Concept explainers
(a)
The free body diagram of the shaft.
The reactions at
(a)
Answer to Problem 74P
The free body-diagram of the shaft is as follows.
The reaction at
Explanation of Solution
The figure below shows the arrangement of shafts.
Figure (1)
The free body diagram of the arrangement of shafts is as follows.
Figure (2)
Write the expression of moment at
Here, the reaction at
Write the expression of moment at
Here, the reaction at
Write the expression of moment at
Here, the reaction at
Write the expression of moment at
Write the expression of net force at
Here, the reaction at
Conclusion:
Substitute
Thus, the reaction at
Substitute
Thus, the reaction at
Substitute
Thus, the reaction at
Substitute
Thus, the reaction at
Substitute
Thus, the reaction at
(b)
The shear force and bending moment diagrams.
(b)
Answer to Problem 74P
The figure below shows the shear force and bending moment diagram in
The figure below shows the shear force and bending moment diagram in
Explanation of Solution
It is clear from the free body diagram of the shaft
The calculations for shear force diagram in
Write the expression of Shear force at
Here, the shear at
Write the expression of Shear force at
Here, the shear force at
Write the expression of Shear force at
Here, the shear force at
The calculations for bending moment diagram in
We known that, the bending moment at the supports of the simply supported beam is zero.
Write the bending moment at
Here, the bending moment at
Write the expression of bending moment at
Here, the bending moment at
Write the expression of bending moment at
Here, the bending moment at
The calculations for shear force diagram in
Write the expression of Shear force at
Here, the shear at
Write the expression of Shear force at
Here, the shear force at
Write the expression of Shear force at
Here, the shear force at
We known that, the bending moment at the supports of the simply supported beam is zero.
Write the bending moment at
Here, the bending moment at
Write the expression of bending moment at
Here, the bending moment at
Conclusion:
Substitute
Substitute
Substitute
Substitute
Substitute
The figure below shows the shear force and bending moment diagram in
Figure (3)
Substitute
Substitute
Substitute
Substitute
The figure below shows the shear force and bending moment diagram in
Figure (4)
(c)
The torsional shear stress for critical stress element.
The bending stress for critical stress element.
The axial stress for critical stress element.
(c)
Answer to Problem 74P
The torsional shear stress for critical stress element is
The bending stress for critical stress element is
The axial stress for critical stress element is
Explanation of Solution
It is clear from the bending moment diagram that the critical stress element is located at just right of
Write the expression of maximum torque acting on the shaft
Here, the maximum torque acting on the shaft
Write the expression of maximum bending moment acting on the shaft
Here, the maximum bending moment acting on the shaft
Write the expression of torsional shear stress for critical stress element.
Here, the torsional shear stress for critical stress element is
Write the expression of bending stress for critical stress element.
Here, the bending stress for critical stress element is
Write the expression of axial stress for critical stress element.
Here, the axial stress for critical stress element is
Conclusion:
Substitute
Substitute
Substitute
Thus, the torsional shear stress for critical stress element is
Substitute
Thus, the bending stress for critical stress element is
Substitute
Thus, the axial stress for critical stress element is
(d)
The principal stresses for critical stress element.
The maximum shear stress for critical stress element.
(d)
Answer to Problem 74P
The principal stresses for critical stress element are
The maximum shear stress for critical stress element is
Explanation of Solution
Write the expression of maximum bending stress on the critical stress element.
Here, the maximum bending stress on the critical stress element is
Write the expression of principal stresses on the critical stress element.
Here, the principal stresses on the critical stress element are
Write the expression of maximum shear stress on the critical stress element.
Here, the maximum shear stress on the critical stress element is
Conclusion:
Substitute
Substitute
Thus, the principal stresses for critical stress element are
Substitute
Thus, the maximum shear stress for critical stress element is
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Chapter 3 Solutions
Shigley's Mechanical Engineering Design (McGraw-Hill Series in Mechanical Engineering)
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