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2024 MCEN 2063 PREP EXAM 1 WITH SHORT ANSWER 100%
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2024 MCEN 2063 PREP EXAM 1 WITH SHORT ANSWER 100%
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2024 MCEN 2063 PREP EXAM 1WITH SHORT ANSWER 100%
What is the dominant stress in shafts? - CORRECT-ANSWERSShear stress
What do we call "angle of twist"? - CORRECT-ANSWERSAngle by which a
cross section of the shaft rotates about the axis of the shaft
How does the shear stress change along the radial line in a cross section of a
solid circular shaft? - CORRECT-ANSWERSshear stress increases linearly with
distance from the axis of the shaft
Can the torsion formula be applied to anyshaft? If not, why? - CORRECT-
ANSWERSShaft should have a round section, small deformations and Hooke's
law must apply
Give an example of two cross sections which have the same surface area,
but different polar moment of inertia - CORRECT-ANSWERSsection 1: plain
circle with DIA=20mm,
section 2:hollow circle with DIAinner=15mm and DIAouter=25mm.
Both section have the same surface area, but J of section 1 is about2x
greater than J for section 2.
Consider a shaft subjected to torque only.Is there any tensile stress and/or
compressive stress in that shaft? Explain - CORRECT-ANSWERSYes: A stress
element aligned with the axis of the shaft will only show pure shear if only a
torque is applied. However rotate the element 45 deg and you will see
tension and compression.
What are the different ways a shaft may fail? - CORRECT-ANSWERSBrittle
failure at 45deg, or plastic yielding
Give a "real world" example of a statically indeterminate shaft - CORRECT-
ANSWERSA machine that is jammed with some shaft elements which are
blocked
What can generate internal loads in a structure (axial forces, bending
moments etc...). Applied Forces? Reaction forces? Gravity? All of the above? -
CORRECT-ANSWERSInternal loads in a structure can be generated by applied
forces, reaction forces, and gravity. This is because internal loads are a
distribution of force that holds the body in equilibrium with its external
forces.
, What are the differences between internal loads and applied loads? -
CORRECT-ANSWERSApplied loads are forces exerted on a body by a person
or object, whereas internal loads result from these external applied loads.
What are the differences between internal loads and stresses? - CORRECT-
ANSWERSInternal loads are the distribution of forces that result from
external loads, whereas stresses are the intensity of these internal forces at
a point in the object.
What is the differences between normal stresses and shear stresses? -
CORRECT-ANSWERSNormal stresses are exerted by forces that act
perpendicular / normal to the surface of an object, whereas shear stresses
are exerted by forces that act parallel to the surface of the object.
Can uniaxial stress be negative? What would that mean physically? -
CORRECT-ANSWERSYes, uniaxial stress can be negative. Physically, this
would mean that the loading is compressive.
Consider a bar in tension. Can uniaxial force be non-uniform in the bar? (i.e.
can the stress be different at multiple points inside the bar?) Give an
example. - CORRECT-ANSWERSYes, the uniaxial stress can be non-uniform in
the bar. This is because there can be discontinuities and changes in the
cross-sectional area of the bar, such as a screw or pin hole. Thus, a non-
uniform cross-sectional area can result in a non-uniform uniaxial stress.
Explain why the shear stress components tau(xy)=tau(yx). - CORRECT-
ANSWERSThe shear stress components tau(xy)=tau(yx) because the
complimentary property of shear states that all four shear stress must be
equal in magnitude and directed towards or away from one another at
opposite edges of the element.
Is it possible to have shear stresses and uniaxial stresses transmitted
through the same section in a component? If you think so, give an example. -
CORRECT-ANSWERSYes, it is possible to have shear stresses and uniaxial
stresses transmitted through the same section in a component. For example,
if you have an inclined member you can have average compressive stresses
in the horizontal and vertical planes along with average shear stress in the
horizontal plane as seen in the textbook Example 1.11.
Explain what deformation is. - CORRECT-ANSWERSDeformation is the change
in the shape or size of a body due to a force applied to that body. This
change can often be an elongation or a change in angle of the material.
What of the following can cause deformation: applied force? gravity? wind?
all of the above? explain. - CORRECT-ANSWERSApplied force, gravity, and
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