DESIGN OF MACHINE ELEMENTS-I(18ME52)

DESIGN OF MACHINE ELEMENTS I

Course Code:18ME52
CIE Marks:40
Teaching Hours/Week (L:T:P):3:2:0
SEE Marks:60
Credits:04
Exam Hours:03

Course Learning Objectives:

 To understand the various steps involved in the Design Process.
 To explain the principles involved in design of machine elements, subjected to different kinds of forces, from the considerations of strength, rigidity, functional and manufacturing requirements.
 To understand and interpret different failure modes and application of appropriate criteria for design of machine elements.
 To learn to use national and international standards, standard practices, standard data, catalogs, and standard components used in design of machine elements.
 Develop the capability to design elements like shafts, couplings, welded joints, screwed joints, and power screws.

Module-1

Introduction: Design Process: Definition of design, phases of design, and review of engineering materials and their properties and manufacturing processes; use of codes and standards, selection of preferred sizes. Review of axial, bending, shear and torsion loading on machine components, combined loading, two- and three dimensional stresses, principal stresses, stress tensors, Mohr's circles. Design for static strength: Factor of safety and service factor. Failure mode: definition and types. , Failure of brittle and ductile materials; even and uneven materials; Theories of failure: maximum normal stress theory, maximum shear stress theory, distortion energy theory, strain energy theory, Columba –Mohr theory and modified Mohr‟s theory. Stress concentration, stress concentration factor and methods of reducing stress concentration.

Module-2

Impact Strength: Introduction, Impact stresses due to axial, bending and torsion loads. Fatigue loading: Introduction to fatigue failure, Mechanism of fatigue failure, types of fatigue loading, S-N Diagram, Low cycle fatigue, High cycle fatigue, Endurance limit. Modifying factors: size effect, surface effect, Stress concentration effects Notch sensitivity, Soder berg and Goodman relationships, stresses due to combined loading, cumulative fatigue damage, and Miner‟s equation.

Module-3

Design of shafts: Torsion of shafts, solid and hollow shaft design with steady loading based on strength and rigidity, ASME and BIS codes for power transmission shafting, design of shafts subjected to combined bending, torsion and axial loading. Design of shafts subjected to fluctuating loads Design of keys and couplings :Keys: Types of keys and their applications, design considerations in parallel and tapered sunk keys, Design of square and rectangular sunk keys. Couplings: Rigid and flexible coupling-types and applications, design of Flange coupling, and Bush and Pin type coupling.

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Module-4

Design of Permanent Joints: Types of permanent joints-Riveted and Welded Joints. Riveted joints: Types of rivets, rivet materials, Caulking and fullering, analysis of riveted joints, joint efficiency, failures of riveted joints, boiler joints, riveted brackets. Welded joints: Types, strength of butt and fillet welds, eccentrically loaded welded joints

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Module-5

Design of Temporary Joints: Types of temporary joints- cotter joints, knuckle joint and fasteners. Design of Cotter and Knuckle Joint. Threaded Fasteners: Stresses in threaded fasteners, effect of initial tension, design of threaded fasteners under static, dynamic and impact loads, design of eccentrically loaded bolted joints.
Power screws: Mechanics of power screw, stresses in power screws, efficiency and self-locking, design of power screws.

Assignment: 
Course work includes a Design project. Design project should enable a group of students (maximum four in a group) to design a mechanical system (like couplings, screw jack, welded joints, bracket mounting using fasteners, etc.). Student should submit assembly drawing and part drawings, completely dimensioned, indicating the necessary manufacturing tolerances, surface finish symbols and geometric tolerances wherever necessary. Design project must be completed using appropriate solid modeling software. Computer generated drawings must be submitted. Design calculations must be hand written and should be included in the report. Design project should be given due credit in internal assessment. 

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Course Outcomes: At the end of the course, the student will be able to:

 CO1: Apply the concepts of selection of materials for given mechanical components. 
CO2: List the functions and uses of machine elements used in mechanical systems. 
CO3: Apply codes and standards in the design of machine elements and select an element based on the Manufacturer‟s catalogue. 
CO4: Analyse the performance and failure modes of mechanical components subjected to combined loading and fatigue loading using the concepts of theories of failure. 
CO5: Demonstrate the application of engineering design tools to the design of machine components like shafts, couplings, power screws, fasteners, welded and riveted joints. 
CO6: Understand the art of working in a team.

Full Notes

Question paper pattern:

 The question paper will have ten full questions carrying equal marks.
 Each full question will be for 20 marks.
 There will be two full questions (with a maximum of four sub- questions) from each module.
 Each full question will have sub- question covering all the topics under a module.
 The students will have to answer five full questions, selecting one full question from each module.