Question

One of the largest manufacturers of pultruded fiberglass shapes is Strongwell Corporation. The company is owned by John D. Tickle, who has been a gracious donor to the College of Engineering. Fiberglass members are made by emdedding glass fibers in a resin. A fiberglass ladder rail has an area of 0.50 square inches. Glass fibers make up 16% of the shape by volume. A 570 pound load is applied to the ladder rail. The modulus of elasticity of the resin is 0.3x106 psi, while the modulus of elasticity of the glass fibers is 5.5x106 psi EXAMPLE NOTES IMAGES DISCUSS UNITS STATS HELP Part History Answer Description Chk 4.36 pts 96 % What is the area of the resin? tries: 2 Show Details A. (include units with answer) Format Check 2% try penalty Hints: 0,0 What is the stress in the resin? (include units with answer) 4.55 pts 100% # tries: 0 Show Details B. Format Check 2% try penalty Hints: 2,0 What is the stress in the fibers? (include units with answer) 4.55 pts 100% # tries: 0 Show Details C. Format Check 2% try penalty Hints: 0,0

Answer 1

(A) Lengths of resin and fibres are same as ladder Therefore Area of resin = 16/100 times 0.5 = 0.08 square Inches. (B) Stress in the resin = Load/Area = 570/0.08 = 7125 psi (C) Stress in febres = E_f/E_r times stress in resin = 5.5 times 10^6/0.3 times 10^6 times 7125 Stress in flbres = 130625 psi