Week 4

BOTTLE CAP CHALLENGE

AIM: This was a model of a bottle cap that comes under a plastic component that should be checked with the geometry and mid surface should be extracted from that which should be processed with the meshing. The outcomes should contain a perfect mid surface extraction, a good mesh flow, optimized tria%, avoiding rotating quads, back to back trias, and to make zero off elements.

PROCEDURE: As this is a plastic component it contains many complex features that should be worked with a keen eye so that no feature is forgotten. The systematical procedure contains as follows.

1. GEOMETRY CHECKS: The primary thing after opening the model is finite the model length into 1 mm both as perimeters and macros that lies under meshing that gives a perfect view of the model to work on and then a topo operation should be done for any detached cons present to bind together. The geometry checks like needle faces, problemed faces were auto fixed but some other errors like triple cons, double cons should be fixed manually by separating the faces using the bullion operations like not, or, and etc operations. The below images shows that the model before and after geometry checks.

After the geometry checks the model is checked for the measurements as that thickness measurement should not exceed >6mm. If the model is >6mm the model is not needed for mddle surface extraction.

2. MEASUREMENTS :

Below are the images calculated for thickness measurements and obtained with a thickness of less than 6mm. There are different options to measure the thickness at different feature areas like cons to cons, weld spot, node to node, etc.

3. MID SURFACE EXTRACTION:

Now this was the important segment as this mid surface extraction decides the mesh outcome flow. The basic option used to extract mid surface is offset as it is a manual method that gives exact extracted surface, based on the areas of complexity the methods to extract the middle surfaces varies. Some of the mid surface extraction methods used in this bottle cap were offset method. This involves measuring thickness, selection of face, and deciding the direction of offsetting the face. The other methods were also helpful like the middle, multi middle. The middle curve is the option that helps to extract the mid surface of features like threads, beads, etc., below are the methods used in the mid surface extraction.

The total mid surface extracted using different options and the achieved mid surface image is shown below :

The above extracted mid surface is now processed for meshing using quality criteria to get a better mesh flow.

4. MESHING:

The meshing of the component which is selected should be first resoluted with the target length given in quality criteria using length option where perimeters and macros can be optimized to target length. Then the next preferable thing is to reconstrut the construction lines present in the midsurface to achieve a better mesh flow over the surface. Some of the reconstructed lines can be seen in the below image as shown

After reconstructing the lines the quality criteria and the mesh parameters should be given so that the mesh can be verified with those criteria and if any errors appear like minimum length, maximum length, jacobian, skewness, angles etc., should be rectified with the suitable options like reconstruct, smooth, split, swap, join, edge to the perimeter, etc were the most used ones to minimize the error where quality issues happen. The meshing can be applied to the mid surface area by using batch mesh, free mesh which are applied on the surface. The mesh quality criteria, mesh parameters were shown in the below table.

S.no.	QUALITY CRITERIA	VALUES
1.	Target/Average length	1
2.	Minimum Length	0.5
3.	Maximum length	3
4.	Aspect ratio	3
5.	warpage	15
6.	skewness	45
7.	Jacobian	0.7
8.	Minimum quad angle	45
9.	Maximum quad angle	135
10.	Minimum tria angle	30
11.	Maximum tria angle	120
12.	Tria Percentage	15

Based on the above criteria this challenge is worked on to achieve the better mesh flow over the surface to a better extent, however, the total off elements in this challenge cannot be removed as triple cons in some complex areas obstruct the mesh flow to get better. So some areas were ignored as at particular areas feature of that model becomes important and triple cons appeared cannot be reconstructed when compared to double cons. Now the below image shows the mesh flow of the complete model as sticked to the above description and the tria% and rotating quads were also reduced up to a maximum extent.

These images are the meshed ones after drawing the component as shell as solid.

NEW THINGS LEARNED FROM THE CHALLANGE :

There were some of the new things learned from this challenge were:

• Finding the thickness using the weld spot option.
• Using the origin in grids that arrange the mesh along the perimeters or along construction lines.
• Creating the curves and making a mid surface using it.
• Extending the surfaces in the required area to fulfill the feature in that area.
• Projecting the hot points and cons to make a new face out of it.

CONCLUSION:

Learning the new things and those applications draws the attention to work on the more models and this was a one challange that makes us think something new with a good hands on the meshing. Though after leaning new things there is always to be learned something like how to fix errors in triple con areas in this challange.

LINK FOR THIS MODEL:

https://drive.google.com/file/d/1r_TLdUQycS98e5kcCEmBHR1WdZgsBuMl/view?usp=sharing