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Note for Design of Machine Elements - DME by Rakesh Kumar

  • Design of Machine Elements - DME
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S.NO 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 3.1 3.2 3.3 Visit : CONTENTS TOPIC UNIT –I STEADY STRESSES AND VARIABLE STRESSES IN MACHINE MEMBERS Load Stress Strain Tensile Stress and Strain Compressive Stress and Strain Young's Modulus or Modulus of Elasticity Shear Stress and Strain Shear Modulus or Modulus of Rigidity Working Stress Factor of Safety Poisson's Ratio Bulk Modulus Relation Between Bulk Modulus and Young’s Modulus Relation Between Young’s Modulus and Modulus of Rigidity Resilience Torsional Shear Stress Shafts in Series and Parallel Bending Stress in Straight Beams 2-Marks 16 Marks Unit –II DESIGN OF SHAFTS AND COUPLINGS Material Used for Shafts Stresses in Shafts Design of Shafts Shafts Subjected to Bending Moment Only Shafts Subjected to Twisting Moment Only Shafts Subjected to Combined Twisting Moment & Bending Moment Shafts Subjected to Fluctuating Loads Keys Types of Keys Shaft Coupling 2 Marks 16 Marks Unit –III DESIGN OF TEMPORARY AND PERMANENT JOINTS Welded Joints Advantages and Disadvantages of Welded Joints over Riveted Joints Types of Welded Joints Visit : PAGE NO 1 1 1 1 2 2 3 3 4 4 4 4 4 4 5 5 6 6 7 9 18 18 18 18 19 19 19 20 20 20 21 22 29 29 29

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3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 4.1 4.2 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5 4.2.6 4.3 5.1 5.1.1 5.1.2 5.2 5.2.1 5.2.2 Visit : Lap Joint Butt Joint Riveted Joints Types of Riveted Joints Lap Joint Butt Joint Important Terms Used in Riveted Joints Efficiency of a Riveted Joint 2 Marks 16 Marks Unit –IV DESIGN OF ENERGY STORING ELEMENTS Springs Types of Springs Helical springs Conical and volute springs Torsion springs Laminated or leaf springs Disc or Belleville springs Special purpose springs Material for Helical Springs 2 Marks 16 Marks UNIT V DESIGN OF BEARINGS MISCELLANEOUS ELEMENTS Sliding Contact Bearings Classification of Bearings Depending upon the direction of load to be supported Depending upon the nature of contact Types of Sliding Contact Bearings Rolling Contact Bearings Advantages and Disadvantages of Rolling Contact Bearings over Sliding Contact Bearings Types of Rolling Contact Bearings 2 Marks 16 Marks Visit : 30 30 31 31 31 31 33 33 33 35 46 46 46 47 47 48 48 48 48 49 50 68 68 68 68 69 70 70 70 71 73

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SYLLABUS Class/Sem: III MECH / V SEM Unit I Steady Stresses and Variable Stresses In Machine Members Introduction to the design process - factor influencing machine design, selection of materials based on mechanical properties -- Preferred numbers, fits and tolerances – Direct, Bending and torsional stress equations – Impact and shock loading – calculation of principle stresses for various load combinations, eccentric loading – Design of curved beams – crane hook and ‘C’ frame - Factor of safety - theories of failure – stress concentration – design for variable loading – Soderberg, Goodman and Gerber relations Unit II Design of Shafts and Couplings Design of solid and hollow shafts based on strength, rigidity and critical speed – Design of keys, key ways and splines - Design of crankshafts -- Design of rigid and flexible couplings. Unit III Design of Temporary and Permanent Joints Threaded fastners - Design of bolted joints including eccentric loading, Knuckle joints, Cotter joints – Design of welded joints, riveted joints for structures - theory of bonded joints. Unit IV Design of Energy Storing Elements Design of various types of springs, optimization of helical springs -- rubber springs -- Design of flywheels considering stresses in rims and arms, for engines and punching machines. Design Of Bearings and Miscellaneous Elements Unit V Sliding contact and rolling contact bearings -- Design of hydrodynamic journal bearings, McKee's Eqn., Sommerfield Number, Raimondi & Boyd graphs, -- Selection of Rolling Contact bearings - Design of Seals and Gaskets -- Design of Connecting Rod. Total: 45 Periods Text Books: 1. Shigley J.E and Mischke C. R., “Mechanical Engineering Design”, Sixth Edition, Tata McGraw-Hill , 2003. 2. Bhandari V.B, “Design of Machine Elements”, Second Edition, Tata McGraw-Hill Book Co, 2007. References: 1. Sundararajamoorthy T. V, Shanmugam .N, "Machine Design", Anuradha Publications, Chennai, 2003. 2. Orthwein W, “Machine Component Design”, Jaico Publishing Co, 2003. 3. Ugural A.C, “Mechanical Design – An Integral Approach, McGraw-Hill Book Co, 2004. 4. Spotts M.F., Shoup T.E “Design and Machine Elements” Pearson Education, 2004. Visit : Visit :

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ME6503 - DME II Mechanical Engineering UNIT –I STEADY STRESSES AND VARIABLE STRESSES IN MACHINE MEMBERS 1.1Load It is defined as any external force acting upon a machine part. The following four types of the load are important from the subject point of view: 1. Dead or steady load. A load is said to be a dead or steady load, when it does not change in magnitude or direction. 2. Live or variable load.A load is said to be a live or variable load, when it changes continually. 3. Suddenly applied or shock loads. A load is said to be a suddenly applied or shock load, when it is suddenly applied or removed. 4. Impact load. A load is said to be an impact load, when it is applied with some initial velocity. 1.2 Stress When some external system of forces or loads act on a body, the internal forces (equal and opposite) are set up at various sections of the body, which resist the external forces. This internal force per unit area at any section of the body is known as unit stress or simply a stress. It is denoted by a Greek letter sigma (σ). Mathematically, Stress, σ = P/A where P = Force or load acting on a body, and A = Cross-sectional area of the body. 1.3 Strain When a system of forces or loads act on a body, it undergoes some deformation. This deformation per unit length is known as unit strain or simply a strain. It is denoted by a Greek letter epsilon (ε). Mathematically, Strain, ε = δl / l or δl = ε.l where δl = Change in length of the body, and l = Original length of the body. 1.4 Tensile Stress and Strain When a body is subjected to two equal and opposite axial pulls P (also called tensile load) as shown in Fig. (a), then the stress induced at any section of the body is known as tensile stress as shown in Fig. (b). A little consideration will show that due to the tensile load, there will be a 1 Visit : PRAVINKUMAR – AP/MECH 2015 - 16 Visit :

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