Minimum member size in shape optimization

Min Member Size specifies the lower limit of the thickness for each component of the optimized shape. The Min Member Size objective is useful if you need to consider practical or manufacturing limitations for your part.

Minimum Member Size Considerations

• The Min Member Size cannot be less than the minimum mesh element size. If you attempt to define a Min Member Size less than the estimated minimum element size, an error message appears. The error indicates that the specified member size is too small.
• The software calculates an initial default value the first time you add a Min Member Size constraint. The default is based on the model size and mesh settings. However, once you apply a user-specified Min Member Size, the value is not adjusted as a result of subsequent mesh settings changes.
• If you change the Mesh Size after setting a Min Member size, no error message appears even if the mesh size is too large. If you try to solve such a study, the solver produces an error message.
• We recommend that you specify a value no less than 2 or 3 times the mesh size. Stated differently, it is good to have two, three, or more elements through the thickness of the members.
• Define a small enough mesh size to accurately represent the optimized shape. The shape is optimized by removing solid elements from the body. If the elements are too coarse, removing a single element can have too big of an impact on the resultant shape. The finer the mesh, the smoother the generated shape.
• The mesh must be fine enough to represent a lattice-like structure having significantly less volume than the original body.

Example

Suppose that you want your manufactured part to have a minimum member thickness of 3 mm. Based on this dimension and the Min Member Size recommendations, the following parameters are a good place to start:

• Mesh Size = 1 mm (absolute)
• Min Member Size = 3 mm