What is an edge dislocation and how does it assist in the process of slip in a crystalline metal?
In: Mechanical Engineering
Explain key reasons why using sandwich structures are beneficial compared with the corresponding homogeneous structures. Give THREE applications of sandwich structures.
In: Mechanical Engineering
State how Mindlin Theory differs from Thin Plate Theory and suggest an application.
In: Mechanical Engineering
1.
(a) Using a normal distribution, define what is meant by both “ machine” and “process” capability and explain the difference by providing three measures that are used in each case. [8 marks]
(b) The following data was obtained from subgroups of parts manufactured to 10.5 mm +/- 0.5 mm
Size Range (mm) Quantity
10.0-10.2 1
10.2 -10.4 4
10.4 -10.6 9
10.6-10.8 6
Determine :
The mean and standard deviation [use N = 20 ] [6 marks]
The values of the capability indices Cm and Cp [4 marks]
If the operation can be judged as “capable” if considered to be a machine or alternatively a process? [2 marks]
In: Mechanical Engineering
Derive the flexural rigidity of a sandwich beam whose breadth is b, which has a core of thickness c and skins of thickness t each. The distance between the centroids of the skins is d, the skin and core moduli are Es and Ec respectively.
In: Mechanical Engineering
Explain two reasons why plate structures affects significantly the lightweight (i.e. ship hull, machinery, outfit and permanent equipment, etc) of a ship.
In: Mechanical Engineering
0.025 of moist air at 18°C dry-bulb and 10°c wet-bulb temperatures mixes with 0.005 kg/s of air at 38°C and 29°c wet-bulb. What is the mixture dry-bulb temperature, humidity ratio, relative humidity, and dew point? What are these parameters if the second stream flow rate is increased to 0.01 kg/s?
In: Mechanical Engineering
For the elastic body defined in Question 1 (below), define the boundary conditions in terms of displacement, assuming the boundary surface at the point in question has direction cosines with respect to x and y and z equal to l=0.8 and m=0.6 and n=0 . Consider the case when the change in volume is negligible.
Are all the compatibility equations satisfied for the Plane Stress conditions? If not, which equations are not satisfied? Explain the case for the Plane Strain conditions?
Question 1:
Write down the equilibrium equations for a three-dimensional isotropic material in terms of displacements. Assume that the material modulus of elasticity, Poisson ratio and density are, and that the body forces are due to the material weigh and the constant gravitational accelerations applied in z-direction.
In: Mechanical Engineering
Based on experimental observations, the acceleration of a particle is defined by the relation a = –(0.1 + sin x/b), where a and x are expressed in m/s2 and meters, respectively. Know that b = 0.96 m and that v = 1 m/s when x = 0.
1)The velocity of the particle
2)The position where velocity is maximum
3)Determine the
maximum velocity. (Round the final answer to three decimal
places.)
The maximum velocity
In: Mechanical Engineering
Write down the equilibrium equations for a three-dimensional isotropic material in terms of displacements. Assume that the material modulus of elasticity, Poisson ratio and density are, and that the body forces are due to material weigh and the constant gravitational accelerations applied in the z-direction.
In: Mechanical Engineering
A gas turbine used for power generation is producing 57MW of power. The turbine’s exhaust temperature is 541°C at a mass flow rate of 132.8 kg/s and is currently emitted to the atmosphere.
Your task is to design a heat exchanger that recovers the waste heat from the exhaust. The recovered heat is to be used to heat water from 40°C to 60°C for use in a closed-loop hydronic heating system for an office building. The heat exchanger is to be placed between the gas turbine’s exhaust and the attached power generator. To not interfere with the power generator, the pressure drop across the hot flow path should not exceed 600Pa. The maximum gas mass flow rate possible through the heat exchanger has been restricted to 4% of the exhaust gas flow rate of the turbine.
QUESTIONS
1.DO LMTD CALCULATION
2. TEMPERATURE CORRECTION FACTOR CALCULATION
In: Mechanical Engineering
A chicken house (20' x 10'x 8') with walls and roof with R-value = 5 hr oF ft2/BTU.
There are 2 wooden doors ( 80” x 36”) with an R-value of 2.5 hr ºF sq.ft/BTU.
The inside temperature is held at 35oC and the exterior temperature is 20oF.
There are 19 chickens in the house with a body temperature of 42oC that can be assumed to radiate as a sphere with a 14" diameter and a emissivity of 0.85.
PART A. Calculate the Heat generation by the chickens in BTU/hr.
Select one:
a. 99.05 BTU/hr
b. 1223 BTU/hr
c. 1040 BTU/hr
d. 1.209e4 BTU/hr
e. 3.440e4 BTU/hr
f. 3276 BTU/hr
In: Mechanical Engineering
4. Explain with schematics the two-photon polymerization technique. What is its advantage over stereo lithography?
In: Mechanical Engineering
A thin plate is suspended in air at 1 atm. with T_infinite=
15°C. Air flows on both sides of the plate where the bottom side
absorbs a uniform radiative heat flux of 1542 W/m2. The plate is
oriented parallel to the flow and the length along the flow
direction is 60 cm. Consider the plate is negligibly thin and the
width of the plate (perpendicular to the flow) is large, so that
the problem can be considered as a 2D problem.
1. If the temperature of the plate is not to exceed 80°C at any
position, what air velocity would be required? Evaluate the air
properties at 310 K. (3 pts)
2. Using the velocity calculated in part 1, find an expression for
the heat transfer coefficient (h) and surface temperature (Ts) as a
function of distance from the leading edge (x). Graph h and Ts for
x = 1 ~ 60 cm.
3. If the length of the plate increases to 1.2 m and other
conditions (including the air properties) remain the same as in
parts 1 and 2, what is the surface temperature at the end of the
plate? Graph h and Ts for x = 0.6 ~ 1.2 m
In: Mechanical Engineering