Impacting the design process using solid modelling and automated finite element mesh generation

Abstract

Finite element analysis is commonly used to obtain information about structural behaviour without building prototypes. Today, it is being used primarily as an after-the-fact verification tool. Using finite element analysis in earlier stages of design can, in addition to verifying that the design meets certain specifications, better impact the actual design concept. Historically, considerable time has been needed to create the finite element model, particularly when using solid elements. The model building time has been large enough to prevent analysis results from impacting the design. The turnaround time for model building and analysis needs to be reduced to increase the impact on the design process. Model building time has been reduced by ever-improving computer graphic model building tools. It is important that finite element preprocessors are both fast and easy to use. The faster they are, the more impact they can have on the early design by decreasing analysis turnaround time. Ease of use increases the potential number of users by allowing casual users and experts to be productive. The combination of a good solid modeller for geometry creation with automated mesh generators shows promise in decreasing analysis turnaround time. The solid modeller offers a variety of ways to create geometry quickly. The mesh generators keep the amount of necessary user interaction and intervention to a minimum. The overall result is a reduction in the time necessary to build many models. This paper discusses aspects of using a solid modelling system in conjunction with mesh generators with a focus on productivity improvements and accuracy of results. Examples generated with the SDRC I-DEAS software system are used to illustrate a range of techniques. The solid modeller (Geomod) is capable of creating objects using a variety of high-level construction techniques, including Boolean operations, profile extrusion, and surface skinning. This allows for geometry creation that is not only fast but easy to use. A free mesh generator (Triquamesh) uses this geometry to generate finite element meshes automatically. It allows meshes to be generated on n-edged surfaces and n-sided volumes with a minimum of user input. By using a combination of these tools, it is possible to reduce model building time significantly. This allows proposed design changes to ve evaluated earlier in the design cycle and have greater impact on the final design.