The diagrams that follow show the mechanical linkage in a pipe organ. The organist presses down on the pedal with his or her foot, which in turn pulls the vertical tracker down, rotates the roller, and pulls the horizontal tracker sideways. While the mechanism is being actuated, the tension in the trackers rises from zero to approximately 1 kgf. The roller arms were made from aluminum alloy rod 4.75 mm in diameter. The end of the rod was turned down to a diameter of 4 mm to fit the hole in the roller, and was riveted over to hold it in place. The turning had been done with a sharp-ended lathe tool, which produced a sharp corner. A fatigue crack had initiated at this sharp corner, and led to the failure of the mechanism after only 2 years in service.
a. Why did the fatigue crack form at the sharp corner?
b. Where around the sharp corner did the fatigue crack initiate?
c. How would you modify the design to increase the fatigue life?
d. What other material would you choose to increase the fatigue life?
Schematic of the mechanical action in the region of the failed components (not to scale). The vertical tracker and the rocker are both made from light wood, and their weight can be neglected in the loading calculations
Fatigue fractures occurred at a sharp change of section in the roller arms. To scale—dimensions in mm. The maximum bending stress in the reduced section of the roller arm is given by the standard equation
Using this equation, calculate (a) the stress amplitude and (b) the mean stress of the stress cycle. Given that the true fracture stress of the alloy is 250 MN m–2, estimate (c) the stress amplitude that would produce the same fatigue life under conditions of zero mean stress.
Hillyard Company, an office supplies specialty store, prepares its master budget on a quarterly basis. The following data have been assembled to assist in preparing the m...May 06 2020
In 1994 AT&T issued 8 5⁄8 percent debentures that will mature on December 1, 2034.a. If an investor purchased one of these bonds ($1,000 denomination) on December 1, 2004...Mar 31 2020
Assume that Chapman Company acquired Abernethy s common stock for $500,000 in cash. Assume that the equipment and long-term liabilities had fair values of $220,000 and $1...Jul 09 2020
Sarah has $300 to allocate between opera tickets and movie tickets. The price of each opera ticket is $60, and the price of each movie ticket is $6. Her marginal rate of ...Apr 03 2020
How is relative humidity measured?Jun 10 2021
Compute for the temperature at which nitrous oxide will have an RMS speed of . 512.15 m/s ?May 14 2021
What is HR’s role in developing glue technology?2. What does it mean for Teva to be an Israeli global company?Mar 30 2020
In which of the following responsibility centers does the control system examine the role of assets in generating profit apart from measuring the monetary value of inputs...Dec 27 2017
Jones Corporation Fiscal Year 2017 Statement of Cash Flows reflected information that cash provided by operating activities was $800,000. The Fiscal Year 12/31/17 Balance...Jul 23 2021
A packed absorption tower was used to absorb compound A from a gas mixture into solvent B. At one point in the tower, the partial pressure of A in the gas stream was 1:51...Mar 27 2020