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E. A. Patterson - One of the best experts on this subject based on the ideXlab platform.

  • local crack plasticity and its influences on the global Elastic Stress field
    International Journal of Fatigue, 2013
    Co-Authors: M.n. James, E. A. Patterson, Colin Christopher
    Abstract:

    Abstract This paper presents the background and development of a novel ‘plastic inclusion’ approach for dealing with the local plasticity which occurs at the tip of a growing fatigue crack. Localised plasticity arises from crack growth mechanisms and essentially blunts the crack, creates a reversed cyclic plastic zone, and induces shear along the crack flanks, along with the possible generation of wake contact Stresses which act on the applied Elastic Stress field at the boundary of the Elastic–plastic enclave surrounding the crack. The paper outlines the development of a meso-scale model of the Elastic Stress field around a growing crack that explicitly incorporates these interaction effects. The outcome is a modified crack tip Stress intensity factor that includes some aspects of the magnitude of plastic wake-induced crack tip shielding and which the authors propose has the potential to help resolve some long-standing controversies associated with plasticity-induced closure. A full-field approach is developed for Stress using photoElasticity and also for displacement using digital image correlation.

  • Towards a new model of crack tip Stress fields
    International Journal of Fracture, 2008
    Co-Authors: C. J. Christopher, M.n. James, E. A. Patterson, K. F. Tee
    Abstract:

    This work introduces a novel mathematical model of the Stresses around the tip of a fatigue crack, which considers the effects of plasticity through an analysis of their shielding effects on the applied Elastic field. The ability of the model to characterize plasticity-induced effects of cyclic loading on the Elastic Stress fields is assessed and demonstrated using full-field photoElasticity. The focus is on determining the form of the shielding Stress components (induced by compatibility requirements at the Elastic–plastic interface along the crack flank and via the crack tip plastic zone) and how they influence the crack tip Elastic Stress fields during a load cycle. The model is successfully applied to the analysis of a fatigue crack growing in a polycarbonate CT specimen.

Norio Hasebe - One of the best experts on this subject based on the ideXlab platform.

  • magneto Elastic Stress subjected to uniform magnetic field over a thin infinite plate containing an elliptical hole with an edge crack
    International Journal of Solids and Structures, 2011
    Co-Authors: Norio Hasebe
    Abstract:

    Abstract Two dimensional solutions of the magnetic field and magneto Elastic Stress are presented for a magnetic material of a thin infinite plate containing an elliptical hole with an edge crack subjected to uniform magnetic field. Using a rational mapping function, each solution is obtained as a closed form. The linear constitutive equation is used for these analyses. According to the electro-magneto theory, only Maxwell Stress is caused as a body force in a plate. In the present paper, it raises a plane Stress state for a thin plate, the deformation of the plate thickness and the shear deflection. Therefore the magneto Elastic Stress is analyzed using Maxwell Stress. No further assumption of the plane Stress state that the plate is thin is made for the Stress analysis, though Maxwell Stress components are expressed by nonlinear terms. The rigorous boundary condition expressed by Maxwell Stress components is completely satisfied without any linear assumptions on the boundary. First, magnetic field and Stress analyses for soft ferromagnetic material are carried out and then those analyses for paramagnetic and diamagnetic materials are carried out. It is stated that those plane Stress components are expressed by the same expressions for those materials and the difference is only the magnitude of the permeability, though the magnetic fields H x , H y are different each other in the plates. If the analysis of magnetic field of paramagnetic material is easier than that of soft ferromagnetic material, the Stress analysis may be carried out using the magnetic field for paramagnetic material to analyze the Stress field, and the results may be applied for a soft ferromagnetic material. It is stated that the Stress state for the magnetic field H x , H y is the same as the pure shear Stress state. Solutions of the magneto Elastic Stress are nonlinear for the direction of uniform magnetic field. Stresses in the direction of the plate thickness and shear deflection are caused and the solutions are also obtained. Figures of the magnetic field and Stress distribution are shown. Stress intensity factors are also derived and investigated for the crack length.

  • magnetic field and magneto Elastic Stress in an infinite plate containing an elliptical hole with an edge crack under uniform electric current
    International Journal of Solids and Structures, 2010
    Co-Authors: Norio Hasebe
    Abstract:

    Abstract Two-dimensional solutions of the electric current, magnetic field and magneto Elastic Stress are presented for a magnetic material of a thin infinite plate containing an elliptical hole with an edge crack under uniform electric current. Using a rational mapping function, the each solution is obtained as a closed form. The linear constitutive equation is used for the magnetic field and the Stress analyses. According to the electro-magneto theory, only Maxwell Stress is caused as a body force in a plate which raises a plane Stress state for a thin plate and the deformation of the plate thickness. Therefore the magneto Elastic Stress is analyzed using Maxwell Stress. No further assumption of the plane Stress state that the plate is thin is made for the Stress analysis, though Maxwell Stress components are expressed by nonlinear terms. The rigorous boundary condition expressed by Maxwell Stress components is completely satisfied without any linear assumptions on the boundary. First, electric current, magnetic field and Stress analyses for soft ferromagnetic material are carried out and then those analyses for paramagnetic and diamagnetic materials are carried out. It is stated that the Stress components are expressed by the same expressions for those materials and the difference is only the magnitude of the permeability, though the magnetic fields Hx, Hy are different each other in the plates. If the analysis of magnetic field of paramagnetic material is easier than that of soft ferromagnetic material, the Stress analysis may be carried out using the magnetic field for paramagnetic material to analyze the Stress field, and the results may be applied for a soft ferromagnetic material. It is stated that the Stress state for the magnetic field Hx, Hy is the same as the pure shear Stress state. Solving the present magneto Elastic Stress problem, dislocation and rotation terms appear, which makes the present problem complicate. Solutions of the magneto Elastic Stress are nonlinear for the direction of electric current. Stresses in the direction of the plate thickness are caused and the solution is also obtained. Figures of the magnetic field and Stress distribution are shown. Stress intensity factors are also derived and investigated for the crack length and the electric current direction.

