Question

i Problem 4: The stress induced by torsion on a circular cross-section is: 11 problems) (A) Maximum at the center line of the member (B) Maximum at the outer surface of a member (C) Constant throughout the section for a member in the elastic range (D) Always negligible Problem 5: The normal stress,, is zero on a cross-section of a bear under bending M (A) at the neutral axis (B) at the top (C) at the bottom (D) along each side Problem 6: The stress distributions at different cross sections are different. However, at locations for away from the support and the applied load, the stress distribution becomes uniform. This is due to (A) - Inelastic Property (B) - Poisson's effect (C) - Saint Venant's Principle (D) - Principle of superposition Problem 7: The shaft is supported by a thrust bearing at A and joumal bearing at D. If the shaft has the cross section shown, determine the absolute maximum bending stress in the shaft (A) Allow = 54.8MPa (B) Allow = 49.4 MPa (C) Allow = 50.1 MPa (D) Ollow = 52.8 MPa 40 mm 25 mm D 52 mm 0.75 m + 1.5m— 13 kN C 10.75 m Y3 IN

Answer 1

4.B) Maximum at the outer surface of a member.

Because The stress due to torsion at the central axis is zero and varies linearly to a maximum value at the outer surface of the shaft.

5.A) At the neutral axis.

Neutral axis by definition is the axis along which normal stress is zero in a cross section.

6.C)) Saint Venant's principle.

7. Bending moment is maximum at the point where shear force is zero.

Shear force is zero in the region BC due to symmetry.

Moment of inertia about neutral axis :

(0.044 - 0.0254) = 1.703 x 10-6m4

Mmar (at B) = 3kN * 0.75m = 2.25kNm

Mc 2.25 * 108*0.04 allowable = 1.703 * 10-6= 52.8M Pa.

Ans D) 52.8 MPa