• Steel and Composite Structures
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• 제33권2호
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• pp.209-224
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• 2019

This paper describes a study of the mapping relationship between the vertical deformation of bridge structures and rail deformation of high-speed railway, taking the interlayer interactions of the bridge subgrade CRTS II ballastless slab track system (HSRBST) into account. The differential equations and natural boundary conditions of the mapping relationship between the vertical deformation of bridge structures and rail deformation were deduced according to the principle of stationary potential energy. Then an analytical model for such relationship was proposed. Both the analytical method proposed in this paper and the finite element numerical method were used to calculate the rail deformations under three typical deformations of bridge structures and the evolution of rail geometry under these circumstances was analyzed. It was shown that numerical and analytical calculation results are well agreed with each other, demonstrating the effectiveness of the analytical model proposed in this paper. The mapping coefficient between bridge structure deformation and rail deformation showed a nonlinear increase with increasing amplitude of the bridge structure deformation. The rail deformation showed an obvious "following feature"; with the increase of bridge span and fastener stiffness, the curve of rail deformation became gentler, the track irregularity wavelength became longer, and the performance of the rail at following the bridge structure deformation was stronger.

• Steel and Composite Structures
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• 제46권1호
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• pp.93-105
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• 2023

This paper examines a high-speed railway CRTS-II ballastless track-bridge system. Using the stationary potential energy theory, the mapping analytical solution between the bridge deformation and the rail vertical geometric irregularity was derived. A theoretical model (TM) considering the nonlinear stiffness of interlayer components was also proposed. By comparing with finite element model results and the measured field data, the accuracy of the TM was verified. Based on the TM, the effect of bridge deformation amplitude, girder end cantilever length, and interlayer nonlinear stiffness (fastener, cement asphalt mortar layer (CA mortar layer), extruded sheet, etc.) on the rail vertical geometric irregularity were analyzed. Results show that the rail vertical deformation extremum increases with increasing bridge deformation amplitude. The girder end cantilever length has a certain influence on the rail vertical geometric irregularity. The fastener and CA mortar layer have basically the same influence on the rail deformation amplitude. The extruded sheet and shear groove influence the rail geometric irregularity significantly, and the influence is basically the same. The influence of the shear rebar and lateral block on the rail vertical geometric irregularity could be negligible.

• 소성∙가공
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• 제22권8호
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• pp.477-485
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• 2013

This paper aims to evaluate quantitatively the springback characteristics that evolve in the sheet metal forming of an S-rail in order to understand the reasons of shape inaccuracy and to find a remedy. The geometrical springback is classified into six modes: angle change of punch and die shoulders, wall curl, ridge curl, section twist, and axial twist. The measuring method for each springback mode is suggested and quantitative measurements were made to determine the tendency towards shape accuracy. Forming experiments were conducted with four types of steel sheets that have different tensile strengths, which were 340MPa, 440MPa, 590MPa and 780MPa, in order to evaluate the effect of the tensile strength and the bead shape on the springback behavior. Springback tendencies show that they are greatly affected by the tensile strength of the sheet and the shape of the tools. Almost all springback modes except the section twist and the axial twist show a linearly increasing trend as the tensile strength of the sheet increases. The results can be used as basic data for design and for compensation of the press die geometry when forming high strength steels which exhibit large amounts of springback.

• 소성∙가공
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• 제12권8호
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• pp.718-723
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• 2003

Tn order to develop springback control technology for high-strength steel sheets, several studies have been conducted: dome stretching test, stepped s-rail forming and springback measurement, and optimally shaped initial blank design. First, to find out the formability of TRIP60, dome stretching test was performed. Next, the stepped s-rail die, which was designed to form a channel type panel with large twist and wall curl, was manufactured and used to evaluate the effect of controlling forming variables, such as blank holding force and flange amount on the springback. Furthermore, new measurement method of the springback was introduced to define wall curl and twist in geometrically complex panels. Finally, the optimally shaped initial blank was employed to verify one of the best ways to control the springback in channel type. high-strength sheet panels.

• Steel and Composite Structures
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• 제29권2호
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• pp.219-229
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• 2018

This paper presents an analytical model to analyze the mapping relationship between bridge lateral deformation and track geometry of high-speed railway. Based on the rail deformation mechanisms, the deformation of track slab and rail at the locations of fasteners are analyzed. Formulae of rail lateral deformation are derived and validated against a finite element model. Based on the analytical model, a rail deformation extension coefficient is presented, and effects of different lateral deformations on track geometry are evaluated. Parametric studies are conducted to evaluate the effects of the deformation amplitude, fastener stiffness and mortar layer stiffness on the rail deformation. The rail deformation increases with the deformation of the girder, and is dependent on the spacing of the fasteners, the elastic modulus of the rail's material, and the moment of inertia of the rail's section.

