Loading Apparatus for High Velocity Tissue Rupture Mechanical Engineering Dalhousie University Senior Design Project Winter 2010

Group 12 Geoff Beck Ben Breen Ruth Domaratzki Rachael Schwartz

SupervisorClient  Dr. Kujath  Mechanical Engineering Dalhousie University  Dr. Lee  Biomedical Engineering Dalhousie University

Background Final Design Testing and Performance Design Requirements Budget Future Considerations Presentation Outline

Application: Determine the mechanics of high-speed failure for a biological specimen Simulate impact trauma Presently: Dalhousie BME,  max = 10 s -1 Limited by servo-hydraulic actuation method Desired: To overcome current tensile testing limitations. Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions Background

Final Design Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Final Design: Grip and Housing Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Contents Background Design Requirements Design Selection Selected Design Budget Future Considerations Conclusions Questions Final Design: Drive Shaft Assembly

Final Design: Engagement Pin Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

DisengagedEngaged Final Design: Engagement Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Final Design: Engagement Use optical encoder to determine pin position Functions using IR sensor Encoder has one hole located (180º) opposite pin position Able to sense when pin has passed solenoid Ensures the solenoid does not engage pin in a partial contact scenario Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Minimize rotating masses. Encase in polycarbonate shield. No controls in immediate area. Started and Controlled via DAQ. Final Design: Safety Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Final Design: Measurement Systems Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Final Design: Measurement Systems Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Final Design: Measurement Systems Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions Verification of LVDT data included implementing high speed video to determine velocities Flywheel angular velocity was verified comparing the controller output to the strobe frequency

Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions Final Design: Measurement Systems

Testing and Performance Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions Tested bovine pericardium tissue.

Testing and Performance Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Testing and Performance Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Testing and Performance Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Testing and Performance Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions Shadwicke RE. Mechanical Design in Arteries. K Exp. Biol. 202, , 1999.

Testing and Performance Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Testing and Performance Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions 1000RPM – 1000fps

Testing and Performance Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions 500RPM – 500fps

Design Requirements Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions Design RequirementStatus The device should fit on table top with face dimensions 30in x 30in. 23in X 22in Operator able to control extension rate Implemented frequency drive to vary flywheel speed Able to achieve a maximum strain rate of 1000 s -1 Achieved maximum strain rate of 800 s -1 Achieve a maximum of 1ms tension load application to fracture Confirmed 4ms

Design Requirements Design RequirementStatus Device should provide measurement of force and displacement with time LVDT and Load Cell incorporated in design. Data processed using DAQ The conditions of the test will be at 100% humidity and 37ºC Client selected implementation of high speed camera over conditions. Used spray bottle to keep sample at conditions. Designed to be safely operated by trained individuals. A shielding component will be incorporated if required Easy to operate. Shielding component was constructed. Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Design Requirements Design RequirementStatus Device should be accompanied by a complete instruction manual Instruction manual supplied to client Device should last five years Robust design; Given client spare critical components Meet all requirements outlined in the MECH DP 2009/2010 handbook On track to meet all requirements Total Design Requirements Met: 7/10 Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

MECHANICAL Frame Flywheel Stainless Steel Main Shaft 0.00 Other ELECTRICAL Motor LVDT & Function Generator Solenoid Frequency Controller Force Transducer Other TOTAL $ Budget Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Substitute stainless steel in place of plastic bath Reduce mass of moving parts in an effort to reduce inertia Reduce moment acting on engagement pin Create dedicated circuit boards or shield electrical components to reduce crosstalk Future Considerations Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Constructed a device that in the future will lead to a better understanding of tissue mechanics Satisfied with dynamics and control of device Several design features that our client will continue to refine and develop Gained valuable knowledge and experience Conclusions Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions

Special Thanks To: Dr. Marek Kujath Dr. J. Michael Lee Mark, Angus, and Albert Dr. Julio Militzer Dr. Darrel Doman Jon MacDonald Peter Jones Acknowledgements

Senior Design Project Team 12 Dalhousie Department of Mechanical Engineering Winter 2010 Questions?

Mechanical / Electrical Crosstalk

Solenoid Selection and Performance

Machine Status: Angular velocity of the flywheel Position of the rotating impact surface (pin) Experimental Variables: Specimen stress Standard strain gauge load cell Specimen displacement Linear Variable Differential Transformer Final Design: Measurement Systems Contents Background Final Design Testing and Performance Design Requirements Budget Future Considerations Conclusions