Development and validation of a set of wheelchair finite element models in frontal, side, and rear impact conditions

Objective

The objective of this study was to develop and validate finite element (FE) models of commercial manual and power wheelchairs, as well as related test fixtures and tiedown hardware, to provide tools for designing integrated wheelchair seating stations for automated and other vehicles.

Methods

The manual wheelchair model is based on a Ki Mobility Catalyst 5, and the power wheelchair is based on a Quantum Rehab Q6 Edge 2.0 with Synergy Seating. A 3D Sense scanner was used to capture wheelchair geometry. Wheelchairs were disassembled into components to collect masses and additional dimensions. These geometric data were used to construct computer-aided design (CAD) models of each product. Additional fixture models were generated from available drawings for the surrogate wheelchair base (SWCB), surrogate wheelchair 4-point strap tiedowns, traditional docking hardware, and hardware meeting Universal Docking Interface Geometry (UDIG). Models were constructed in LS-DYNA. For each wheelchair, between 1 and 3 dynamic sled tests in front, lateral, and rear directions were conducted for a total of 13 tests with varying wheelchair securement methods to obtain validation data. Frontal and rear impact tests used a Hybrid III midsized male, whereas the side impact tests used the ES-2re. Validation sled pulses were nominally 20 g–48 km/h for frontal tests, 10 g–22 km/h for lateral tests, and 14 g–30 km/h for rear impact tests. CORrelation and Analysis (CORA) scores were calculated for head and chest resultant accelerations.

Results

Validation results include comparison of component masses, overall wheelchair and anthropomorphic test device (ATD) kinematics, ATD head and chest signals, and calculation of CORA scores for head and chest resultant accelerations. For the 2 wheelchairs and SWCB, total model mass was within 1% to 4% of physical mass. Across the 13 test conditions, head acceleration CORA scores ranged from 0.71 to 0.92 in 8 conditions and from 0.52 to 0.67 in 5 conditions. For chest acceleration, CORA scores ranged from 0.73 to 0.96 in 8 conditions and from 0.51 to 0.67 in 5 conditions. In addition, residual deformation was similar between test and model in conditions where it occurred.

Conclusions

These publicly available tools will allow vehicle safety engineers to design equitable occupant protection systems for occupants who travel while seated in their wheelchairs. They will also be the baseline for ongoing research to develop parametric wheelchair models for additional occupant sizes.