• Journal of the Society of Naval Architects of Korea
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• v.41 no.6
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• pp.91-101
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• 2004

For the grillage which is common types of structures in marine and land-based structural system, the elastic response and design methods are usually applied. However, plastic analysis and design methods are considered Tn those structures to maintain the structural stability at the limit states. In grillage design, the central intersection point load may be used as a worst loading condition. However, a point load may often move around on the grid system. in such case, the worst load point would not necessarily be at the central point. To investigate the variation of plastic collapse load according to the location of moving load between intersections, the plastic collapse loads are obtained for the three types of grillages with simply-supported ends. From the result of each case, it is confirmed that the worst load point is located between intersections. General formulae related with plastic collapse loads for the three groups of grillages with simply-supported boundaries are derived. Those plastic collapse formulae for the grillages are applied to the design of pontoon deck, and optimum design procedure is illustrated. Consequently, general formulae for the plastic collapse of grillages derived from this study can be easily applied to the plastic analysis and optimum design of similar grillages.

• International journal of steel structures
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• v.18 no.4
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• pp.1397-1409
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• 2018

Stiffened plates with high slenderness parameters show large out-of-plane deflections, due to elastic buckling, which may occur before the plates reach their ultimate strength. From a serviceability point of view, restriction of out-of-plane deflections exceeding the fabrication tolerance is of primary importance. Compressive strength at the serviceability limit state (SLS) for slender stiffened plates under uniaxial stress was investigated through nonlinear elasto-plastic finite element analysis, considering both geometric and material nonlinearity. Both normal and high-performance steel were considered in the study. The SLS was defined based on a deflection limit and an elastic buckling strength. Probabilistic distributions of the SLS strengths were obtained through Monte Carlo simulations, in association with the response surface method. On the basis of the obtained statistical distributions, partial safety factors were proposed for SLS. Comparisons with the ultimate strength of different design codes e.g. Japanese Code, AASHTO, and Canadian Code indicate that AASHTO and Canadian Code provide significantly conservative design, while Japanese Code matches well with a 5% non-exceedance probability for compressive strength at SLS.

• Journal of the Korean Geotechnical Society
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• v.20 no.7
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• pp.207-215
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• 2004

In this study, the upper bound theory is applied to a reinforced slope to develop an limit state analysis method. As processing of this upper bound theory in formulating finite element, the basic idea of numerical method can be obtained from a macroscopic point of view with an anisotropic homogeneous material. The reinforced soil strength reliability depends on properties of reinforcements which consist of the interaction of interfaces between back fill and reinforcements. Both soil's mechanical property and overall behaviour of reinforced soil can be controlled via arranging geometry and relative proportions of reinforced soil. Therefore, the upper bound theory can not only predict the particular limit state action of reinforced soil slope but also is efficiently able to estimate the local plastic failure.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.6
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• pp.164-171
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• 2008

A modified generalized particle algorithm, MGPA, was suggested to improve the computational efficiency of standard SPH method in numerical analysis of high speed impact behavior. This method uses a numerical failure mechanism than material failure models to describe the target penetration. MGPA algorithm was more effective to describe the impact phenomena and new boundaries produced during the calculation process were well recognized and treated in the target penetration problem of a bullet. When bullet perforation problems were analyzed by this method, MGPA algorithm calculation gives the stable numerical solution and stress oscillation or particle penetration phenomena were not shown. The error range in ballistic velocity limit is less than $2{\sim}13%$ for various target thickness.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.481-487
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• 2011

This paper provides a comparison between finite element analysis results and test data of rupture disc. Rupture disc is safety device of high pressure equipment. Rupture disc of solid rocket motor is a device to control rupture pressure. Rupture discs were made of AISI 316L. By the elastic-plastic analysis, the stress limit of rupture discs were compared to the test results. The results can be used to control the rupture pressure by the change of the disc size.

• Structural Engineering and Mechanics
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• v.13 no.1
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• pp.35-52
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• 2002

It was shown in the previous study (Lee and Bertero 1993) that incremental collapse can lead to the exhaustion of the plastic rotation capacity at critical regions in a structure when subjected to the number of load cycles and load intensities as expected during maximum credible earthquakes and that this type of collapse can be predicted using the shakedown analysis technique. In this study, a minimum-weight design methodology, which takes into account not only the prevention of this incremental collapse but also the requirements of the serviceability limit states, is proposed by using the shakedown analysis technique and a nonlinear programming algorithm (gradient projection method).

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.127-132
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• 2001

By the use of a similar numerical method as the forming limit strain by coating method of coated sheet metals is investigated, in which the FEM is applied and J2G(J2-Gotohs Corner Theory) is utilized as the plasticity constitutive equa-tion. Circular bonded sheet metals with dissimilar sheets on both surface planes are stretched in a plane -strain state, with various work-hardening exponent n-values and thicknesses of each layer. Processes of shear-band formation in such com-posite sheets are clearly illustrated. It is concluded that, it the bonded state, the higher limiting strain of one layer is reduced due to the lower limiting strain of the other layer and vice versa, and does not necessarily obey the rule of linear combination of the limiting strain of each layer weighed according thickness.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.11
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• pp.1379-1386
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• 2013

The present work reports the mismatch limit loads for a V-groove welded pipe for a circumferential crack using finite element (FE) analyses. To integrate the effect of groove angles on mismatch limit loads, one geometry-related slenderness parameter was modified by relevant geometric parameters including the groove angle, crack depth, and root opening based on plastic deformation patterns in the theory of plasticity. Circumferential through-wall cracks are located at the centre of the weldments with two different groove angles ($45^{\circ}$, $90^{\circ}$). With regard to the loading conditions, axial (longitudinal) tension and bending are applied for all cases. For the parent and weld metal, elastic-perfectly plastic materials are considered to simulate and analyze under- and over-matching conditions in plasticity. The overall results from the proposed solutions are found to be similar to the FE results.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.831-838
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• 2004

To study on mechanical characteristics of weathered granite masses are difficult because of undisturbanced sampling and in-situ test. Generally, pressuremeter test is widely used to investigate the behavior of weathered rock masses. However, it has many problems to get a limit pressure because of cavity collapse, membrane damage, ete. This study aims to evaluate the mechanical characteristics of weathered granite masses using in-situ pressuremeter test and numerical analysis depending on the ratio of length and diameter of the membrane(L/D=5, 8, 10, 15, 20). Test results and data are shown that strength parameters are reduced exponentially varing weathering degree, and numerical analysis results are approximately coincided with the test results. And the ratio of length and diameter of the membrane arc not affected the parameters such as modulus of pressuremeter, shear modulus, etc. But limit pressure is increased decreasing membrane length based on numerical analysis. On the other hand, increasing the membrane length, yield pressure is decreased and plastic radius is increased in the case of same weathering degree.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.3 s.246
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• pp.269-278
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• 2006

This paper proposes slip line fields for bending of unequally notched specimens in plane strain that have a sharp crack in one side and a sharp V-notch in the other side. Depending on the back angle, two slip line fields are proposed, from which the limit moment and crack tip stress fields are obtained as a function of the back angle. Excellent agreement between slip line field solutions with those from detailed finite element limit analysis based on non-hardening plasticity provides confidence in the proposed slip line fields. One interesting point is that, for the unequally notched specimen, the difference between the crack tip triaxial stress for tension and that for bending increases significantly with increasing the back angle. This suggests that such a specimen could be potentially useful to investigate the crack tip constraint effect on fracture toughness of materials. In this respect, the possibility of designing a new toughness testing specimen with varying crack tip constraint is discussed.