Questions

Answer the following eight questions after reviewing this module week's presentation.

1. A load of 25,000 N is applied on a part of radius 15 mm, what is the shear stress, τ?
Hint, shear stress = load/cross sectional area.

2. If the maximum shear stress, τ, is 250MPa and the applied load is 40,000 N what must the area be to ensure it is a safe design?
Hint, load/shear stress = area.

3. A rivet of radius 5 mm has a shear stress maximum of 170 MPa. What force can it withstand before failure?
Hint Shear stress x area = load.

4. If a fuselage has a diameter of 4 m and material thickness of 1 mm, how will its ability to resist shear stress be compared against a fuselage of 8 m with the same thickness?
Hint, think about the ratio of thickness to diameter.

5. Explain the principle of the polar second moment of area, J, and why its units are m4.

6. A shaft of 2m length, 30 mm radius, with a wall thickness of 5 mm has a torque applied of 450 N.If the material has a G value of 275 GPa, what is the angular deflection in radians and degrees?
Hint, you need to calculate the J value, T x l/J x G = deflection, and then convert to degrees.

7. A torque of 1500 N on a shaft of 20 mm radiuswill have what shear stress, τ?
Hint, Shear stress = Torque/ cross sectional area.

8. Estimate the diameter and radius of the car you drive, or family friend, if the Torque is 75 N what would be the load?
Hint, Torque/radius.