MAE 311 Machines and Mechanism I

Home Works & Solutions

Spring 2003


Homework Policy:

Students may work on homework individually or in small groups no larger than three people total.  A single assignment may be turned in for groups, with each personís name clearly written on the upper right hand corner.  Homework MUST BE turned in during class on the date due or the student will receive no credit.

Note: Book answer to problems are not always correct. Feel free to email TAs if u have any doubt on the Hw.




Due Date



13-30, 14-2, 14-4, 14-15*,  14-17**

*use steel with Sut=135 kpsi and HB=300 (not allowable stress) given. Use a safety factor of 2.
**use steel with Sut=135 kpsi and HB=300. Determine the factor of safety for 100 million cycles of leading.

28 April



HW #8

11-2, 11-6, 12-1, 12-7,12-12*,  and 12-17.

*Requires iteration. Also check this final design against the design criteria discussed in class. see notes.

18 April 2003



HW #7

 9-1, 9-10*, 10-3, 10-7, 10-14, 10-16**

 * For 9-10, no direct shear.

 ** For 10-16, load varies between 0 to 60 N

31 March 2003


HW #6

 8-11*, 8-21**, 8-24, 8-30, 8-37***, 8-39

* For 8-11, use kb/(kb+km) = C = 0.213

** For 8-21, use C = 0.213, use Goodman relation instead of Gerber relation.

*** For 8-37, assume bracket pivots about lower edge.

24 March 2003


HW #5

7-20, 7-23, 7-24, 7-26, 7-29

3 March 2003


HW #4

#1. 7-1
#2. 7-5 (reversed bending, see sect 5-4 for tensile strength)
#3. 7-11 (infinite life and static failure (yielding))
#4. A 1.25 inch diameter hot-rolled steel rod has a 0.125 inch diameter hole drilled through it. Its (ultimate) tensile strength is 60 kpsi. The rod is subjected to a reversed (alternating) torque of 2000 in-lbs. Estimate the factor of safety for infinite life and against yielding. What would be the safety factor if a life of 20,000 cycles was needed?    

17 Feb 2003


HW #3

Probs 6-1*, 6-6, 6-16** and Extra Q.

Extra Q: Show that "Shear Strength Ssy of a material is 0.5Sy for MSST and 0.577Sy for Distortion Energy.


Note: *Max shear stress & Distortion Energy Only. **The max bending moment is 23.1 Nm.


Hint: For Question 6-16, first find the location where maximum shear and moment occur using shear and moment diagram. Then find the location (cross section) where maximum stress occur (two location).

10 Feb 2003



HW #2

Probs 2-42, 2-43, 2-48, 2-49, 2-67**No octahedral.


Note: For Question 2-42 & 2-43, you need to first determine it is a "Thin wall" or a "Thick wall" Structure, then use the corresponding Equation.

31 Jan 2003



HW #1

Probs. 2.1*, 2.5**, 2.9, 2.26a, 2.29
 *also sketch a physical component, e.g., beam or rod,  and applied loading that would result in the stress components in (a) thru (d).
**don't  bother with octahedral stresses.

24 Jan 2003







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