Types Of Corrugation Research Articles

Analysis of Vibrations Generated by the Presence of Corrugation in a Modeled Tram Track

In recent years, there has been a significant increase in the development of the railway system. Despite the huge benefits of railways, one of the main drawbacks of this mode of transport is vibrations caused by vehicles in service, especially in the case of trams circulating in urban areas. Moreover, this undesirable phenomenon may be exacerbated by the presence of irregularities in the rail-wheel contact. Thus, an analytical model able to reproduce the vibrational behavior of a real stretch of tram track was implemented. Besides, a simulation of different types of corrugation was carried out by calculating in an auxiliary model the dynamic overloads generated by corrugation. These dynamic overloads fed the main model to obtain the vibrations generated and then transmitted to the track.

Optimal design of a functionally graded corrugated rods subjected to longitudinal deformation

In this paper, first, we consider corrugated rods, i.e., those in which the values of amplitude and step corrugations are varied continuously as a function of position along a central axis direction to achieve a required function. The latter corrugation type is called the functionally gradient corrugation (FGC). State equations obtained via the homogenization procedure are projected onto the central direction. Second, we study problems regarding the optimization of the FGC rods with variable amplitude and variable step of corrugation. In result of our approach, the optimal profiles of corrugated rods are obtained guaranteeing the largest stiffness of the FGC rods regarding a longitudinal deformation. We have applied the most important, from an engineering point of view, constraints of keeping constant length of the curvilinear rod axis and both linear dimension (projection onto a straight line axis of symmetry) and number of waves of corrugations.

Study on the cause and treatment of rail corrugation for Beijing metro

This paper presents the results of a study concerning a special type of rail corrugation occurring on Beijing metro. Field observations, investigations and measurement results show that the dynamic behavior of the train–track interaction is responsible for corrugations. When the train speed is more than 60km/h, as is the case for Beijing metro, the train/track dynamic interactions at the dominant frequencies are recognized to be the cause for corrugation. The natural frequencies of the Egg system track structure were identified by the hammer test, which correlated well with the dynamic response frequency spectrum of the rail when the metro trains pass by. In order to verify the investigative results and provide a method to reduce rail corrugation, a test section was installed at a typical corrugated curve by avoiding the dominant frequencies of the track structure. When monitoring rail roughness, results show the method used is an effective way to control the development of the wavelength-fixed corrugation in the case of Beijing metro.

Theoretical Predictions of Freestanding Honeycomb Sheets of Cadmium Chalcogenides

Two-dimensional (2D) nanocrystals of CdX (X = S, Se, Te) typically grown by colloidal synthesis are coated with organic ligands. Recent experimental work on ZnSe showed that the organic ligands can be removed at elevated temperature, giving a freestanding 2D sheet of ZnSe. In this theoretical work, freestanding single- to few-layer sheets of CdX, each possessing a pseudo honeycomb lattice, are considered by cutting along all possible lattice planes of the bulk zinc blende (ZB) and wurtzite (WZ) phases. Using density functional theory, we have systematically studied their geometric structures, energetics, and electronic properties. A strong surface distortion is found to occur for all of the layered sheets, and yet all of the pseudo honeycomb lattices are preserved, giving unique types of surface corrugations and different electronic properties. The energetics, in combination with phonon mode calculations and molecular dynamics simulations, indicate that the syntheses of these freestanding 2D sheets could ...

Surface Corrugation Effects on the Water–Graphene Interfacial and Confinement Behavior

We carried out a systematic molecular simulation study of the behavior of a pair of finite-size graphene plates immersed in water at isobaric–isothermal conditions to provide insights into the nature of the water–graphene (corrugated) surface interactions. The goal was to address the link between the corrugation-driven hydration free energy changes in the association process involving graphene plates and the resulting water–graphene interfacial tension, to interrogate the effect of the surface corrugation and confinement on the thermodynamic response functions and the dynamics of confined water and to put the observed behavior in the context of Wenzel’s modification of Young’s equation. We found that graphene confinement induces a significant increase in the isothermal compressibility and isobaric thermal expansivity as well as a pronounced slowdown of the dynamics of water over that of the corresponding bulk counterpart, whose magnitudes depend on the type of surface corrugation involved. Our simulation ...

