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  1. 3 points
    Selection of material is an important aspect for manufacturing industries . The quality of product is highly depends upon its material properties. These properties are used to distinguish materials from each other. For Example: A harder material is used to make tools.A ductile material is used to draw wires. So the knowledge of mechanical properties of material is desirable for any mechanical student or for any person belongs to mechanical industries. This post brings top 18 mechanical properties. Mechanical properties of material: There are mainly two types of materials. First one is metal and other one is non metals. Metals are classified into two types : Ferrous metals and Non-ferrous metals. Ferrous metals mainly consist iron with comparatively small addition of other materials. It includes iron and its alloy such as cast iron, steel, HSS etc. Ferrous metals are widely used in mechanical industries for its various advantages. Nonferrous metals contain little or no iron. It includes aluminum, magnesium, copper, zinc etc. Most Mechanical properties are associated with metals. These are #1. Strength: The ability of material to withstand load without failure is known as strength. If a material can bear more load, it means it has more strength. Strength of any material mainly depends on type of loading and deformation before fracture. According to loading types, strength can be classified into three types. a. Tensile strength: b. Compressive strength: 3. Shear strength: According to the deformation before fracture, strength can be classified into three types. a. Elastic strength: b. Yield strength: c. Ultimate strength: #2. Homogeneity: If a material has same properties throughout its geometry, known as homogeneous material and the property is known as homogeneity. It is an ideal situation but practically no material is homogeneous. #3. Isotropy: A material which has same elastic properties along its all loading direction known as isotropic material. #4. Anisotropy: A material which exhibits different elastic properties in different loading direction known as an-isotropic material. #5. Elasticity: If a material regain its original dimension after removal of load, it is known as elastic material and the property by virtue of which it regains its original shape is known as elasticity. Every material possess some elasticity. It is measure as the ratio of stress to strain under elastic limit. #6. Plasticity: The ability of material to undergo some degree of permanent deformation without failure after removal of load is known as plasticity. This property is used for shaping material by metal working. It is mainly depends on temperature and elastic strength of material. #7. Ductility: Ductility is a property by virtue of which metal can be drawn into wires. It can also define as a property which permits permanent deformation before fracture under tensile loading. The amount of permanent deformation (measure in percentage elongation) decides either the material is ductile or not. Percentage elongation = (Final Gauge Length – Original Gauge Length )*100/ Original Gauge Length If the percentage elongation is greater than 5% in a gauge length 50 mm, the material is ductile and if it less than 5% it is not. #8. Brittleness: Brittleness is a property by virtue of which, a material will fail under loading without significant change in dimension. Glass and cast iron are well known brittle materials. #9. Stiffness: The ability of material to resist elastic deformation or deflection during loading, known as stiffness. A material which offers small change in dimension during loading is more stiffer. For example steel is stiffer than aluminum. #10. Hardness: The property of a material to resist penetration is known as hardness. It is an ability to resist scratching, abrasion or cutting. It is also define as an ability to resist fracture under point loading. #11. Toughness: Toughness is defined as an ability to withstand with plastic or elastic deformation without failure. It is defined as the amount of energy absorbed before actual fracture. #12. Malleability: A property by virtue of which a metal can flatten into thin sheets, known as malleability. It is also define as a property which permits plastic deformation under compression loading. #13. Machinability: A property by virtue of which a material can be cut easily. #14. Damping: The ability of metal to dissipate the energy of vibration or cyclic stress is called damping. Cast iron has good damping property, that’s why most of machines body made by cast iron. #15. Creep: The slow and progressive change in dimension of a material under influence of its safe working stress for long time is known as creep. Creep is mainly depend on time and temperature. The maximum amount of stress under which a material withstand during infinite time is known as creep strength. #16. Resilience: The amount of energy absorb under elastic limit during loading is called resilience. The maximum amount of the energy absorb under elastic limit is called proof resilience. #17. Fatigue Strength: The failure of a work piece under cyclic load or repeated load below its ultimate limit is known as fatigue. The maximum amount of cyclic load which a work piece can bear for infinite number of cycle is called fatigue strength. Fatigue strength is also depend on work piece shape, geometry, surface finish etc. #18. Embrittlement: The loss of ductility of a metal caused by physical or chemical changes, which make it brittle, is called embrittlement.
  2. 3 points

