Geometric Cleanup and meshing Plastic Container model

Objective: To mesh the given component by extracting mid-surface and perform mesh quality checks

Target Element Length = 4mm

S.N	Quality Criteria	Value
1	Aspect Ratio	5
2	Skewness	45
3	Warping	15
4	Taper	0.5
5	Min. Length	2mm
6	Max. Length	6mm
7	Min angle Quad	45
8	Max angle Quad	135
9	Min angle Tria	20
10	Max angle Tria	120
10	Tria %	10

Component Study: The component is a plastic Container trim body, part of a vehicle body for crashworthiness analysis.

we observe the following things:

1. The part consists of a central base which is of 2.8mm Thickness and the rest of the features are of various thicknesses.
2. The part has some solid features, which are unsuitable for 2D meshing, which is our objective. we will be ignoring these features of thickness more than 6mm.
3. There are some geometrical errors, and free edges, which we have to correct before we move on to mid-surface extraction.
4. There are a number of strengthing ribs of various dimensions, which we have to mesh accordingly.

Theory:

The Pre-processing of a plastic model is done by extracting the mid-surface.

First, I can extract the Mid-Surface and assigned the thickness in various areas to account fie any thickness variation, The mesh is a finite element representation of the original model, which can be used for crash test analysis on stress-strain analysis.

We will be using 2D shell Quad and Trai elements, With each node having 5 DOFs, 3 Translational, and 2 rotational.

The reason for using 2DShell Quad and the trial element is that they are ideal for situations where one of the dimensions is much smaller than the other 2. It is the thickness of the part.

Procedure

1. Importing, Geometry cleanup, and Mid-Surface Extraction:

1. Import the model in Hypermesh, in the Radioss module. Check for any geometry errors, prepare the model for extracting Mid-Surface. Geometry errors that are fixed: Open edges and Surface Deformities.

We will be defeaturing the model and simplifying surface to as to be able to extract a simple and easy to mesh mid-surface while still maintaining accuracy.

2. Since Part Geometry is fairly complex, we will be extracting Mid-Surface manually.

Regions, where the thickness is more than 6 mm, is ignoring for the Extracting the mid-Surface

After MidSurfacing extraction, the geometry cleanup is performed on it and the results are evaluated to check for any abnormalities.

Geometry Cleanup: Eliminating small edges, small fillets, fixing the abnormal surface, a region where element size would be smaller than minimum allowable element size.

Topology edges are toggled on/ off as per requirement

The surface is extended and trimmed o intersect with each other as per parent geometry.

B. Symmetry check

1. In this Model, First of all, I am checking Symmetry checking. The models are symmetric in X and x directions. So I can Hide the 75% model and work only 2% model. as shown in the image below.

C. Meshing

1. After the Mid-Surface is properly extracted and geometry cleanup is performed, the various Surfaces are moved into different collectors according to their thickness. The collectors are appropriately named as per thickness.
2. The surface area meshed using the following criteria.
3. Meshing Procedure:

For a Plastic component with varying thickness as a separate collector. This way we can quickly view, hide, and mesh the surface.

The different thicknesses are allotted with a tolerance of 0.1mm so as to achieve a satisfactory capturing of the parent body int the form of mesh.

Any tapering ribs are meshed by dividing the rib into collectors accordingly to the average thickness.

Meshing Small Surfaces:

Meshing The Mid-Surface

C. Mesh Quality and Remeshing

1. After the mesh is generated, we can check the mesh as per quality criteria using the following tools:

2D Quality Index

Check Elems

Before we use these options, we have to enter the required mesh quality criteria in 2D-Elements Cleanup.

This criterion is automatically imported into the quality index option which checks the mesh quality and displays the failing elements with highlighting colour.

After Checking as per quality criteria. the following image shows the meshed complete model.

Quality Index:

Conclusion:

In Project 1, I can Understand the Topological cleanup, Meshing the geometry, and checking as per the given criteria.