OBLIQUE AND LATERAL IMPACT RESPONSE CHARACTERISTICS OF A DENUDED PMHS THORAX A Thesis Presented in Partial Fulfillment of the Requirements for The Degree of Bachelors in Science with Distinction in the Undergraduate School of The Ohio State University By, Geoff Brown ************ The Ohio State University 2008 Honors Examination Committee: Dr. John Bolte, IV, Advisor Dr. James Schmiedeler Approved by _________________________ Advisor Department of Mechanical Engineering Abstract Thoracic trauma is directly responsible for 25% of all trauma related fatalities and indirectly contributes to another 25%. Since most thoracic trauma is caused by automobile crashes, the need for accurate data regarding thoracic impact grows continuously as more and more cars are on the road. Many of these automobile crashes are side impacts, which lead to a primary direction of force on the person inside to be oblique and anterior to lateral. The purpose of this project is to determine the response of a denuded human thorax to oblique and lateral blunt force impacts. Specifically the project will focus on the linear and rotational stiffness characteristics of a denuded post-mortem human subject (PMHS) thorax. There is a lack of data regarding anterior oblique and posterior oblique thoracic impact response characteristics and this project will focus on obtaining the response of the PMHS thorax to these types of impacts. The current impact tests and anthropomorphic test devices (ATDs) account for frontal and lateral direction crashes only. Response in the oblique direction was previously assumed to be similar to lateral responses, but new research has shown that this may not be the case. This project consisted of both designing the fixture to be used to support the thorax during testing as well as the experimentation and analysis of the results. The thoraces were obtained from fresh post-mortem human subjects and all research was done at the Injury Biomechanics Research Laboratory (IBRL). The data from this project will be used in conjunction with results from other projects at the IBRL in order to determine a more accurate definition of the biomechanical response of the human thorax during a vehicle crash. This data can then ultimately be used to create a new anthropomorphic test dummy thorax for use in crash testing. 2 Dedication Dedicated to my friends and family who were always there to provide support. Without them I never could have completed this research. 3 Vita August 29, 1985……………………………………….……………………Born- Hamilton, Ohio Fields of Study Major Field: Mechanical Engineering 4 Table of Contents Abstract ........................................................................................................................................... 2 Dedication ....................................................................................................................................... 3 Vita .................................................................................................................................................. 4 Fields of Study ................................................................................................................................ 4 List of Tables .................................................................................................................................. 7 List of Figures ................................................................................................................................. 8 1. Introduction ........................................................................................................................ 10 2. Anatomy ............................................................................................................................. 12 3. Background ........................................................................................................................ 15 a. Studies completed prior to 2006 ..................................................................................... 15 b. Shaw et al. 2006 ............................................................................................................. 16 4. Fixture Design .................................................................................................................... 21 a. Design Conditions .......................................................................................................... 21 b. Initial Design used for first test ...................................................................................... 21 c. Design changes between first and second test ............................................................... 26 5. Methods.............................................................................................................................. 29 a. Dissection Procedure ...................................................................................................... 29 b. Attachment Procedure ........................................................................................................ 33 c. Instrumentation .................................................................................................................. 35 d. Testing Methods................................................................................................................. 38 i. Subject Information ........................................................................................................ 38 ii. Test Information ......................................................................................................... 38 iii. Data Collection ........................................................................................................... 39 6. Results ...................................................................................................................................... 40 7. Discussion ................................................................................................................................ 51 a. Conclusions ........................................................................................................................ 52 List of References ......................................................................................................................... 53 Appendix ....................................................................................................................................... 55 5 a. Dissection Procedure ......................................................................................................... 55 b. Attachment Procedure ........................................................................................................ 59 c. Test day Checklist .............................................................................................................. 60 d. Data Processing Script ....................................................................................................... 65 e. Data Analysis MATLAB Script ......................................................................................... 74 6 List of Tables Table 1: Shaw et al. test matrix [4] ............................................................................................... 17 Table 2: Subject Information ....................................................................................................... 38 Table 3: Test Matrix..................................................................................................................... 39 7 List of Figures Figure 1: Primary Direction of Force during Side Impacts [4] .................................................... 11 Figure 2: Anterior View of Thoracic Skeletal Structures [6] ...................................................... 12 Figure 3: Posterior View of Thoracic Skeletal Structures [6] ...................................................... 14 Figure 4: Pendulum Test -- Pre-test view [4]............................................................................... 18 Figure 5: Oblique and Lateral Chest Band Contours [4] ............................................................. 19 Figure 6: Force vs. Deflection Corridors for Oblique and Lateral Impacts [4] ........................... 20 Figure 7: Initial Fixture Design.................................................................................................... 23 Figure 8: Close up of Sternum Support Hinge............................................................................. 24 Figure 9: Fixture w/ Thorax attached and sternum support ......................................................... 25 Figure 10: Assembled Fixture -- after design changes ................................................................ 27 Figure 11: Close up view of lower sternum plate support ........................................................... 28 Figure 12: Dissection -- Skin removal from back ........................................................................ 30 Figure 13: Lamina and Spinous Process ...................................................................................... 31 Figure 14: PMHS Thorax just after removal w/ intact diaphragm .............................................. 33 Figure 15: Thorax attached to fixture using spacers .................................................................... 34 Figure 16: Strain Gage and Photo Target Placement ................................................................... 36 Figure 17: Sternum Accelerometer block ...................................................................................