Week 12:Project 2-Meshing of Rear Wheel Holder challenge
AIM - To mesh the rear wheel holder of a car following the element quality criteria given.
OBJECTIVE - To mesh the given model of rear-wheel holder following the element quality criteria are shown below and to assign required thickness to the component.
Target Element Length = 5 Units
| S.N | Quality Criteria | Value |
| 1 | Aspect Ratio | 5 |
| 2 | Skewness | 45 |
| 3 | Warping | 15 |
| 4 | Taper | 0.5 |
| 5 | Min. Length | 2 Units |
| 6 | Max. Length | 8 Units |
| 7 | Min angle Quad | 45 |
| 8 | Max angle Quad | 135 |
| 9 | Min angle Tria | 20 |
| 10 | Max angle Tria | 120 |
| 10 | Tria % | 10 |
INTRODUCTION - A combination spare wheel holder and step for use with a vehicle bumper having an upright rear edge, comprising a wheel holding frame having an upper end portion and a lower end portion provided with a frame extension having a bottom end, a flat step surface on said wheel holding frame adjacent said upper end portion, means on the other side of said wheel holding frame from said step surface for detachably supporting a spare wheel thereon, and means arranged to pivotally attach said wheel holding frame at said lower end frame extension to the bumper whereby said wheel holding frame is rotatable between an upright position and a substantially horizontal position, said flat step surface being arranged to face upwardly in a horizontal position of said wheel holding frame to serve as a step surface, said frame extension terminating at its bottom end in a flat edge disposed substantially in a horizontal plane in the upright position of said wheel holding frame, the pivotal axis of said frame being located above the flaT bottom edge when the frame is in an upright position, said flat bottom edge being arranged to engage against an upright surface supported by the bumper in the horizontal position of said wheel holding frame to hold the latter in stopped horizontal position.
There are some terms that are important for the quality criteria are:
warpage - whenever we have a quad element in two different planes then we will have the element failing for warpage. Ideally, the element should be in a single plane, when they are in two different planes and if we split the quad along the diagonal and measure the angle between the normals it will give the element warp angle.
skewness - skewness is the quality of elements in terms of angle. For a quad element the skewness will be:
skewness = 90 - (θmin)(θmin)
Aspect ratio - The aspect ratio is the ratio of maximum length to the minimum length. when you see a quad element one side smaller than the remaining three sides then the element will fail for aspect ratio.
Jacobian - The deviation of the element from the ideal shape is measured through jacobian. The ideal value of jacobian is 1.
PROCEDURE - I will start by importing the geometry as a rear-wheel holder model is given to me. so for importing the geometry, I will go to import and select the file. The model after importing is shown below:
Now before extracting the mid surface I will do the geometry cleanup that will also involve defeaturing the geometry because in the model there are some features that will cause element failures. So I will manually clean the geometry using the quick edit panel, surface, defeature, etc commands. The model after the geometry cleanup is shown below:
After the geometry cleanup is done I will extract the mid surface of the component. so for extracting the mid surface I will just go to the mid surface under the geometry section and select the method of extraction as skin offset. The mid-surface of the component is shown below:
After extracting the mid surface I will just mesh the component. But before meshing I will create the criteria file according to the element quality criteria given. The criteria file is shown below:
For meshing, I will go to auto mesh and specify the target element size as 5 units and will start meshing the surfaces. After meshing the component is shown below:
After the meshing is done I have to check for the element failures. so for that, I will to tool and then check elements and see which are the elements failing and will rectify those element failures. For rectifying the element failures I will use the following commands.
- Drag tria command under the quality index
- Element optimization under the quality index
- place node command under the quality index
- Translate command to translate nodes. This command will be under the tool section
- smooth command which will smooth the mesh and ultimately remove the element failures
- Element edit command to split, create and combine elements.
so using the above-mentioned command I will clear the element failures. The final mesh of the rear wheel holder component free from any element failures is shown below:
Now I will assign thickness to the component as the rear wheel holder is the sheet metal component so thickness will be constant. For assigning I have to create a property and specify the thickness and assign it to the component. The property is shown below:
After assigning the property the component is shown below:
RESULT - The final thickened mesh of the rear wheel holder component is shown below:
CONCLUSION - The meshing of the rear-wheel holder of a car has been completed successfully and the thickness was also assigned to the component.