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A shaft is subjected to a maximum bending stress of 80 N/mm<sup>2</sup> and maximum shearing stress equal to 30 N/mm<sup>2</sup> at a particular section. If the yield point in tension of the material is 280 N/mm<sup>2</sup> and the maximum shear stress theory of failure is used, then the factor of safety obtained will be
A
2.5
B
2.8
C
3.0
D
3.5
Correct Answer:
2.8
Tresca or maximum-shear stress criteria assumes that yielding occurs when the maximum shear stress reaches a value of the shear stress in the uniaxial tension test. Assume the principal stress being σ1, σ2, σ3 where σ1 is largest, and σ3 is the smallest principal stresses. Find the value of minimum shear stress to cause yielding, given that yield stress in tension is equal to σo?
A
τ = σo
B
τ = σo/2
C
τ = σo/3
D
τ = σo/4
Examine the following statements :
i) Factor of safety for steel should be based on its yield stress,
ii) Factor of safety for steel should be based on its ultimate stress,
iii) Factor of safety for concrete should be based on its yield stress,
iv) Factor of safety for concrete should be based on its ultimate stress.
The correct statements are
A
(i) and (iii)
B
(i) and (iv)
C
(ii) and (iii)
D
(ii) and (iv)
From an alloy, two specimens are machined and tested separately under tension and compression. The engineering stress-strain curves as well as the true stress-true strain curves for tension and compression are plotted in the same diagram. Identify the correct statements:
P. The engineering stress-strain curves in tension and compression are identical.
Q. The true stress-true strain curve in compression is lower than the true stresstrue strain curve in tension due to Bauschinger effect.
R. The true stress-true strain curve in tension is above the corresponding engineering stress-strain, curve.
S. The true stress-true strain curve in tension and compression are identical.
A
P, Q
B
Q, R
C
Q, S
D
R, S
A shaft of diameter D is subjected to a twisting moment (T) and a bending moment (M). If the maximum bending stress is equal to maximum shear stress developed, then M is equal to
A
$$\frac{{\text{T}}}{2}$$
B
T
C
2T
D
4T
A flange mounted shear pin is used on a shaft as a safety device. The steel shear pin has a diameter of 2.38 mm and is to be mounted on the flange of shaft rotating at 650 rpm. The maximum power transmitted by the shaft is 4.5 KW. If the shear strength of material of pin is 30 MPa, the radial distance of its mounting is ____
A
5.02 mm
B
11.98 mm
C
47.94 mm
D
301.20 mm
Elastic failure of a material occurs, when the tensile stress equals yield strength, yield point or the elastic limit. Also, the elastic failure occurs according to maximum strain theory, when the maximum tensile strain equals (where, $$\sigma $$ = yield strength and E = modulus of elasticity)
A
E
B
$$\sigma $$
C
$$\frac{\sigma }{{\text{E}}}$$
D
$$\frac{{\text{E}}}{\sigma }$$
A shaft is subjected to bending moment M and a torque T simultaneously. The ratio of the maximum bending stress to maximum shear stress developed in the shaft, is
A
$$\frac{{\text{M}}}{{\text{T}}}$$
B
$$\frac{{\text{T}}}{{\text{M}}}$$
C
$$\frac{{2{\text{M}}}}{{\text{T}}}$$
D
$$\frac{{2{\text{T}}}}{{\text{M}}}$$
Study the following information and answer the questions. Point A is 8m to the west of Point B. Point C is 4m to the south of Point B. Point D is 4m to the east of Point C. Point F is 6m to the north of Point D. Point E is 8m to the west of Point F. Point G is 2m to the south of Point E. If point G is 4m to the north of Point H, then what is the distance between H and D?
A
11m
B
8m
C
6m
D
4m
The layout of a shaft supported on bearings at A & B is shown. Power is supplied by means of a vertical belt on pulley B which is then transmitted to pulley C carrying a horizontal belt. The angle of wrap is 180’ and coefficient of friction is 0.3. Maximum permissible tension in the rope is 3kN. The radius of pulley at B & C is 300mm and 150mm. If allowable shear stress in the shaft is 70N/mm² and torsional and bending moments are M=1185000N-mm and m=330000N-mm, find the diameter of the shaft.
A
36.8mm
B
39.7mm
C
44.7mm
D
40.3mm
If the specimen is deformed plastically beyond the yield stress in one direction, e.g., tension and then after unloading it is loaded in the opposite direction, e.g., compression, it is found that the yield stress is less than the original yield stress. This dependence of yield stress on direction loading is called ____________
A
bauschinger effect
B
strain hardening
C
residual stress
D
nabarro–herring effect