Send in Reinforcements

Background of composite materials and usage

Composites are not recent innovations: Wood Composites

Plywood (3500 BC) Veneer

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

Structural Composites are used in Building Construction

Name Philadelphia City Hall (masonry) Comcast Center

Year 1901 2008

Height 548 ft 975 ft

Cost $27 million $540 million

Aerospace Industry parts: less labor, less weight

Name P-51 Mustang (Best Fighter of WWII) F-22 Raptor

Year ~1940’s 2000’s

Speed 490 mph ~1650 mph (Mach 2.5)

Cost $54,000 $200 million

Range 1000 miles 2315 miles

http://igotech.cahttp://curedcomposites.netfirms.com

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

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