• 대한조선학회논문집
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• 제33권1호
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• pp.77-89
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• 1996

Mindlin 판이론에 바탕을 둔 두꺼운 판의 굽힘문제에 대한 유한요소 개발에 많은 연구가 수행되어 왔다. 두꺼운 판의 전단변형을 고려하기 위하여 주로 근사적인 일정전단회전각이론(CSAT)을 사용하여 왔지만, 두께가 두꺼워질수록 단면의 전단변형의 영향을 효과적으로 고려할 수 없을 것이다. 판 단면의 워핑(warping)을 가능한 정확하게 나타내는 것이 바람직할 것이다. 본 논문은 전단변형과 전단워핑의 영향을 고려한 새로운 판의 이론을 전개하고, Mindlin 판이론에 의한 결과와 비교 검토하기 위하여 다양한 파라미터 연구를 수행하여 두꺼운 판에 대한 전단변형과 전단워핑의 영향을 좀 더 깊이 고찰하고자 한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.680-685
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• 2001

In this paper, RKPM is extended for solving moderately thick and thin structures. General Timoshenko beam and Mindlin plate theory are used far formulation. Shear locking is the main difficulty in analysis of these kinds of structures. Shear relaxation factor, which is formulated using the difference between bending and shear strain energy, is introduced to overcome shear locking. Analysis results obtained reveal that RKPM using introduced method is free of locking and very effectively applicable to deeply as well as shallowly beams and plates.

• 한국정밀공학회지
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• 제16권10호
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• pp.187-193
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• 1999

Dimensional difference by welding deformation is usually occurred at steel bridge manufacturting or multi-pass welding used at joining of thick plates. Be this, root gap out of standard is frequently developed at butt weld joints. For example, although standard root gap below 6mm at butt weld joints of plates under 15mm thickness, maximum 30mm root opening is developed at the weld field. At this case, 24mm parts out of standard is generally built up. But, there are no accumulated data and restriction about this built up welding pars. In this study, therefore, the accumulation of data for built up parts and the verification of the mechanical properties of weld part as root gap is performed. It is included that tensile, bending, impact, hardness test and microstructural review for each welding specimen of 0mm, 6mm, 30mm root opening.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제17권2호
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• pp.67-85
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• 2013

Reproducing Polynomial Particle Method (RPPM) is one of meshless methods that use meshes minimally or do not use meshes at all. In this paper, the RPPM is employed for free vibration analysis of shear-deformable plates of the first order shear deformation model (FSDT), called Reissner-Mindlin plate. For numerical implementation, we use flat-top partition of unity functions, introduced by Oh et al, and patchwise RPPM in which approximation functions have high order polynomial reproducing property and the Kronecker delta property. Also, we demonstrate that our method is highly effective than other existing results for various aspect ratios and boundary conditions.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 가을 학술발표회논문집
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• pp.16-23
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• 1993

The new p-version crack model is proposed to estimate the bending stress intensity factors of the thick cracked plate under flexure. The proposed model is based on high order theory and $C^{\circ}$-plate element including shear deformation. The displacements fields are defined by integrals of Legerdre polynomials which can be classified into three groups such as basic mode, side mode and internal mode. The computer implementation allows arbitrary variations of p-level up to a maximum value of 10. The bending stress intensity factors are computed by virtual crack extention approach. The effects of ratios of thickness to crack length(h/a), crack length to width(a/W) and boundary conditions are investigated. Very good agreement with the existing solution in the literature are shown for the uncracked plate as well as the cracked plate.

• Steel and Composite Structures
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• 제47권6호
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• pp.693-707
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• 2023

This article investigates the static thermo-mechanical response of anisotropic thick laminated composite plates on Visco-Pasternak foundations under various thermal load conditions (linear, non-linear, and uniform) along the transverse direction (thickness) of the plate, while keeping the mechanical load constant. The governing equations, which represent the thermo-mechanical behavior of the composite plate, are derived from the principle of virtual displacements. Using Navier's type solution, these equations are solved for the composite plate with simply supported condition. The Visco-Pasternak foundation type is included by considering the impact of the damping on the classical foundation model, which is modeled by Winkler's linear modulus and Pasternak's shear modulus. The excellent accuracy of the present solution is confirmed by comparing the results with those available in the literature. The study investigates the impact of geometric ratios, thermal expansion coefficient ratio, damping coefficient and foundation parameters on the thermo-mechanical flexural response of the composite plate. Overall, this article provides insights into the behavior of composite plates on visco-Pasternak foundations and may be useful for designing and analyzing composite structures in practical applications.

