Draw a typical creep curve and show the 1st, 2nd and 3rd Creep zones on them and explain the creep mechanisms that occur in these zones.
In: Mechanical Engineering
Consider an orthogonal machining process carried out on a steel alloy of 600 MPa shear strength, the width of the cut is 10mm. The depth of cut is 0.5 mm and the chip thickness 0.7mm. The cutting speed is 2400 m/sec, the coefficient of friction is 0.364 and the rake angle of the tool is 10 oC. Estimate : a) Material removal rate b) specific power in shear c) specific power in friction
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A Parter governor with upper and lower arms (250 mm) equal length, each pivoted at a distance ( 30 mm) from the spindle axis. The ball and dead mass ( 10 & 25 kg) respectively. the friction force (± 10 N). Determine the maximum and minimum speed when the upper arm makes angle equal to (60 deg) with vertical.
In: Mechanical Engineering
Fatigue is a condition which usually causes damage in aircraft
structures. The damage of an
aircraft structure could possibly lead to failure.
(a) Discuss how to sustain damage in aircraft structures before an
inspection can be done. Provide
appropriate mathematical equations to support your answer
In: Mechanical Engineering
Level 0 from the product structure indicate the subassemblies at the lower level? T OR F
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What is the closure problem, which occurs when applying
Reynolds-averaging to the Navier-
Stokes equations, and why is it a problem? How does one work around
it?
In: Mechanical Engineering
Consider a very long rectangular fin attached to a flat surface such that the temperature at the end of the fin is essentially that of the surrounding air, i.e. 20°С. Its width is 5.0 cm; thickness is 1.0 mm; thermal conductivity is 200 W/m·K; and base temperature is 40°C. The heat transfer coefficient is 20 W/m2 .K. You can use Table 1(a) for assistance. (i) Estimate the fin temperature at a distance of 5.0 cm from the base, and; (ii) Calculate the rate of heat loss from the entire fi
In: Mechanical Engineering
A converging-diverging nozzle is designed to operate with an
exit Mach number of 2. The nozzle is supplied from an air reservoir
at 600 kPa and temperature is 300 K. The throat area of the nozzle
is 5 cm2.
Determine:
(a) The ratio of exit-to-throat area and exit area.
(b) Given the area ratio in part (a), find the range of back
pressure over which the nozzle is choked. What is the critical
pressure and design pressure?
Also, calculate the mass flow rate when the nozzle is choked and at
design conditons.
(c) Determine the mass flow rate for a back pressure of 450 kPa and
500 kPa.
(d) Determine the mass flow rate for a back pressure of 0
kPa.
(e) Plot pressure variation along centerline of nozzle and mark all
the points (back pressures) on it.
(f) Use excel sheet to plot mass variation Vs back pressures and
mark all points on it.
In: Mechanical Engineering
Interpret typical creep curve and use mathematical analysis to predict creep behaviour
In: Mechanical Engineering
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Problem 3 (36 Pts)
The steel pipe is 0.5 m long and has an internal diameter of 60 mm and an external diameter of 80 mm. The Young’s modulus E is 200 GPa and the Poisson ratio ν is 0.32. The pipe experiences a twisting moment of 8 kNm and a bending moment of 3.5 kNm.
4p a) Sketch roughly how the angle of rotation and vertical displacement change as a function of distance from the free end of the pipe to the wall.
8p b) Determine the torsion angle and vertical displacement at the free end of the pipe.
6p c) Determine the stress at the top and bottom of the beam at an arbitrary cross- section, say at a-a.
6p d) Determine (i) the principal stress, (ii) the maximum shear stress, and (iii) average normal stress if available.
4p e) Determine whether plastic deformation occurs. Here, the elastic limit for steel is 250 MPa.
4p f) The base of the rod is fastened to the wall by 4 bolts, 2 vertical and 2 horizontal. Analyze different stresses (in normal stress, shear stress, or both) experienced by different bolts.
4p g) If the bolts are 6 mm in diameter and made of the same steel. With the increase of two moments in proportion, which bolt will yield first and how will the yield look like?
In: Mechanical Engineering
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THERMODYNAMIC
The specifications of a typical reciprocating internal
combustion engine coupled with a
generator are given in Table Q2. With the aid of a P-v diagram,
determine the following
engine performance characteristics by using constant specific heat
at room temperature:
i) the total mass contained in the cylinder per cycle,
ii) the mass of fuel burned per cycle,
iii) the mean effective pressure,
iv) the engine power in kW, and
v) the specific fuel consumption in g/kWh .
Table Q2
Item Specification
Cycle 4-stroke
Fuel Type Diesel
Fuel Calorific Value 43 MJ/kg
Combustion Efficiency(%) 95
Compression Ratio 19
No. of Cylinder 4
Engine Capacity (cc) 2000
Intake Pressure (kPa) 95 kPa
Intake Temperature (°C) 30
AFR 28:1
Engine Speed (rpm) 1800
In: Mechanical Engineering
A laboratory scale experiment has been planned to
study the vortex shedding induced loading on a
structural member. For doing this, the accurate
measurements of flow velocity and vortex shedding
frequency is of prime importance. The member is
placed vertically across the flow having mean flow
velocity of 50 m/s. The diameter of the member is 5
cm. If the Strouhal number is 0.2, determine the
following:
appropriate sensor type for measurements and its
characteristics ?
vortex shedding frequency?
sampling frequency required to resolve the
frequency content?
sampling frequency necessary to reconstruct the
waveform and amplitude?
would you filter the signal before acquisition, if
yes
then mention reasons?
In: Mechanical Engineering