CAD geometry preparation issues effecting FE simulation accuracy

When generating a design for a complex assembly, large amounts of detail are produced in the CAD model. Whilst this level of detail is paramount in generating a Bill-Of-Materials (BOM) and visualising mechanical conformance, it can be detrimental to additional finite element (FEA) operations. Complex CAD-centric assemblies must be prepared for FEA, such as removing unwanted parts, and part geometry defeaturing. Part defeaturing can be considered the most important step in CAD FEA preparation as it can be the largest error contributor. However, the removal of certain features has the potential to create artificial stress risers in the part, that can result in false positive FEA solutions. Additionally, if bulk material is added/removed by defeaturing, structural and thermal properties of the parts can be greatly altered leading to inaccurate solutions.
Conversely, if these features are left in, they can lead to poor quality mesh that can lead to inaccurate results, non-converging solutions, excessive computing time and power requirements.
From discussions with industry partners, the main barriers to them using FEA effectively are the issue around proper defeaturing to ensure accurate results, and the time needed to perform model preparation. The work presented here is aimed at understanding and defining the effects that changes in geometry and mesh attributes can have on simulation results. Certain solutions which have already been evaluated, such as rapid part removal for assembly preparation, are also included. Additionally, this work highlights how current automated defeaturing solutions are not suitable for more complex FEA simulation preparations.
Keywords, CAD, FEA, Mechanical design, defeaturing