Week 12 - Project-1

Link for the files- https://1drv.ms/u/s!AlDYq9nTGAGChAR1ndeubGAa_LN3?e=aa70Tb

Objective : To create a 2D shell elements in the side door of a car according to the given quality criteria and assign thickness to different parts of the geometry

Procedure :

• Open the given geometry of the plastic Side door of a car in Hyper mesh. The geometry is incomplete with missing surfaces and is distorted in some regions.
• The geometry is a plastic component and hence it has a variable thickness.
• Clean up the topology of the parent CAD by using the options under the geometry menu and tools menu

Extracting mid–surface of component

• In order to extract the mid surface we first make sure that the model is free from errors
• Then we extract the mid surface using auto mid surface options in geometry panel.
• But here this method is failed because of the complexity of the model. Hyper mesh fails to properly midsurface the components.
• There is another option left with us to go for manual midsurfacing for that first check the thickness of the components. It can be found out using the distance option
• Then for manual midsurfacing we can use the OFFSET option in SURFACES EDIT By pressing SHIFT+F9.Place the radio button in OFFSET and select the outer surfaces of the component and duplicate it to the current component and type the distance as half of the thickness and check the normal using vector normal option and if the vector is not in the required direction then reverse it by using the reverse normal option and hit OFFSET.That will give us the required midsurface.
• Repeat this step for all the surface and generate a uniform midsurface of the whole model
• There are ribs in the model which needs to connect to the base surface. For that follow one of the following step
• Surface edit -> extend -> select surface to be extended -> select base surface -> extend
• Surface -> Drag along vector -> select the base line along ribs -> give distance -> MMB. No surface edit -> trim surface with surface -> select both the surface -> trim. Delete additional surfaces
• The Yellow line should appear at the intersection of ribs and base surface.
• Remove all these issues before the process of meshing we need to do the topology clean up.
• We can use EQUIVALANCE option in edge edit, TOGGLE option in quick edit can also be used, if these two can’t solve the problem we can make use of spline and ruled surface options in SURFACE panel. Also, we can use the replace point option in quick edit tab.

Meshing and Quality check for the component

• set meshing parameters and Quality criteria under preference menu.
• we have entered the required criteria, we can go on to mesh the mid-surface that we have generated.
• For meshing, the auto-mesh options under the 2d menu were used. the target length was kept as 5mm and the element type was set as mixed so that we can avoid rotating quad as far as possible
• Then the whole surfaces got meshed. With the radio button in density we can clean change the nodal densities at various locations so as to get a smooth mesh with lower number of trias. Before accepting the mesh we should change the densities in such a way that the maximum tria removal is possible. Then accept the mesh. Reduce the maximum number of trias in the model with proper remeshing technique.
• Try to avoid rotating quads and tria elements as far as possible.
• we should make them follow the quality criteria .For that the tools used are:
• Replace node option. For that PRESS F3 the replace the nodes with each other
• Go to QUALITY INDEX then use ELEMENT OPTIMISE ,this is used to optimize the elements based on the criteria we typed in the criteria file settings in the preferences option in menu bar.
• Also we can use place node option in clean up tools in quality index. We can move the node along the surface /Normal to surface to optimize the element.
• Also smooth tool in TOOL panel also can be used.
• PRESS F5 which is the mask option so we can save the elements from check elements tab and then we can retrieve those elements using mask option, and we can work on those failed elements without disturbing the other quality elements.
• Eliminate the tria using Quality setting > clean up tools> drag tria elements
• Smooth the mesh for proper mesh flow.
• we need to EQUIVALENCE the elements at the middle. Since the proper connectivity between the exact. For this Go to TOOL panel>FIND >choose FIND EDGES>PREVIEW EQUIVALENCE>EQUIVALENCE. This will ensure there are no free edges in between elements.
• The whole component is now meshed according to the required quality criteria

Assign thickness to the individual component

• Create different property file with different thickness and colour code it similar to its component colour for simplification
• Assign these properties to respective component
• Check using display 2D mesh option to check for the thickness in mesh
• Select the 2d traditional and detailed element representations to preview the thickness assigned to the component.

Conclusion:

This activity helped us understand the basic procedure to mesh the component with variable thickness using manual midsurfacing and manual meshing and controlling the mesh quality for such complicated geometry.