To Compare the physical Vibration test results and arrive at a Finite Element Model which matches the Physical test results. Using this as reference, the customer wants to run reliable tests using the simulation technique. The main requirement is the achieve complete NVH analysis of the BIW along with the cross-members. This would include a variety of different steps such as 3D scanning, reverse engineering, vibration testing, CAE analysis, material testing, obtaining data regarding the mechanical properties of each part after material testing, and finally BOM has to be prepared.
Scope of work
The Scope of work that we had accepted includes
•Full Vehicle Teardown & Teardown documentation
•Stagewise 3D Scanning with necessary referencing for part level scanning & alignment.
•Creation of Level wise Bill of Materials to correlate sub assembly modeling & Assembly documentation, Material composition analysis & Grade identification, Suggestion of Alternatematerials, Correlation of Grade physical properties with actually measured properties on critical parts.
Tools Used for specific activities
The tools used during this process were :
1.COMET L3D blue light scanner :Scanning is the process of capturing a multiple number ofpoints from the surface of the part and forming point cloud data which later after processing is used asan STL file to do reverse engineering(CAD modeling). 2.Geomagic Design-X 3D software :This software is used for reverse engineering. With the help ofthis software a cad model is prepared from the STL file. 3.Solid Works :This software is used for assembly alignment. 4.Mechanical toolssuch as grinding machine, drilling machine, gas cutter, hammer, chisel, etc. 5.Vibration testing equipment kit. 6.Spectrometer :This machine is used for material testing(chemical composition). 7.Universal Testing Machine :This machine is used to obtain the value for tensile strength, yieldstrength, and elongation. 8.Total Materia :This tool is used to obtained the grade of the material according to their chemicalcomposition as well as the mechanical properties of the material.
1. 3D scanning of car in assembly position
The first step of this project is 3D scanning which involves a series of steps such as:
• Cleaning of the car.
• Pasting target stickers on the surface of the car, which are used as references for scanning.
• After sticker pasting is done, white powder is sprayed on the car which aids in the scanning of the surface of the car.
• Then the scanning of the full car is done.
2. Tear Down
• After the scanning of the full car in assembly position, the car was torn down to BIW level. Once again, it has to be scanned in BIW condition with cross members.
3. Scanning of BIW with cross members
• Next, the scanning is done for BIW with cross members. This is done for the inner surface, the outer surface, and the underbody surface of the car.
4. Scanning of BIW without cross members
• The area which is covered by cross-members and not scanned is now scanned after the removal of the cross-members. This completes the scanning of the BIW in assembly position.
5. Scanning of individual cross-members
• When the cross-members are removed from the assembly they are not fully scanned. This way, each cross-member can get scanned individually after it gets removed from the BIW.
6. NVH testing
• Actual NVH testing is performed to authenticate the accuracy of the simulation results.
7. Tear down of BIW to individual parts
• After the BIW and cross-members were completely scanned, the BIW and each of the cross-members were torn down into individual parts.
• While removing each individual part the thickness, weight, and different types of weldments (spot weld(2T &3T), laser weld, arc weld and plug weld) is noted down for each part.
• BIW parts are segregated into seven different sub-assemblies which are :
Side outer LHS panel assembly, Side outer RHS panel assembly, Roof assembly, Dash and Cowl panel assembly, Rear panel assembly, Floor assembly and Engine compartment assembly.
• Cross-members are segregated into five different sub-assemblies :
Front bumper guard assembly, Rear bumper guard assembly, Front suspension cross-member assembly, Rear suspension cross-member assembly, and Instrument panel assembly.
8. Scanning of individual parts
• The individual part that gets dismantled from the BIW or cross-members assembly. The individual part then gets scanned which aids us in individual part modeling.
9. Cad modeling
• BIW cad modeling is done assembly-wise such that all the parts and sub-assemblies are perfectly assembled considering the actual thicknesses and the thickness directions.
• All the parts are model and it is shown bellow as outer panels, inner panels and underbody panels which also includes floor panels. Similar to BIW, cross-members also get modeled taking care of all the procedure followed in modeling during BIW.
• All the five cross-members are modeled and shown below :
10. Material testing
• Material testing is done for getting the chemical composition for all the individual parts of BIW and cross-members. The machine used for getting chemical composition is Spectrometer.
• With the chemical composition the materials is segregate into different grades. This is done with the help of a tool called “Total Materia”.
• During the process of Material analysis, we identified thirty different grades in this vehicle.
11. Tensile testing
• Tensile testing is done to get the tensile strength, yield strength and elongation percentage.
• Tensile testing is done for each grade and the machine used to do this is Universal Testing Machine.