Design of machine elements.

Problem 1. (2 marks)
A bar of AISI 1030 hot-rolled steel has a minimum yield strength in tension and compression of
_____ MPa (look it up from Table A-20). Using the distortion-energy and maximum-shear-stress
theories determine the factors of safety for the following plane stress states:
(1) sx = 175 MPa, sy = 105 MPa
(2) sx = 105 MPa, sy = -105 MPa
(3) sx = 140 MPa, txy = -70 MPa
(4) sx = -84 MPa, sy = 105 MPa, txy = -63 MPa
Problem 2. (2 marks)
The rotor shaft of a helicopter drives the rotor blades that provide the lifting force to support the helicopter in the air. As a consequence, the shaft is subjected

to a combination of torsion and axial loading. For a 50mm diameter shaft transmitting a torque ?= 2.4kN.m and a tensile force P = 125kN, determine
(1) The maximum tensile stress, maximum compressive stress, and maximum shear stress in
the shaft.
(2) If the yield strength of the shaft material is 290 MPa, compute factors of safety of the rotor
shaft, based upon the distortion energy theory and maximum-shear-stress theory. Comment
on the safety of the design.

Problem 3. (3 marks)
(1) For a spur gearset with f = 20° at a ratio mG = 2.5, while avoiding interference, find The
smallest pinion tooth count, and the largest gear tooth count possible with this pinion;
(2) For a parallel helical gearset with fn = 20? and ? = 30? at a ratio mG = 2.5, while avoiding
interference, find the smallest pinion tooth count and the largest gear tooth count possible
with this pinion;

Question 2: Is romantic love a code, a script, a narrative or a delusion, or, all of

the above? Discussthe discourse of romantic love. Compare and contrast two different theoretical approaches to love from weeks 1-6 ofthe
course.

Question 3: Is love an expression ofthe self or a meeting with the other? In what differentways might we think about the

relation between sameness and difference in interpersonal relationships? Compare and contrast two different theoretical approaches to love
from weeks 1-6 ofthe course.

Question 4: Is ‘lov e’the bestterm for describing contemporary relationships? ls intimacy a more

relevant orflexible term? Compare and contrast two different theoretical approachesto love from weeks 1-6 ofthe course.

Question 5:

Considerthe relation between intimacy/love and technology? How, in the contemporary context, are our modes and mechanisms of relationality
mediated and impacted bytechnology? Compare and contrast two different theoretical approachesto love from weeks 1-6 ofthe

course.

(3) For the case in (2), with mt = 3 mm, calculate the normal, transverse, and axial circular
pitches, and the center-to-center distance of the two gears.

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