Background and Objective: The relationship between rib fracture risk and Hybrid III (H3) chest deflection in a frontal crash is dependent on the type of restraint employed. In contrast, the prediction of thoracic injury based on cadaver chest deflection is less dependent of the type of restraint employed. To investigate this limitation in H3 thoracic injury prediction, this study investigates the relationship between H3 and cadaver chest deflection under loading from various restraints in matched frontal sled tests.
Methods: Chest deflection results were examined for matched H3 and cadaver frontal sled tests performed at UVA using four different test configurations: A) driver’s side position, forcelimited 3-point belt plus airbag restraint; B) passenger’s side, force-limited 3-point belt plus airbag restraint; C) passenger’s side, standard (not force-limited) 3-point belt plus air bag restraint; D) lap belt plus air bag restraint. All tests were performed with target ΔV’s of 48 km/h. For each cadaver test, Rd was defined as the ratio of maximum cadaver chest deflection (measured externally by chest bands) to maximum H3 chest deflection (measured internally by the H3 sternum “slider”) under matched test conditions.
Results: The average (and 95% confidence interval) Rd values for each test configuration were as follows: A) RdAVG = 0.66±0.30; B) RdAVG = 0.87±0.17; C) RdAVG = 0.75±0.14; D) RdAVG = 0.59±0.07.
Discussion: These analyses suggest that the relationship between H3 and cadaver maximum chest deflection is dependent on the type of restraint employed. This may result in the observed restraint dependence of H3 chest-deflection-based thoracic injury prediction. It is shown that the H3-based thoracic injury risk function may be transformed, approximately, into the restraintindependent cadaver-chest-deflection-based injury risk function using the ratios described above.