Chapter 9 Welding, Bonding, And The Design Of Permanent
Chapter 9Welding, Bonding, and theDesign of PermanentJoints
Chapter OutlineShigley’s Mechanical Engineering Design
Introduction Welding is the process of joining two pieces of metaltogether by hammering, pressure or fusion. Filler metalmay or may not be used. Thestrongest and most common method of permanentlyjoining steel components together. Arc welding is the most important since it is adaptable tovarious manufacturing environments and is relativelycheap. A weldment is fabricated by welding together a collectionof metal shapes.Shigley’s Mechanical Engineering Design
Introduction Apool of molten metal in which the components andelectrode material coalesce, forming a homogeneouswhole (ideally) when the pool later resolidifies. The materials of components and electrode must becompatible from the point of view of strength, ductilityand metallurgy.Shigley’s Mechanical Engineering Design
Welding Symbols Welding symbol standardized by American Welding SocietySpecifies details of weld on machine drawingsFig. 9–4Shigley’s Mechanical Engineering Design
AWS Standard Weld symbol Graphic symbol that indicates weld requiredWelding symbol Following eight elements: Reference line (required) Arrow (required) Basic weld symbols Dimensions and other data Supplementary symbols Finish symbols Tail Other specifications
Welding Symbol Components
Welding SymbolsFig. 9–1Shigley’s Mechanical Engineering Design
Weld symbols on drawingsJoints in drawings may be indicated: by detailed sketches, showing every dimension by symbolic representation
Elementary Weld SymbolsSquare Groove WeldSingle V Groove Weld
Elementary Weld SymbolsSingle Bevel Groove WeldSingle V Groove Weld with Broad Root Face
Elementary Weld SymbolsSingle Bevel Groove Weld with Broad Root FaceSingle U Groove Weld
Elementary Weld SymbolsSingle J Groove WeldBacking Weld
Elementary Weld SymbolsFillet WeldPlug / Slot Weld
Elementary Weld SymbolsSpot WeldSeam Weld
Elementary Weld SymbolsEdge WeldSurfacing
SUPPLEMENTARY SYMBOLSWeld ProfileFlatConvexConcave
SUPPLEMENTARY SYMBOLSMToes blendedsmoothlyPermanent BackingStripMRRemovableBacking Strip
SUPPLEMENTARY SYMBOLSPeripheral Welds
Welding SymbolsArrow side of a joint is the line, side, area, or near member towhich the arrow points The side opposite the arrow side is the other side Shape of weld is shown with the symbols below Fig. 9–2Shigley’s Mechanical Engineering Design
Welding Symbol Examples Weld leg size of 5 mmFillet weldBoth sides Intermittent andstaggered 60 mm alongon 200 mm centers Leg size of 5 mmOn one side only(outside)Circle indicates all theway around Shigley’s Mechanical Engineering Design
Welding Symbol ExamplesFig. 9–5Shigley’s Mechanical Engineering Design
Welding Symbol ExamplesFig. 9–6Shigley’s Mechanical Engineering Design
Tensile Butt Joint Simple butt joint loaded in tension or compressionStress is normal stressThroat h does not include extra reinforcementReinforcement adds some strength for static loaded jointsReinforcement adds stress concentration and should be groundoff for fatigue loaded jointsFig. 9–7aShigley’s Mechanical Engineering Design
Shear Butt Joint Simple butt joint loaded in shearAverage shear stressFig. 9–7bShigley’s Mechanical Engineering Design
Transverse Fillet Weld Joint loaded in tensionWeld loading is complexFig. 9–8Fig. 9–9Shigley’s Mechanical Engineering Design
Transverse Fillet Weld Summation of forces Law of sines Solving for throat thickness tFig. 9–9Shigley’s Mechanical Engineering Design
Transverse Fillet Weld Nominal stresses at angle q Von Mises Stress at angle qFig. 9–9Shigley’s Mechanical Engineering Design
Transverse Fillet WeldLargest von Mises stress occurs at q 62.5º with value ofs' 2.16F/(hl) Maximum shear stress occurs at q 67.5º with value oftmax 1.207F/(hl) Fig. 9–9Shigley’s Mechanical Engineering Design
Parallel Fillet Welds Same equation also applies for simpler case of simple shearloading in fillet weldThroat Width 0.707hFig. 9–11Shigley’s Mechanical Engineering Design
Fillet Welds Loaded in TorsionFillet welds carrying bothdirect shear V and moment M Primary shear Secondary shear A is the throat area of allweldsr is distance from centroid ofweld group to point ofinterestJ is second polar moment ofarea of weld group aboutcentroid of group Fig. 9–12Shigley’s Mechanical Engineering Design
Shigley’s Mechanical Engineering Design
Example of Finding A and J Rectangles representthroat areas. t 0.707 hFig. 9–13Using the parallel axis theorem, the secondpolar moment of area of the weld group isShigley’s Mechanical Engineering Design
