LARGE VEHICLE BRACKET DESIGN
Pneumatic systems support bracket design and modal analysis
Collaborative Project - Sep 2021 to Dec 2021 | Modal Analysis | CAD | Vibration Testing
Summary
Let's shake it up.
My second task at Tesla was to design a vibration test fixture for large vehicle pneumatic system subassemblies to troubleshoot current fatigue failures seen in road testing. During the test, I offered to redesign a couple of structural brackets based on the failure analysis of vibration tests. To design these new brackets, I taught myself modal analysis within a week to ensure all my designs were properly tested before installing them on the fixture.
Fixture Design Objectives
Resist Bending
High Weight Capacity
Cheap
Bracket Design Objectives
Increased Stiffness
Simple Geometry
Easy-to-install
Test Fixture
More steel tubes...
Sketches
Similar to the pressurized bend test fixture, I used steel tubes to create the structure because of their stiffness and price.
CAD Model
Prototypes
Time to improve our current designs!
Troubleshooting
The brackets that were failing during the vibration test had a natural frequency similar to the frequencies the system was excited to during the test. This caused the bracket to vibrate with resonance and achieved fatigue failure much quicker than originally anticipated.
Therefore, I needed to increase the stiffness of the bracket by changing its geometry to increase its natural frequency above the vibration profile's frequencies.
Increase Stiffness
Increase Natural Frequency
Quantifying Stiffness
As I started to develop new bracket designs, I wanted to get an approximate bending stiffness to see how the stiffness would change with each new geometry.
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Define stiffness about point A
Modal Analysis
Now for the fun part - design and iteration. I went through several different bracket designs until I found one that was stiff, simple, and easy-to-fabricate.
Original Design
Flimsy
Complex
Difficult to fabricate
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Final Similation Results
For NDA purposes, I cannot share any more data other than screenshots.
Highlights
Shake it up...
Vibration Test Fixture
Designed a stiff and durable test fixture that could withstand intense vibration testing while supporting heavy assemblies without bending or deforming
Assembled and installed large pneumatic systems by hand
Worked tireless hours to rework the failing sub-assemblies to keep the whole test running
New Bracket Design
Devised a method to quantify the stiffness of each bracket iteration to better understand why the natural frequency was changing
Created a modal analysis simulation that accurately reflects the boundary conditions of the vibration test
Developed 7 versions of this bracket and fabricated the final design for further vibration testing
Presented final designs and simulation results to the reliability and testing team