The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Andrzej Seweryn - One of the best experts on this subject based on the ideXlab platform.
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Damage accumulation and ductile fracture modeling of notched specimens under biaxial loading at room temperature
International Journal of Solids and Structures, 2018Co-Authors: L. Derpenski, J. Szusta, Andrzej SewerynAbstract:Abstract This paper presents the results of ductile fracture tests conducted on axisymmetric specimens with notch made from EN AW 2024 T351 aluminum alloy. Tests were conducted for five notch radius and seven cases of biaxial, proportional loading with tensile force and torsional moment. A model of damage accumulation and fracture based on variables of stress strain state and damage on a Physical Plane is proposed. The fracture criterion assumes that crack initiation will occur when a certain combination of normal and shear stress on the Physical Plane (elliptical criterion in the tensile stress zone and Coulomb criterion in the shear stress zone) reaches a critical value dependent on the value of the damage state variable on this Plane. The damage accumulation law was formulated incrementally, and the increment of the damage state variable was made dependent on the increment of plastic deformations and stress values on the Physical Plane. This model was successfully verified by experimental tests and numerical simulations, which are presented in papers by Derpenski and Seweryn (2016a,b) .
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Fatigue Crack Growth Predictionby the Non-local Critical Plane Model
2013Co-Authors: Zenon Mróz, Andrzej Seweryn, Adam TomczykAbstract:The present paper is concerned with modelling of fatigue crack initiationand propagation by applying the non-local critical Plane model, proposed by Sewerynand Mroz [1,2]. Using the linear elastic stress field at the front of crack or sharp notchthe damage growth on a Physical Plane is specified in terms of mean values of stressand strength function. When the damage zone reaches a critical length, crack growthaccompanies damage evolution. The model is applied to study crack propagation undercyclically varying tension-compression and predictions are compared with experimen-tal data.
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Low-cycle fatigue model of damage accumulation – The strain approach
Engineering Fracture Mechanics, 2010Co-Authors: J. Szusta, Andrzej SewerynAbstract:Abstract The paper presents a model of damage accumulation designed to analyse fatigue life of structural elements exploited in multiaxial, non-proportional, low-cycle loading conditions. The discussed approach consists of two calculation blocs. In the first bloc the components of stress and strain tensor are determined. This module, in which Mroz’s multisurface model was used, contains constitutive relations and the law of kinematic hardening. The second bloc contains the dependencies which determine the growth of anisotropic measure of damage accumulation (associated with the Physical Plane) and crack initiation criterion. The growth of the damage accumulation measure was associated with the loading damage accumulation function and the increment of non-dilatational plastic strain on the Physical Plane. It was assumed that crack initiation occurs when stress or a measure of damage accumulation on any Physical Plane reaches critical values.
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low cycle fatigue model of damage accumulation the strain approach
Engineering Fracture Mechanics, 2010Co-Authors: J. Szusta, Andrzej SewerynAbstract:Abstract The paper presents a model of damage accumulation designed to analyse fatigue life of structural elements exploited in multiaxial, non-proportional, low-cycle loading conditions. The discussed approach consists of two calculation blocs. In the first bloc the components of stress and strain tensor are determined. This module, in which Mroz’s multisurface model was used, contains constitutive relations and the law of kinematic hardening. The second bloc contains the dependencies which determine the growth of anisotropic measure of damage accumulation (associated with the Physical Plane) and crack initiation criterion. The growth of the damage accumulation measure was associated with the loading damage accumulation function and the increment of non-dilatational plastic strain on the Physical Plane. It was assumed that crack initiation occurs when stress or a measure of damage accumulation on any Physical Plane reaches critical values.
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A non-local fatigue crack growth model and its experimental verification
Journal of Theoretical and Applied Mechanics, 2004Co-Authors: Andrzej Seweryn, Adam Tomczyk, Zenon MrózAbstract:The present paper is concerned with the modelling of fatigue crack initiation and propagation by applying the non-local critical Plane model, proposed by Seweryn and Mroz (1996, 1998). Using the linear elastic stress field at the front of a crack or sharp notch, the damage growth on a Physical Plane is specified in terms of mean values of the stress and strength function. The model is applied to study crack propagation under cyclically varying tension-compression conditions. The predictions are compared with experimental data.
Didier Clamond - One of the best experts on this subject based on the ideXlab platform.
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New exact relations for steady irrotational two-dimensional gravity and capillary surface waves
2017Co-Authors: Didier ClamondAbstract:Steady two-dimensional surface capillary-gravity waves in irrotational motion are considered on constant depth. By exploiting the holomorphic properties in the Physical Plane and introducing some transformations of the boundary conditions at the free surface, new exact relations and equations for the free surface only are derived. In particular, a Physical Plane counterpart of the Babenko equation is obtained.
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New exact relations for steady irrotational two-dimensional gravity and capillary surface waves
Philosophical Transactions of the Royal Society A, 2017Co-Authors: Didier ClamondAbstract:Steady two-dimensional surface capillary–gravity waves in irrotational motion are considered on constant depth. By exploiting the holomorphic properties in the Physical Plane and introducing some transformations of the boundary conditions at the free surface, new exact relations and equations for the free surface only are derived. In particular, a Physical Plane counterpart of the Babenko equation is obtained. This article is part of the theme issue ‘Nonlinear water waves’.
Chao Xie - One of the best experts on this subject based on the ideXlab platform.