Jarkko Niiranen - One of the best experts on this subject based on the ideXlab platform.

  • gradient Elastic Stress analysis near cylindrical holes in a plane under bi axial tension fields
    International Journal of Solids and Structures, 2017
    Co-Authors: Sergei Khakalo, Jarkko Niiranen
    Abstract:

    Abstract This paper is devoted to a gradient-Elastic Stress analysis of an infinite plate weakened by a cylindrical hole and subjected to two perpendicular and independent uni-axial tensions at infinity. The problem setting can be considered as an extension and generalization of the well-known Kirsch problem of the classical Elasticity theory which is here extended with respect to the external loadings and generalized with respect to the continuum framework. A closed-form solution in terms of displacements is derived for the problem within the strain gradient Elasticity theory on plane Stress/strain assumptions. The main characters of the total and Cauchy Stress fields are analyzed near the circumference of the hole for different combinations of bi-axial tensions and for different parameter values. For the original Kirsch problem concerning a uni-axially stretched plate, the analytical solution fields for Stresses and strains are compared to numerical results. These results are shown to be in a full agreement with each other and, in particular, they reveal a set of new qualitative findings about the scale-dependence of the Stresses and strains provided by the gradient theory, not common to the classical theory. Based on these findings, we finally consider the physicalness of the concepts total and Cauchy Stress appearing in the strain gradient model.

Peter J Budden - One of the best experts on this subject based on the ideXlab platform.

  • approximate Elastic Stress estimates for elbows under internal pressure
    International Journal of Mechanical Sciences, 2011
    Co-Authors: Seok Pyo Hong, Yun Jae Kim, Kamran Nikbin, Peter J Budden
    Abstract:

    This paper presents closed-form approximations to Elastic Stresses in thick- and thin-walled elbows with attached straight pipes under internal pressure, based on three-dimensional Elastic finite element analysis. Elastic Stresses in the centre of an elbow are found to be close to an existing closed-form solution, suggesting that the hoop Stress varies with the longitudinal position. The FE results indicate that the hoop Stress varies linearly with the longitudinal position. Moreover, Stresses in the junction of an elbow and straight pipe are shown to be the average of those in the centre of the elbow and in the straight pipe.

  • Elastic Stress intensity factors and crack opening displacements for circumferential through walled cracked elbows
    Engineering Fracture Mechanics, 2010
    Co-Authors: Yun Jae Kim, Peter J Budden
    Abstract:

    This paper provides tabulated solutions of Elastic Stress intensity factors and crack opening displacements for circumferential through-wall cracked elbows under internal pressure and under in-plane bending, based on extensive three-dimensional Elastic finite element analyses covering a wide range of crack lengths and elbow/pipe geometries. The effect of crack length and elbow/pipe geometry on the results is discussed, with particular emphasis on the crack closure behaviour under in-plane bending.

M.n. James - One of the best experts on this subject based on the ideXlab platform.

  • local crack plasticity and its influences on the global Elastic Stress field
    International Journal of Fatigue, 2013
    Co-Authors: M.n. James, E. A. Patterson, Colin Christopher
    Abstract:

    Abstract This paper presents the background and development of a novel ‘plastic inclusion’ approach for dealing with the local plasticity which occurs at the tip of a growing fatigue crack. Localised plasticity arises from crack growth mechanisms and essentially blunts the crack, creates a reversed cyclic plastic zone, and induces shear along the crack flanks, along with the possible generation of wake contact Stresses which act on the applied Elastic Stress field at the boundary of the Elastic–plastic enclave surrounding the crack. The paper outlines the development of a meso-scale model of the Elastic Stress field around a growing crack that explicitly incorporates these interaction effects. The outcome is a modified crack tip Stress intensity factor that includes some aspects of the magnitude of plastic wake-induced crack tip shielding and which the authors propose has the potential to help resolve some long-standing controversies associated with plasticity-induced closure. A full-field approach is developed for Stress using photoElasticity and also for displacement using digital image correlation.

  • Towards a new model of crack tip Stress fields
    International Journal of Fracture, 2008
    Co-Authors: C. J. Christopher, M.n. James, E. A. Patterson, K. F. Tee
    Abstract:

    This work introduces a novel mathematical model of the Stresses around the tip of a fatigue crack, which considers the effects of plasticity through an analysis of their shielding effects on the applied Elastic field. The ability of the model to characterize plasticity-induced effects of cyclic loading on the Elastic Stress fields is assessed and demonstrated using full-field photoElasticity. The focus is on determining the form of the shielding Stress components (induced by compatibility requirements at the Elastic–plastic interface along the crack flank and via the crack tip plastic zone) and how they influence the crack tip Elastic Stress fields during a load cycle. The model is successfully applied to the analysis of a fatigue crack growing in a polycarbonate CT specimen.