Geometry cleanup and mid surface extraction of a side door panel using three methods as per the quality criterion

Aim: To perform the mid surface extraction of the given geometry using the manual method, automatic method, and combination of auto and manual method in ANSA with a quality mesh and thickness.

Procedure:

• Initialize the given geometry in ANSA and correct various geometry errors in the model using ANSA auto fix and manual surface correction tools
• After making sure geometry is fixed and error-free using ANSA checks manager one can be procced for mid surface extraction
• The mid surface extraction depends upon the complexity of the model and the type of fillets and overall thickness of the model
• The three methods usually used for mid surface extraction are automatic extraction method, manual method, and a combination method.
• After the mid surface is extracted, as per the quality criterion is given one should mesh the model using any of the mesh techniques available in ANSA.
• Once the mesh is made, check for the off elements if any and correct them using tools like swap, mv surface, etc
• Once all the errors are removed then the mesh can be released from the model.
• The three methods for mid surface extraction used are as follows:

1. Automatic method:

• Once the given geometry is fully fixed of all the geometrical errors one can directly proceed for mid surface extraction. In this method, Use the option mid surface under the faces tab.
• Click the casting option from the menu of mid surface option then select the entire model.
• But before doing so make sure to measure the overall thickness of the model using measure tool and the weld spots tool to get the average thickness of the model.
• After the average thickness is measured then one can provide the minimum thickness asked in the option, along with element length and the type of fillet extraction required.
• Now click on the OK button and proceed with the menu till the mid surface in the form of FEM is extracted.
• This is the easiest method among the methods as it required less time and also the mesh created has the least amount of errors as compared to other methods.
• This method is not able to capture all the required features of the geometry given as we can see many of the features are either left or destroyed in mesh and mid surface extraction.
• This method requires less time but the error regarding the feature extraction is the most in this method.

2. Manual method

• In this method, one can use two options either offset or middle. Both of them are found in the faces menu.
• With the offset menu, one can select a face and then offset it with respect to the thickness of the portion of the geometry extracted.
• The offset menu doesn\'t create a separate PID as it created the mid surfaces extracted as a part of the initial geometry.
• The middle option is much more suitable if the feature to be extracted is of non-unifform thickness.
• The middle option can be used as single or multi depending on the complexity of the feature to be extracted.
• During the manual method its advisable to extract the plane area first and then go for the features.
• After the features are extracted on can use the create new planes using project option and form new faces to connect it to the base geometry.
• This is a very time-consuming method and is more accurate as compared to the other three methods

3. Auto and manual method

• In this method, the mid surface is using an auto method first and then the manual method is used to extract the complex features present in the geometry.
• In this method based on the parent geometry, one has to extract the features so that it can coincide with the parent geometry.
• The curves option is used to create the extracted feature as per the geometry and then the mid surface and the mesh is modified accordingly.
• This method takes lesser time as compared to manual method and is more error-free as compared to the automatic method.

Results

• Given geometry

• Automatic method

• Manual method

• Auto and manual method

Conclusion

1. The given geometry is cleaned up of any geometrical errors
2. Three methods for extraction of mid surface and meshing it is successfully performed.
3. The mesh for mid surfaces extracted from the three methods is done according to the quality criteria.
4. The mesh created is checked for errors and has been cleaned up of it.