Evaluation of Hybrid-III 6YO ATD chest jacket shape and position

Abstract

In previous work, belt fit on the Hybrid-III six-year-old (6YO) anthropomorphic test device (ATD) was found to depend on the positioning of the chest jacket of the ATD. Moreover, differences were noted between jackets manufactured by Denton-ATD and First Technology Safety Systems (FTSS). The objective of this study was to quantify differences between the manufacturers’ jackets by detailed measurements of exemplar jackets and to assess the effects of jacket installation procedure on jacket position. A custom fixture was designed to hold rigidly the thorax, pelvis, and head of a 6YO ATD while allowing the chest jacket to be installed and removed. Testing was conducted with two jackets from FTSS and one from Denton. In pilot testing, jacket position was affected by the installation procedure and by the initial position of the shoulder components. Detailed measurements were made using a portable surface measurement device (laser scanner) with each jacket in six conditions defined by initial shoulder position and the manner in which the jacket was installed. Quantitative comparisons in jacket position and shape were conducted in software using the laserscan data. Notable differences in jacket shape were observed between the FTSS and Denton jackets, with the FTSS jacket having a wider, flatter profile in the lateral shoulder area and the Denton jacket extending more forward in the upper chest area. However, the effects of jacket positioning were much larger than differences between manufacturers in jacket shape. Pulling the jacket down firmly resulted in jacket shoulder positions relative to the spine differing by more than 25 mm from those obtained by pulling the jacket down lightly, with results dependent on the initial positions of the shoulder components. The results of this study indicate that careful attention to jacket positioning is needed to obtain a consistent relationship between the chest and shoulder surfaces and the ATD skeleton. Pulling the jacket down firmly after initially placing the shoulder components in a downward/rearward position is suggested. Monitoring and adjusting the location of reference points on the jacket relative to specified hard points on the ATD skeletonprovides a means for ensuring that the jacket is consistently placed for static or dynamic testing.