Structural Simulation of Components with Defects - A Workflow from Computed Tomography to Finite Element Simulation

This presentation was held at the 2020 NAFEMS UK Conference "Inspiring Innovation through Engineering Simulation". The conference covered topics ranging from traditional FEA and CFD, to new and emerging areas including artificial intelligence, machine learning and EDA.

Resource Abstract

Deviations between the designed and the manufactured part can be identified by means of non-destructive inspection methods, e.g. computed tomography (CT). Beside major geometrical differences like shrinkage and distortion, surface and internal defects become visible. As in general defects are sources of stress concentration, it is important to evaluate their impact on the structural performance of a component. Thus, including microdefects into a structural mechanics simulation would be desirable.

Building a Finite Element Model that includes a huge amount of microstructural defects will create an enormous effort in FE mesh generation. To resolve stress concentrations in the vicinity of each defect, fine discretization is necessary. This will result in very large simulation models that can hardly be handled. The simulation effort can be reduced significantly including only the critical defects that will affect the structural performance in the FEM simulation.

By using a specific finite element variant, a so called immersed-boundary solver, an accurate pre-simulation including all detected pores can be done easily. These immersed-boundary methods do not require a geometry conforming mesh but operate directly on the image data, which is a big advantage for simulation of components with very complex geometrical features. This approach is implemented in the Structural Mechanics Simulation module of VGSTUDIO MAX by Volume Graphics. It simulates local stress distributions for linear elastic material properties directly on computed tomography (CT) scans which accurately represent complex material structures and internal discontinuities. From the stress fields calculated by the immersed boundary finite element simulation, the microstructural defects can be sorted with respect to their severity and thus critical pores can be identified. This reduction of geometrical complexity makes a classical FEM simulation feasible which allows the use of the wide range of functionalities that are offered by a fully capable finite element software (e.g. non-linear material models). The volume meshing module in VGSTUDIO MAX enables efficient creation of a tetrahedral mesh on the CT scan and therefore bridges the gap between image data and classical FEM simulation.

A workflow from CT scanning, analyzing most critical defects and efficient meshing to nonlinear structural simulation with ANSYS maintaining the relevant features of the scanned object will be presented. It enables to assess the mechanical performance of the manufactured part.