Chapter 9

1. Chapter 9 Welding, Bonding, and the Design of Permanent Joints Dr. A. Aziz Bazoune King Fahd University of Petroleum & Minerals Mechanical Engineering Department Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

2. Chapter Outline 9-1 Welding Symbols 9-2 Butt and Fillet Welds 9-3 Stresses in Welded Joints in Torsion 9-4 Stresses in Welded Joints in Bending 9-5 The Strength of Welded Joints 9-6 Static Loading 9-7 Fatigue Loading 9-8 Resistance Welding 9-9 Bolted and Riveted Joints Loaded in Shear 9-10 Adhesive Bonding Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

3. LECTURE-40 9-4 Stresses in Welded Joints in Bending 9-5 The Strength of Welded Joints 9-6 Static Loading 9-7 Fatigue Loading Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

4. 9-4 Stresses in Welded Joints in Bending • A FBD diagram of the beam would show a shear force Vand a moment diagram M. • Theshear force produces a primary shear in the welds of magnitude • The moment M introduces a throat shear stress component of 0.707 τin the welds. • Treating the two welds of Fig. 9-17b as lines we find the second moment of area to be (a) (b) Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints • Fig. 9-17a shows a cantilever welded to a support by fillet welds at top and bottom.

5. 9-4 Stresses in Welded Joints in Bending (c) (d) Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints • The second moment of area I, based on weld throat area, is • The nominal throat shear stress is now found to be • The model gives the coefficient of 1.414, in contrast to the predictions of Sec.9-2 of 1.197 from distortion energy, or 1.207 from maximum shear. • The second moment of area in Eq. (d) is based on the distance d between the two welds.

6. Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

7. 9-5 The Strength of Welded Joints • The matching of the electrode properties with those of parent metal is usually not so important as speed, operator appeal, and the appearance of the completed joint. • The properties of electrodes vary considerably, but Table 9-3 lists the minimum properties for some electrode classes. Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

8. It is preferable, in designing welded components, to select a steel that ill result in a fast, economical weld. • Best results are obtained for steels having a UNS specifications between G10140 and G10230. • All these steels have a tensile strength in the hot-rolled condition in the range of 60 to 70 kpsi. • Permissible stresses are now based on the yield strength of the material instead of the ultimate strength, and the code permits the use of a variety of ASTM structural steels having yield strengths varying from 33 to 50 kpsi. • For these ASTM steels, Sy = 0.5 Su. • Table 9-4 lists the formulas specified by the code for calculating these permissible stresses for various load conditions. Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

9. Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

10. The fatigue stress concentration factors listed in Table 9-5 are suggested for use. These factors should be used for the parent metal as well as for the weld metal. Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

11. Table 9-6 gives steady-load information and minimum fillet sizes. Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

12. 9-6 Static Loading Table A-20, Sy = 27.5 kpsi Example 9-2 (Textbook) h =3/8=0.375 in t = 1/2 in l = 2 in Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

13. Example 9-2 (Cont.’d) h =3/8=0.375 in t = 1/2 in l = 2 in Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

14. Table A-20, Sy = 32 kpsi, Sut= 58 kpsi Example 9-4 (Textbook) Table 9-3, Sy = 50 kpsi, Sut= 62 kpsi Table 9-2, pattern 2, b=3/8 = 0.375 in and d= 2in Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

15. E6010 electrode Table 9-3, Sy = 50 kpsi, Eq. 6-21 Ssy= 0.577 Sy Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

16. Given n=3 Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

17. 9-7 Fatigue Loading • The conventional methods will be provided here. • In fatigue, the Gerber criterion is best; however, you will find that the Goodman criterion is in common use. • Recall, that the fatigue stress concentration factors are given in Table 9-5. • For Welding codes, see the fatigue stress allowables in the AISI manual. Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

18. Example 9-5 (Textbook) Table A-20, Sy = 32 kpsi, Sut= 58 kpsi Table 9-5, Kfs=2.7 Table 9-3, Sy = 62 kpsi, Sut= 50 kpsi Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

19. (7-4) A = 2 x 0.707 x h x l (7-25) h = 3/8=0.375 in l = 2 in (7-8) (7-17) Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

20. Example 9-6 (Textbook) Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

21. (7-4) (7-8) (7-25) (7-17) (7-56) (7-10) Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

22. QUESTIONS ? Thank U ! Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints

23. Dr. A. Aziz Bazoune Chapter 9: Welding, Bonding, and the Design of Permanent Joints