Bending deformation limits of corrugated unidirectionally reinforced composites

This paper concerns about deformation limits of circular corrugated unidirectional reinforced composites for bending dominated applications. Hence, a two-dimensional analytical stress function approach is used which takes through-thickness normal stresses into account. Hereby, the possible failure modes, namely fibre fracture and layer delamination, of unidirectional laminated circular corrugated sheets are predicted. Additionally, the accurate representative bending stiffness in corrugated-direction is extracted by using an energy approach. The influence of corrugation geometric parameters on deformation limits and stiffness is experimentally as well as theoretically investigated. For this reason, large curvature validation experiments of four different corrugation types are conducted by means of a specially constructed bending device. Finally, bending charts are provided facilitating the choice of an appropriate corrugation geometry during a preliminary design phase.

Investigation into the Mechanism of Type of Rail Corrugation of Metro

An investigation into the corrugation mechanism of rails in both tangent and curved tracks of a metro with Cologne fasteners is carried out through a detailed observation,an extensive measurement at sites and a numerical analysis.The rail corrugation presents the three different wavelengths which are respectively 20 mm,40 mm to 50 mm and 200 mm.The uneven wear of 40 mm to 50 mm is dominant in the corrugation development.In the investigation,first,a relationship between the characteristics of the rail corrugation and the track structure is analyzed based on the field measured data of the rail corrugation and the modal test of the track by using hammer knocking.Then a three-dimensional numerical model for the track is established by using finite element code ABAQUS to further verify such the relationship.The results are obtained by the numerical method coincide with those of the field tests.Through extensive field experiments and detailed theoretical analysis,the mechanism of the corrugation is understood basically and the resonance of the metro track mainly plays an important role in the rail corrugation generation.The numerical model is also used to analyze the effect of the stiffness and damping of the fasteners on the track resonances and the stiffness and damping of the Cologne fasteners have a great influence on the rail corrugation.

이질 누화 특성이 개선된 UTP LAN 케이블의 설계

본 논문에서는 이질 누화 특성이 개선된 UTP(Unshielded Twisted Pair) LAN(Local Area Network) 케이블의 설계를 제안하였다. 제안된 LAN 케이블은 불규칙적인 돌비 형태의 구조를 갖는 피복과 필요시 특수 제작된 크로스필러가 사용될 수 있게 설계되었다. 피복 내부면에 존재하는 서로 다른 높이와 폭을 갖는 돌비는 특정한 주파수 대역이 아닌 넓은 주파수 대역에 걸쳐 차폐부를 구현시킴으로서 외부의 다른 LAN 케이블에 끼치는 간섭을 줄일 수 있는 구조이다. 본 논문의 구조를 이용함으로서 케이블 피복에 구현되어진 차폐부로 인하여 이질 누화 특성을 향상시킬 수 있다. 또한 제안된 구조는 국제 규격인 ANSI/TIA/EIA-568-B.2-10 등을 만족시킨다. In this paper, the design of UTP LAN cable with enhanced alien crosstalk characteristic is proposed. Proposed LAN cable is made with jacket of the irregularly corrugation type. If necessary, it is possible to use the special cross-filler. The alien crosstalk characteristic is enhanced by using proposed cable with inner jacket of the irregularly corrugation type in wide frequency band. The design of the cable was based on parameters of the standard EIA/TIA 568-B.2-10.

The Distribution Laws of Interlayer-Gliding Structure Controlled by Panji Anticline and the Research of Quantitative Evaluation in Seams

Based on the research of interlayer-gliding structures in Panbei and Panji No.1 coal mine that are located in the each wing of Panji anticline, the Panji mining area is divided into 9 main interlayer-gliding areas and 29 sub-regions. The results indicate that the interlayer-gliding structures mainly developed in the anticline wings, which show obvious symmetry at the type and distribution. The types of the interlayer-gliding structures are fault-sliding and corrugation type in the wings and fracture type in the core area. The type and manifestation of the interlayer-gliding structures also show symmetry in the similar depth. From up to down, the interlayer-gliding type show obvious regularity that fracture type is mainly developed in the shallow area, down is fault-sliding type and corrugation type is mainly developed in the deep or the interchange of the faults. Take fuzzy comprehensive evaluation method to evaluate the inter-gliding structure in west area of Panji No.1 coal mine. The results showed that the results from using fuzzy comprehensive assessment were similar with the results exposed by coal mine. Good effects were obtained for predicting the development intensity of the seam-gliding structure in deep unmined areas in combination with geological conditions of coal mine, providing references for production arrangement of coal mine.

