Logistics Information

Quick Links

Chassis Reinforcement Attempt 1 meeting - Mechanical - Confluence (atlassian.net)

https://docs.google.com/document/d/1B2brtRLK9Q83bQ87CmbALqR1k8uJYuV-0p5O8A_-x6Q/edit

https://docs.google.com/presentation/d/1QQaFrP_eXH-VLmBz8twwj8uvzSL7mxke4xi0hvFKOWw/edit#slide=id.ge4b8a20e23_0_27

Working Session Goals

1. Review sheet metal solution FEA that was completed by Min

2. Review previous Chassis simulations completed by Jason (MS14) and Matt, Shalin (MS12)

3. Try to insert current sheet metal model into old simulation setups to see if results will change

4. Investigate sheet metal solution by using a single sheet metal that is similar to BP (bonded to all tubes), but make it out of steel instead of composites

5. Arrange detailed FEA review meeting with Mech Advisors to discuss steps and next results
   Update team on slackReinforcement Rev 2.0

1. Reviewing Sheet Metal Solution FEA

...

Section Reviewed	Notes
ACP (Pre)
Engineering Data	Material data seems ordinary 4130 Chromoly - Yield Strength - 435 MPa Structural Steel - Yield Strength - 250 MPa
Geometry	Note: When Kimberly was working on collision setup, she found that the tube elements weren’t all properly connected Using the Prepare > Beams > Connect feature, it is shown that not all beam elements are connected properly. This may have been fixed when contacts were later applied under ACP (Pre) Model Setup, but efforts will be placed to correct these errors right now. Image RemovedImage Added After modifying the beam elements, number of gaps have greatly reduced Image RemovedImage Added
Model	Contacts have been automatically generated for all bodies Contacts are all bonded This can cause error or inaccuracy because this results in contacts being formed between objects that are actually not in contact. FIX: Create automatic connections with specific bodies in mind. Use manual contact regions if necessary. E.g. A separate connection group for gussets, bulkheads Note: I still feel some uncertainty regarding how to fully check that all the correct contacts have been made in a time efficient manner (as opposed to checking every single contact). Soln: check every suspicious tube Double Soln: Run the simulation and check if tubes deform weirdly. If they do, it’s probably because it has been unreasonably contacted. Mesh size: 15 mm
Setup	This is the standard stackup for A, B, C bulkheads The fibres in the ModelingGroup.Ply are showing up correctly
Static Structural (B Pillar)
Static Structural Model	See Note below
Static Structural Setup	Static Structural Solution/Results
Static Structural (Side 60)
Static Structural Model	Static Structural Setup	Static Structural Solution/Results
Static Structural (Top 30)
Static Structural Model	Static Structural Setup	Static Structural Solution/Results

Concluding Note:

I have tried to review and edit the simulation file so that it is fixed with better space claim geometry and contacts. The initial goal was to hopefully see that these fixes would improve results and get more accurate solutions.

For some reason, I still have solver pivot error due to an under constrained model on a tube that has so many contacts. This shouldn’t be happening because the tube has been constrained with so many contacts. There is no way for it to fly into space.

At this point, I conclude that it is not worth trying to solve these errors and move onto the next task.

Min’s original simulation is able to compile and have solutions. This means that I will use that file for the next tasks and investigations.

Update:

Asked Min if there existed a compiled solution sims. Unfortunately it somehow got lost.

Back to troubleshooting

Found this resource that taught about this contact tool to check contacts:
A solver pivot warning or error has been detected — Ansys Learning Forum

Need to learn more about how to resolve these contact issues.

2. Review Previous Chassis Simulations

MS14

MS12

3. Inserting Current Solution into Old FEA Setups

4. Sheet Metal Inquiry

5. Setup Detailed FEA Review Meeting

Resources

1. Mech Advisor Contact List - Mechanical - Confluence (atlassian.net)

2. Facebook group chat

Plan

1. Looking to finish work deliverables tonight

2. Look to schedule detailed FEA review meeting for Monday, July 19, or Tuesday, July 20

3. Send out messages and arrange meeting by end of day Saturday, July 17

   1. Chassis Specialty People: Matt, Shalin, Jason

2. Review Previous Chassis Simulations

I don’t think this is worth the time.

Better to focus on current solution

MS14

MS12

3. Inserting Current Solution into Old FEA Setups

I don’t think this is worth the time.

Better to focus on current solution

4. Sheet Metal Inquiry

I don’t think this is worth the time.

Better to focus on current solution

5. Rev 2.0

...

I added a reinforcement in the middle to see if it lowers stresses because it would distribute forces more.

It was found that stresses were the same or increased.

It was also found that some scenarios had the reinforcements suppressed for some reason.

Reconsidering how the fixed boundaries and accelerations are done.

I also played around with the masses. Observations based on Top 30. One of our worst cases.

With all masses suppressed, stresses are below 415 MPa (max 350 ish)

If only front 2 passengers is enabled, it reaches like 1000 MPa.

With only battery box enabled, it reaches like 700 MPa.

I believe how we assign the mass is greatly influencing the stresses.
The current geometry assignments for mass are very concentrated.

When we had the bottom panel, the faces on its surface could be used as geometry assignment which distributed the mass vastly.

6. Rev 3.0 - Surfaces for distributed masses

All these stresses are higher than the 1.0 setup mentioned in step 1.

It is worth noting that the surface used was 1 inch thickness using foam density meaning there is extra mass.

Although it does seem to prove that surfaces do not have a major effect in reducing stresses.

7. Notes for Later

Stackup of A, B, C Bulkheads for Min’s sheet metal solution FEA
Purpose: Put really thin layers in the explorative FEA (step 4)

...