• Geomechanics and Engineering
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• v.19 no.6
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• pp.513-522
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• 2019

This study presents an elasto-plastic (EP) solution for drained cavity expansion on the basis of unified strength failure criterion and considers the influence of initial stress state. Because of the influence of initial consolidation of soil mass, the initial stress may be anisotropic in the natural soil mass. In addition, the undrained hypothesis is usually used in the calculation of cavity expansion problem, but most of the cases are in the drained situation in practical engineering. Eventually, the published solution and the presented solution are compared to verify the suitability of the study.

• Steel and Composite Structures
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• v.29 no.2
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• pp.161-173
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• 2018

Point bending is often used for cambering and curving structural steel girders. An analytical solution, applicable in the elasto-plastic range only, that relates applied loads to the desired curve was recently developed for inducing horizontal curves using four-point bending. This solution does not account for initial residual stresses and geometric imperfections built-in hot-rolled sections. This paper presents results from a full-scale test on a hot-rolled steel section curved using four-point bending. In parallel, a numerical analysis, accounting for both initial geometric imperfections and initial residual stresses, was carried out. The models were validated against the experimental results and a good agreement for lateral offset and for strain in the elasto-plastic and post-plastic ranges was achieved. The results show that the effect of initial residual stresses on deformation and strain is minimal. Finally, residual stresses due to cold bending calculated from the numerical analysis were assessed and a revised stress value for the service load design of the curved girder is proposed.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.499-505
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• 2001

In order to classify the mechanical phenomena of thermal elasto-plastic behavior on the multi-spot welded joints, this study has tried to carry out three-dimensional thermal elasto-plastic analysis on them. However, because the shape of multi-spot welded joints is not taxi-symmetric, unlike the cafe of single-spot welded joint, the solution domain for simulation should be three dimension. Therefore, in this paper, firstly, the three-dimensional thermal elasto-plastic program is developed by an iso-parametric finite element method. Secondly, from the results analyzed by developed program, this has clarified mechanical characteristics and their production mechanism on single and multi-spot waled joints. Moreover, it has been intended to make clear effects of pitch length on welding residual stresses, plastic strain of multi-spot welded joints.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1988.10a
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• pp.24-29
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• 1988

In this paper, it is proposed hew the rigid element method suggested in the first paper can be applied to the elastic and elasto-plastic analysis of spherical shell with the open stiff ring. In the analytical model, the solution domain is divided into rectangular-shaped spherical bending elements. Each contact surface of two adjacent elements is interconnected with four elastic springs, and it is assumed that the internal forces are distritributed into springs. The 6 degrees of freedom of the element are placed in the center of elements, and the 6 cen-teroidal rigid displacements affect other elements through springs around elements. And then the solution domain is estimated by the behavior of elements and springs. In this study, these concepts are applied to the elastic and elasto-plastic analysis for the eight cases of the spherical shell according to the condition of stiff ring, the condion of loading and the size of opening. And then some numerical results such as the distribution of stresses, the force-displacement curves and the mode of fractures will he shown.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.185-192
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• 1988

Computation of the elasto-plastic solution of ball indentation was carried out by the quadratic programming method. The problem was formulated as an elasto-plastic contact problem under the assumption of small displacement and small deformation and then transformed into a minimization problem. Finite element approximation resulted in a quadratic programming problem. Numerical and experimental study were done with aluminium Al 2024-T351 and commercially pure copper. The computed load-displacement curves were in good agrement with those obtained from experiments. Tabor's relationship for representative strains was also examined. Stress distributions were found to resemble closely those results available in the literature.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.8 s.227
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• pp.1196-1202
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• 2004

A meshfree multi-scale method has been presented for efficient analysis of elasto-plastic problems. From the variational principle, problem is decomposed into a fine scale and a coarse scale problem. In the analysis only the plastic region is discretized using fine scale. Each scale variable is approximated using meshfree method. Adaptivity can easily and nicely be implemented in meshree method. As a method of increasing resolution, partition of unity based extrinsic enrichment is used. Each scale problem is solved iteratively. Iteration procedure is indispensable for the elasto-plastic deformation analysis. Therefore this kind of solution procedure is adequate to that problem. The proposed method is applied to Prandtl's punch test and shear band problem. The results are compared with those of other methods and the validity of the proposed method is demonstrated.

• Geomechanics and Engineering
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• v.32 no.4
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• pp.397-409
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• 2023

This study examines two traditional approaches (non-linear elastic and elasto-plastic) in association with 2D and 3D FEM analyses of a box-section pile embedded in sand. A particular emphasis is placed on stress singularities concerning both reentrant corners of the pile section and the resulting tension zones. From the experience gained in this study, non-linear elastic soil models are less restrictive when one considers stress singularities and their possible effects on convergence of the solution. At least for monotonic loading, when compared with field tests, non-linear elastic models yield better results than the plasticity ones. On the other hand, although elasto-plastic models are not limited to monotonic loading, they are much more sensitive to stress singularities. For this reason, a spherical elastic region is necessary at the pile tip to ensure convergence. Without this region, one must artificially impose an apparent cohesion to limit the tension stresses within a sand medium.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.809-815
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• 2002

For clarifying the mechanical phenomena of thermal elasto-plastic behavior on the multi-spot welded joints, this study has tried to carry out three-dimensional thermal elasto-plastic analysis on them. However, because the shape of multi-spot welded joints is not axi-symmetric, unlike the case of single-spot welded joint, the solution domain for simulation should be three-dimensional. Therefore, in this paper, from the results analyzed using the developed the three dimensional unstationary heat conduction and thermal elasto-plastic programs by an iso-parametric finite element method, mechanical characteristics and their production mechanism on single- and multispot welded joints were clarified. Moreover, effects of pitch length on temperature, welding residual stresses and plastic strain of multi-spot welded joints were evaluated, indicating that a pitch of 30mm was advantageous compared to a pitch of 15mm.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.327-334
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• 2001

This paper presents a non-linear analysis procedure for plane frame structures by finite element formulation with assumptions of Timoshenko beam theory. Finite element displacement method based on Lagrangian formulation is used and two-noded and isoparametric line element is adopted to represent finite element model. The layered approach is used for the elasto-plastic analysis of the plane frame structures with rectangular and I cross sections. A load incremental method combined with the tangent stiffness and the initial stiffness methods for each load increment is used for the solution of non-linear equations. Numerical examples are presented to investigate the behavior and the accuracy of the elasto-plastic non-linear application and the results of this study are compared with other solutions using the concept of plastic hinge.

• Structural Engineering and Mechanics
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• v.14 no.4
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• pp.455-472
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• 2002

The paper involves the study on the elastic and elasto-plastic stress wave propagation in the 1-D and 2-D solid media. The Smooth Particle Hydrodynamics equations governing the elastic and elasto-plastic large deformation dynamic response of solid structures are presented. The proposed additional stress points are introduced in the formulation to mitigate the tensile instability inherent in the SPH approach. Both incremental rate approach and leap-frog algorithm for time integration are introduced and the new solution algorithm is developed and implemented. Two examples on stress wave propagation in aluminium bar and 2-D elasto-plastic steel plate are included. Results from the proposed SPH approach are compared with available analytical values and finite element solutions. The comparison illustrates that the stress wave propagation problems can be effectively solved by the proposed SPH method. The study shows that the SPH simulation is a reliable and robust tool and can be used with confidence to treat transient dynamics such as linear and non-linear transient stress wave propagation problems.