Example of Finding A and J Note that t3 terms will bevery small compared tob3 and d3Usually neglectedLeaves JG1 and JG2 linearin weld widthCan normalize bytreating each weld as aline with unit thickness tResults in unit secondpolar moment of area, JuSince t 0.707h,J 0.707hJuFig. 9–13Shigley’s Mechanical Engineering Design
Common Torsional Properties of Fillet Welds (Table 9–1)Shigley’s Mechanical Engineering Design
Common Torsional Properties of Fillet Welds (Table 9–1)Shigley’s Mechanical Engineering Design
Example 9–1Fig. 9–14Shigley’s Mechanical Engineering Design
Example 9–1Fig. 9–15Shigley’s Mechanical Engineering Design
Example 9–1Fig. 9–15Shigley’s Mechanical Engineering Design
Example 9–1Fig. 9–15Shigley’s Mechanical Engineering Design
Example 9–1Shigley’s Mechanical Engineering Design
Example 9–1Fig. 9–16Shigley’s Mechanical Engineering Design
Example 9–1Fig. 9–16Shigley’s Mechanical Engineering Design
Fillet Welds Loaded in Bending Fillet welds carry both shear V and moment MFig. 9–17Shigley’s Mechanical Engineering Design
Bending Properties of Fillet Welds (Table 9–2)Shigley’s Mechanical Engineering Design
Bending Properties of Fillet Welds (Table 9–2)Shigley’s Mechanical Engineering Design
Strength of Welded JointsMust check for failure in parent material and in weld Weld strength is dependent on choice of electrode material Weld material is often stronger than parent material Parent material experiences heat treatment near weld Cold drawn parent material may become more like hot rolled invicinity of weld Often welded joints are designed by following codes rather thandesigning by the conventional factor of safety method Shigley’s Mechanical Engineering Design
Minimum Weld-Metal Properties (Table 9–3)Shigley’s Mechanical Engineering Design
Stresses Permitted by the AISC Code for Weld MetalTable 9–4Shigley’s Mechanical Engineering Design
Allowable Load or Various Sizes of Fillet Welds (Table 9–6)Shigley’s Mechanical Engineering Design
Minimum Fillet Weld Size, h (Table 9–6)Shigley’s Mechanical Engineering Design
Example 9–2Table A-20, Sy 27.5 kpsiFig. 9–18Shigley’s Mechanical Engineering Design
Example 9–2h 3/8 0.375 int 1/2 inl 2 inShigley’s Mechanical Engineering Design
Example 9–2Shigley’s Mechanical Engineering Design
Example 9–4Table A-20,Sy 32 kpsi, Sut 58 kpsiTable 9-3,Sy 50 kpsi,Sut 62 kpsiFig. 9–20Shigley’s Mechanical Engineering Design
Example 9–4Shigley’s Mechanical Engineering Design
Example 9–4Eq. 5-19Eq. 5-21Ssy 0.577 SyShigley’s Mechanical Engineering Design
Example 9–4Given n 3Shigley’s Mechanical Engineering Design
Fatigue Stress-Concentration Factors Kfs appropriate for application to shear stressesUse for parent metal and for weld metalFor Welding codes, see the fatigue stress allowable in the AISI manual.Shigley’s Mechanical Engineering Design
Example 9–5Fig. 9–21Shigley’s Mechanical Engineering Design
Example 9–5axial loadShigley’s Mechanical Engineering Design
Example 9–5Shigley’s Mechanical Engineering Design
Example 9–6Fig. 9–22Shigley’s Mechanical Engineering Design
Example 9–6Shigley’s Mechanical Engineering Design
Example 9–6Shigley’s Mechanical Engineering Design
Resistance WeldingWelding by passing an electric current through parts that arepressed together Common forms are spot welding and seam welding Failure by shear of weld or tearing of member Avoid loading joint in tension to avoid tearing Fig. 9–23Shigley’s Mechanical Engineering Design
Adhesive BondingAdhesive bonding has unique advantages Reduced weight, sealing capabilities, reduced part count, reducedassembly time, improved fatigue and corrosion resistance, reducedstress concentration associated with bolt holes Fig. 9–24Shigley’s Mechanical Engineering Design
Types of Adhesives May be classified by Chemistry Epoxies, polyurethanes, polyimides Form Paste, liquid, film, pellets, tape Type Hot melt, reactive hot melt, thermosetting, pressure sensitive,contact Load-carrying capability Structural, semi-structural, non-structuralShigley’s Mechanical Engineering Design
Mechanical Performance of Various Types of AdhesivesTable 9–7Shigley’s Mechanical Engineering Design
Stress DistributionsAdhesive joints are much strongerin shear loading than tensile loading Lap-shear joints are important fortest specimens and for practicaldesigns Simplest analysis assumes uniformstress distribution over bonded area Most joints actually experiencesignificant peaks of stress Fig. 9–25Shigley’s Mechanical Engineering Design
