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Mechanical Engineering
Mechanical Engineering is a branch of engineering that encompasses the generation and application of heat and mechanical power and the design, production, and use of machines and tools. Mechanical engineering involves application of the principles of dynamics, control, thermodynamics and heat transfer, fluid mechanics, strength of materials, materials science, electronics, and mathematics.
10,989 Questions
How is machanical advantage calculated for a third class lever?
Mechanical advantage:
Class-I lever . . . can be any positive number
Class-II lever . . . always less than ' 1 ' (and more than zero)
Class-III lever . . . always more than ' 1 '
How do you calculate the mechanical advantage of any machine?
distance over which the force is applied
________________________________
Distance over which the load was moved
or
MA= Effort Force
_________
Load force
OR
MA= Length of Load arm
____________________X Weight/mass
Length of Effort arm
Mechanical properties of EN 31 STEEL?
What are the mechanical properties of EN 8 and E N 26 steel.
Whether it is advisable to use this material for seawater pump shafts
What are examples of conduction convection and radiation?
Conduction is heat transfer by bringing two systems at different temperatures into physical contact. The molecules of the warmer system bang against the molecules of the cooler system more energetically than vice versa, consequently the energy of the warmer system gradually transfers to the cooler system until they come into thermal equilibrium (same temperature). You get conduction through a system if the edges of the system are at different temperatures.
Convection occurs when flow of a fluid at a higher temperature into a fluid of lower temperature. This can either be "forced convection" - requiring a pump or fan, or "natural convection". Where the movement is due to buoyancy effects due to the difference in density between warmer and cooler fluids; as air or liquid heats up, it expands and becomes less dense, which causes it to rise. It is replaced by cooler air or liquid, which is then heated as well.This is why we heat liquids from underneath, and why your house will be warmer if your heater is on the bottom floor.
Radiation is the flow of energy as waves through space (and, in some cases, matter). Some examples of radiation are visible light, radio waves, and radiant heat. That's how the heat of the sun gets to us.
What is the sensitivity in load cell?
A load cell is an electronic device (transducer) that is used to convert a force into an electrical signal. This conversion is indirect and happens in two stages. Through a mechanical arrangement, the force being sensed deforms a strain gauge. The strain gauge converts the deformation (strain) to electrical signals. A load cell usually consists of four strain gauges in a Wheatstone bridge configuration. Load cells of one or two strain gauges are also available. The electrical signal output is typically in the order of a few millivolts and requires amplification by an instrumentation amplifier before it can be used. The output of the transducer is plugged into an algorithm to calculate the force applied to the transducer.
Sensitivity (mV/V) = Full Scale Output (mV) / Excitation Voltage (V)
mV = milli Volt
V = Volts
Standard sensitivities are 2 mV/V and 3 mV/V
Example:
For a load cell with 10V excitation has 20 mV full scale output, sensitivity is 20mV / 10V i.e. 2mV/V.
How do calculate heat rate turbine gas?
Turbine cycle heat rate is a measure of the turbine efficiency. It is determined from the total energy input supplied to the turbine divided by the electrical energy output. The energy input is the difference between the energy in the steam supplied to, and leaving from the turbine. The total energy supplied is the sum of the steam mass flow rates to the turbine multiplied by their respective enthalpies. The energy leaving is the sum of mass flow rates exiting the turbine multiplied by their respective enthalpies. Take the difference in the total energy supplied and leaving, divide by the electrical output and this gives you heat rate, typically expressed in Btu/kWh or kJ/kWh. This is easy for a single source of steam passing through the turbine to a condenser, but gets a bit more tricky for reheat turbines with multiple extractions as all the streams in and out have to be accounted for.
Shear force bending moment diagram?
a simple definition " IT'S A COUPLE OF FORCE HAVING EQUAL MAGNITUDE BUT OPPOSITE IN DIRECTION & HAVING VERY LESS DISTANCE BETWEEN THEM"
What are the factors that contribute to the cutting tool efficiency of a single point cutting tool?
taik kuceng
WHAT IS DIfference between ANSI and ASTM F 2413-11?
ANSI is the American National Standards Institute. They coordinate the development of US Voluntary National Standards in private and public sectors with regards to information management and data communications.
