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This paper aims at providing exact expressions for the mechanical fields induced by Laser Shock Peening and comparing them to their numerical estimations. We use a uniaxial strain field hypothesis with an elastic perfectly plastic behavior to derive the stress wave equation. An exact solution to this equation is given using the method of characteristics for a step time profile for the pressure loading, and numerically using finite differences schemes adapted for this hyperbolic equation. An additional residual stress modeling is used, providing the residual stress distribution assuming a planar infinite plate with a finite thickness. Results are presented for three loading pressures, each one corresponding to a different structure in the exact solution. The exact and numerical results present a good match, allowing either the use of the exact solution for an initial estimation of the mechanical fields, or to test the accuracy of other numerical methods. [ABSTRACT FROM AUTHOR]

Copyright of Matériaux et Techniques is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

From the elaboration of composites at relatively high temperatures, result the residual stresses highly localized in the fiber and the matrix in the nearest vicinity of their interface. These shear stresses put the fiber in compression and the matrix in tension. The objective of this work is to study, three-dimensionally by the finite element method, the effect of these constraints on the behavior of cracks initiated in a composite of a matrix of Al fiber reinforced Al2O3. This behavior is analyzed in terms of variation of the stress intensity factor in modes I, II and III. The effect of the size of the crack, its orientation, its localization, its propagation as well as its penetration has been highlighted. [ABSTRACT FROM AUTHOR]

Copyright of Matériaux et Techniques is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Matériaux et Techniques is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Matériaux et Techniques is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Thin sheet buckling modeling and applications for strip rolling. In some material forming processes, as in strip rolling, residual stresses inevitably appear and may resulting buckling which is translated to geometric defects. This requires predicting this mechanical instability phenomenon in order to define defect geometry and amplitude. For that reason, a complete buckling model having a postbuckling computing capability is recommended. In this paper, we present a residual stress buckling plate model which has a critical load and post-buckling computing capability. Several academic applications and a rolling case are treated. [ABSTRACT FROM AUTHOR]

Solid round steel columns are commonly used as legs and also as diagonal and horizontal members of communication towers. The Canadian standard Antennas, towers, and antenna supporting structures, CSA S37-01, specifies empirical expressions for the compressive resistance of solid round columns based on the Structural Stability Research Council (SSRC) column curves for non solid round columns as well as the results from experimental investigations on solid rounds that have been carried out since 1965. As such, it was felt necessary to conduct an experimental study on non-stress-relieved steel solid round columns to refine the available design equations for such columns. This paper provides a summary of a recent test program on the compressive resistance of non-stress-relieved steel solid rounds. Correlation between the results from these tests and the current practice for the design of solid rounds is investigated. The paper concludes with a proposed compressive resistance equation for economical design of such columns. [ABSTRACT FROM AUTHOR]

Abstract: This article discusses the reconstruction methods for the inversion of the residual stresses in rods under the Navier–Bernoulli or the Vlassov (containing warping) kinematic conditions. The proposed framework permits us to express the residual stresses in terms of the Airy stress potential expressed as the solution of an ordinary differential equation. The particular case of the Navier–Bernoulli kinematics leads to a closed-form solution. To cite this article: A. Constantinescu, A. Oueslati, C. R. Mecanique 336 (2008). [Copyright &y& Elsevier]

Abstract: Neutron diffraction provides one of the few means of mapping residual stresses deep within the bulk of materials and components. This article reviews the basic scientific methodology by which internal strains and stresses are inferred from recorded diffraction peaks. Both conventional angular scans and time-of-flight measurements are reviewed and compared. Their complementarity with analogous synchrotron X-ray methods is also highlighted. For measurements to be exploited in structural integrity calculations underpinning the safe operation of engineering components, measurement standards have been defined and the major findings are summarised. Examples are used to highlight the unique capabilities of the method showing how it can provide insights ranging from the basic physics of slip mechanisms in hexagonal polycrystalline materials, through the materials optimisation of stress induced transformations in smart nanomaterials, to the industrial introduction of novel friction welding processes exploiting stress residual measurements transferred from prototype sub-scale tests to the joining of full-scale aeroengine assemblies. To cite this article: P.J. Withers, C. R. Physique 8 (2007). [Copyright &y& Elsevier]

The numerical simulation of the internal stresses genesis in processes of heat treatment holds, indeed, to the formulation of the coupled thermomechanics–metallurgic problem taking into account several and severe physical non linearities. This study aims to develop at least, a multipurpose model for prediction of the residual stresses state generated by a superficial heat treatment in solid phase without diffusion. For the generality of the models set up, to the sense of the thermomechanical history and other coupling terms importance, we consider the case of the treatment by a moving laser source and self quenching. Thus, the solution of this evolution problem, will lie in both the thermal and thermomechanical aspects as well as in the phase transformation effects. For the thermal analysis, we propose a non linear transient model allowing the simulation of the whole thermal history during the treatment process until the return to the thermal balance. The thermomechanical analysis is dealt with a non linear incremental model whereby we simulate the mechanical history since the beginning of the treatment until the residual stress state establishing. In the numeric scheme developed within a FEM code, the mechanical features are described in space–time evolutions depending on the temperature and the local instantaneous phases which are present throughout the domain. We introduce a global dilatometric coefficient to take into account the simultaneous and cumulated thermal and phase transformation strains.The comparison of numeric and experiment results reveals on the one hand a better qualitative consistency of the model, and tends on the other hand towards a new description of the structural transformations to reach a truly quantitative model. [Copyright &y& Elsevier]

Residual stresses which are currently observed in solid bodies can result from non-compatible initial strains. Theses stresses can then be determined, in general, from the incompatibility tensor associated to the initial strains tensor. However, even if the incompatibility tensor is zero, residual stresses may exist, when the solid is not simply-connected or when discontinuity surfaces are present. Several examples are provided. To cite this article: P. Be´rest, G. Vouille, C. R. Mecanique 331 (2003). [Copyright &y& Elsevier]