Project 2
MODELLING REAR SUSPENSION WITH CONECTIONS
AIM :
The final achievement in this project is to check for the geometry errors, mid surfacing in required areas (where part is less than 6mm) and others can be solid meshed and all the connections (like rigid bolt, weld, cluster connections) should be given properly so that model should be prefered for the analysis.
PROCEDURE :
Basically this project is a combination of many modules to work on like shell mesh, solid mesh, connections using nastran deck and we can just go with a some predefined process like geometric checks, extracting mid for required areas, solid mesh for other areas and then connections.
1. GEOMETRIC CHECKS:
The basic thing when the model is imported that should be refined with perimeters and macros using mesh module-length so that the model can be converted into a good refined one and can be worked on conveniently with it.
Now here firstly thing that can be done is to check for geometry errors like single con, triple con, unchecked faces, overlapping faces if any in the model and that can be rectified using the specific tools like paste, release etc., and can be proceeded further.
After this all the components of the model should be assigned into a seperate PID's so that working on the components will become much easier.
Below is the image showing the each and every component that is kept in seperate PID's.
The below image shows the model before and after the geometric checks :
2. MEASUREMENTS :
After carried out or clearing the geometric errors taking the measurements of each and every component and saving is very important so that can be used for the future reference.
Below is the images shown of the sample measurings of thickness of all components :
3. MIDSURFACING :
After taking the measurements the parts which are less than 6mm should be extracted with mid surface and the remaining surfaces should be carried out with solid meshing. The some of the components of the model like base frame, plate consisting in the spring rod were taken as mid as they are falling under <6mm thickness.
The below are the images of the mid surfaces extracted :
So before going to the meshing there is one important thing that should be given is mesh parameters and quality criteria for the mesh so that errors or quality issues occured can be rectified with the quality criteria given.
4. QUALITY CRITERIA :
There are different types of components in this model that should be meshed and according to the type of component quality criterias were given for which is solid or shell meshed. Below were the images of the Quality criteria that are prefixed for this model. The quality criterias for different components were given below :
5. MESHING :
The next process that is one of the important phase to be carried out is meshing as there will be two types of meshing in this model that is shell mesh and solid mesh.
SHELL MESH :
Before carrying out with the shell mesh the mesh perimeters and macros should be set to the target element length and the using different meshing alogarithms mesh is applied to the mid extracted surface. Below is the meshed surfaces of the mid surfaces extracted.
SOLID MESH :
So in the solid mesh the components which are >6mm in thickness throught uniform that can be rearranged with lines and mesh is imposed on to the model, so here in solid the mesh tria and ortho tria elements were used to mesh, but most of the parts if there is a curve features ortho tria meshed is used and some flat faces tria elements can be used and final theme should be achieving the better mesh flow and eliminate the quality issues.
After mesh is imposed and reconstructed to elimate the errorsthen in volume module the hollow shell component should be defined with the volume and set a PID for that volume then that volume component is meshed using the tetra rapid mesh or tetra fem meshing alogarithm so that the volume defined is meshed.
Then the volume which is meshed should mainly checked for the TET collapse issues and should be rectified so that no quality issues were occured.
Below were some of the images of the solid meshed components shown :
6. CONNECTIONS :
Basically this was the final most part of this modelling which provided the connections i.e., it acts as a joint medium between two un attached parts. This connections between the different components of the model can be found in the deck called Nastran deck where we can give bolted, welded, cluster connections that represent the connections when analysis is carried out.
Below is the image showing the connections deck :
some of the connections in the model ca have the mechanisms that can be represented by the cluster RBE2 elements and if any springs were to be represented those can be represented by CBAR elements.
The some of the types of connections like cluster, cbar, were shown below in form of images :
These were some of the connections which are mainly important for the suspension model and others were bolted with rigid connectons to fix and arrest the degrees of freedom.
CONCLUSIONS :
Though there were most of rigid connections due to some of the irregular cad i.e., mismatching of holes at rim part can be rectified for achieving the better connections and all other connections given in this model is satisfactory.
LEARNING OUTCOMES :
- Learned to recreate the defective faces which are given in the cad surfaces.
- Learned to analyse the models more effectively and defining them into different PID's.
- Learned to choose better that which meshing to be done for which components.
- Improved to analyse in giving apt results in connections.
LINK FOR THE MODEL :