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Answer the following questions briefly. Torsional rigidity and lateral rigidity Torsional Rigidity Torsional rigidity is the resistance against torsional deformation. Or the minimum force required to deform the object by twisting.  It is the product of modulus of rigidity(G) and polar moment of inertia (J), denoted by k, having S.I. Units N. m 2 It is given by Lateral rigidity Lateral rigidity is the resistance against the bending deformation .or the minimum force required to deform the object by bending. It is represented by EI. Surface Hardening A number of components require only a hard surface to resist wear and tear and a tough core to resist shock loads instead of the complete component being made hard. These two properties do not exist in one steel. For toughness, one finds that the core should not exceed 0.3% carbon content, also sometimes it is not desirable to harden the complete components. For example, it is undesirable to have case-harden screw threads. The threads wou...

Explain the following in brief (20 marks) BIS code BIS is the National Standard Body of India established under the BIS Act 2016 for the harmonious development of the activities of standardization, marking and quality certification of goods and for matters connected therewith or incidental thereto. Hardness and Toughness Toughness The toughness of a material is its ability to withstand both plastic and elastic deformations. It is a highly desirable quality for structural and machine parts to withstand shock and vibration. Manganese steel, wrought iron, mild steels are tough materials. Example: If a load is suddenly applied to a piece of mild steel and then to a piece of glass the mild steel will absorb much more energy before failure occurs. Thus, mild steel is said to be much tougher than glass. Toughness is a measure of the amount of energy a material can absorb before acmal fracture or failure takes place. "The work or energy a material absorbs is called modulus of toughness” T...

Explain the following terms: Stress concentration factor. In order to consider the effect of stress concentration and find out localized stresses, a factor called the stress concentration factor is used. It is d enoted by  K t  and defined as, or  where  σ 0  and τ 0  are stresses determined by elementary equations and σ max  and τ max  are localized stresses at the discontinuities. The subscript t denotes the ‘theoretical’ stress concentration factor. Notch sensitivity factor Notch sensitivity is defined as the susceptibility of a material to succumb to the damaging effects of stress raising notches in fatigue loading. The notch sensitivity factor q is defined as Fatigue strength reduction factor This factor accounts for geometrical stress concentration factors due to thickness variations; weld geometries, surface notches or environmental conditions. The range of factor Kg is between 1 and 4, with its minimum value for smooth geometrical shapes a...

Explain briefly and draw the suitable diagram if required (10 x 2) What do you understand by a factor of safety? While designing a component, it is necessary to provide sufficient reserve strength in case of an accident. This is achieved by taking a suitable factor of safety ( f s ). The factor of safety is de fined as  f s  = failure stress/allowable stress or   f s  = failure load/work ing load Define ductility and malleability. Ductility The ductility of the material enables it to draw out into thin wire on the application of the load. Mild steel is a ductile material. The wires of gold, silver, copper, aluminium, etc. are drawn by extrusion or by pulling through a hole in a die due to the ductile property. The ductility' decreases with the increase in temperature. The per cent elongation and the reduction in area in tension are often used as empirical measures of ductility. Malleability The malleability of a material is its ability to be flattened into thin ...

Answer any four. Clutches A clutch is a machine member used to connect a driving shaft to a driven shaft so that the driven shaft may be started or stopped at will, without stopping the driving shaft. The use of a clutch is mostly found in automobiles.  In order to change gears or to stop the vehicle, it is required that the driven shaft should stop, but the engine should continue to run. It is, therefore, necessary that the driven shaft should be disengaged from the driving shaft. The engagement and disengagement of the shafts are obtained by means of a clutch which is operated by a lever. Following are the two main types of clutches commonly used in engineering practice: Square jaw clutch Spiral jaw clutch Friction clutches A friction clutch has its principal application in the transmission of the power of shafts and machines which must be started and stopped frequently. Its application is also found in cases in which power is to be delivered to machines partially or fully loaded...

Answer briefly on the following Free body diagram A free-body diagram is a sketch of an object of interest with all the surrounding objects stripped away and all of the forces acting on the body shown. The drawing of a free-body diagram is an important step in the solving of mechanics problems since it helps to visualize all the forces acting on a single object. The net external force acting on the object must be obtained in order to apply Newton's Second Law to the motion of the object. Different types of loads Point load This type of load acts relatively on a smaller area. For example, the force exerted by a  chair or a table leg on the supporting floor or load exerted by a beam on a supporting column are both considered to be concentrated.  Distributed load As the name itself implies, a uniformly distributed load is spread over a large area. Its magnitude is designated by its intensity (N/m or kN/m). The water pressure on the bottom slab of a water tank is an example of suc...