NAME:___________________________
ME 171 Design of Elements
Final Exam
DATE: Tuesday May 11, 2010 3:30 – 6:30 PM
RULES: Open book and open notes
Answer 3 out of 4 questions. Circle which problems you want to be graded: 1
2
3
4
1. Given: The figure below shows a shaft, gear and bearing assembly. The figure shows
forces acting on the gears at points A (lies in X-Z plane) and C (lies in X-Y plane). The
shaft spins at a constant velocity of 1,000 r.p.m. with no forces or torques other than that
shown in the figure The bearings are frictionless. The gears have a pressure angle of 20
degrees. The magnitude of force FA is 500 N.
Required: a. Determine the magnitude of force FC.
b. Determine the total force acting in the Z direction on the bearings.
2. A solid round steel rod with Sy = 300 MPa is 0.5 m long and 40 mm in diameter, with a safety
factor of 3, what axial compressive load can be applied if
a. Both ends are hinged?
b. Both ends are built-in, i.e. it is a double cantilever?
Hint use the figure below.
3. Find the maximum value of stress at the hole and semicircular notch for the plate-like
member shown below.
4. A journal bearing 100 mm in diameter and 75 mm long has a diametral clearance of 0.25 mm.
The journal rotates at 4,000 rpm and is lubricated with SAE 20 oil at a temperature of 70 deg C.
Using Petroff’s equation estimate the power loss and friction torque.