• Journal of Mechanical Science and Technology
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• v.18 no.2
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• pp.221-229
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• 2004

In this work, an elastic-plastic stress analysis has been conducted for silicon carbide fiber reinforced magnesium metal matrix composite beam. The composite beam has a rectangular cross section. The beam is cantilevered and is loaded by a single force at its free end. In solution, the composite beam is assumed perfectly plastic to simplify the investigation. An analytical solution is presented for the elastic-plastic regions. In order to verify the analytic solution results were compared with the finite element method. An rectangular element with nine nodes has been choosen. Composite plate is meshed into 48 elements and 228 nodes with simply supported and in-plane loading condations. Predictions of the stress distributions of the beam using finite elements were overall in good agreement with analytic values. Stress distributions of the composite beam are calculated with respect to its fiber orientation. Orientation angles of the fiber are chosen as $0^{circ},\;30^{circ},\;45^{circ},\;60^{circ}\;and\;90^{circ}$. The plastic zone expands more at the upper side of the composite beam than at the lower side for $30^{circ},\;45^{circ}\;and\;60^{circ}$ orientation angles. Residual stress components of ${\sigma}_{x}\;and \;{\tau}_{xy}$ are also found in the section of the composite beam.

• Journal of Welding and Joining
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• v.12 no.1
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• pp.73-79
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• 1994

Low cycle fatigue test was performed by companion specimens method to compare the properties of cyclic strain for the weldments of controlled rolling steel CR60 and welding structural steel SM58Q. And the result does not showed any difference of low cycle fatigue life between weldments. Especially, the values of coefficient of cyclic plastic strain $C_{p}$ and exponent of cyclic plastic strain $K_{p}$ of heat affected zones of CR60 steel and SM58Q steel were same. And $C_{p}$ and $K_{p}$ of CR60 steel were equal to the values of weld it means a good combination between the base metal, the heat affected zone and the weld of CR60 steel.eel.eel.

• International Journal of Korean Welding Society
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• v.2 no.1
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• pp.62-66
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• 2002

The Friction Stir Welding (FSW) is a new joining method that was developed at The Welding Institute (TWI) in England in 1991. It applied heating by the rotational friction and material plastic flow. It was developed as a new joining method to solve the problems of epochally in the welding of Al alloys. In the study, 6000series of Alloy composed of Al-Mg-Si, one of the Al alloys that are utilized for shipbuilding and construction, is selected as a specimen and the numerical is executed against the welded zone of FSW. The material used in this study had the unique properties of strength and anti-corrosion, but since the welded joint of this material is easily softened by the welding heat, FSW is executed and the numerical analysis is carried out around the joint. To examine the mechanical behaviors and properties, F.E.M analysis is executed and the developed thermal-elastic-plastic finite analysis are used.

• Structural Engineering and Mechanics
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• v.75 no.1
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• pp.101-108
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• 2020

The present study intends to analyze damage in thin-walled steel cylinders undergoing constant internal pressure and thermal cycles through use of anisotropic continuum damage mechanics (CDM) model coupled with nonlinear kinematic hardening rule of Chaboche. Materials damage in each direction was defined based on plastic strain and its direction. Stress and strain distribution over wall-thickness was described based on the CDM model and the return mapping algorithm was employed based on the consistency condition. Plastic zone expansion across the wall thickness of cylinders was noticeably affected with change in internal pressure and temperature gradients. Expansion of plastic zone over wall-thickness at inner and outer surfaces and their boundaries demarking elastic and plastic regions was attributed to the magnitude of damage induced over thermomechanical cycles on the thin-walled samples tested at various pressure stresses.

• Structural Engineering and Mechanics
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• v.82 no.6
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• pp.713-724
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• 2022

Effects of coal tensile strength and plow configuration on the coal fragmentation process was modeled by two-dimensional particles flow code (PFC2D). Three tensile strength values, 0.5, 1,5 and 3.5 MPa were considered in this numerical study. The cutters of plow penetrated in the coal for 4 mm at a rate of 0.016 m/s. According to the PFC manual, the local damping factor was 0.7. Three failure mechanism of coal during the fragmentation process by plow were modelled. The coal material beneath the cutters showed the elastic, plastic and fracturing behaviors in this analysis. In all the models, the plastic zone was fractured and some micro-cracks were induced but the elastic zone remained undamaged. It was observed that the tensile strength affected the failure mechanism of coal significantly and as it increased the extent of the fractured zone underneath the plow cutter decreased during the fragmentation process.

