Plastic bottle cap Meshing

AIM: To correct the topological errors and take the mid surface meshing for the given bottle cap geometry.

Procedure:

• First, we need to correct the topological errors present in the model using appropriate tools.

• Most of the geometric errors are triple cons and single cons. Triple cons can be fixed by ANSA UI, the ones which are not fixed can be done manually.

• To fix the triple con errors release the cons and zoom in to get an idea of why triple cons are forming.

• Most of the times triple cons forming basis is related to two parts intersecting each other.

• If that\'s the case then use the intersect option to cut the unnecessary geometry.

• Most of the single cons are just parts lying in the space.

MID Surface extraction

• To get the mid surface, we need to do it manually or an automatic algorithm which is provided in the ANSA interface.

• The geometry given is a complex and there are more curves, because of this reason automatic mid surface option won\'t give you the proper result.

• To do it manually, first, divide the geometry into parts or just start with the bottom portion of the cap.

• The options used to get manual mid surface are MIDDLE in TOPO tab, MIDDLE in CURVES tab and OFFSET in the TOPO tab.

• First work on the bottom surface of the cap, to get the mid surface use offset option or middle option.

• After done with the bottom surface, work on the stiffeners attached to the same inside and outside of the surface of the bottom, use the middle multi option to get the mid surface of stiffeners.

• After getting done with the bottom surface, the next part is the middle surface of the cap. To get mid of this use offset option.

• After being done with the middle surface, move on to the inner middle surface, for this mid can be obtained using the middle multi-option.

• In the middle surface, we have threads which are a complex geometry to obtain the mid.

• To get mid for this use middle in curves option and get the curves, after getting the curves we need to create the surface in between these.

• After creating the surface, then extend this to the part to which it is connected to.

• After being done with the threads, the next important details are the fins that are attached to the bottom of the top surface of the cap.

• To get mid for these, we have to work in the same way as we worked on threads using the middle option in the curves tab.

• Now, most part of the geometry is done with mid surface extraction, now we can proceed to mesh after creating mid for top surface using offset.

MESHING:

• The first thing we need to do as soon as we open the meshing tab is to give the input for QC and meshing parameters.

• After QC, start using spot meshing option to mesh the geometry. Start meshing from the most complex part of the geometry and work until it\'s done.

• Before moving on to the next part check with the off elements, because it\'s easy to correct now than later looking in more elements.

• If you\'re not satisfied with the mesh produced, use the reconstruction option under the shell mesh tab.

• After being done with mesh, look in off elements and if there are any then try to correct them using MV surf and MV free options under the GRIDs tab.

• Most of the off elements are because of failing min length criteria, we can correct these by using MV surf option and MV free in the places where the MV surf option is failing.

• Using MV free option can cause the distortion of the mesh, try to use MV free option as less as possible.

RESULT: We obtained the mid surface of the bottle cap geometry with mid surface meshed according to the QC.