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Singularities in the complex Physical Plane for deep water waves
Journal of Fluid Mechanics, 2011Co-Authors: Gregory R. Baker, Chao XieAbstract:AbstractDeep water waves in two-dimensional flow can have curvature singularities on the surface profile; for example, the limiting Stokes wave has a corner of $2\lrm{\pi} / 3$ radians and the limiting standing wave momentarily forms a corner of $\lrm{\pi} / 2$ radians. Much less is known about the possible formation of curvature singularities in general. A novel way of exploring this possibility is to consider the curvature as a complex function of the complex arclength variable and to seek the existence and nature of any singularities in the complex arclength Plane. Highly accurate boundary integral methods produce a Fourier spectrum of the curvature that allows the identification of the nearest singularity to the real axis of the complex arclength Plane. This singularity is in general a pole singularity that moves about the complex arclength Plane. It approaches the real axis very closely when waves break and is associated with the high curvature at the tip of the breaking wave. The behaviour of these singularities is more complex for standing waves, where two singularities can be identified that may collide and separate. One of them approaches the real axis very closely when a standing wave forms a very narrow collapsing column of water almost under free fall. In studies so far, no singularity reaches the real axis in finite time. On the other hand, the surface elevation $y(x)$ has square-root singularities in the complex $x$ Plane that do reach the real axis in finite time, the moment when a wave first starts to break. These singularities have a profound effect on the wave spectra.
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Singularities in the complex Physical Plane for deep water waves
2010Co-Authors: Chao Xie, Gregory R. BakerAbstract:A boundary integral technique is used to simulate deep water wave motion. A spectral procedure is used to form-fit the Fourier spectrum of the curvature of the wave profile to a prescribed asymptotic expression. The fit provides information on the power and location of the closest curvature singularity to the real axis of the complex arclength Plane. This singularity proves to be a pole singularity in the complex arclength Plane, and is not an artifact of the parametrization. It approaches the real axis when a plunging breaker occurs and wanders above some level in the complex arclength Plane for non-breaking waves. This singularity is found theoretically equivalent to Tanveer's result. When the surface elevation is viewed as a function of horizontal distance x, a square root type singularity occurs in the complex x Plane. It corresponds to a breaking wave when it reaches the real axis of the horizontal coordinate.
Scott L. Douglass - One of the best experts on this subject based on the ideXlab platform.
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Overhauser boundary elements solution for periodic water waves in the Physical Plane
Engineering Analysis with Boundary Elements, 1993Co-Authors: Juan C. Ortiz, Scott L. DouglassAbstract:Abstract An Overhauser boundary element method (BEM) for the modeling of nonlinear periodic waves in the Physical Plane is described. The Overhauser element, used to eliminate discontinuities of the slope on the free surface of the wave, is described in detail. Examples for non-linear steady and breaking waves are shown. The Overhauser element is compared to Lagrangian linear and cubic elements. It is noted that the Overhauser element system is very stable. Neither ‘smoothing’ nor any other manipulation of the BEM results are necessary within the time-stepping algorithm to achieve a stable solution.
Gregory R. Baker - One of the best experts on this subject based on the ideXlab platform.
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Singularities in the complex Physical Plane for deep water waves
Journal of Fluid Mechanics, 2011Co-Authors: Gregory R. Baker, Chao XieAbstract:AbstractDeep water waves in two-dimensional flow can have curvature singularities on the surface profile; for example, the limiting Stokes wave has a corner of $2\lrm{\pi} / 3$ radians and the limiting standing wave momentarily forms a corner of $\lrm{\pi} / 2$ radians. Much less is known about the possible formation of curvature singularities in general. A novel way of exploring this possibility is to consider the curvature as a complex function of the complex arclength variable and to seek the existence and nature of any singularities in the complex arclength Plane. Highly accurate boundary integral methods produce a Fourier spectrum of the curvature that allows the identification of the nearest singularity to the real axis of the complex arclength Plane. This singularity is in general a pole singularity that moves about the complex arclength Plane. It approaches the real axis very closely when waves break and is associated with the high curvature at the tip of the breaking wave. The behaviour of these singularities is more complex for standing waves, where two singularities can be identified that may collide and separate. One of them approaches the real axis very closely when a standing wave forms a very narrow collapsing column of water almost under free fall. In studies so far, no singularity reaches the real axis in finite time. On the other hand, the surface elevation $y(x)$ has square-root singularities in the complex $x$ Plane that do reach the real axis in finite time, the moment when a wave first starts to break. These singularities have a profound effect on the wave spectra.
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Singularities in the complex Physical Plane for deep water waves
2010Co-Authors: Chao Xie, Gregory R. BakerAbstract:A boundary integral technique is used to simulate deep water wave motion. A spectral procedure is used to form-fit the Fourier spectrum of the curvature of the wave profile to a prescribed asymptotic expression. The fit provides information on the power and location of the closest curvature singularity to the real axis of the complex arclength Plane. This singularity proves to be a pole singularity in the complex arclength Plane, and is not an artifact of the parametrization. It approaches the real axis when a plunging breaker occurs and wanders above some level in the complex arclength Plane for non-breaking waves. This singularity is found theoretically equivalent to Tanveer's result. When the surface elevation is viewed as a function of horizontal distance x, a square root type singularity occurs in the complex x Plane. It corresponds to a breaking wave when it reaches the real axis of the horizontal coordinate.
