EMD223 Machine Component Design Dr. Mohamad Yusof Idroas Room: 3.10 (SoME) EMD223 Machine Component Design Dr. Mohamad Yusof Idroas Room: 3.10 (SoME)

Group Homework #1 Uploaded in eLearning on 19 April 2012 Submission Due Date: 26 Apr (Thu) 9am in class

Group Project #2 To be uploaded in eLearning by 24 Apr Submission Due Date: WW14 Date to be advised later

Welded Joints

Provide attractive alternatives for fastening (alternative to bolts & rivets). Provide alternatives for fabricating parts with lower cost than casting or forging. Most industrial welding is done by fusion. Fusion welding involves workpieces melting at their surfaces due to the heat by an electric arc passing between an electrode & the work, - by high-amperage electric current passing through the mating workpieces OR - by gas flame Welding Processes

Figure 1: Machine parts fabricated by fusion welding (a) wheel, (b) control crank, (c) pivot block Reference: Robert C. Juvinall and Kurt M. Marshek. Fundamentals of Machine Component Design – 2 nd ed. John Wiley & Sons. ISBN

Electric arc welding: Shielded metal arc welding (SMAW) Gas metal arc welding (GMAW) Gas tungsten arc welding (GTAW) Flux-cored arc welding (FCAW) Submerged arc welding (SAW) Resistance welding Gas welding Fusion welding: Laser beam welding Plasma arc welding Electron beam welding Electroslag welding Nonfusion or solid-state welding: Inertia welding Ultrasonic welding applicable to both metals & thermoplastics Vibration welding Various Welding Techniques

Welding Symbols Welding symbols are standardized by American Welding Society (AWS) Few basic weld symbols as illustrated: Figure 2: Arc and gas-weld symbols Reference: Joseph E. Shigley, Charles R. Mischke, Richard G. Budynas. Mechanical Engineering Design - 7th ed. McGraw-Hill. ISBN

Welding Symbols Figure 3: Fillet welds. (a) The number indicates the leg size; the arrow should point only to one weld when both sides are the same. (b) The symbol indicates that the welds are intermittent and staggered 60 mm along on 200- mm centers Reference: Joseph E. Shigley, Charles R. Mischke, Richard G. Budynas. Mechanical Engineering Design - 7th ed. McGraw-Hill. ISBN

Welding Symbols Figure 4: The circle on the weld symbol indicates that the welding is to go all around Reference: Joseph E. Shigley, Charles R. Mischke, Richard G. Budynas. Mechanical Engineering Design - 7th ed. McGraw-Hill. ISBN

Welding Symbols Figure 5: Butt or groove welds: (a) square butt-welded on both sides; (b) single V with 60 o bevel & root opening of 2 mm; (c) double V; (d) single bevel Reference: Joseph E. Shigley, Charles R. Mischke, Richard G. Budynas. Mechanical Engineering Design - 7th ed. McGraw-Hill. ISBN

Welding Symbols Figure 6: Special groove welds; (a) T joint for thick plates; (b) U and J welds for thick plates; (c) corner weld; (d) edge weld for sheet metal and light loads Reference: Joseph E. Shigley, Charles R. Mischke, Richard G. Budynas. Mechanical Engineering Design - 7th ed. McGraw-Hill. ISBN

Welded Joints  SUBJECTED TO STATIC AXIAL AND DIRECT SHEAR LOADING Figure 7 shows a single V-groove weld loaded by the tensile force F. Figure 7: A typical butt or groove joint Reference: Joseph E. Shigley, Charles R. Mischke, Richard G. Budynas. Mechanical Engineering Design - 7th ed. McGraw-Hill. ISBN

Welded Joints Figure 8: A parallel fillet weld Reference: Joseph E. Shigley, Charles R. Mischke, Richard G. Budynas. Mechanical Engineering Design - 7th ed. McGraw-Hill. ISBN

Welded Joints Kind of LoadingThroat-Shear Stress (Welding Code Method) Figure 9: Transverse and Parallel Fillet Welds*

Welded Joints Figure 10: Fillet weld (concave weld and convex weld) Reference: Robert C. Juvinall and Kurt M. Marshek. Fundamentals of Machine Component Design – 2 nd ed. John Wiley & Sons. ISBN

Weld Analysis The basis for weld analysis or design employs: Under the circumstances of examining & estimating: - Primary shear stresses due to external forces. - Secondary shear stresses due to torsional & bending moments. - The strength(s) of the parent metal(s) - The strength of deposited weld metal. - Permissible load(s) for parent metal(s). - Permissible load for deposited weld metal.

Exercise Q1: The plates in Figure Q1 are 12 mm thick and made of steel having S y = 350 Mpa. They are welded together by convex fillet welds along sides AB and CD, each with the length of 50 mm. Yield strength of the weld metal is 350 Mpa. Determine the static load F of the parallel-loaded welds that can be carried using 6-mm weld leg, with the safety factor of 3. Figure Q1: Parallel-loaded fillet welds

Reference Apply Distortion Energy Theory: Background info of DET:

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