Structural FEA of a Stack Parking Structure with Pallet Assembly

A maker of stack parking systems asked Shirsh Technosolutions to check its structure together with the pallet assembly that carries the parked car. A stack parker holds cars one above the other, so a weak member is a safety concern before it is a warranty one.

The client wanted to know whether the structure would carry vehicle loads within its stress and deflection limits, and where to strengthen it if not. We analysed the complete assembly in ANSYS Mechanical.

We simplified the geometry to the members that actually carry load and assigned the material properties. Wheel loads were applied as concentrated loads at the wheel positions, with separate values for the front and rear axles. The structure was fixed at its bolting positions.

The first analysis showed the vertical members as the weak point, with stress above the allowable. We modified those members where needed and ran the analysis again, repeating until the stress was below the allowable and the deflection was within its limit.

Common questions

Why apply wheel loads as point loads instead of spreading the car's weight? The pallet feels the car through four tyre contact patches, and the front and rear axles carry different shares. Point loads at those positions bend the pallet and frame the way a parked car does, while a uniform pressure would understate local bending.

Why fix the model at the bolt positions? It sends the load into the foundation along the right path. A fixed support is a little stiffer than a real bolted base, so stresses right next to the supports are read with that in mind.