Molecular dynamics study of temperature-dependent ripples in monolayer and bilayer graphene on 6H—SiC surfaces

Using classical molecular dynamics and a simulated annealing technique, we show that microscopic corrugations occur in monolayer and bilayer graphene on 6H—SiC substrates. From an analysis of the atomic configurations, two types of microscopic corrugations are identified, namely periodic ripples at room temperature and random ripples at high temperature. Two different kinds of ripple morphologies, each with a periodic structure, occur in the monolayer graphene due to the existence of a coincidence lattice between graphene and the SiC terminated surface (Si- or C-terminated surface). The effect of temperature on microscopic ripple morphology is shown through analysing the roughness of the graphene. A temperature-dependent multiple bonding conjugation is also shown by the broad distribution of the carbon-carbon bond length and the bond angle in the rippled graphene on the SiC surface. These results provide atomic-level information about the rippled graphene layers on the two polar faces of the 6H—SiC substrate, which is useful not only for a better understanding of the stability and structural properties of graphene, but also for the study of the electronic properties of graphene-based devices.

Rail corrugation development in high speed lines

Abstract Rail corrugation wear is one of the most important types of track wear in the railroad industry. The most common cases of rail corrugation that have been documented in the literature were classified by Grassie [1] in six categories, according to the damage and wavelength fixing mechanisms. Except for heavy haul railroads corrugation and for light rail corrugation, in all the other four types of rail corrugation the damage mechanism is wear. This paper analyses the possible existence and degree of rail corrugation wear on four types of high speed tracks (RHEDA 2000, AFTRAV, STEDEF and high performance ballasted track), examining different vehicle velocities and track radii, and taking into account the dynamic behaviour of the high speed wheelset rolling on the rails. A numerical method that takes into account the dynamics of the track and the wheelset as well as the wear mechanism has been used. The four high speed tracks are ranked according to rail corrugation wear development.

Corrugation of a flexible ring under external hydrostatic compression

The initial non-linearly elastic stage of a change in the shape of thin flexible ring under an external hydrostatic pressure is described. At this stage, the formation of alternating bulges and hollows in the ring in a circular direction is due to the balance of non-linearity and dispersion effects. A model is proposed which enables the dependence of the curvature of the deformed ring on the external pressure to be obtained. The shape of the ring is established from the known curvature by methods of differential geometry. Possible types of corrugation of the initial circular ring are obtained. The change in the shape of the ring around a rigid rod, placed inside the ring, is described. The strict relation between the amplitude of the bulges and hollows in the circumferential direction of the ring also prevents the formation of rigid edges on its surface.

Band-gap engineering and ballistic transport in edge-corrugated graphene nanoribbons

We calculate the band structure and the conductance of periodic corrugated graphene nanoribbons within the framework of the tight-binding $p$-orbital model. We consider corrugated structures based on host ribbons with armchair and zigzag edges and three different types of corrugations (armchair edges, zigzag edges as well as a rectangular corrugation). We demonstrate that for armchair host ribbons, depending on the type of corrugation, a band gap or low-velocity minibands appear near the charge neutrality point. For higher energies the allowed Bloch state bands become separated by mini-stopbands. By contrast, for corrugated ribbons with the zigzag host, the corrugations introduce neither band gaps nor stopbands (except for the case of the rectangular corrugations). The conductances of finite corrugated ribbons are analyzed on the basis of the corresponding band structures. For a sufficiently large number of corrugations the conductance follows the number of the corresponding propagating Bloch states and shows pronounced oscillations due to the Fabry-Perot interference within the corrugated segments. Finally we demonstrate that edge disorder strongly affects the conductances of corrugated ribbons. Our results indicate that observation of miniband formation in corrugated ribbons would require clean, edge-disorder free samples, especially for the case of the armchair host lattice.

