A ductile hot-rolled steel bar has a minimum yield strength in tension and compression of 350 MPa. Using the distortion-energy and maximum-shear-stress theories determine the factors of safety for the following plane stress states:
(a) σx = 100 MPa, σy = 100 MPa
(b) σx = 100 MPa, σy = 50 MPa
(c) σx = 100 MPa, τxy = −75 MPa
(d) σx = −50 MPa, σy = −75 MPa τxy = −50 MPa
(e) σx = 100 MPa, σy = 20 MPa τxy = −20 MPa
(a)
The factor of the safety using maximum shear stress theory.
The factor of the safety using maximum distortion energy theory.
If
Answer to Problem 1P
The factor of the safety using maximum shear stress theory is
The factor of the safety using maximum distortion energy theory is
Explanation of Solution
Write the expression for the maximum principle stress.
Here, the normal stress in x direction is
Write the expression for the minimum principle stress.
Here, the normal stress in x direction is
Write the expression for the factor of the safety for MSST.
Here, the yield strength of the material in tension is
Write the expression for the factor of the safety for MDET.
Here, the yield strength of the material in tension is
Conclusion:
Substitute
Substitute
The maximum value from
Substitute
Thus, the factor of the safety using maximum shear stress theory is
Substitute
Thus the factor of the safety using maximum distortion energy theory is
(b)
The factor of the safety using maximum shear stress theory.
The factor of the safety using maximum distortion energy theory.
If
Answer to Problem 1P
The factor of the safety using maximum shear stress theory is
The factor of the safety using maximum distortion energy theory is
Explanation of Solution
Conclusion:
Substitute
Substitute
The maximum value between
Substitute
The factor of the safety using maximum shear stress theory is
Substitute
Thus, the factor of the safety using maximum distortion energy theory is
(c)
The factor of the safety using maximum shear stress theory.
The factor of the safety using maximum distortion energy theory.
If
Answer to Problem 1P
The factor of the safety using maximum shear stress theory is
The factor of the safety using maximum distortion energy theory is
Explanation of Solution
Conclusion:
Substitute
Substitute
The maximum value between
Substitute
Thus, the factor of the safety using maximum shear stress theory is
Substitute
Thus, the factor of the safety using maximum distortion energy theory is
(d)
The factor of the safety using maximum shear stress theory.
The factor of the safety using maximum distortion energy theory.
If
Answer to Problem 1P
The factor of the safety using maximum shear stress theory is
The factor of the safety using maximum distortion energy theory is
Explanation of Solution
Conclusion:
Substitute
Substitute
Calculate
The maximum values among
Substitute
Thus, the factor of the safety using maximum shear stress theory is
Substitute
Thus, the factor of the safety using maximum distortion energy theory is
(e)
The factor of the safety using maximum shear stress theory.
The factor of the safety using maximum distortion energy theory.
If
Answer to Problem 1P
The factor of the safety using maximum shear stress theory is
The factor of the safety using maximum distortion energy theory is
Explanation of Solution
Conclusion:
Substitute
Substitute
Calculate
The maximum values among
Substitute
Thus, the factor of the safety using maximum shear stress theory is
Substitute
Thus, the factor of the safety using maximum distortion energy theory is
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Chapter 5 Solutions
Shigley's Mechanical Engineering Design (McGraw-Hill Series in Mechanical Engineering)
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