ASTM is the American Society for Testing and Materials. They develope, publish standards, definition of materials, methods for testing materials, installation practices and specifications for materials.
Ok since ASTM develops the standards how does that affect OHSA standards to ANSI on safety ie.. Z87 stamp on safety glasses?
Why casting is preferred over other methods of manufacturing?
Machining allows greater control over the geometry of the finished part.
How do you I calculate the Rockwell Hardness number?
Converting between different hardness scales is not an exact science, but there are many charts available that will show the approximate relationship between different scales.
One chart is available at http://www.carbidedepot.com/formulas-hardness.htm
Another useful website for converting between different hardness scales is http://www.efunda.com/units/hardness/convert_hardness.cfm Tianxing Testing Instruments Co. Ltd. is a professional manufacturer of portable hardness testers http://www.hardnesstesters.biz/
Steel is a relatively cheap metal to sell and you would need a lot of it to get a large profit. The price of steel varies depending on the current market. Contacting a local scrap yard would be the best way to know the current rate.
Depending on what test you are talking about...
Hardness can be tested by a device that divots the metal with a calibrated point and measures the force required to make a certain depth divot. Also it can be roughly tested by a set of files that have varying hardness. If the file cuts the steel, its harder than the steel.
Structure testing (checking for cracks) can be done by a process called "Magnaflux" which creates a magnetic field in the piece, and filings are sprinkled on it. The filings will indicate the place where the crack is, because the crack makes opposing poles of magnetism in the piece. Another way is called "Dye Penetrant" in which a fluorescent dye is introduced to the surface of the metal and allowed to penetrate the cracks. The rest is washed off with a solvent, which can't remove the dye in the cracks, which show up under black light.
There are literally thousands of tests that can be carried out on a piece of steel, so its hard to answer this generic question, but those are the two most common practical tests I can think of.
How the tensile strength of a metal is increased by alloying?
Alloying metals make them stronger because in pure metals all the atoms are the same size and ordered but when another element is added then it makes the atoms irregular making the layers harder to shift, making it stronger.
An alloy is a mixture of two elements, one of which is a metal. Alloys often have properties that are different to the metals they contain. This makes them more useful than the pure metals alone. For example, alloys are often harder than the metal they contain.
Alloys contain atoms of different sizes, which distorts the regular arrangements of atoms. This makes it more difficult for the layers to slide over each other, so alloys are harder than the pure metal.
it is a mechanical equipment to reduce friction. It is used in moving parts very often.
What are the different advantages and disadvantages?
advantage - increase for workers with an increase in marginal cost disadvantage - loss of potential profit for the monopsony x
How much Gas is required to produce 5 MW power in Gas turbine?
You must provide details of the :-
1) Inlet air temperature
2) Fuel characteristic (LHV, sulphur contents, etc.)
3) Site elevation
4) Inlet / Exhaust loss
5) Open cycle type of GT ? Heat Recovery ?
Then the supplier will calculate for you.
What is the importance of impact test?
Impact test determines the amount of energy absorbed by a material during fracture. This absorbed energy is a measure of a given material's toughness and acts as a tool to study temperature-dependent brittle-ductile transition.
It is to determine whether the material is brittle or ductile in nature.
Which type of motor is used in lathe?
The type of motor used depends on the size of the lathe.
Small "hobby" lathes use small fractional (1/8, 1/4...) horsepower ac motors which run on household single-phase power.
The lathes which are used to produce crankshafts for huge marine diesel engines - or the rotor shafts of the massive alternators used to generate megawatts of electrical power - must use giant-sized motors, producing hundreds of horsepower.
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DC SHUNT MOTORS.
Three-phase electric motor.
What are some examples of pneumatic devices?
Yes there is. Pneumatic valve springs. They are metal bellows that have air in them. Their use is in replacing metal wire springs in a high-speed combustion engine. An example would be formula one engines.
Think of uniform as everything moving together.
For example, in uniform circular motion describes the motion of a body traversing a circular path at constant speed.
The distance of the body from the axis of rotation remains constant at all times.
If the motion was non-uniform the distance of the body from the axis of rotation would vary.