    Version 1.1.0

    23,705 downloads

    A COMPLETE INSTRUCTOR AND STUDENT SUPPLEMENT PACKAGE - Continued These ppts are set of instructor and student supplements. . A FOCUS ON DIAGNOSIS AND PROBLEM SOLVING The primary focus of these ppts is to satisfy the need for problem diagnosis. Time and again, the author has heard that technicians need more training in diagnostic procedures and skill development. To meet this need and to help illustrate how real problems are solved, diagnostic stories are included throughout. Each new topic covers the parts involved as well as their purpose, function, and operation, and how to test and diagnose each system.
  3. 2 points
    saurabhjain

    Types of Welding

    Welding is a process of joining similar and dissimilar metals or other material by application of heat with or without application of pressure and addition of filler material. It is used as permanent fasteners. Welding is essential process of every manufacturing industries. In fact, the future of any new metal may depend on how far it would lend itself to fabrication by welding. The weldability has been defined as the capacity of being welded into inseparable joints having specified properties such as definite weld strength proper structure. The weldability of any metal depends on five major factors. These are melting point, thermal conductivity, thermal expansion, surface condition, and change in microstructure. Types of welding: Basically welding may be classified into three types. 1. Plastic welding: In plastic welding or pressure welding process, the pieces of metal to be joined are heated to a plastic state and then forced together by external pressure. These welding are also known as liquid-solid welding process. This procedure is used in forge welding and resistance welding. 2. Fusion welding: In the fusion welding or no pressure welding process, the material at the joint is heated to a molten state and allowed to solidify. These welding are also known as liquid state welding process. This includes gas welding, arc welding, thermite welding etc. 3. Cold welding: In this welding process, the joints are produced without application of heat, but by applying pressure which results diffusion or inter-surface molecular fusion of the parts to be joined. It is also known as solid state welding process. This process is mainly used for welding nonferrous sheet metal, particularly aluminum and its alloys. This includes ultrasonic welding, friction welding, Explosive welding etc. 4 Main Welding Processes: 1. Arc Welding (Fusion Welding): In this type of welding process, weld metal melted from the edges to be joined and allow to solidifies from the liquid state and usually below the recrystallization temperature without any applied deformation. Arc welding is most extensively employed method of joining metal parts by fusion. In this welding the arc column is generated between an anode, which is the positive pole of power supply, and the cathode, the negative pole. When these two conductors of an electric circuit are brought together and separated for a small distance such that the current continues to flow through a path of ionized particles called plasma, an electric arc is formed. This ionized gas column acts as a high resistance conductor that enables more ions to flow from the anode to the cathode. Heat is generated as the ions strike the cathode. This heat used as melting of metal to be joined or melting the filler metal which further used as joining material of welding metal. The electrode is either consumable or non-consumable as per welding requirement. The temperature at the center of the arc being 6000 OC to 7000OC 2. Gas Welding: The gas welding is done by burning of combustible gas with air or oxygen in a concentrated flame of high temperature. As with other welding methods, the purpose of the flame is to heat and melt the parent metal and filler rod of a joint. It can weld most common materials 3. Gas Metal arc welding (MIG): This welding is also known as metal inert gas welding. In this type of welding a metal rod is used as one electrode, while the work being welded is used as another electrode. It is a gas shielded metal arc welding which uses the high heat of an electric arc between a continuously fed, consumable electrode wire and the material to be welded. Metal is transferred through protected arc column to the work. In this process the wire is fed continuously from a reel through a gun to constant surface imparts a current upon the wire. In this welding the welding area is flooded with a gas which will not combine with the metal. The rate of flow gas is sufficient to keep the oxygen of the air away from the hot metal surface while welding is being done. 4. Gas Tungsten Arc Welding (TIG): This welding is also known as tungsten inert gas welding is similar to the MIG in that is uses the gases for shielding. This arc welding process uses the intense heat of an electric arc between a no consumable tungsten electrode and the material to be welded. In this process the electrode is not consumable during welding process and gas is used to protect the weld area form atmospheric air.
  4. 2 points
    There are two reasons why cooling is required in I.C. Engines. Heat is produced due to burning of fuel inside the engine. Due to heat, thermal stress develops in the engine components. This results in unwanted change in shape (Expantion and contraction). For proper funtioning the moving components should be in there desired shape and size. Other important reason of cooling is for proper lubrication. Yes, due to excess heat the engine oil looses its vicosity and the moving components will not get proper lubrication. Every fulid have a boiling point. At a particular temprature it starts to convert into vapours. Without cooling piston, Bigend, Smallend, crank bearings,Cam, Valves and other mating parts will sieze.
  5. 1 point
    Which one will cool faster?? You have a cold drink bottle at room temperature. In order to cool it, you place it in the refrigerator. But you want it get chilled faster. Now you have two options, place it vertical or horizontal. Assuming the effects of forced convection are negligible in your refrigerator, which way will the bottle cool fast either Horizontal or Vertical?
  6. 1 point
    Hetal Patel

