0
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
What means of 2Hi rolling mill?
"HI" is a latin word, its real meaning is horiontal roll, now u can easly understand the meaning of 2hi, 4hi, 6hi & 20 hi , for example 2hi mean two horizontal roll which is used for rolling the iron.
What is a reaction steam turbine?
Steam turbine is when a device that has the extract thermal energy from pressurized steam. It is used to do mechanical work on a rotating output shaft. The steam turbine was invented by Sir Charles Parsons in 1884.
Where you will use the transfer pump and the booster pump?
transfer pupm is use in that area where systems need more pressure(low to high) and booster pump is use in that area where system need low pressure.
How do brittle and ductile materials differ in their behaviour in a compression test?
(a) Ductile materials: For ductile material such as mild steel, the load Vs compression diagram would be as follows
(1) The ductile materials such as steel, Aluminum, and copper have stress - strain diagrams similar to ones which we have for tensile test, there would be an elastic range which is then followed by a plastic region.
(2) The ductile materials (steel, Aluminum, copper) proportional limits in compression test are very much close to those in tension.
(3) In tension test, a specimen is being stretched, necking may occur, and ultimately fracture fakes place. On the other hand when a small specimen of the ductile material is compressed, it begins to bulge on sides and becomes barrel shaped as shown in the figure above. With increasing load, the specimen is flattened out, thus offering increased resistance to further shortening ( which means that the stress - strains curve goes upward ) this effect is indicated in the diagram.
Brittle materials ( in compression test )
Brittle materials in compression typically have an initial linear region followed by a region in which the shortening increases at a higher rate than does the load. Thus, the compression stress - strain diagram has a shape that is similar to the shape of the tensile diagram.
However, brittle materials usually reach much higher ultimate stresses in compression than in tension.
For cast iron, the shape may be like this
Brittle materials in compression behave elastically up to certain load, and then fail suddenly by splitting or by craking in the way as shown in figure. The brittle fracture is performed by separation and is not accompanied by noticeable plastic deformation.
How is an electric motor different from generator?
Motor is device which converts electrical energy to mechanical energy,where as generator converts mechanical energy to electrical energy
Pipes that are manufactured using centrifugal casting. These tubes can withstand a lot ofinternal pressure.
What is the rockwell of 1018 steel?
Rockwell Hardness of steel 1018 ranges from 71 to 78 converted from Brinell hardness. The difference from 71 to 78 is caused by manufacturing metods and/or purity of the alloy.
The corresponding test for 1018 is RHB wich must be done using 1/16 a ball penetrator.
Why tensile strength is higher than shear strength?
because of how the molecules are arranged, most materials are a lot stronger in tension than in shear. This is not true for all materials, like chalk or concrete, which are much stronger in shear than in tension.
What is the purpose of Ferrite test?
The amount of ferrite present in austenitic or duplex stainless steels is called "FN" or Ferrite Number. For austenitic SS, a small amount of ferrite will decrease the tendency for hot cracking during solidification. Company specifications should have a required FN range in their welding specs. Too low of a number may indicate that there are hot cracks. Too high of a number may decrease the corrosion resistance, or the ferrite can convert to sigma at higher temperatures. Ferrite is magnetic whereas austenite is not.
Duplex SS nominally contains 50% ferrite/austenite, although the acceptable range for ferrite is much broader than exactly 50%.
There are several ways to measure the FN. As mentioned by Metalguy, you can use a Magne-Gage. I have used a Severn Gage and a Feritscope.
What is the Tangential flow in turbine?
When flow of water on turbine is tangential, flow is tangential flow
What is the role of physics in mechanical engineering?
Many lessons with engineering physics has a direct connection. Like. mechanics. motion. forces. electrical energy. Light. heat. Resistance materials. Vertical jump.
stress is load per unit area; when an object is loaded it is under stress and strain and it stretches (strains) until it breaks at its ultimate strength. Stress i srelated to strain in the elastic region by Hooke's law: stress = elastic modulus times strain where modulus is a property of the material and strain is deflection over length
Which material provide tensile strength and compressional strength to bone?
the collagen fibers of bone have great tensile strength(the strength to endure stretching forces), while the calcium salts, which are similar in physical properties to marble, have great compressional strength (the strength to endure squeezing forces)
What is a safety valve gag on a boiler?
A gagging tool is used on the water drum safety valves for the pressure setting. The safety valves are gagged one by one and the blow off presure is set for the other.
Why cavitation will occur in Centrifugal Pumps and not in displacement pumps?
Cavitation occurs when the pressure on a liquid drops below the vapor pressure for the liquid or when gas is otherwise introduced to a pump such that it disrupts the flow of the liquid through the pump.
Positive displacement pumps trap a quantity of liquid (or gas) and then increase the pressure by pushing (displacing) it into the discharge pipe. External pressure pushes the liquid into the pump chamber which then is made smaller before the pump chamber discharges its contents. If any gas enters the pump chamber along with a liquid it is simply compressed along with the liquid. Positive displacement pumps work just fine with both gases and liquids - although when gases are being compressed it is usually necessary to cool the pump chamber which heats up quite a bit during the almost adiabatic compression step of the pump. Cavitation does not occur in part because the pressure in the pump chamber is almost completely uniform. If the compression chamber drops below the vapor pressure of a liquid being pushed into it, the external pressure will continue to push the liquid in, then when the pump begins to decrease the volume, the valve allowing the liquid to enter will close and the volume of the contents is decreased until the pressure rises back above the vapor pressure of the liquid and it condenses in the pump chamber.
A centrifugal pump uses a rotating impeller to increase the pressure and flow rate of a fluid. In centrifugal pumps, pressure is added by increasing the kinetic energy of the liquid and then, in essence, "throwing" the liquid into the discharge pipe where the higher kinetic energy liquid pushes on the liquid ahead of it to increase pressure. As the impeller moves through the liquid being pumped, it pushes on the liquid ahead of it, imparting additional kinetic energy to it. The liquid behind the impeller, however, actually experiences a little bit of a drop in pressure as the impeller tries to move away from it. Because liquids are fairly incompressible, this usually does not create any problem and the internal pressure of the liquid is sufficient to keep it in contact with the backside of the impeller. If the drop in pressure is low enough that the pressure drops below the vapor pressure of the liquid at the temperature present in the pump, the liquid will begin to vaporize. Once gas is present in the pump, it begins to cavitate - the liquid separates from the back of the impeller - especially near the tips. For this reason, introducing air or other gas into the liquid can cause cavitation, even if the pressure never drops below the vapor pressure of the liquid being pumped. This is also why centrifugal pumps are usually "primed" prior to being started up - to get all, or at least most, of the gas out of the line so that the pump won't cavitate.
Why flux is not used in tungsten gas arc welding?
The gas acts as the flux would, in shielding the molten steel from the oxygen in the air.
What is the maximum plant load factor a gas turbine gives when operating in open cycle?
Depends on what type of gas, plant size and cycle and carriage.
What is a statically indeterminate beam?
If you can solve the beam reactions by the equations of equilibrium, then it is statically deterrminate.
If not, that is, more unknown reactions than the equations of equilibrium, then it is indeterminate, and you need to know something about its deformation to solve the reactions.
