Introduction

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Branch of Science which deals with the study of Internal and External Forces It deals with the effects of these forces on various structures, machines and fluids
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Mechanics

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Strength Of Materials
Study of Internal forces developed due to elastic deformation under the action of loads Stress  Resisting force developed at a point Design Criterion Strength - Permissible strength  Rigidity - Permissible deformation Design High Strength Rigidity Economic Low Weight High life

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Differences
Difference between Mechanics and MOS EM - Rigid Bodies MOS - Deformable bodies Difference between MOS and Machine Design(MD) MOS - Static Loading MD - Dynamic Loading

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Criterion
Strength Criterion Shear Stress  = T/Zp Normal Stress = P/A Bending Stress = M/Z Rigidity Criterion Normal Strain = PL/AE Shear Strain = TL/GJ

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Factor of Safety
Factor of Safety (N) = Failure Stress / Permissible Stress Static Loading Ductile Material = Yield Strength Brittle Material = Ultimate Strength Yield Strength is considered in Ductile materials to avoid Permanent (Plastic) Deformation Margin of Safety (m) = N - 1 In Pressure Vessels, N => 4.5  Reserve Strength = Failure Strength - Permissible Strength Drawbacks: Cost increases

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Deformation in Punching
Deformation in Punching Punch - Elastic Deformation Plate - Plastic Deformation

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Assumptions of MOS
Material Isotropic Homogenous Prismatic Uniform Cross Section Static Load Follows Hooke's law Self Weight is neglected

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Load
Load is an external force applied on a body Load is classified on the basis of  Time Cross Section Load Distribution (Loading Type)

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Load Classification wrt Time
Caption: :

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Classification of Loads wrt Cross Section

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Classification of loads wrt Type of Load
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Loads wrt Time
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Caption: : Dead Load
Caption: : Gradually Applied Load

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Impact Loading
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Caption: : Impact Loading
An Impact is a high force or shock applied over a short time period. (Δt tends to 0) Examples - IC Engine, Piston, Connecting Rod Springs in shock absorber Spur gears high pitch line velocity Punching, Forging etc.

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Impact Factor
Used to determine the Impact Strength of a given material Ratio of Dynamic Deformation to Static Deformation is defined as Impact Factor when h--->0, I.F ---->2 which gives rise to Impact Loading Supports Rigid Support - Static Bending Flexible Support - Impact Bending

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Fatigue Loads
Failure of Machine Components is caused due to Fatigue Loads Type of Fatigue Loads Fluctuating  Only Magnitude changes Completely Reversed Only Direction changes Alternating Both Magnitude and Direction change

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Beams
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Load is always perpendicular Span is defined as the distance between supports A beam is said to be statically determinate when          No. of Reaction forces = No. of Equilibrium Equations  A beam is said to be Statically indeterminate when          No. of Reaction forces > No. of Equilibrium Equations Cantilever beam is always Statically Determinate Fixed and Continuous beams are always Statically Indeterminate In SSB Span = Length of the beam Is generally Statically Determinate but can be Statically Indeterminate under Variable Temperature condition

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Bending
Bending is a process by which metal can be deformed by plastically deforming the material Sagging and Hogging Sagging Bending Moment is positive Sagging - u Sagging - Compressive Force Hogging Bending Moment is negative Hogging - n Hogging - Tensile Force

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Pure Bending
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Equal and Constant Couples Bending Moment is constant throughout the beam length Neutral Fibre - Axis where the length is the same before and after bending Point of Contraflexure Contra - Opposite. Flexure - Bending Point where Sagging and Hogging meet Bending Moment is zero

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Shear Force
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Convention Clockwise - Positive AntiClockwise - Negative Bending Moment is maximum when Shear Force is Zero 

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