COMPARISON OF ARM UP AND DOWN IN SIDE IMPACTS WITH BIOSID AND DIFFERENT ARMRESTS

BioSID dummy tests were run with the arm down at the side during loadi ng of different armrests in simulated side impact crashes. The Hyge sl ed tests duplicated previous studies of BioSID with the arm up, SID, a nd animals. When the BioSID arm is against the side, the arm extends f rom the shoulder to the bottom of the third rib and has a steel shank covered by foam and vinyl. Loading through the arm transfers force to the three chest ribs and shoulder. In comparison, direct armrest loadi ng of the chest or abdomen primarily involves a single rib and substan tial rib deflection, when the armrest crush-force exceeds the strength of the rib. The Viscous response in BioSID showed the greatest differ ence of all criteria for the arm up or down. The response of the third rib correlated with injury risks determined from animal tests using t he different armrest designs in a simulated high position. While injur y data are not available for the arm at the side or for the armrest in the low position, the STIFF armrest may cause injury when the arm is not at the side and the armrest loads the liver and spleen. R ib defle ction in BioSID showed the protrusion of the STIFF armrest into the ab dominal region in both arm positions, because the loading was below th e arm even in the down position. However, the arm extends laterally so it involves the upper ribs earlier than in the arm-up condition where more space is available. Torso deflection showed similar maxima with the arm down and a high armrest position, because the bridging action of the arm and shoulder increases the stiffness of the dummy. The armr est designs cover a range in crush characteristics for occupant protec tion systems based on experience with other interior safety features, knowledge of human tolerance, and results of injury in animal tests. T he SOFT design was most appropriate for interior use. The STIFF design produced serious injury in companion tests with animals, and the BioS ID correctly assessed injury risk by peak rib deflection or Viscous re sponse when tested similarly. In contrast, SID and TTI(d) did not indi cate injury risks or safety performance. The current study indicates t hat response differences can be expected with arm placement, and BioSI D can assess safety implications of different armrest types and arm pl acement.