The biomechanical response of the lower abdomen to belt restraint loading.

The biomechanical response of the lower abdomen was investigated by simulated belt-restraint loading to the lower abdomen in a supine, rigidly supported, anesthetized swine. Impacts were delivered through a belt interface to the external ventrodorsad dimension of the lower abdomen at L4. A combination of a velocity and compression varying from 1.6-6.6 m/s and 6-67%, respectively, constituted one impact. Logist analysis indicated that maximum Compression (Cmax), maximum Viscous response (VCmax), and particularly peak Force-maximum Compression (FmaxCmax), were effective correlates to injury severity at AIS greater than or equal to 3 and 4. Statistical fit to AIS greater than or equal to 4 injury probability was strongest with a multi-parametric Logist analysis of Cmax and VCmax which indicated that abdominal injury may be related to both a velocity and compression mechanism. Force-deformation curves, characterized by a gradual, almost linear rise followed by rapid unloading, provided information on the stiffness of the lower abdomen in response to belt loading. Force-deflection curves based on total load indicated a reasonable correlation (R2 = 0.61) between estimated lower abdominal stiffness and velocity.