1998-02-23

Open-Loop Chestbands for Dynamic Deformation Measurements 980857

Originally designed for measuring closed-loop contours such as those around a human thorax, the External Peripheral Instrument for Deformation Measurement (EPIDM), or chestband, was developed to improve the measurement of dummy and cadaver thoracic response during impact. In the closed-loop configuration, the chestband wraps around on itself forming a closed contour. This study investigates the use of the chestband for dynamic deformation measurements in an open-loop configuration. In the open-loop configuration, the chestband does not generally form a closed contour. This work includes enhanced procedures and algorithms for the calculation of chestband deformation contours including the determination of static and dynamic chestband contours under several boundary conditions. Accurate numerical techniques and chestband gauge calibration procedures were developed to ensure accuracy when integrating curvatures from a single boundary condition on one end of the chestband to the unknown boundary other end of the chestband.
The device demonstrated reliability and repeatability in a series of open-loop static and dynamic tests. These tests include a static open loop deformation using a sinusoidal mandrel, a dynamic test using a 127 mm diameter cylindrical impactor, and an S-shaped impactor of approximately 120 mm and 180 mm diameter at each loop. The two dynamic impactors were tested at a low velocity of approximately 4 m/s and a high velocity of approximately 6 m/s. Computer generated contours from these static and dynamic tests were compared to contours determined from high speed video analysis. A high degree of correlation was found between the two sets of contours to support the use of the chestband in an impact environment in an open-loop configuration.
Potential areas of application include the measurement of dynamic deformations during automobile toepan intrusion, the measurement of local dynamic deformation of a restraint belt, and the measurement of the dynamic deformation of dash panels under occupant knee/leg impact.

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