TESLA | UNDERSIDE ABUSE FIXTURE

When a battery pack is tested outside the vehicle, the boundary conditions change. The pack no longer sees the stiffness and constraint of the surrounding monocoque, and its structural response under abuse loads shifts. A fixture that is too stiff will over-constrain the pack and mask real failure modes. A fixture that is too compliant will let the pack deform in ways it never would in the car. Getting this right is the difference between a test that tells you something useful and one that doesn't.

I designed an underside abuse fixture whose stiffness is tuned to match the bending behavior of the vehicle monocoque at the pack mounting interface. This required working through the structural stiffness of the vehicle architecture, translating that into a fixture geometry, and iterating until the fixture-to-vehicle stiffness match was within an acceptable range. The work involved hand calculations, CAD modeling, and close collaboration with the crash safety and test engineering teams to define load cases and acceptance criteria.

Fixture design for crash-level abuse testing is deceptively hard. The loads are high, the failure modes are violent, and the fixture has to survive repeated tests without drifting out of spec. Every design decision — material choice, fastener layout, stiffener placement — feeds back into the boundary condition the pack sees. This project taught me to think about test design as a structural problem in its own right, not just a jig to hold the part.