Loading Apparatus for High Velocity Tissue Rupture

Mechanical EngineeringDalhousie University

Senior Design ProjectWinter 2010

Group 12

Geoff Beck

Ben Breen

Ruth Domaratzki

Rachael Schwartz

Supervisor Client

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, emax = 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

Disengaged Engaged

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 scenarioContents

• 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, 3305-3313, 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 Requirement Status

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 Requirement

Status

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 Requirement

Status

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 50.00

Flywheel 40.00

Stainless Steel 173.00

Main Shaft 0.00

Other 536.00

ELECTRICAL

Motor 230.00

LVDT & Function Generator 800.00

Solenoid 16.00

Frequency Controller 335.00

Force Transducer 260.00

Other 35.00

TOTAL

$2475.00

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 KujathDr. J. Michael LeeMark, Angus, and

Albert Dr. Julio MilitzerDr. Darrel DomanJon MacDonaldPeter 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