VI Classifications of Weldments Good Bad AM 11/03 1
Outline TWI Classification system AISC classification system An alternative classification system AM 11/03 2
B - Longitudinal butt AM 11/03 3
C - longit. Butt w/ Reinforcement AM 11/03 4
C - Transverse Butt, Machined AM 11/03 5
D - Long. Butt w/ Start-stop AM 11/03 6
D - Butt weld w/ good toe AM 11/03 7
E - Butt weld w/ bad toe AM 11/03 8
F2 - Trans. butt in rolled section AM 11/03 9
F - Trans. Butt w/ backing strip AM 11/03 10
F - Attachments on plate face AM 11/03 11
F - Groove welded cruciform AM 11/03 12
G - Attachments near edge AM 11/03 13
F2 - Load carrying fillet weld AM 11/03 14
W - Fillet weld metal AM 11/03 15
TWI - Classification system AM 11/03 16
Application of TWI system AM 11/03 17
Application of TWI system AM 11/03 18
TWI rules AM 11/03 19
Outline TWI Classification system AISC classification system An alternative classification system AM 11/03 20
AISC classification system 100 Weld Category A B 10 C D E F 1 10 4 10 5 10 6 Fatigue Life, N (cycles) 10 7 10 8 AM 11/03 21
AISC category B and C 10 3 S = 239.55 * N^-0.15296, r = -0.50264, s = 0.13542 10 2 10 1 99% survival with 50% confidence 99% survival with 95% confidence The good welds! failures run-outs logn = 8.1064-1.6518*logS, r = -0.45032, s = 0.44503 10 0 10 2 10 3 10 4 10 5 Fatigue life, N (cycles) 10 6 10 7 AM 11/03 22
AISC category D and E 10 3 failures run outs 10 2 S = 159.20 * N^-0.16648, r^2 = 0.173, s = 0.1718 10 1 99% survival with 50% confidence 99% survival with 95% confidence logn = 6.8974-1.03751*logS, r = -0.2387, s = 0.4293 The bad welds! 10 0 10 3 10 4 10 5 Fatigue life, N (cycles) 10 6 10 7 AM 11/03 23
AISC category best fit lines to data 10 3 10 2 99% survival with 95% confidence A B A-S99% B-S99% C-S99% D-S99% E-S99% F-S99% C 10 1 D E F 10 0 10 3 10 4 10 5 Fatigue life, N (cycles) 10 6 10 7 AM 11/03 24
6.3 A Suggestion for the Classification of Weldments Good Bad AM 11/03 25
Weld stress concentrations Personal view Termination Ripple Toe Root AM 11/03 26
Ripple 70 50 Ripple Groove Welds Non-Load-Carrying Fillet Welds Load-Carrying Fillet Welds Terminations Fatigue Life, N (cycles) 30 10 8 6 4 10 5 10 6 10 7 Nominal Stress Range, DS (MPa) AM 11/03 27
Groove welded butt joints 70 50 Ripple Groove Welds Non-Load-Carrying Fillet Welds Load-Carrying Fillet Welds Terminations Fatigue Life, N (cycles) 30 10 8 6 4 10 5 10 6 10 7 Nominal Stress Range, DS (MPa) AM 11/03 28
Non-load-carrying fillet welds 70 50 Ripple Groove Welds Non-Load-Carrying Fillet Welds Load-Carrying Fillet Welds Terminations Fatigue Life, N (cycles) 30 10 8 6 4 10 5 10 6 10 7 Nominal Stress Range, DS (MPa) AM 11/03 29
Transverse attachments 70 50 Ripple Groove Welds Non-Load-Carrying Fillet Welds Load-Carrying Fillet Welds Terminations Fatigue Life, N (cycles) 30 10 8 6 4 10 5 10 6 10 7 Nominal Stress Range, DS (MPa) AM 11/03 30
Longitudinal attachments 70 50 Ripple Groove Welds Non-Load-Carrying Fillet Welds Load-Carrying Fillet Welds Terminations Fatigue Life, N (cycles) 30 10 8 6 4 10 5 10 6 10 7 Nominal Stress Range, DS (MPa) AM 11/03 31
Good, bad, maverick S (MPa) 500 300 Ripple Groove Welds Non-Load-Carrying Fillet Welds Load-Carrying Fillet Welds Terminations 100 80 60 40 10 5 10 6 10 7 Fatigue Life, N (cycles) AM 11/03 32
Good welds, Bad welds, Mavericks Nominal Stress Range, S (ksi) 100 10 Non-Load-Carrying Fillet Bad Good Fatigue Life, N (cycles) Ripple 500 Transverse Groove Welded Butt 100 Terminations Maverick Termination Partial Penetration Load-Carrying Fillet 10 5 10 6 10 7 AM 11/03 33 50 Nominal Stress Range, S (MPa)
The good welds: weld toe failures C Detail #3 Kf = 1.87 ²S design = 27.0 ksi. C Full-Penetration Groove Weld: Detail #10 Kf =2.12 ²S design = 23.3 ksi. C Non-Load Carrying Fillet Weld: Detail #25 Kf =2.23 ²S design = 22.1 ksi. AM 11/03 34
The bad welds: terminations C,Cs Load Carrying Fill et Weld: Detail #20 Kf =3.12 ²S design = 17.5 ksi. C Weld Termination: Detail #30 Kf =3.27 ²S design = 14.5 ksi. AM 11/03 35
Fatigue severity of terminations C Starts and stops introduce weld discontinuities. Residual stresses very high. 3-D stress concentrations effects. AM 11/03 36
Examples of terminations C C C L P L-P L-P C C b a C AM 11/03 37
The mavericks: something undefined P C Partial penetration weldment. The amount of penetration is generally unknown. C, Cs C, Cs Undercut. Failu re occurs at the undercut on wrap-around weld where the arris of the plate is melted. the amount of the undercut is generally unknown. AM 11/03 38
The mavericks: complex components C C Multiple failure sites. The stress distribution in the joint changes as fatigu e cracks initiate and grow at various locations. L L-P L-P P C Local stresses uncertain because of structural redundancy AM 11/03 39
Summary Viewed from the perspective of crack initiation site, weldments could be grouped into four categories: ripple, toe, root, and terminations. This classification scheme leads to the conclusion that there are Good and Bad weldments and Mavericks - weldments for which a critical piece of information is unavailable and hence their behavior is undefined. AM 11/03 40