Biomechanics of liver injury by steering wheel loading.

Abdominal injury induced by steering wheel contact at a velocity of 32 km/hr was investigated using anesthetized swine as the surrogate on a Hyge sled. The lower rim of the wheel was positioned 5 cm below the xyphoid. By varying wheel stiffness, wheel orientation, and column angle, resultant abdominal injury ranged from fatal or critical to minor or none. Wheel stiffness was found to be the primary determinant of abdominal injury severity. The mechanism of abdominal injury was identified to be the rim impacting the abdomen and exceeding a combined velocity and compression sensitive tolerance limit. Abdominal injury occurred within the initial 15 ms of wheel contact before whole body movement of the surrogate of column compression, which were initiated by hub contact with the thorax. The severity of abdominal injury correlated with the peak viscous response which can be represented by the product of the instantaneous velocity of abdominal deformation and abdominal compression. It did not correlate with spinal acceleration.