Figure. Cut surfaces (left) should be addressed first; then cut edges with surrounding (right) should be improved.
To get a draft of the final output result, ProTOp takes the optimized FEA model and generates a triangulated surface of the part. Because this surface is generated from a material function mapped onto a discrete FE mesh, it unavoidably contains jagged surface areas and other irregularities, making it far from being smooth. This necessitates surface improvement that can be achieved by utilizing four basic procedures as follows:
In general, these four procedures have to be utilized interchangeably several times until the desired result is achieved. The procedure should typically be a cyclic one, where each improvement cycle should roughly be as follows:
Typically, several cycles are needed and mesh simplification might need to be inserted at some stages.
ProTOp distinguishes between two types of surfaces that can be improved, as follows:
Figure. Cut surfaces (left) should be addressed first; then cut edges with surrounding (right) should be improved.
Typically, cut surfaces should be improved first. After that cut edges with surrounding should be addressed.
Peaks and pits are identified numerically on the basis of the vertex normal vector and the corresponding triangle edge vectors. When peaks and pits are removed, care should be taken to adjust the mesh fineness accordingly. Namely, when a peak or pit vertex is moved to a new position, the supporting vertices are kept fix. This means that the change done on the mesh depends drastically on the mesh fineness.
Figure. Rough mesh: a relatively large surface change is caused by a peak removal.
Figure. Fine mesh: a relatively small surface change is caused by a peak removal.
The mesh refinement and mesh simplification procedures perform two tasks. Firstly, they change mesh fineness and they repair or remove highly distorted triangles. While the repair of distorted triangles does not require special attention, the mesh fineness should be carefully observed and tuned to achieve the desired effect. Namely, the effects of peaks/pits removal and smoothing procedures are highly dependent on the fineness of the mesh.
Figure. Both, refinement and simplification should be used interchangeably to fine tune mesh fineness at all stages of mesh improvement.
NOTE. Mesh refinement and/or simplification should be carefully engaged in order to achieve the desired effects of peaks/pits removal and surface smoothing.
The surface smoothing procedure moves vertices with the objective to align optimally each triangle normal with the average normal of its vertices. The effects of surface smoothing are also highly dependent on the fineness of the mesh. Therefore, mesh fineness should be tuned carefully for each surface smoothing operation.
Figure. Surface smoothing moves vertices in order to adjusts optimally triangle and vertex normal vectors.