Design of Temperature Insensitive Ribs for Crash Test Dummies

The Isodamp damping material (also known as Navy Damp) used in the ribs of current crash test dummies provides human-like damping to the thorax under impact. However, the range of temperature over which it can be used is very small. A new rib design using laminates of steel, fiberglass, and commercially available viscoelastic material has been constructed. Load-deflection response and hysteresis of the laminated ribs were compared with corresponding conventional ribs fabricated from steel and Isodamp. Impact tests were conducted on laminated and conventional ribs at 18.5° C, 22.2° C and 26.6° C. Results indicate that the response of the laminated ribs is essentially the same as that of the ribs with Isodamp at 22.2° C, which is the operating temperature of the conventional ribs. The variation in the impact response of the newly developed laminated ribs in the temperature range of 18.5° C to 26.6° C was less than 10%. The variation was well within the allowed reproducibility range, and significantly less than the 30-40% variation seen with the Isodamp material. Repeated impact tests indicate that the new laminate construction is generally robust and provides repeatable response. FE modeling was used to predict the properties of alternative materials needed to provide adequate damping over the required range of temperature. Damping properties of various materials were evaluated using cantilever beam tests followed by single rib tests of most promising materials. This paper will present details on the design, development, and testing of the new laminate rib.