Homework #1
Assigned: January 18, 2002
Due: January 25, 2002
 

1. Textbook P2.1

2. Textbook P2.5

3. Textbook P2.7

4. Textbook P2.17

5. You have a polypropylene resin that is filled with an E-glass filler at 30% by weight in a random 2D pattern. The modulus of the polypropylene is 200,000 psi and a yield strength of 2,000 psi. The glass fibers are 10 microns in diameter, have a modulus of 10,000,000 psi, and an ultimate fracture strength of 250,000 psi. The specific gravity of the glass fiber is 2.5 and of the polypropylene is 0.91.

a) Determine the critical length of the fiber for it to be considered "long".

b) Determine the modulus of this composite.

c) A supplier claims to have a nano-clay filled polypropylene resin (specific density = 0.93) that allows you to use only 10% by weight fibers and get the same modulus as a neat resin with 30% by volume glass fiber. Determine the modulus of this nano-clay filled polypropylene. Does this value seem reasonable to you? (www.nanocor.com).