1

Computer-Aided Engineering Design

Homework

Assignment 3

Due on September 24

2

24 ft8.7 ft

250 lb

3 ft

250 lb

250 lb

250 lb

250 lb

The members of the roof truss shown in the accompanying figure have a cross-sectional area of 21.5 in2 and are made of Douglas-fir wood with a modulus of elasticity of E=1.9 x 106 lb/in2. Using ANSYS, determine the deflection of each joint, the stresses in each member, and reaction forces. Also, replace one of the fixed boundary conditions with rollers and obtain the stresses in each member. Discuss the difference in results.

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The members of the truss shown in the accompanying figure have a cross-sectional area of 2.3 in2 and are made of aluminum alloy (E=10.0x106 lb/in2). Using hand calculations, determine the deflection of joint A, the stress in each number, and reaction forces, verify your results.

D (0, 4, 0)

E (1.0, 2.5, 0)

A (0, 0, 0)

B (-0.5, 2.0, 2.0)1000 lb