Papers by Keyword: Residual Strains

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Authors: Aaron C. Lam, Jian Guo Lin
Abstract: An analytical method suitable for modelling the creep-age forming (CAF) of doubly curved aluminium plates is presented. This new mechanics model combines an efficient numerical integration method with a robust set of CAF constitutive equations that has been experimentally validated with AA7055 at a CAF condition. Corresponding finite element simulations show good agreement with the analytical results. Using the validated analytical model to investigate a three-stage CAF process (loading, creep-ageing, and unloading), through-thickness strain distributions are studied for aluminium plates that have been subjected to different creep-ageing time. A creep activation point (CAP) is revealed and a correlation is found between the two parameters introduced in this work – the normalised location of CAP, zCAP and normalised bend ratio, β. More specifically, a linear relationship is found between β and zCAP, which indicates that the onset of creep strain, and hence the sizes of the pure elastic core and the outer creep region, can be readily predictable within the limits of study. It is now possible to simulate two-dimensional bending CAF processes for aluminium alloys that have non-spherical precipitates.
Authors: Evgeniy Dats, Sergey Mokrin, Evgeniy Murashkin
Abstract: The dimensional problem of a formation of the residual stresses in the thin circular elastoplastic plate under the given thermal action was analytically solved. The generalized Prandtl-Reuss thermoelastoplastic model was used. The effect of the non-stationary temperature gradient on the residual stresses field formation was investigated under the condition that the yield stress depends on a temperature. The borders of the irreversible deformation domain and unloading domain were computed. The level of residual stresses was calculated.
Authors: Nils Letouzé, Rénald Brenner, Olivier Castelnau, Jean Luc Béchade
Authors: Brent L. Adams, Dorte Juul Jensen, Henning Friis Poulsen, R.M. Suter
Authors: Pavol Mikula, Petr Lukáš, Miroslav Vrána
Abstract: The performance of an unconventional high-resolution neutron diffractometer using Bragg diffraction optics that can be efficiently employed in strain/stress diffractometers are reported. Presented results demonstrate their experimental abilities for powder diffraction, namely for residual strain/stress measurements. In addition to the macrostrain scanning capability, the device can also be used for microstrain/stress studies by suitable analysis of the diffraction profiles. Two examples of the strain measurements are presented.
Authors: Girolamo Costanza, R. Donnini, Saulius Kaciulis, Giorgio Maddaluno, Roberto Montanari
Abstract: W is a promising material to use as protection for thermal shields in future nuclear fusion reactors, however the joining to other metals is really challenging. For realizing such joints plasma spraying (PS) has been used for its simplicity, the possibility to cover complex and extended surfaces and the relatively low cost. An appropriate interlayer must be optimized to increase the adhesion of W on the substrates and to provide a soft interface for better thermo-mechanical compatibility.The present work demonstrates that high-temperature X-ray diffraction (HT-XRD) permits to quickly assess the reliability and quality of the coating-interlayer-substrate system by measuring the strain of coating. This is very useful to orientate the work for optimizing the structure and composition of the interlayer and the parameters of deposition process.
Authors: A.H. Fischer, Robert A. Schwarzer
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