From See. 3-12, the maximum shear stress in a solid round bar of diameter. d , due to an applied torque. T , is given by τ max = 16 T / ( π d 3 ) . A round, cold-drawn 1018 steel rod is subjected to a mean torsional load of T ¯ = 1.5 kN · m with a standard deviation of 145 N · m. The rod material has a mean shear yield strength of S s y ¯ = 312 MPa with a standard deviation of 23.5 MPa. Assuming the strength and load have normal distributions, what value of the design factor n d ¯ corresponds to a reliability of 0.99 against yielding? Determine the corresponding diameter of the rod.
Solution Summary: The author explains the design factor, the diameter of rod, and the coefficient of variance for strength.
From See. 3-12, the maximum shear stress in a solid round bar of diameter. d, due to an applied torque. T, is given by
τ
max
= 16
T
/
(
π
d
3
)
. A round, cold-drawn 1018 steel rod is subjected to a mean torsional load of
T
¯
= 1.5 kN · m with a standard deviation of 145 N · m. The rod material has a mean shear yield strength of
S
s
y
¯
= 312
MPa with a standard deviation of 23.5 MPa. Assuming the strength and load have normal distributions, what value of the design factor
n
d
¯
corresponds to a reliability of 0.99 against yielding? Determine the corresponding diameter of the rod.
A bar of 50 mm diameter is subjected to a axial Pull of 65 kN. The measured extension on gauge length of 170 mm is 0.25 mm and change in diameter is 0.003 mm. Calculate: (i) Young’s Modulus, (ii) Poisson’s ratio (iii) Shear Modulus. and (iv) Bulk Modulus
(i) The Young's modulus is (N/mm2) = _________________
(ii) Poisson's ratio = ___________________
(iii) The shear modulus is (unit in N/mm2) = ________________
(iv) The Bulk modulus is (unit in N/mm2) = ________________
The load on a helical spring is 1282 lb and the corresponding deflection is to be 3.4 inches. Rigidity modulus is 11 x 106 psi and the maximum intensity of safe torsional stress is 60,000 psi. If the wire diameter and the mean diameter are 0.5 in. and 3 in., respectively. Determine the number of active coils. Don't round your answer to preferred size.
Round your answer to 4 significant figures
A plate made of steel 20C8 (Sut = 440 N/mm2 ) in hot rolled and normalized condition is shown in Fig. It is subjected to a completely reversed load of 30 kN. The notch sensitivity factor q can be taken as 0.8 and the expected reliability is 90%. The size factor is 0.85. The factor of safety is 2. Determine the plate thickness for infinite life. (V. B. Bhandari Example 5.3)
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