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FEA

The Mimics FEA Module enables you to link from scanned images to Finite Element Analysis and Computational Fluid Dynamics by exporting the files in the appropriate file format. You can calculate 3D objects based on the scanned images and prepare these surface meshes for Finite Element Analysis purposes. The Remesher in the FEA Module assures that you'll end up with the most optimal input for that FEA package. Materials can be assigned to volumetric meshes, based on the Hounsfield Units in the scanned images.

 

Create a 3D object in Mimics from the scanned data
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Remesh the 3D object with the Mimics Remesher in the FEA Module
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Export the 3D object to a Patran neutral, Ansys or Abaqus surface mesh in the FEA Module
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Convert the surface mesh to a volume mesh in a pre-processor (e.g. Patran,…)
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Load the Patran neutral, Ansys or Abaqus volume mesh in the FEA module
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Assign materials based on the scanned images to the volume mesh in the FEA Module
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Export the volume mesh with material assignment to a Patran neutral, Ansys or Abaqus file in the FEA Module

 Case represented by Prof. Dr. J. Vander Sloten, T. Van Cleynenbreugel, Dept. of Biomechanics and Engineering Design, KU Leuven, Belgium

 

Mimics Remesher

 

Mimics Remesher significantly improves the quality and speed of FE analyses on STL models. It allows the easy transformation of irregularly shaped triangles into more or less equilateral triangles. In addition to the automatic remeshing option, the Remesher offers further techniques for improving triangle quality manually. This optimises the model for FEA purposes.

 

3D view of a vessel, before (left) and after remeshing (right).

Wide range of quality measurement parameters

Mimics Remesher provides 14 of the most common quality inspection parameters. To facilitate the subsequent FE analysis you want to perform, you can choose the most suitable method for calculating triangle quality.

 

Easy automatic remeshing

The Remesher can improve mesh quality automatically. The software searches for all triangles whose quality is below the indicated level and transform them to triangles with a better shape.


Manual remeshing

In some cases, a few triangles with a shape inferior to the required quality level may remain after automatic remeshing. The Remesher offers a unique toolbox to reshape those triangles manually.

 

Quality histogram of the triangles before (left) and after remeshing (right)

Increased reliability and accuracy of FE analyses

The Mimics Remesher is a highly automated interface with FEA packages. It significantly increases the reliability and accuracy of FEA results on STL models. Most FE packages don't allow you to manipulate or optimise the mesh generated when you import a part. This might reduce the accuracy of the results. With the Remesher you can optimise the file and deliver good meshes that will run in the FEA software.

 

Reduced calculation times

Calculation times for running a sub-optimal mesh can be very lengthy. The optimised meshes generated by the Remesher usually take a much shorter time.

Material assignment

 

After loading a volume mesh, the FEA Module calculates an appropriate Hounsfield value for each element of the mesh based on the scanned images. You can then specify several Hounsfield Unit ranges that each represent a material. You can also assign a density, an E-Modulus and Poisson coefficient for those materials. The volumetric mesh with the assigned materials can then be exported to a Patran neutral, Ansys or Abaqus file.


Material assignment. The red triangles indicate a higher HU.

Assigning materials with a Uniform method

Subdivide the range of Hounsfield units of the volume mesh into a number of equal sized intervals that each represent a material. Assign a density value to each material using an empirical expression to convert the Hounsfield units into density values. Then specify an E-modulus expression and/or Poisson coefficient expression for the materials.

 

The FEA Module interface shows easy-to-use histograms that show the number of elements for each Hounsfield value (left) or the number of elements in each material (right).

 

 

Assigning materials with a Look-up file

Define intervals of Hounsfield units with a certain density assigned to each interval in a xml file and import this xml file in the FEA module. Assign the densities to the elements of the volume mesh according to the look-up file. Then specify an E-modulus expression and/or Poisson expression for the materials.

 

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