4. Image-Based Simulation#

4.1. Introduction#

Image-based simulation is a technique which enables more accurate geometries of components to be modelled. Imaging techniques, such as X-ray computed tomography (CT) scanning, enable the characterisation of internal features within a component, from which a more accurate mesh can be generated compared with an idealised CAD-based equivalent. These methods are able to capture features present due to manufacturing methods, such as asymmetry or micro-cracks, yielding simulations with increased accuracy. That is, image-based meshes allow simulations of components ‘as manufacutred’ rather than ‘as designed’.

4.2. Sample & Simulation#

In this example, a CT scan of a dog-bone sample is used in a tensile test. The image-based mesh used for this simulation can be downloaded here. See www.ibsim.co.uk for further information on the image-based simulation methodology.

4.3. Task 1#

Action

The RunFile RunTutorials.py should be set up as follows to run this simulation:

Simulation='Tensile'
Project='Tutorials'
Parameters_Master='TrainingParameters_IBSim'
Parameters_Var=None

VirtualLab=VLSetup(
           Simulation,
           Project
           )

VirtualLab.Settings(
           Mode='Interactive',
           Launcher='Process',
           NbJobs=1
           )

VirtualLab.Parameters(
           Parameters_Master,
           Parameters_Var,
           RunMesh=True,
           RunSim=True,
           RunDA=True
           )

VirtualLab.Mesh(
           ShowMesh=False,
           MeshCheck=None
           )

VirtualLab.Sim(
           RunPreAster=True,
           RunAster=True,
           RunPostAster=True,
           ShowRes=True
           )

VirtualLab.DA()

Ensure that the downloadedi mage-based mesh has been saved to the following location Output/Tensile/Tutorials/Meshes/Tensile_IBSim.med

Launch VirtualLab using the following command:

VirtualLab -f RunFiles/RunTutorials.py

Looking at Input/Tensile/Tutorials/TrainingParameters_IBSim.py you will notice Sim has the variable ‘Displacement’ but not ‘Force’, meaning only a controlled displacement simulation will be run.

From the results shown in ParaViS you should notice the asymmetric nature of the displacement, stress and strain profiles. These are as a result of the subtle imperfections in the non-idealised Tensile_IBSim mesh compared with an idealised CAD-based mesh.

https://gitlab.com/ibsim/media/-/raw/master/images/VirtualLab/IBSim_Tensile.png

Fig. 4.1 Comparison of CAD-based (idealised) and image-based simulation results.#