Rib kinematics analysis in oblique and lateral impact tests

Abstract

Understanding thorax kinematics and rib breaking mechanisms in conditions of oblique and lateral impact is crucial in safety systems development. To increase knowledge level on this subject, simulation and experimental tests are necessary. The purpose of this study was to obtain single rib kinematics in the case of oblique and lateral impact conditions using numerical simulation approach. Two impact tests using human body model of a 50th percentile man (THUMS v4.0.1 AM50) were performed in LS-Dyna R7.1.1. Impactor was a rigid cylinder with a diameter of 152 mm, and velocity equal to 6.7 m/s. Impact angle measured to sagittal plane was 30 and 90°, respectively in oblique and lateral impact case. Kinematics of ribs from 3rd to 6th were analyzed. Results shown significant similarities between oblique impact and kinematics of ribs tested in frontal impact conditions in the literature, with maximal costochondral joint displacement relatively to costovertebral joint varying from 65.4 mm (3rd rib) to 82.0 mm (5th rib). Deformation of rib in lateral impact conditions was different than during oblique impact test, with distinctive "flattening" approximately in the middle of the rib. Maximal relative displacement varies from 16.4 mm (6th rib) to 26.6 mm (5th rib) and its location depends on the analyzed rib. Oblique impact scenario may be simulated for the single rib on an experimental way using set-up of the frontal impact. Experimental simulation of the lateral impact for the single rib should not use the same set-up, as the kinematics analysis showed significant differences between simulated cases.