• 소성∙가공
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• 제17권3호
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• pp.197-202
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• 2008

The control of springback is very important in sheet metal forming since springback affects the dimensional inaccuracy of product. The object of this study is to design the manufacturing process for the improvement of the performance of seat rail by DP780. The influence of process variables such as bend angle and pad force on the springback has been firstly investigated through the comparison between the results of FE-analysis and trial out for initial design based on designer's experience. The process variables of the initial design have been modified in order to improve the dimensional accuracy of seat rail from the prediction of springback by FE-analysis. It was shown from experiment that the improved design satisfied the required specifications such as the dimensional accuracy and the strength of seat rail.

• 한국자동차공학회논문집
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• 제15권1호
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• pp.186-192
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• 2007

In general, pulsation damper is installed in fuel rail for conventional MPI engine to decrease undesirable noise in vehicle cabin room. However, pulsation damper is so expensive that there are prevailing studies to reduce fuel pressure pulsations with integrated damping effect. This paper is one of basic studies for development of fuel rail to abate pulsations with self-damping effect. Primarily, the pressure pulsation characteristics was investigated with aspect ratio of cross section, wall thickness, and materials of fuel rail. A high aspect ratio or thin wall was found to absorb the pressure pulsations effectively. But volume effects on the fuel pressure pulsation reductions were not especially significant than cross section effects because volume increment rate is larger than pressure pulsation reduction rate. The fuel rail made of aluminum is effective for reduction of pressure pulsation than that of low-carbon steel. Pressure change period increases on the basis of same lengths of supply line and fuel rail as the volume is enlarged and/or the thickness of wall is thinned.

• Steel and Composite Structures
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• 제36권4호
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• pp.481-492
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• 2020

To study the rail mapped deformation caused by the pier settlement of simply - supported bridges with China Railway Track System III (CRTS III) slab ballastless track (SBT) system under the mode of non-longitudinal connection ballastless track slab, this study derived an analytical solution to the mapped relationships between pier settlement and rail deformation based on the interlayer interaction mechanism of rail-pier and principle of stationary potential energy. The analytical calculation results were compared with the numerical results obtained by ANSYS finite element calculation, thus verifying the accuracy of analytical method. A parameter analysis was conducted on the key factors in rail mapped deformation such as pier settlement, fastener stiffness, and self-compacting concrete (SCC) stiffness of filling layer. The results indicate that rail deformation is approximately proportional to pier settlement. The smaller the fastener stiffness, the smoother the rail deformation curve and the longer the rail deformation area is. With the increase in the stiffness of SCC filling layer, the maximum positive deformation of rail gradually decreases, and the maximum negative deformation gradually increases. The deformation of rail caused by the pier settlement of common-span bridge structures will generate low-frequency excitation on high-speed trains.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1607-1614
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• 2011

As the connection between spread footing and pile is very important structural connection, it acts as the inter-loading medium to transfer the rail loads applied by superstructure to ground through the body pile of foundation. The experimental study is the method how to reinforce the pile cap between steel pile and footing utilizing perfobond plate with protruding keys. It were experimented on the compression punching tests and bending moment tests against the vertical loading and horizontal loadings acting on head of steel tube pipe. As a result, the tension capacity of the perfobond plate exhibited the superior performance due to the interlocking or dowel effects by the sheared keys of perfobond plate, and there were showing the sufficient strength and ductile capacity against the bending moment of horizontal loading tests. Therefore, it is judged that "the embedded method of perfobond plate in pile cap and footing" which is utilizing the shear connection of perfobond plate with protruding keys has a sufficient structural stability enough to be replaced with the current specification of reinforced method of pile cap with vertically deformed rebar against the vertical compression loads and bending moments that are able to occur in the combination structure of steel pile and the footing foundation.

• 한국철도학회논문집
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• 제12권6호
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• pp.974-982
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• 2009

본 연구는 교량/궤도 종방향 해석 및 교량/차량 동적영향을 고려한 설계기법에 대한 효율성 및 경제성을 증명하기 위하여 수행하였다. 신뢰성에 기초한 생애주기비용 최적설계는 기존 설계기법에 의한 설계, 초기비용에 기초한 최적설계, 등가 생애주기비용 최적설계에 의한 최적설계와 비교하기 위하여 5$\times$(1@50m) 경간 소수주형 교량을 대상으로 적용하였다. 신뢰성에 기초한 최적설계 결과 교량/궤도 종방향 해석 및 교량/차량 동적영향을 고려한 고속철도 교량 설계 단면이 교량/궤도 종방향 해석 및 교량/차량 동적영향을 고려하지 않은 설계 단면보다 훨씬 효율적임을 확인 하였다.