[en] This paper presents a review of work carried out to ascertain the residual stresses present within a T- plate section. The contour method, the incremental deep hole drilling (iDHD) and the incremental centre hole drilling (ICHD) are coupled to determined longitudinal and transverse components of residual stress in the weld tope of the fillet weld in the as-welded condition. This paper presents first the measurement using the iDHD method and the measurement obtained using the contour method is then presented. The accuracy and resolution of the contour method results are directly linked to the quality of the electro- discharge machining (EDM) cut made. The challenges incurs by cutting complex geometry like this T- plate section are identified and their influence on residual stresses calculated by the contour method is quantified. (author)

[en] While defect assessment standards such as BS 7910 “Guide to methods of assessing the acceptability of flaws in metallic structures” present residual stress profiles for T butt welds in thick sections they inherently assume that the weld pass placement strategy is such that the last weld pass is always on the base plate. There is limited information on what the residual stress profiles are if alternative pass placement strategies are used in high strength weldments and structures. Similarly there is limited information on what are the residual stress profiles under the body of the weld and the superimposition on the balancing residual stresses in the base plate away from the weld on pre-existing residual stresses. This paper presents neutron strain scanning work on a high strength, curved base plate, double sided T Butt weld undertaken such that the pass placement in each layer progressed away from the base plate towards the abutting member to determine the potential of reduction in residual stresses at the base plate weld toes. Key results were validated by the Deep Hole Drilling Technique. The results obtained show that a major reduction in the magnitude of the residual stresses occurred at the weld toes of the base plate with a corresponding increase in the center of the weld. Weld toe through thickness profiles were reduced from those of BS 7910. Balancing residual stresses in the base plate were minimal. Discussion includes comparison to results obtained in similar test plates welded with a different pass placement strategy. (author)

[en] A method for evaluating residual stress using an instrumented indentation test was developed some decades ago. More recently, another method was developed, using a Knoop indenter. The conversion factor ratio, which is one of the key factors in the evaluation algorithm, has been taken to be 0.34, although this value comes from an experimental result and its physical meaning has not been examined. Here we examine the physical meaning of this conversion factor from the previous residual stress model, and calculate its ratio using analytical model of the stress field beneath the indenter. In this process, we assumed that the conversion factor ratio was the ratio of the projected area of the plastic zone generated during the Knoop indentation test. An analysis of the stress field beneath the indenter was performed by FE simulation. Actual nanoindentation was conducted after Knoop indentation testing, using the interface-bonding technique, to identify the plastic zone. In addition, the conversion factor ratio was also calculated for the case where residual stress was present, and the geometric ratio of the Knoop indenter was different. A comparison of our results with those from previous studies showed that the conversion factor ratio obtained using our assumption was in good agreement with previous studies.

[en] A mechanical measuring method is presented for inexpensive measuring of internal stresses. The accuracy of the method is assessed by considering a number of errors and is checked by means of comparative measurements. The distributions of internal stresses in depth determined so far are physically plausible. (orig./HP)

[en] The effect of preheating temperature of substrates and thickness of coatings on residual stress and the influence of them on the adhesion of Al2O3-40wt.% TiO2 coatings manufactured by oxy fuel flame spraying process were studied. Previously to spraying process, the substrate were preheating to 150 and 250°C and then, feedstock powders were sprayed during different times obtaining coatings between 0.05mm and 0.3mm in thickness. Residual stresses were measured using the bending method from Modified Stoney and Brenner-Senderoff equations and the adhesion tests were performed by the pull-off test. The results obtained indicate that the residual stress produced in all samples was compressive, and their magnitude increases with the thickness of coating and decreasing the preheating temperature of the substrate, and then, the higher resistance was reached in thin coatings deposited onto substrates preheated at 250°C. (Author)

[en] Here, we study the shear jamming of athermal frictionless soft spheres, and find that in the thermodynamic limit, a shear-jammed state exists with different elastic properties from the isotropically-jammed state. For example, shear-jammed states can have a non-zero residual shear stress in the thermodynamic limit that arises from long-range stress-stress correlations. As a result, the ratio of the shear and bulk moduli, which in isotropically-jammed systems vanishes as the jamming transition is approached from above, instead approaches a constant. In contrast to these striking differences, we argue that in a deeper sense, the shear jamming and isotropic jamming transitions actually have the same symmetry, and that the differences can be fully understood by rotating the six-dimensional basis of the elastic modulus tensor.

[en] Full-text: Residual stress is the existing stress in a material without the influence of external load or service application. These stresses can cause structural failure in values under the actual strength of the materials. One of the methods that can be used in the measurement of residual stress especially for thick structural materials is through Neutron Diffraction (ND). Among the advantages of Neutron Diffraction is the high penetration capability suitable for thick objects and stress measurement capabilities in three directions. This paper proposes several key points to be considered prior to the design and development of Neutron diffraction facilities to meet the requirements for the residual stress measurement. (author)

No abstract available

[en] Additive Manufacture of metals is an area of great interest to many industrial sectors. All metal additive manufacturing processes suffer with problems of residual stresses and subsequent distortion or performance issues. Wire + Arc Additive Manufacture (WAAM) is a metal additive manufacture process that is suitable for the production of large scale engineering structures. Paramount to the successful industrial application of WAAM is the understanding and control of residual stress development and their subsequent effects. Vertical inter-pass rolling can be used to reduce these residual stresses, but its potential is limited due to the absence of lateral restraint of the wall. So it deforms the wall in its transverse direction rather than reducing longitudinal tensile residual stresses, which is the main source of the distortion. The potential of a new pinch-roller concept is currently being investigated at Cranfield University with very promising preliminary results: It was possible to entirely eliminate the distortion of a Ti-6Al-4V WAAM wall. (author)

[en] A decoration technique for the visualization of microcracks based on chemical impregnation and transmitted light optical investigation is described. (Author)