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Abstract
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This paper summarizes an analysis, design, and test project in which a dummy chest structure was developed. The chest consisted of mechanical elements that had been characterized by computer simulations as giving responses to blunt frontal impacts necessary for biofidelity.
An analysis of mechanical rib structures indicated that materials having a high ratio of yield stress to modulus of elasticity were required. Only metals having unusually high yield strengths, such as spring steels, qualified.
A mechanical system was developed with steel ribs pivoted at each end as a primary spring. A secondary spring was a pair of commercially available die springs acting in parallel with the ribs after 25.4 mm (1.00 in) deflection. A fluid damper was developed to provide the damping.
The chest structure was tested under conditions modified from those used by Kroell. The modifications were holding the spine rigidly and reducing the impact masses. The response of the mechanical system was similar to that predicted by the mathematical model. It satisfied the 4.92 m/s (11 mph) response corridor and was very near the 7.15 m/s (16 mph) corridor. Further adjustments are necessary to adapt the chest to a crash test dummy. The chest must still be tested as part of the total dummy structure under the impact conditions specified by Kroell. Testing under these conditions is necessary, but not sufficient, to assure biofidelity. |