Week 3 - 2D meshing for sheet metal

Aim

To take the mid surface to the hood component and check the element quality criteria. The hood is an automotive component used to provide aerodynamic structure to the car and to provide safety to a pedestrian by lowering the severity of the head injury. In front-engine cars, the engine is placed under the hood. It can be opened by pulling the plug below the steering column to provide an allowance for a mechanic during services.

Procedure

Initially import CAD model geometry into ANSA. As Ansa accepts only supports .ansa, .step, .iges, .stl files. In this challenge, the model has been given in a step file. After importing of step file, the length parameter as 1 is to be provided to improve the resolution of the model. First, initially start with a single component like latch support. The thickness of the PID model is being measured according to find whether it is uniform or a non-uniform thickness. After the conclusion of the latch to be uniformly thicker about 1.75mm we extracted the mid surface by selecting faces->mid surface tool and select any one face and provide ok to perform mid surface extraction. Before extraction remove the unnecessary hot points and join the cons which were not placed near any fundamental geometry changed area. After geometry cleanup and mid surface extraction, the modal has meshed accordingly to the quality criteria as provided

S.No	Quality Criteria	Value
1	Target/Average length	5
2	Minimum Length	2
3	Maximum Length	7
4	Aspect	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

After completion of the latch model, the following procedures were being followed to further components. In hinges, the part two parts are looking identical to each other so by meshing one part can be copied or transformed using the transform option by using the default plane as a mirror plane. The outer shell of the hood is simply a plane surface with a hemming region on the edges the outer part is being meshed accordingly concerning quality criteria. The inner panel of the hood is a bit more complicated so we found the identical parts as symmetry they are being cut to decrease the time and complexity of the model so that the time required to complete the model can be reduced to 50% as the model is being split and deleted into half except the hinge area to be presented. The inner panel is being meshed accordingly to achieve the quality criteria. The meshed model is being copied symmetrically using the transform option and 3point plane selection. The copied and original mid surface model has been joined and run through topo geometry cleanup and the unmeshed surface has meshed with the target element size as 5.

Learning outcome

In this challenge, I have learned how to extract mid surface from uniformly thickness model and application of transform option such as move, copy, rotate, symmetry, etc., how to provide quality criteria and save them in file format. Learned how to use split, paste, cut macros to distribute uniform mesh flow across the model

Conclusion

The given hood structure is being meshed accordingly to match the quality criteria as above mentioned. The meshed elements were being properly aligned to give proper mesh flow.