Mechanical properties of materials by ombaran singh

Mechanical properties of materials by ombaran singh

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  DAYALBAGH EDUCATIONAL INSTITUTE,AGRA PRESENTATION ON “MECHANICALPROPERTIES OF MATERIALS” Made By: Ombaran (156397) 3rd Year Mechanical
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  MECHANICAL PROPERTIES: The propertiesof material that determine its behaviour under applied forces are known as mechanical properties. They are usually related to the elastic and plastic behaviour of the material. These properties are expressed as functions of stress- strain,etc. A sound knowledge of mechanical properties of materials provides the basis for predicting behaviour of materials under different load conditions and designing the components out of them.
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  STRESS AND STRAIN Experienceshows that any material subjected to a lload may either deform, yield or break, depending upon the The Magnitude of load Nature of the material Cross sectional dime. The sum total of all the elementary interatomic forces or internal resistances which the material is called upon to exert to counteract the applied load is called stress. Mathematically, the stress is expressed as force divided by cross-sectional area.
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  Strain is thedimensional response given by material against mechanical loading/Deformation produced per unit length. Mathematically Strain is change in length divided by original length.
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  STRENGTH The strength ofa material is its capacity to withstand destruction under the action of externalloads. It determines the ability of a material to withstand stress without failure. The maximum stress that any material will withstand before destruction is called ultimatestrength.
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  ELASTICITY: The property ofmaterial by virtue of which deformation caused by applied load disappears upon removal of load. Elasticity of a material is the power of coming back to its original position after deformation when the stress or load is removed. F bonds stretch returnto initial  Elastic means reversible.
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  PLASTICITY: The plasticity ofa material is its ability to undergo some degreeof permanent deformation without rupture or failure. Plastic deformation will take only after the elastic limit is exceeded. It increases with increase in temperature.
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  STIFFNESS: The resistance ofa material to elastic deformation or deflection is called stiffness orrigidity. A material which suffers slight deformation under load has a high degree of stiffness orrigidity. E.g. Steel beam is more stiffer or more rigid than aluminium beam. The slow and progressive deformation of a material withtime at constant stress is called creep. Depending on temperature, stresses even below the elastIclimit can cause some permanent deformation. It is most generally defined as time-depndent strain occuring under stress. CREEP:
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  DUCTILITY: It is theproperty of a material which enables it to draw out into thin wires. E.g., Mild steel is a ductile material. The percent elongation and the reduction in area in tension is often used as emperical measures of ductility.
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  Malleability: Malleability of amaterial is its ability to be flattened into thin sheets without cracking by hot or cold working. E.g Lead can be readily rolled and hammered into thin sheets but can be drawn intowire.
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  RESILIENCE: It is thecapacity of a material to absorb energy elastically. The maximum energy which can be stored in a body upto elastic limit is called the proof resilience, and the proof resilience per unit volume is called modulus of resilience. The quantity gives capacity of the material to bear shocks and vibrations.
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  HARDNESS: Hardness is afundamental property which is closely related to strength. Hardness is usually defined in terms of the ability of a material to resist to scratching, abrasion, cutting, identation,or penetration. Methods used for determining hardness: Brinel, Rockwell ,Vickers.
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  BRITTLENESS: of breaking muchItis the property permanent distortion. material is considered without to be brittleNon-Ductile material. E.g, Glass, Cast iron,etc.