    CAD software to use?

    First I would advice you to go to basics for learning (AutoCAD) then switch to other softwares if you are just starting. I you already have some insite on using basic softwares then it totally depends on you what further process or operation you want to do and according te softwares changes.
  7. 1 point
    What kinds of work mechanical engineering graduates can carry out in which engineering industries – or how you could pursue a totally different career. I request - Just do not read post - Start by contributing to this post What ever you have heard or seen Mechanical Engineer doing or their profiles - Jobs and responsibilities Please reply to this post and share this post to as many mechanical engineers as you can Some of the industries where Mechanical Engineer work are listed below - Do not limit to these - share your expertise..... elaborate what you have seen...or what you are doing in your work profile... Aerospace industry – researches, designs, manufactures, operates and maintains aircraft Automotive industry – designs, manufactures, distributes and markets motor vehicles Chemical industry – covers oil companies, chemicals manufacturers and the businesses that support them (eg to build new plants or develop new process technologies) Construction industry – designs and builds infrastructure, buildings and buildings services (eg heating and ventilation) Defence industry – provides equipment, support and services for the armed forces and national security Electronics industry – designs and manufactures components and complete equipment for sectors from automotive to medicine and the military Fast moving consumer goods industry – manufactures products such as household cleaning items, personal hygiene goods and convenience foods Marine industry – develops and helps operate vessels Materials and metals industry – activities include developing new materials and manufacturing components or end products Pharmaceuticals industry – develops and manufactures drugs Rail industry – designs, constructs, manages and maintains rail system components from trains and tracks to electrical power systems and train control systems Utilities industry – helps supply power, water, waste management and telecoms.
  8. 1 point

