What is a solid solution and what are the common types encountered in metals? Provide examples of common engineering alloys for each type (e.g. steel). Explain how a solid solution can help raise the strength of a metal. List some of the other methods of strengthening metals.
In: Mechanical Engineering
5) i) A two axes of an x-y positioning table are each driven by a stepping motor connected to a lead screw with a 10:1 gear reduction. The number of step angles on each stepping motor is 25. Each lead screw has a pitch = 7.5 mm and provides an axis range = 300 mm. There are 16 bits in each binary register used by the controller to store position data for two axes. (a) What is the control resolution of each axis? (b) What are the required rotational speeds and corresponding pulse train frequencies of each stepping motor in order to drive the table at 600 mm/min in a straight line from point (25,25) to point (100,150)? (10)
ii) The designer of a polar configuration robot is considering a portion of the manipulator consisting of a rotational joint connected to its output link. The output link is 25 in long and the rotational joint has a range of 75 degrees. The accuracy of the joint-link combination, expressed as a linear measure at the end of the link which results from rotating the joint, is specified as 0.030 in. The mechanical inaccuracies of the joint result in a repeatability error= +-0.03 degrees of rotation. It is assumed that the link is perfectly rigid, so there is no additional error due to deflection. (a) Show that the specified accuracy can be achieved, given the repeatability error. (b) Determine the minimum number of bits required in the binary register of the robot’s control memory to achieve the specified accuracy. (10)
In: Mechanical Engineering
A 5 kW split-phase motor running at 1750 rev/min is used to
drive a rotary pump, which operates 24 hours per day. An engineer
has specified a 200 mm small sheave, and 300 mm large sheave, and
B3000 belts. The service factor was 1.3. Analyze the drive and
estimate:
(a) center-to-center distance.
(b) suitable number of belts.
(c) F1, F2, Fc and Fi.
(d) the factor of safety.
(e) the belt life in passes
In: Mechanical Engineering
Justify selection of a non-destructive testing method to be used for inspection of welds on a 3m high 2m diameter steel storage tank on a remote worksite.
In: Mechanical Engineering
Which type of process does the equation dQ= T dS hold?
| A. |
reversible |
|
| B. |
isothermal |
|
| C. |
isobaric |
|
| D. |
irreversible |
In: Mechanical Engineering
how would you manfacture a 1mm hole 200mm deep and inside a metal block? (process) (introduction to manufacturing ,1st year engineering)
In: Mechanical Engineering
1. a) Make sketches to differentiate between microstructures in castings generated by homogeneous and by heterogeneous nucleation. What sort of structures provide the best mechanical properties?
b) For a simple binary alloy exhibiting complete solid solubility, describe how a typical composition will solidify from the moltern state. What is coring and what would encourage such an alloy to be cored? Can coring happen in alloys exhibiting an eutectic reaction?
In: Mechanical Engineering
Design fins/convection enviornment to remove 27 W/cm2 from a square copper surface (50x 50 cm) while keeping the surface at a temperature of 80oC or below. The convection environment has a bulk temperature of 20oC. (neglect any contact resistance between the surface and the fins)
In: Mechanical Engineering
Explain why glass fiber are very strong in tension and bulk glass generally is not.
In: Mechanical Engineering
Give an example of a stress state where Mohrs circle degenerates to a point.
In: Mechanical Engineering
QUESTION 1
In the case of arbitrary planar curvilinear motion the best choice for coordinate system is tangential-normal system
| A. |
yes |
|
| B. |
no |
QUESTION 2
Tangential coordinate axis is selected so that its positive direction is in the direction of motion of particle
| A. |
yes |
|
| B. |
no |
QUESTION 3
Normal coordinate is selected so that its positive direction is in
| A. |
arbitrary direction |
|
| B. |
direction towards the center of curvature |
|
| C. |
direction opposite to the center of curvature |
QUESTION 4
Normal acceleration is
| A. |
inversely proportional to speed |
|
| B. |
proportional to the radius of the curvature |
|
| C. |
inversely proportional to the radius of curvature |
QUESTION 5
Particle moves along curvilinear path with velocity of 30 mi/h. If the radius of curvature at position P is 1,500 ft, what is normal acceleration of the particle at position P in [ft/s2]?
In: Mechanical Engineering
Name or describe in some detail a technique that can be used to determine the elemental composition of surfaces. YOU SHOULD mention one technique and write more details about it
In: Mechanical Engineering
Manufacturing Process
list the similarities and differences between direct extrusion and drawing.
In: Mechanical Engineering
From the expressions we derived for the kinetic theory of gases, it can be shown that the fraction of gas molecules having speeds in excess of a particular speed c is
f(c) = 1 + [2*alpha/sqrt(pi)] exp(-alpha2) - erf(alpha)
where alpha = c/cm , cm is the most probable speed and erf() is the error function. Consider now 1000 H2 atoms in thermal equilibrium at 0oC. Consider the range of speeds from 0 to 3,000 m/s divided into 100 m/s intervals.
(a) Usint the equation above, plot the number of molecules in each increment
(b) Also, on your plot, show cm, c bar (average speed), and crms (rms speed)
In: Mechanical Engineering
A cast aluminium-silicon alloy containing 12 % silicon which cannot be age hardened would normally solidify with a hyper-eutectic structure. This alloy can be used for both sandcasting and metal die-casting. Describe THREE methods in which the cast metal can be strengthened by controlling the microstructure during solidification.
In: Mechanical Engineering