Week 12:Project-1-Meshing of Door Inner Panel Challenge

AIM - To extract the mid surface of the given plastic component Side door and mesh the model acc. to given quality criteria and assign the thickness.

Follow the Quality Criteria and mesh the following component and assign thickness:

Target Element Length = 4 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	6 Units
7	Min angle Quad	45
8	Max angle Quad	135
9	Min angle Tria	20
10	Max angle Tria	120
10	Tria %	10

PROCEDURE -

Import the CAD model - First we import the CAD file into hypermesh by using import geometry in the menu bar.

Fig.1

In order to extract the midsurface we make sure that the CAD model imported is free from topological errors like, free edges, crack , missing surface , duplicate surface or any deformation occurs in the surface while importing the file into hypermesh . if any such errors are present then eliminate those errors in the model . Also remove the surface fillet in the rib or parent surface in order to capture the feature properly in midsurface . for removing fillet goes into geometry > Defeature > surface fillet > find fillet in selected and choose the surface and give min. value 0.1 and max. value 15 and then find and surface fillet got selected and removed.

Fig.2

Extraction of midsurface:- Now the given plastic component is free from topological errors , now we can proceed to extract the mid surface of the component. First we extract the midsurface using the auto extraction method.

So in mid-surface by auto extraction method there are some surfaces that get overlapped and some surfaces get distorted and missing due to the complexity of the model so now we delete the midsurface and create a midsurface by manual techniques. Now we use an offset option to get a midsurface for that first we measure the thickness of each component , it's a plastic component so thickness is varying in each part. first we offset a base surface which is 2.8 mm thick . press shift + F9 or go to surface edit > offset > Continuous offset > select as surface > duplicate the surface > give offset value (half of 2.8 ) > choose vector direction > offset.

Fig.3

For extracting a mid surface of rib we also used the offset option and for linear rib we also used another command which is in Midsurface > final edit tools > select both side of surface > extract.

fig.4

now extend the rib to the base surface by using extend option which is in geo. > surface edit > extend > choose extend over edges > choose surf to extend is surf. to target . select the free edges line in line to extend over and select a surface over which line is extended in surf. to target then extend.

fig.5

Then we have to mesh the complex surfaces first in order to maintain the proper mesh flow and make meshing easier. While meshing the midsurface we make sure that we maintain the trias percentage as low as possible. while meshing curved or complex surfaces, if the mesh doesn't properly catch the surface then we increase or decrease the node count so that mesh attaches the surface properly.

Then eliminate the failure element as per given quality criteria - After meshing the midsurface we check for element failure as per given quality criteria .This is performed in 2D > quality index > check element. We use various options like swap edge, drag element, split element etc in order to eliminate the errors caused due to violation of quality criteria we eliminate the rotating quads and trias present near the free or feature edges. We also reduce the trias concentration by dragging the trias to the free ends or combing the opp. trias by dragging them near to each other. There may be a lot of quality errors which fail for warpage ,min. length, max. length, aspect etc, so we rectify all the quality errors by using quality tools. Min. or max. length error can be rectified by increasing or decreasing the distance between two nodes. After clearing that many error you have meshed model looks like this

Fig.6

Assign the thickness to model and convert shell element into solid elements - After completion of meshing, now we assign the thickness to midsurface. After assigning a thickness to the model its looks like this in fig.7

fig.7

RESULT :- As per the given quality criteria we achieve whatever we want from our model.

FINAL MODEL IMAGE :-