducing “Trial and Error”
• Increase material efficiency (i.e. less material = lighter designs)

     

In other words, simulation saves time, reduces costs and essentially strengthens the competitiveness of companies and thus their market position.          

So, how does the standard CAE process looks like?                                    

Once the objective of the simulation task is identified, the standard FEM process may be subdivided into 3 steps:                                    

                                    

namely Preprocessing, Analysis and Postprocessing (corresponding Hyperworks products in blue color).         In a simplified and generalised form the corresponding steps are described below, starting with preprocessing .       After the CAD model (e.g. CATIA, STEP, UG, IGES, etc.) is imported, the geometry (in many times) needs to be  “cleaned up” (or “improved”). This is because surfaces are not stiched together, surfaces are too small resulting in a poor quality mesh etc.                                    

                                            

   

After the geometry cleanup is completed, the meshing phase starts. Once the mesh is created, its compatibility, and  quality (including the orientation of the element normals) needs to be checked. If necessary the element quality is improved by upating the underlying geometry or by editing elements directly.    

After the meshing phase you typically assign material properties to the elements, apply loads (e.g. forces, pressures, temperatures, …) and constraints. Loads and constraints are then “bundled” into a so called loadstep or subcase.                               

   

This step basically completes the preprocessing phase. The FEM model is now exported as an ASCII file using the FEM syntax of the FEM solver of choice (e.g. RADIOSS, …).                                

                             

   

The postprocessing (in HyperView) and the evaluation of the simulation results represent the next steps of  the standard FEM process.    Provided that the virtual model (i.e. a single component or an entire system) meets the requirements such as max. allowed stresses, displacements etc. the project may be considered to be completed.             

Otherwise, the above process must be re-entered again, starting with a new and improved CAD design (based on the findings of the first iteration). In fact, many times multiple iterations are needed involving both, the CAE engineer and the CAD designer. During these  iterations the dimensions of the CAD design (e.g. internal ribs) may change -  the overall concept remains the same, however.                     

A very efficient way to speed up this process is called MORPHING. Employing this technology allows the CAE engineer to modify the geometry of the FEM model. Depending on the magnitude the geometry was altered, there may be not even the need to remesh the component. In these cases the tedious geometry cleanup and meshing operations are excluded, allowing the CAE engineer to re-run the analysis almost on the fly.         

     

“Some” questions remain:                      

 Are you really sure that the “performance” of  the system or component can’t be further improved, for instance with respect to its weight, stifness, eigenfrequencies, etc.?                    

Can’t we start the entire process with an “optimized” CAD design already?                        

This requirement – to start the CAE process with an optimized concept  design sounds contradictorily - how to start with something being optimzed while searching for the best solution …?                      

             

Topology-, topography, or free size optimization are employed to “deliver” optimized concept designs. These optimzed designs are then used as a starting configuration in the above described process.    The HyperWorks applications involved in this process are marked in blue: