1. EGGG 101: Introduction to Engineering Dr. Jill Higginson Assistant Professor Department of Mechanical Engineering University of Delaware ME Lecture 4

2. Today’s objectives Introduction Introduction What can MEs do? What can MEs do? What is biomechanics? What is biomechanics? Newton’s laws Newton’s laws Introduction to biomechanics lab Introduction to biomechanics lab

3. Introduction Course webpage Course webpage Course webpage Course webpage Schedule Schedule Schedule

4. Engineers… Apply tools of math and science to develop cost-effective solutions to technological problems in society Apply tools of math and science to develop cost-effective solutions to technological problems in society Design consumer products Design consumer products Develop machinery, factories (processes) and quality control systems for manufacturing products Develop machinery, factories (processes) and quality control systems for manufacturing products Make useful things that work! Make useful things that work!

5. Mechanical Engineering Liberal arts of engineering Liberal arts of engineering Diverse applications Diverse applications –Biomechanics –Composites and materials –Environmental and bio-fluid mechanics –Robotics and control –Fuel cells (clean energy) –Manufacturing science

6. Mechanically engineered products Micro-electro-mechanical sensors in airbags Micro-electro-mechanical sensors in airbags HVAC for office buildings HVAC for office buildings Off-road construction equipment Off-road construction equipment Hybrid vehicles Hybrid vehicles Gears, bearings, machine components Gears, bearings, machine components Artificial hip implants Artificial hip implants Deep-sea research vessels Deep-sea research vessels Robotic manufacturing systems Robotic manufacturing systems Replacement heart valves Replacement heart valves Planetary exploration spacecraft Planetary exploration spacecraft

7. Top Ten Achievements 1. Automobile 2. Apollo program 3. Power generation 4. Agricultural mechanization 5. Airplane 6. Integrated-circuit mass production 7. Air conditioning and refrigeration 8. Computer-aided engineering technology 9. Bioengineering 10. Codes and standards

8. Automobile High power, lightweight engines (ICE) High power, lightweight engines (ICE) Efficient mass production Efficient mass production Safety, fuel economy, comfort, emission control Safety, fuel economy, comfort, emission control Hybrid technology, antilock brakes, air bags, composite materials, fuel injection systems, GPS, fuel cells Hybrid technology, antilock brakes, air bags, composite materials, fuel injection systems, GPS, fuel cells

9. Computer-aided engineering technology Automation technologies Automation technologies Performing calculations Performing calculations Preparing technical drawings Preparing technical drawings Simulating performance Simulating performance Controlling machine tools Controlling machine tools Analysis software Analysis software Information databases Information databases Prototyping equipment Prototyping equipment

10. What is biomechanics? The science that examines forces acting upon and within a biological structure and effects produced by such forces

11. EXPERIMENTATION and INTERVENTION CYTOMECHANICS FLUID DYNAMICS IMAGING MODELING and SIMULATION

12. Running shoes Goals Goals –protect foot, run faster, keep cool Materials selection Materials selection –Foam, air pockets, gel, springs Absorb shock Absorb shock Promote stability / flexibility Promote stability / flexibility Ventilation (thermodynamics!) Ventilation (thermodynamics!) Sensors Sensors Fashion statement! Fashion statement!

13. Sports equipment Windsurfing Windsurfing –Board: strength, weight, shape (speed) –Sail: weight, fatigue (stretch), strength, transparency, shape, composites (reinforcements)

14. Injury mechanisms Forces on the musculoskeletal system Forces on the musculoskeletal system Moment = tendency of a force to make an object rotate Moment = tendency of a force to make an object rotate Depends on force and lever arm Depends on force and lever arm M=∑Fd M=∑Fd

16. The time rate of change of momentum of a body is equal to the magnitude of the applied force and acts in the direction of the force

18. Inverse dynamics Calculate elbow joint moment (M=∑Fd) Calculate elbow joint moment (M=∑Fd) M=(10N)(0.13m) + (20N)(0.30m) M=(10N)(0.13m) + (20N)(0.30m) M=7.3 Nm M=7.3 Nm M=(F biceps )(0.025m) M=(F biceps )(0.025m) F biceps = 292 N F biceps = 292 N F=20 N F=10 N M=? 30 cm 2.5 cm

19. Optimization Estimate muscle forces from joint moment Estimate muscle forces from joint moment Choose optimization function Choose optimization function Infinite solutions possible! Infinite solutions possible!