    Version

    7,053 downloads

    ANSYS offers engineering simulation solution sets in engineering simulation that a design process requires. Companies in a wide variety of industries use ANSYS software. The tools put a virtual product through a rigorous testing procedure (such as crashing a car into a brick wall, or running for several years on a tarmac road) before it becomes a physical object. This pdf gives good start to understand and learn ANSYS
  9. 1 point
    Pattern is replica or model of object which to be created. It is used to make hollow cavity in sand mold in which molten metal is poured and allow solidifying to create object. The size and shape of cast object is highly depends of shape and size of pattern. Mostly pattern are made by aluminum, wood, wax etc. Metal pattern are used for mass production. The pattern making is most critical work in casting because the object is highly depended on it. A good pattern should follow following requirements. Low cost and easy to cast. Easy to repair. It should light in weight which make it easy to handle. It should able to withstand ramming forces without deformation. It should does not change its dimensions in presence of moisture. It should be easily removable from mould. It should have long life without change in its dimensions. Types of pattern: As we discussed, casting objects are highly depend on pattern. According to the shape and size of casting and method of making cavity, pattern can be classified as follow. Single Piece Pattern: It is simplest type of pattern which is made in single piece. It is used for simple objects. It is either placed into cope or in drag according to the simplicity of operation. It is used to cast stuffing box of steam engines. Split Pattern or Multi Piece Pattern: These patterns are made into two or more pieces. The first half of pattern placed into cope and other half into drag. It is used for complex objects where removal of single piece pattern from mould is impossible. When pattern is made in more than three parts cheeks are also used for easy removal. Cope and Drag Pattern: These are two piece split pattern as discussed above. It is used for large objects Match Plate Pattern: Match plate pattern is a split pattern in which cope and drag section mounted on opposite sides of a plate. The plate is known as match plate. These will make easy to cast any shape with high production rate. Mostly runner, gates etc. are also mounted on same plate which will easy to mould making work. These patterns are used for mass production. Loose Piece Pattern: When removal of pattern is impossible due to an extended surface at either upper half or lower half, the extended part made as loose piece so this extended part can be removed first before removal of whole pattern. This will make easy removal of pattern without effect on the cavity. These patterns are known as loose piece pattern. Gated Pattern: These are simply more than one looses piece which are attached with a common gating system. These are used for mass production. It is used to produce small size cavities into one mould. Sweep Pattern: These pattern are used for large rotational symmetrical casting. A sweep is a section of large symmetrical object which is rotated along a edge into sand which make a large symmetrical mould. These patterns makes easy pattern making work of large objects. Skeleton Pattern: These patterns used for large simple castings. In these patterns, skeleton like structure made by using simple pattern sections. These will save both time and material. Follow Board Pattern: Follow board is a wooden board which is used to support pattern during moulding. It acts as sit for pattern.
  10. 1 point
    The purpose for a governor on at CI engine is the same as the purpose for a governor on any machine: to maintain constant speed under varying load conditions. DrD
  11. 1 point
    There are 3 reasons for this point. "Why Tractors have vertical exhaust in the front" 1. Design level reason : Tractor is made of 2 piece construction. The rear portion (with the rear axle and drive line) can be seperated from the front portion (with engine, transmission). Hence, the silencer and exhaust tail pipe has to be kept along with the front part of the tractor. If the exhaust was to be facing the ground, then the hot gas will blow on the Driver's legs and will cause uncomfort for the user. Hence, the exhaust gas is sent vertically upward. 2. Functional level reason : If Silencer has to be placed facing the rear, (as in car), then the silencer has to be kept at the bottom. If the exhaust tail pipe is kept at a lower level, the fast blowing exhaust gas will lift up the loose sand in the crop field, now, this has multiple negative impacts 2.1. Top layer of any crop field is the fertile sand, which will get blown-off if tractor silencer is fitted like in cars. If this is allowed, every time, tractor is used, the crop field will loose its fertile sand and ultimately will become barren land. 2.2. Another effect, is these blown-off loose sand, will fall and settle on the crops, forming a layer which will cover the crop and thus stopping the Photosynthesis process of the crops. So the crop yield will be badly affected 3. Yes, keeping the silencer and tail pipe at the bottom will have other packaging issue, where, due to the articulation in crop fields, there is every chance of the silencer getting damaged due to ground hits. By the way , I m in Automobile Service Industry for the last 12 years.
  12. 1 point
    Nice effort
  13. 1 point
    Amit2007

    What is priming & why it is done ?

    During priming of a pump, its impeller is fully submerged in the liquid (say water) to remove any air trap (any kind of cavity that can lead to pressure drop), vapors, etc. This is important because lower density fluid produces a head rise proportional to the ratio of its density to the liquid to be pumped. If the pump is placed above the liquid's upper surface, then suction line has a cavity that does not allow proper suction. To avoid this, priming is necessary. This is for centrifugal pumps and not for positive displacement pumps.
  14. 1 point
    saurabhjain

    mini stirling engine

    From the album Engines

  15. 1 point

    Version

    11,215 downloads

    The Internal-Combustion Engine in Theory and Practice Volume I : Thermodynamics, Fluid Flow, Performance Second Edition, Revised by Charles Fayette Taylor Professor of Automotive Engineering, Emeritus Massachusetts Institute of Technology
  16. 1 point
    Lisho Thomas

    Why tyres are made black in color?

    Tyres are mixture of various rubbers with carbon black added. Carbon black improves traction and wear resistance of pure rubber. Another reason is that black color has higher absorption capability by which the tyre of any vehicle becomes adhesive to road
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