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Unformatted text preview: ME 382 Fall 2008
Midterm 1
Monday, October 6, 2008 This is a closed book exam; students are allowed to use an unmarked copy of the
ME382 data book.
Answer all questions.
Show all calculations (on this exam) for full credit.
There are a total of 9 pages to this exam.
Use a ruler/ straight edge to read from graphs for full credit (marks will be deducted
for excessive inaccuracy or sloppy graphs associated with not using a ruler where
appropriate.) 50/0 édn S wry/ﬂ Name: Section: Honor Pledge: Question 1
A circular, hollow cylinder is made of an aluminum alloy with a yield stress of 180 MPa. It is subjected to a torque T = 150 Nm and a compressive load
P = 12.0 kN. The inner radius of the cylinder is R, = 5.0 mm and the outer radius is R2 = 10.0 mm. The elastic modulus is 70.0 GPa and the Poisson’s ratio is
0.330. (a) What are the normal strains in the hoop and the axial directions? 0’9
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{\k r a) :915l0l.q MPa.’ Tugfwso C61 “+69 = “SD'C‘E’ —. 45% we. (d) What is the safety factor against yielding (under von Mises) if the load P is tensile
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L '2. "S— Question 2 An alloy is made from two elements: Bidenium (Ed) and Palinium (Pn). Bidenium melts at 1200 °C and exhibits two allotropes: a bodycentered—cubic
phase (a) above 900 °C, and a facecentered—cubic phase ([3) below 900 °C. The atomic mass of Bidenium is 28 g/gmole. Palinium melts at 800 °C, and forms a hexagonal—closepacked structure. The atomic mass of Palinium is 56 g/gmole. Palinium and Bidenium have no solubility in each other. They do, however, form
a compound dePny which has a melting temperature of 1500 °C. The unit cell of
this compound has a facecentered cubic structure with a Palinium ion at each
corner and a Bidenium ion in the middle of each face. There is no solubility of either Bd or Pn in the compound. An alloy consisting of 20 % by weight Pn exhibits a eutectic reaction at 700 °C.
An alloy consisting of 20 % by weight Bd exhibits a eutectic reaction at 600 °C. Using this information answer the following questions: What is the chemical formula of the compound dePny? Pm; 8 a] Bol Q :3
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temperature to vary with time.
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A material has a simple cubic crystal structure. A plot of the potential energy of an atom against separation, is given below, along with a plot of the force between
the two atoms at 0 K. You may assume that the vibrational energy of these atoms is given by kT, where k is Boltzman's constant, and T is the absolute temperature. 410£1 210'21
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 Winter '08
 Thouless
 Absolute Zero, Cubic crystal system, °C, eutectic reaction, ruler/ straight edge

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