Development of a Strain Gage Signal Analysis Technique to Determine Time of Rib Fracture in Thoracic Impacts

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Date

2011-06

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The Ohio State University

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Abstract

In 2010, 32,788 fatalities occurred due to automobile accidents, with a large portion of fatalities resulting from thoracic injuries. Data gathered from research on post mortem human surrogates (PMHS) can be used to improve the biofidelity of crash test dummies, a tool used to increase the safety of today’s automobiles. The Injury Biomechanics Research Laboratory (IBRL) at The Ohio State University has conducted 13 PMHS tests to determine the response of the body to thoracic impacts. Strain gauges were attached to ribs to measure strain and predict the time of fracture of the ribs during the impact. However, upon initial inspection, the strain signals were not a reliable predictor of time of fracture. The purpose of this study was to analyze the strain gauge signals from previous tests to determine a quantitative measure that would signal if a fracture occurred or not. In this study, signals were compared to autopsy reports, which revealed the locations of actual fractures on the ribs. Single rib fracture studies were also completed, where ribs with strain gauges were broken ex vivo under the view of a high speed camera. From these tests, the strain gauge signal can be directly compared to the time of fracture, because the initiation of the fractures is evident on the video. Results from these tests and analysis of prior data show that there is correlation between the slope and strain drop-off in the signals and the time of rib fracture in the PMHS. The resulting quantitative analysis of the strain signals can be used to predict time of failure of ribs in past and future tests so proper injury predicting criteria of the thorax can be determined and used to improve the biofidelity of crash test dummies.

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biomechanics, rib, fracture, strain, gage

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