• Geomechanics and Engineering
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• v.8 no.3
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• pp.323-359
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• 2015

This paper presents an elasto-plastic model for determination of the ground response curve of a circular underwater tunnel excavated in elastic-strain softening rock mass compatible with a nonlinear Hoek-Brown yield criterion. The finite difference method (FDM) was used to propose a new solution to calculate pore water pressure, stress, and strain distributions on periphery of circular tunnels in axisymmetric and plain strain conditions. In the proposed solution, a modified non-radial flow pattern, for the hydraulic analysis, is utilized. To evaluate the effect of gravitational loads and variations of pore water pressure, the equations concerning different directions around the tunnel (crown, wall, and floor) are derived. Regarding the strain-softening behavior of the rock mass, the stepwise method is executed for the plastic zone in which parameters of strength, dilatancy, stresses, strains, and deformation are different from their elasto-plastic boundary values as compared to the tunnel boundary values. Besides, the analytical equations are developed for the elastic zone. The accuracy and application of the proposed method is demonstrated by a number of examples. The results present the effects of seepage body forces, gravitational loads and dilatancy angle on ground response curve appropriately.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.43-48
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• 2004

When structures are loaded by a combination of primary and secondary stresses, plasticity effects occur which cannot be evaluated by a simple linear addition of the effects resulting from the two independent stress systems. Thermal stress due to temperature gradient is classified as secondary stress. It is known that secondary stress is released as increase of plastic zone. In this paper, two and three dimensional elastic-plastic finite element analyses are performed for the cracked plates and pipes under combined thermal and mechanical loading. And V-factor is introduced to account for plasticity effect. The present results provide that V-factor is function of thermal factor and loading and is consistent regardless of geometry. We developed the prediction method of elastic-plastic fracture mechanics parameter under combined primary and secondary loading from the present results.

• Journal of Welding and Joining
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• v.6 no.2
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• pp.19-29
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• 1988

This paper reports on the elatic-plastic analysis and fracture behavior of cylinder with outer surface crack which is under external or internal pressure. For the studuty of crack length effects in cylinder, ratios of crack lengths to finite thickness (a/t) are dertermined 0.3, 0.4, 0.5. For the study of curvature effects in cylinders, ratios of mean diameter to finite thicknees (Rm/t) are determined 10.0, 15.0, 20.0. Analysis is conduceted using the theory of fracture mechanics and two dimensional finite element solution assuming the axi-symmetrical plane strain conditon. Main results of this study are as follows. 1) It is known from this paper that elastic-plastic strain is initiated near crack tip and enlarged between crack tip and inner side of cylinder. 2) $K_{1}$ of cylinder under external or internal pressure is evaluated memebrane stress .root..pi.* crack length. The results of this study are inclined to Lomacky's results and Kobayshi's result. 3) Distribution of stress near crack tip is looked higher than of other zone, as crack length of equal model is longer, and as diameter of cylinder is longer. 4) When other conditions are equal, displacemenet near crack tip is looked duller, as length is longer.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.290-297
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• 1998

In this paper, we propose to a method to estimate the elasto-plastic buckling for single layer latticed domes. First, we assume that each member consists of the rigid zone and elastic spring at both end joint, the elastic element and three elasto-plastic spring to judge for yeilding the member. Next, the member which has most influence on buckling for structures is determined by a distributed pattern of the strain energy which is calculated through linear eigenvalue analysis. And then, normalized slenderness ratio of the element is derived considering the axial force at elastic buckling load. Later, we execute elasto-plastic nonlinear analysis that based on loading increasement method and displacement increasement method. From this results, we discusses the effect of the joint rigidity and the half open angle $\theta$$_{0}$ on the buckling strength of single layer lattice domes ; (1) how the joint rigidity contributes to the reduction of buckling loads, (2) how the reduction can be interrelated to compressive strength curves in terms of the generalized slenderness for the member most relevant to the overall buckling of domes.s.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.2
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• pp.122-130
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• 1981

Equation of equilibrium is derived and solved for an infinite isotropic solid under applied hydrostatic stress which is uniform at large distance, and disturbed by a spherical precipitate which has isotropoc elastic constants dirrerent form those of the matrix. A linear strain hardening behavior of the matrix is assumed, and an elasto-plastic sloution is obtained. The difference of the total strain energy stored inthe infinite solid with and without a precipitate is computed, and compared with that for purely elastic case. Finally the effect of the ratio of the bulk modulus of the precipitate to that of the matrix and the effct of linear strain hardening rate on the plastic zone size and the energy difference are discussed.