20. Force-length curve Force-velocity curve muscle fiber length muscle force active passive muscle fiber velocity lengthening shortening l l l Muscle force

21. Strength

22. Applications Rehabilitation devices Rehabilitation devices Exoskeleton (rehab, carry load) Exoskeleton (rehab, carry load) Accident reconstruction Accident reconstruction Helmet design Helmet design

23. Scientific Method Develop hypotheses (possible explanations) of a physical phenomenon Develop hypotheses (possible explanations) of a physical phenomenon Design an experiment Design an experiment Analyze the results Analyze the results –support or reject hypotheses Generalize the experimental results Generalize the experimental results Publish the results Publish the results

24. Biomechanics Lab Objectives: Objectives: –To develop the force-length curve based on isometric strength of the quadriceps muscle group –To quantify changes in pressure under the foot as a function of footwear –To manipulate ground reaction forces during dynamic activities

25. Motivation Oscar Pistorius Oscar Pistorius –Blade Runner –Fastest man on no legs –“I’m not disabled, I just don’t have any legs” Double amputee world records: 100m, 200m, 400m Double amputee world records: 100m, 200m, 400m –2008 Paralympic gold (100,200) 400 m 400 m –2004 Olympic gold (men): 44.00 –Pistorius world record: 46.56 –1928 Olympic gold (men): 47.8 IAAF 2007: ban the use of “any technical device that incorporates springs, wheels or any other element that provides a user with an advantage over another athlete not using such a device” IAAF 2007: ban the use of “any technical device that incorporates springs, wheels or any other element that provides a user with an advantage over another athlete not using such a device” Does Pistorius have an unfair advantage? Does Pistorius have an unfair advantage?

26. Oscar Pistorius

27. Cheetahs Stage 1: absorbs 97% impact, stores energy (higher speed -> higher force) Stage 1: absorbs 97% impact, stores energy (higher speed -> higher force) Stage 2: gluts and quads provide propulsion Stage 2: gluts and quads provide propulsion Stage 3: blade releases energy at push-off Stage 3: blade releases energy at push-off

28. Natural leg Stage 1: Achilles tendon absorbs and stores impact energy Stage 1: Achilles tendon absorbs and stores impact energy Stage 2: gluts, quads and plantarflexors provide propulsion Stage 2: gluts, quads and plantarflexors provide propulsion Stage 3: plantarflexors releases energy at push-off Stage 3: plantarflexors releases energy at push-off

29. Methods M A max “isometric strength” P = F / A “plantar pressures”

30. Methods “ground reaction forces”

31. Lab Report Due: Wednesday by 5:00 pm Due: Wednesday by 5:00 pm Answer questions on template! Answer questions on template! Describe experimental and analytical methods (brief) Describe experimental and analytical methods (brief) Results Results –What measurements were recorded and computed? –How does strength vary with knee flexion angle? Discussion and Conclusions Discussion and Conclusions –At what knee angle is performance best? –How does peak pressure vary with shoe selection? –How does force change with dynamic activities? –What factors should be considered in the design of a prosthesis for Oscar Pistorius? Lab report template

32. Logistics Spencer 209 Spencer 209 You will rotate through 3 stations You will rotate through 3 stations Data may be collected solo or with a partner Data may be collected solo or with a partner

33. Resources Running shoes http://people.bath.ac.uk/mnp21/Adv_mat _sports.htmhttp://people.bath.ac.uk/mnp21/Adv_mat _sports.htm www.basf.com/corporate/elastollan.html http://engineeringworks.tamu.edu/?p=29 Cheetah: http://www.wired.com/wired/archive/15. 03/bladefast.htmlhttp://www.wired.com/wired/archive/15. 03/bladefast.html