Fatigue of Welded Structures (2nd Edition)

Abstract

Welded structures affect our lives, since welding is the principle joining method employed in the fabrication industry. This book, consisting of 15 well-written chapters and an appendix, details various aspects of fatigue. The author is a well known researcher and contributor on welded structures.Chapter I and II discuss the basic aspects of fatigue, including S/N curves and stresss concentrations. The comparatively new subjects of the application of fracture mechanics to fatigue crack growth is considered starting from the basics to the more complicated.Chapter III covers the fatigue strength of unwelded steel specimens with reference to the fatigue of notched and unnotched samples and offers with a brief discussion of the nonpropagating crack (Frost relationship).Chapter IV focuses upon transverse butt welds in steel. The effect of weld shape (important role as a stress concentrator), machining the weld reinforcement (improvement of fatigue life) plus the proper preparation of plate edge are important in weld fabrication.Chapter V and VI continue with a discussion of fillet welds. S/N curves are presented for high strength steel for both longitudinal and transverse types of weld. Continuing with welded steel beams which are the simplest form of engineering construction, the effects of nub stiffness, splices, flange cover plates are considered in the light of good design.Chapters VII, VIII, and IX focus upon tubular joints and their prime importance in offshore structure design. The various nondimensional parameters are considered in stress analysis.

Fatigue properties of 6061-T6 aluminum alloy butt joints processed by vacuum brazing and tungsten inert gas welding

“…According to the experimental S-N curves of 4-mmthick TIG weldment and 4-mm-thick VB specimen, the thickness corrections were carried out using equations (8) and (9). After the mean stress correction was conducted by re-applying equations (5) and (6), the predicted life and experimental life were compared.…”

“…6 The fatigue properties of welded structures are function of welding material, shape of the welded structure, radius of weld toe, weld angle, height of the reinforcement, and welding quality. [7][8][9][10] With respect to the studies on the fatigue in aluminum alloy weldments, most literature discussed the fatigue behaviors of weldments prepared by the molten welding methods, such as inert-gas metal-arc welding, 11 TIG welding, [12][13][14] and friction stir welding. [15][16][17][18][19] Few studies investigated the diffusion-bonding weldments.…”

Fatigue damage analysis of welded structural members by using damage mechanics

“…The heat input in a T-joint is different from a butt joint. This effect can be taken into account by replacing the heat input Q by an equivalent heat input Q'=2Qh/(2hf+hw)(see Fig.3) and the value of b0 is given by the following equation: (6) where hw and hf are the plate thickness of the web and the flange, respectively.…”

“…(4) and (5), while the distribution can be obtained by Eqs. (6) and (9). The inherent strain distribution in I-joint can also be evaluated by means of the same procedure.…”

A simple expression to estimate the fatigue endurance of welded joints

“…However, there still exists a dominance of the traditional nominal stress method, which has been prevailing for over 45 years in the fatigue design of welded structures. To ensure that the full effect of the three key features dominating the fatigue life of welded joints (geometric stress concentrations, welding flaws, and residual stresses) are allowed for in design, most fatigue design rules consist of series of ∆σ-N curves based on data obtained from constant amplitude fatigue tests on actual weldments [3][4][5], and employ classification methods of specifying design curves in terms of the fatigue strength at a given number of cycles (e.g. 2x10 6 or 10 7 ).…”