MCDESG-116 Design Elements
Assignment 7:
Shaft design: Stresses in Shafts
MCDESG-116 Page 1
Name __________________________________________
Item Shaft A Shaft B Co
ections
1
a Properties A, I, S, J and Zp /10 /10
Torque, T /10 /10
c Angular deformation, /5 /5
d Axial Stress, – shaft A only /10 -
e Maximum Bending Stress, . /10 /10
f Direct Shear Stress, . /10 /10
g Maximum Torsional Stress, . /10 /10
h Maximum Bending Shear Stress. /10 /10
2 Maximum Shear Stress. /10 /10
3 Stress Concentration /10 /10
4 Endurance Strength /10 /10
Total Score /200
Total Percent % %
Multiplied by 5.00% % %
On Time Bonus (0.50%) % %
Added to Grade % %
Use G = 11.5 x 106psi or 80 GPa (steel) in these problems.
Be careful of units in metric!
1m = 103mm but 1m2 = 106mm2, etc.
MCDESG-116 Design Elements
Assignment 7:
Shaft design: Stresses in Shafts
MCDESG-116 Page 2
MCDESG-116 Design Elements
Assignment 7:
Shaft design: Stresses in Shafts
MCDESG-116 Page 3
Review Chapters 4 & 5 in the textbook. Concentrate on the areas dealing with Power, Torque,
Torsional Stress (Solid Round Shafts), Bending and Stress Concentrations.
Problem Axial Force Max Shear Max Moment Power RPM Diameter Length
A 180 lb 264.1 lb 2,905 lb.in 75 HP XXXXXXXXXX” 32.0”
B None 988.9 N 333.3 N.m 15 Kw XXXXXXXXXXmm 2,200 mm
1. For the two Shafts listed above (stay in metric for the second one), find:
a. The properties: A, I, S, J and Zp (Cross Sectional Area, Resistances to Bending and Twisting).
. Find the Torque, T, in the shafts.
c. Find the Angular deformation, , in degrees.
d. Find the Axial Stress, – shaft A only.
e. Find the maximum Bending Stress, .
f. Find the Direct Shear Stress, .
g. Find the maximum Torsional Stress, .
h. Find the maximum Bending Shear Stress.
2. Use equation from the end of Chapter XXXXXXXXXX, 6th; 4-16, 5th; 4-13, 4th)
as shown right to find maximum Shear Stress using only Moment and
Torque.
3. From the textbook, do problems 3.66 and 3.67. Draw a diagram and mark up the Stress
Concentration Factor Charts on the back of the cover sheet. Don’t forget that you’re finding the
stress, not just the stress concentration factor.
4. Read Chapter 5 with a focus on “Procedure for Estimating Actual Endurance Strength”
a. Assume that the shaft in problem A is machined from AISI
1050 OQT 400 steel and is subjected to rotating bending.
Look up the tensile strength, su, in Appendix 3. Follow the
example problems and find Estimated Actual Endurance
Strength, sn’. The desired reliability is .99. mark up the
τmax=
√M2 + T2
Zp
If you use the Chart to
calculate the Size factor, Cs,
mark up the chart on the
ack of the cover sheet.
MCDESG-116 Design Elements
Assignment 7:
Shaft design: Stresses in Shafts
MCDESG-116 Page 4
Endurance Strength Chart at the end of the assignment and attach to your calculation.
. Assume that the shaft in problem B is machined and ground from AISI 4140 OQT 700 steel
and is subjected to rotating bending. Look up the tensile strength, su, in Appendix 3. Follow
the example problems and find Estimated Actual Endurance Strength, sn’. The desired
eliability is .90. mark up the Endurance Strength Chart at the end of the assignment and
attach to your calculation.
MCDESG-116 Design Elements
Assignment 7:
Shaft design: Stresses in Shafts
MCDESG-116 Page 5
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