





Department of Mechanical and Materials Engineering

The University of Western Australia Notes on DESIGN AND ANALYSIS OF MACHINE ELEMENTS Department of Mechanical and Materials EngineeringThe University of Western Australia Douglas Wright

CONTENTS

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NOMENCLATURE

DESIGN

What is Design?; why do we design ?; how do we design - problem statement, creating a bank of solution candidates, constraints & criteria, practicalising the candidates, evaluating the candidates, the feasibility study; where do we go from here?; more advanced considerations.

Appendices - an improvement problem; analysis of a spring driven vehicle; springs as energy stores; extract from JCH Roberts, Creativity.



Safety factor; stress concentration; static indeterminacy; elementary load building blocks; stress & strain resolution; failure theories; putting it all together; design equations for static round shafts; power transmission shafts.

Appendix - indeterminate assemblies of multiple components.



Castigliano's theorem; curved beams; asymmetric bending; contact stresses.



Types of springs; close coiled round wire helical compression springs; the spring characteristic; stresses & stiffness; buckling; wire materials; presetting; fatigue loading; spring design.

Appendix - presetting a torsion bar.



Thread geometry; screw thread mechanics; static failure; loads in an elastic bolted assembly; preload and its control; fluid pressurised joints; bolt fatigue; non-uniformly loaded bolt groups.



Fillet welded joints; geometric properties of lines; traditional analysis; throat stresses and joint safety; unified analysis; conclusion.

Appendix - the compliant lap joint.



Axial stress; thin cylinders; thick cylinders; design equations; strains; autofrettage; compound cylinders; torsional loading.



Corrosion; welded joint efficiency; thin shells of revolution - heads; compensation; pipes and flanges; inspection openings; supports; design.



Characteristics of a steady load and of a motor; matching a motor to a given steady load; acceleration; periodic loading. Hydraulic couplings.

Appendix - integration in practice.



Overall geometry; kinetics; fatigue; drive selection; effectiveness; approximate solutions; V-flat and pivoted motor drives. Traction mechanics.

Appendix - commercial selection tables.



System dynamics; linings. Brake analysis: translating brakes - short and long shoes; drum brakes - short, long rigid and hinged shoes; twin shoe brakes. The braked wheel; braking of vehicles; wheel lock; the vehicle and brake control characteristics.



Overall kinetics of a gear pair; epicyclic trains; conjugate tooth action; the involute tooth; the generation process - tooth systems; profile shift; gear meshing. Gear failure - reliability; tooth forces; bending strength; pitting resistance; varying duty.

Appendices - continued fractions; geometry of the involute gear tooth.



Buckling of thin walled structures; stability of equilibrium; effects of imperfections. Submerged pipelines. Practical columns - design equations.



Fatigue of ductiles; stress concentration; linear elastic fracture mechanics; plasticity; yielding fracture mechanics - the R6 technique; fatigue crack growth. Crack growth kinetics.



Linear 1-networks; extension to 2- and 3-networks. The Rayleigh-Ritz method. Finite element theory applied to elasticity - equilibrium of the discretised body; element stiffness. Implementation; condensation and bandwidth; discretisation.

Appendices - the refining process; "FEM1" User's Guide.



PROGRAM DIRECTORY

Copyright 1999-2005 Douglas Wright, doug@mech.uwa.edu.au

last updated May 2005