1. Send in Reinforcements Background of composite materials and usage

2. Composites are not recent innovations: Wood Composites Plywood (3500 BC)Veneer

3. Composites are not recent innovations Fiber – reinforced composites – Egyptians used straw and horsehair in mud bricks – Asbestos fibers in cement paste (1890’s) – Metal rods and stone fill in concrete Improved properties – Toughness – Ductility – Crack resistance 4-point bending

4. Structural Composites are used in Building Construction NamePhiladelphia City Hall (masonry)Comcast Center Year19012008 Height548 ft975 ft Cost$27 million$540 million

5. Aerospace Industry parts: less labor, less weight NameP-51 Mustang (Best Fighter of WWII)F-22 Raptor Year~1940’s2000’s Speed490 mph~1650 mph (Mach 2.5) Cost$54,000$200 million Range1000 miles2315 miles http://igotech.ca http://curedcomposites.netfirms.com

6. Natural Composites and Biomechanics Xylem (plant cell wall) Bone (trabecular) Arteries (collagen and elastin) Necessary because of – function – resistance to deformation (mechanics) http://journals.prous.com

7. What role do engineers play? Improve materials (composites) Use mathematics to describe how structures behave under load. Computer simulations show an end result based on the mathematical description of behavior. Computer simulations used to model the geometry and expected stress distribution

8. Testing Toughness Experimental setup – Place composite on supports – Drop weight from specified height – Try to hit the center of the structure 5 inches h m

9. Basic Physics Potential energy – PE=m*g*h m is mass, in kilograms g = 9.8 m/s^2 h= height, in meters Toughness is the amount of energy a material can absorb before it breaks m h

10. Results RunMass (grams) Height (meters) Energy J = Nm Fracture (yes / no) 1m0.20.2*m 2m0.50.5*m 3m1.01.0*m 4M0.20.2*M 5M0.50.5*M RunMass (grams) Height (meters) Energy J = Nm Fracture (yes / no) 1m0.750.75*m 2m1.01.0*m 3M0.50.5*M 4M0.750.75*M 5M1.01.0*M Ice SheetNewspaper – Ice Composite m is small mass; M is larger mass