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A STATISTICAL INVESTIGATION OF THE FATIGUE LIVES OF Q235 STEEL‐WELDED JOINTS
Author(s) -
Fuqiang Zhao,
Peng Gao,
Lei Sun
Publication year - 1998
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1046/j.1460-2695.1998.00064.x
Subject(s) - weibull distribution , log normal distribution , generalized extreme value distribution , extreme value theory , reliability (semiconductor) , weibull modulus , shape parameter , welding , statistics , mathematics , structural engineering , materials science , engineering , physics , thermodynamics , metallurgy , power (physics)
An investigation into the fitting of six assumed distributions (three‐parameter Weibull, two‐parameter Weibull, extreme minimum value, extreme maximum value, normal and lognormal distributions) of 23 groups of fatigue life data for Q235 steel‐welded joints is performed in terms of linear regression analyses. The results reveal that the fatigue life distribution shapes mostly tend to be positively skewed. Therefore, the extreme minimum value and normal distributions are not the most appropriate distributions to assume for a fatigue life evaluation. The three‐parameter Weibull distribution may give misleading results in fatigue reliability analyses because the shape parameter is often lesss than 1. This means that the hazard rate decreases with fatigue cycling. This is contrary to the general understanding of the behaviour of welded joints. Reliability analyses may also be affected by slightly non‐conservative evaluations in tail regions of the three‐parameter Weibull distribution. The two‐parameter Weibull distribution does not give as good a fit as either the extreme maximum value distribution or the lognormal distribution. On the other hand, the extreme maximum value and lognormal distributions can be safely assumed in reliability analyses due to the good total fit effects and the conservative evaluations in tail regions. In addition, the extreme maximum value distribution is in good agreement with the general physical understanding of the structural behaviour of welded joints.