Double-lap Joint Classic analysis of double-lap joint known as shear-lag modelDouble joint eliminates complication of bending fromeccentricityFig. 9–26Shigley’s Mechanical Engineering Design
Double-lap Joint Shear-stress distribution is given byFig. 9–26bShigley’s Mechanical Engineering Design
Example 9–7Fig. 9–26Shigley’s Mechanical Engineering Design
Example 9–7Shigley’s Mechanical Engineering Design
Example 9–7Fig. 9–27Shigley’s Mechanical Engineering Design
Example 9-7Shigley’s Mechanical Engineering Design
Example 9-7Shigley’s Mechanical Engineering Design
Single-lap JointEccentricity introduces bending Bending can as much as double the resulting shear stresses Near ends of joint peel stresses can be large, causing joint failure Fig. 9–28Shigley’s Mechanical Engineering Design
Single-lap JointShear and peal stresses in single-lap joint, as calculated by Golandand Reissner Volkersen curve is for double-lap joint Fig. 9–28Shigley’s Mechanical Engineering Design
Adhesive Joint Design GuidelinesDesign to place bondline in shear, not peel. Use adhesives with adequate ductility to reduce stressconcentrations and increase toughness to resist debondpropagation. Recognize environmental limitations of adhesives and surfacepreparation. Design to facilitate inspection. Allow sufficient bond area to tolerate some debonding beforebecoming critical. Attempt to bond to multiple surfaces to support loads in anydirection. Consider using adhesives in conjunction with spot welds, rivets, orbolts. Shigley’s Mechanical Engineering Design
Design Ideas for Improved BondingFig. 9–29Shigley’s Mechanical Engineering Design
Design Ideas for Improved BondingFig. 9–29Shigley’s Mechanical Engineering Design
Design Ideas for Improved BondingFig. 9–29Shigley’s Mechanical Engineering Design
Graphic symbol that indicates weld required Welding symbol Following eight elements: Reference line (required) Arrow (required) Basic weld symbols Dimensions and other data . Seam Weld Elementary Weld Symbols . Edge Weld Surfacing Elementary Weld Symbols . SUPPLEMENTARY SY
Part One: Heir of Ash Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 Chapter 24 Chapter 25 Chapter 26 Chapter 27 Chapter 28 Chapter 29 Chapter 30 .
6.3 Mechanised/automatic welding 114 6.4 TIG spot and plug welding 115 7 MIG welding 116 7.1 Introduction 116 7.2 Process principles 116 7.3 Welding consumables 130 7.4 Welding procedures and techniques 135 7.5 Mechanised and robotic welding 141 7.6 Mechanised electro-gas welding 143 7.7 MIG spot welding 144 8 Other welding processes 147 8.1 .
Modern Chemistry 1 Chemical Bonding CHAPTER 6 Chemical Bonding SECTION 1 Introduction to Chemical Bonding OBJECTIVES 1. Define Chemical bond. 2. Explain why most atoms form chemical bonds. 3. Describe ionic and covalent bonding. 4. Explain why most chemical bonding is neither purely ionic or purley 5. Classify bonding type according to .
TO KILL A MOCKINGBIRD. Contents Dedication Epigraph Part One Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Part Two Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18. Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 Chapter 24 Chapter 25 Chapter 26
from electric shock. Bonding and earthing are often confused as the same thing. Sometimes the term Zearth bonding is used and this complicates things further as the earthing and bonding are two separate connections. Bonding is a connection of metallic parts with a Zprotective bonding conductor. Heres an example shown below.
comparing with Au wire bonding. Bonding force for 1st bond is the same range, but approx. 30% higher at 2nd bonding for both Bare Cu and Cu/Pd wire bonding but slightly lower force for Bare Cu wire. Bonding capillary is PECO granular type and it has changed every time when new cell is used for bonding
the welding processes most often used in today's industry including plasma arc cutting, oxyfuel gas cutting and welding, Gas Metal Arc Welding (GMAW), Flux-Cored Arc Welding (FCAW), Shielded Metal Arc Welding (SMAW), and Gas Tungsten Arc Welding (GTAW). Flat welding positions and basic joints will be practiced. Pipe and tube welding
3. Classification of Underwater Welding Underwater welding may be divided into two main types: a) Wet welding b) Dry welding Fig. 3.1 Classification of underwater welding 3.1 Wet welding 3.1.1. Wet welding with coated electrode Wet welding is performed at ambient pressure with the welder-diver in the water and no physical barrier
