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Application and recent research on direct analysis with completed projects in Macau and Hong Kong
Published in Kok Keong Choong, Mustafasanie M. Yussof, Jat Yuen Richard Liew, Recent Advances in Analysis, Design and Construction of Shell and Spatial Structures in the Asia-Pacific Region, 2019
Siu-Lai Chan, Y. P. Liu, S. W. Liu
Member imperfection may increase the bowing effect and induce the P-δ moment, which is important when the member is subjected to a large compression. Member imperfections include initial geometric imperfections and residual stresses. The initial geometric imperfections may be due to one or several aspects such as cambering, sweeping, twist, out of straightness, and cross-section distortion. The residual stresses can be due to manufacturing and fabrication processes. In de Normalización (2005) and CoPHK (2011), the two kinds of imperfections are simply combined into an equivalent geometric imperfection, while AISC (2016) adopts 0.1% member length as geometric imperfection and explicitly considers residual stress by a modified modulus approach. In this chapter, the equivalent initial bowing imperfections following CoPHK (2011) is adopted for the tapered I-beams. The beam-column element described in the previous section is used to model the tapered I-beams.
Surface Integrity and Fatigue
Published in Eliahu Zahavi, Vladimir Torbilo, Fatigue Design, 2019
Eliahu Zahavi, Vladimir Torbilo
The residual stresses may be determined by either analytical or experimental methods. Analytical methods, developed by a number of authors, allow us to compute the distribution of residual stresses in the surface layer on the basis of the following factors: mechanical properties of the processed material, shape and dimensions of the part, and the loading condition. Because of the complexity of these methods, their application is limited. Often, important data is unavailable, such as strength and heat transfer properties of the material in a transformed surface layer or the intensity of heat sources. Or, the predicted residual stresses are inaccurate. In view of the above, the residual stresses are determined mostly by experimental methods.
Welds, Their Quality and Inspection Ability for High Integrity Structures and Components
Published in Peter Hirsch, David Lidbury, Fracture, Plastic Flow and Structural Integrity, 2019
R.E. Dolby, I.J. Munns, C.R.A. Schneider, R.H. Leggatt
The use of these analytical and experimental techniques has led to a greater knowledge and understanding of the effect of component geometry, restraint, welding procedure, thermal properties, mechanical properties, phase changes and transformation plasticity on the magnitudes and distributions of residual stresses in welded joints.20 This knowledge has led to more accurate analysis of the role of residual stresses in failure mechanisms, to the development of techniques for reducing residual stresses in sensitive locations, and to the preparation of standardised residual stress profiles for use in assessing the acceptability of defects in welded structures.21–23
Electromagnetic (EM) sensor measurement for residual stress characterisation in welded steel plates
Published in Nondestructive Testing and Evaluation, 2023
Edosa Osarogiagbon, Russ Hall, Lei Zhou, Janka Cafolla, Claire Davis
Residual stresses are stresses in materials or finished components in the absence of applied stress. Welded components are particularly prone to the effects of residual stresses, welding is a high-energy process which causes residual stresses around the weld which can affect a component’s strength, toughness and fatigue life. The presence of residual stresses can cause unexpected failures; measurement of residual stresses allows their effects to be managed [1]. Various methods of measuring residual stress have been developed [1,2], including destructive and non-destructive methods [3–6]. Destructive methods include the contour method [7–10], slitting method [11–14], blind hole drilling (BHD) method [15–17], deep hole contour (DHC) method [18–20] and deep hole drilling method [21–25]. Non-destructive techniques include X-ray diffraction [19–21], neutron diffraction [26, 27], electromagnetic (EM) [28–30] and ultrasonic methods [31–36].
A systematic overview on activated-Tungsten inert gas welding
Published in Welding International, 2022
K. B. Vysakh, A. Mathiazhagan, S. Krishna Prasad
The thermal cycles inherent in the welding method induce residual stress. The residual stresses can present potential problems since they can introduce brittle fracture, diminishing the buckling capacity of the weld structures. The residual stress values can be determined by destructive methods or non-destructive methods like X-ray diffraction technique, ultrasonic methods etc. Distortion of the welded joints may be avoided by using rigid grips during the welding process; however, it can enhance the generation of residual stresses. As a matter of fact, residual stress and distortion values must be balanced in order to establish a sound welded connection [63]. Angular distortion measurements are done at different grid points marked in a weldment, using height gauges and dial gauge. A schematic diagram showing the angular distortion measurement setup is shown in the figure 12.
Machining-induced surface integrity and nanocrystalline surface layers in cryogenic finishing turning of Inconel 718
Published in Machining Science and Technology, 2022
Guher Pelin Toker, Julius Schoop, Haluk Karaca
The high plastic deformation that occurs during machining due to the thermo-mechanical loads between tool and sub-surface tends to result in a shallow surface layer of residual stresses, which may be compressive or tensile near the surface (Coz et al. 2010). Generally, mechanical loads tend to induce compressive residual stress, while thermal effects tend to promote tensile residual stresses (Coz et al. 2010; Arunachalam et al. 2004). Residual stresses could be either beneficial or detrimental for materials, although compressive stresses are generally considered positive, as they promote increased fatigue and creep life, while tensile residual stresses accelerate crack propagation (El-Khabeery and Fattouh 1989; Arunachalam et al. 2004). As Inconel 718 is commonly used to construct cyclically loaded components (e.g., turbine blades), compressive residual stresses are widely considered to be a desirable surface layer condition.