Introduction

Mesh generation can only be started after an Analytical design run has been finished. The mesh generator does not check the input data for validity, if bad data is fed to it, it will produce a bad mesh.

The first step is to generate the input data for the mesh. The first 6 menu items in the Mesh2D popup menu allows the creating of input data and its visualization. The next set of buttons allow the mesh generation process to be started. Mesh generation is done in a separate thread so you can pause, resume, and terminate it for any reason. You also control the thread priority.

The other buttons allow you to view the mesh, check its integrity, see different parts of the mesh, etc. Once mesh generation is complete, FEA can be started.

You can control the mesh properties from the properties button. The size of the triangles in different parts of the mesh and mesh order can be set here.

Mesh Input Data

Mesh Output Data

Triangle Order

First order triangles use linear basis functions. There are three points in each triangle.

First order triangle

Second order triangles use quadratic basis functions. There are six points in each triangle.

Second order triangle

Third order triangles use cubic basis functions. There are ten points in each triangle.

Third order triangle

Mesh Settings

The mesh settings can be accessed via the Mesh properties menu item or toolbar.

The mesh generation page can be used to set several properties that define the mesh generated. The area of triangles in each part of the motor cross section can be controlled to refine the mesh depending on the specific motor when required. The mesh order can be set, the number of air gap layers, the number of points in each air gap layer, and the size of the external bounding box where the magnetic potential boundary conditions are applied can be set here. While choosing the partial motor model, the user can force a minimum of 2 poles to be included and Samarium will search for minimal symmetry. Samarium does not support single magnet pole model for 2 pole motors, it does not support half of a single magnetic pole either. If air gap layers are used, the default air gap height for a full motor model is larger than in a partial motor model. Additional layers can be specified if the layer height is to be made smaller and the Sub gap size parameter can be adjusted.

Certain other parameters can also be set and are self explanatory. If the full motor model is checked, the mesh will be generated on the full motor. If it is unchecked, the motor is searched for symmetry and only a part of the motor is meshed resulting in a faster or/and more accurate FEA result for a given mesh size.

The mesh inputs page contain setting for the number of points that define each part of the motor such as number of input points on the magnet OD, etc. The visual page has settings for mesh colors, etc.

Full motor model and partial motor model

Reusable Mesh

Samarium optionally supports reusing the mesh during multiruns with different rotor positions. Presently this option has its full capability with the full motor model, with the partial motor model the air gap region can be identical with each step while the interior regions are re-meshed. The mesh generation can be set up such that there is no difference in mesh generated in the air gap at different rotor positions providing more accurate results for force and torque after finite-element analysis.

12 slot, 4 pole rotor, rotated 90 degrees

Adaptive Meshing

Automatic adaptive meshing based on FEA results is enabled form here. When the adaptive meshing is enabled, the mesh cannot be reused. Several parameters in the mesh properties control the over all behavior of the mesh. Certain features in FEA calculations are also affected by the mesh properties. For example, the surface integration method of torque calculations is unavailable when the mesh is not reused and air-gap layers are not used.