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Mesh Quality Check with SOLIDWORKS Simulation (FEA)
  • Mesh Quality Check with SOLIDWORKS Simulation (FEA)

    Posted on Apr Fri, 2018 by Do Thai Quoc Dung

    Creating Mesh in SOLIDWORKS Simulation is very easy. There are few parameters to control and choosing mesh element is mostly depending on the type of geometry. For example: Long Weldment structures with uniform section can be meshed as Beam Elements; Sheet metal parts can be meshed as Shell Elements and all the bulky models can be meshed as Solid Elements.

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    Figure: 1 Solid Tetrahedral Element

    Basically almost every model can be meshed as the Solid Tetrahedral Elements. It is extremely important to check Mesh Quality; otherwise this would leads to a questionable result of the simulations. So how can we know whether the Mesh Quality when using Solid Elements is good for the model? Here are few methods to check the Mesh Quality:

    • Mesh layers in the thickness direction:

    After creating the Mesh using Solid Elements, Make sure there are at least 2-3 layers of high quality Mesh layers across the thickness direction in the model. Noted that we only use Draft Quality to check the boundary conditions and to make sure the system works as expected. Sometimes Draft Mesh can be used for final calculation. If you decided to use Draft mesh, 4-6 layers need to be created in the thickness direction.

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    Figure: 2 Mesh Layers

    • Aspect Ratio Check Plot:

    For a solid Mesh, numerical accuracy is best achieved by a Mesh with uniform perfect tetrahedral elements whose edges are equal in length. For a general geometry, it is not possible to create a Mesh of perfect tetrahedral elements. Due to small edges, curved geometry, thin features, and sharp corners, some of the generated elements can have some of their edges much longer than others. When the edges of an element become much different in length, the accuracy of the results deteriorates.

    Aspect Ratio is defined as the ratio between the longest distorted edge and the short normal dropped from a vertex to the opposite face normalized with respect to a perfect tetrahedral. By definition, the aspect ratio of a perfect tetrahedral element is 1.0. The aspect ratio check assumes straight edges connecting the four corner nodes. The aspect ratio check is automatically used by the program to check the quality of the mesh.

    For this method, Aspect ratio equal to or more than 1.0 and less than 40 is considered suitable.

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    Figure: 3 Aspect Ratio

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    • Jacobian Check Plot:

    Parabolic elements can map curved geometry much more accurately than linear elements of the same size. The mid-side nodes of the boundary edges of an element are placed on the actual geometry of the model. In extremely sharp or curved boundaries, placing the mid-side nodes on the actual geometry can result in generating distorted elements with edges crossing over each other. The Jacobian of an extremely distorted element becomes negative. An element with a negative Jacobian causes the analysis program to stop.

    In general Jacobian- Measures the displacement of the mid-side nodes and is available for high quality parabolic elements only and not for draft quality linear element. Perfect Tetrahedral will have a Jacobian of 1.0. When the element mapped into the curved geometry the distortion of the mid sided node occurs.

    Maintain Jacobian more than 1.0 and less than 50.

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    Figure: 5 Jacobian Points

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    Figure: 6 Jacobian Points

    How to create the Mesh check plot? Right Click the mesh folder – Create Mesh Plot and choose Aspect Ratio.

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    Figure: 5 Jacobian Points

    How to achieve the better Mesh Quality?

    • Change the Mesh parameters used in the mesh settings
    • Apply Mesh control on the local areas.

    To know more the SOLIDWORKS Simulation Mesh settings and Parameters Please refer to the Solidworks Simulation Help Documentation.

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