• Computers and Concrete
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• 제18권1호
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• pp.53-68
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• 2016

In this study, an investigation is made from the statics and economic aspects of the possibility of using the composite material ferrocement on the surfaces of squat cylindrical grain silos. For this purpose, the geometry of two model silos, each of height 5 m and diameter 5 m and 12.5 m, was designed. Five different reinforced plates of 10 and 20 mm thickness were produced to research the most suitable ferrocement plates to be used on the surface of these silos. Most durable reinforcement type for covering the silo surface was determined by pressure and bending tests. Grade 30 and Grade 55 steel plates were also considered for use in covering steel-coated silos. In the statics analysis performed with SAP2000, the least plate thicknesses needed for silos surfaced with Grade 30 and Grade 55 steel were found to be 6.20 mm and 4.70 mm respectively for silos of diameter 5 m, and 6.70 mm and 5.00 mm for silos of diameter 12.5 m. In the economic analysis, it was found that 20 mm thick Type 4 (with a wire diameter of 0.30 mm and a mesh aperture of $2mm{\times}2mm$ square type) reinforced ferrocement surfacing material was 5.6-6.1 times more economical than Grade 30 steel surfacing material and 4.4-4.7 times more economical than using Grade 55 steel. These results show that ferrocement can be used in place of steel from the point of view both of statics and economy.

• 한국CDE학회논문집
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• 제10권4호
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• pp.254-261
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• 2005

The purpose of this research is to develop a method for cutting non-circular holes on a bent thick plate. Generally in order to cut the holes on the large plates, a special-purpose 5-axis machine is needed. However, such a machine is unavailable in most of the machine shops. This paper provides a description of such a method that utilizes a general-purpose 5-axis water-jet machine in place of the special-purpose machine: First, the bent piece is transformed into a flat plate, where the shape of the holes is reconstructed by considering deformation during bending. Then, after a 5-axis NC data is generated, the holes on the flat plate are cut using the 5-axis water-jet machine. The final step is to return to its, original shape by bending the plate with its newly-cut holes. The proposed methodology is implemented as a dedicated system by customizing a commercial CAD/CAM system. Some illustrations are provided throughout the paper in order to show the validity of the proposed methods and the developed system.

• 대한기계학회논문집A
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• 제35권11호
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• pp.1437-1443
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• 2011

선박 건조를 위한 기본 자재인 후판은 압연공정을 통해 생산된다. 본 논문에서는 후판압연 중에 발생하는 폭방향 휨을 일으키는 비대칭 요인들을 제어할 수 있는 설정모델을 제시한다. 일련의 삼차원 유한요소해석을 통해서 휨과 비대칭 요인 사이의 관계를 예측한다. 그 관계를 무차원 변수로 이루어진 선형 방정식으로 수식화 시킴으로써 설정모델을 도출한다. 소재 폭방향으로 두께 편차와 온도차이가 있는 경우에 대해서 파이롯트 압연 시험으로 통해서 설정모델의 정도를 검증한다. 본 모델에 의해 예측된 휨 곡률이 각각의 비대칭 요인들에 의해 측정된 휨 곡률과 상당히 일치하는 결과를 보여 주었다.

• Steel and Composite Structures
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• 제32권5호
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• pp.571-582
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• 2019

This study aimed to assess the feasibility on the wide and long 9%Ni steel plate for use in the LNG storage inner tank shell. First, 5-m-wide and 15-m-long 9%Ni steel plates were test manufactured from a steel mill and specimens taken from the plates were tested for strength, toughness, and flatness to verify their performance based on international standards and design specifications. Second, plates with a thickness of 10 mm and 25 mm, a width of 4.8~5.0 m, and a length of 15 m were test fabricated by subjecting to pretreatment, beveling, and roll bending resulting in a final width of 4.5~4.8 m and a length of 14.8m with fabrication errors identical to conventional plates. Third, welded specimens obtained via shield metal arc welding used for vertical welding of inner tank shell and submerged arc welding used for horizontal welding were also tested for strength, toughness and ductility. Fourth, verification of shell plate material and fabrication was followed by test erection using two 25-mm-thick, 4.5-m-wide and 14.8-m-long 9%Ni steel plates. No undesirable welding failure or deformation was found. Finally, parametric design using wide and long 9%Ni steel plates was carried out, and a simplified design method to determine the plate thickness along the shell height was proposed. The cost analysis based on the parametric design resulted in about 2% increase of steel weight; however, the construction cost was reduced about 6% due to large reduction in welding work.