Azimuthal selection of modes in free-electron masers with coaxial Bragg resonators

A comparative analysis of the selective characteristics of Bragg resonators with various types of periodic corrugation is performed. In the simplest case of the azimuthal symmetric corrugation in a highly overmoded resonator (a large ratio of the perimeter to the wavelength), the Q factors of modes with different numbers of azimuthal variations are almost equal and the mode frequencies are close on the scale of the gain band of electron flow. A certain rarefaction of the mode spectrum can be attained using the helical corrugation when the traveling wave is coupled with the whispering-gallery modes and the frequency interval between the high-Q modes of the resonator with different azimuthal indices is determined by the interval between the critical frequencies of the whispering-gallery modes. The doubly periodic corrugation employed in the 2D Bragg resonators at the same (as in the case of the helical corrugation) intermode distance allows the Q-factor selection of a single azimuthal symmetric mode. The analysis is based on the method of coupled waves and the direct numerical simulation using standard codes.

Rail corrugation: Characteristics, causes, and treatments

Rail corrugation is a phenomenon of great diversity but appears now to be substantially understood. This review proposes some differences in classification of the phenomenon to take account of work undertaken since a widely cited review was published by Grassie and Kalousek in 1993, it attempts to fill holes in an overall understanding of the problem, and answers questions that remained open in 1993 and several that have arisen since. All types of corrugation that have been documented to date are essentially constant-frequency phenomena. By treating the vehicle—track system in its entirety, treatments are proposed that impinge upon track and vehicle design as well as upon the wheel—rail interface where corrugation appears. There is no neat solution to rail corrugation, but it can be treated comprehensively and in many cases also prevented by using products that are already commercially available. Since the frequency of common wavelength-fixing mechanisms varies roughly in the range 50—1200 Hz, trains travelling at different speeds can produce corrugation of substantially similar wavelength by different mechanisms in different locations. Although historical data can no longer be checked, this is the most likely explanation of the belief that rail corrugation was a substantially constant-wavelength phenomenon.

Axial Crushing Characteristics of Circular Tubes with Radial Corrugation

In this paper, the effect of radial corrugation on the crushing behaviors of circular tubes is studied by using the finite element method. The numerical analysis is carried out on two geometrically different types of corrugations, ”radial corrugated tube” (RCT) and ”radial corrugated tube with corners” (RCTC). To compare crushing behaviors of those of corrugated circular tubes, a non-corrugated circular tube (CT) is also analyzed. It is revealed that, in the crushing process, the crushing mode of RCT becomes more unstable than that of CT since the wavelength of the fold becomes long and the fold concentrates to the center of the wavelength. However, when the length and the diameter of the tubes are set to the same levels, RCT demonstrates good energy absorption characteristics. Further, it is shown that the compressive load and load efficiency of RCTC increases due to the corner part.

Development of corrugation as a result of varying normal load

Rail corrugation is initiated by a varying normal load with constant tangential load; by a varying tangential traction with constant normal load; or, occasionally, by a combination of the two. The types of corrugation proposed by Grassie and Kalousek [S.L. Grassie, J. Kalousek, Rail corrugation: characteristics, causes and treatments, J. Rail Rapid Transit, Proc. Inst. Mech. Eng. 207F (1993) 57–68] can usefully be categorized in this way. A simple expression is derived here for the growth rate of those types of corrugation that develop initially from varying normal load. It is shown that the initial growth rate is typically less than or the same order as the steady-state wear rate. This is similar to measured rates of corrugation development on an operating railway. The mechanism considered here corresponds essentially to a “free response” that reflects the dynamic behaviour of the system. While the mechanism could readily be included in a feedback loop that reflected also the “forced response” arising from development of the corrugation itself, this has not been done here.

Prediction of corrugation in rails using a non-stationary wheel-rail contact model

Most of the models used for simulating the conditions existing in the wheel-rail contact are based on stationary theories. In such theories, the parameters associated with the wheel-rail contact are independent on the conditions applied on it previously. This supposition is a simplification of the real phenomenon, whose validity lies in the rapid convergence of the contact parameters to their stationary values. However, the conditions simulated by means of non-stationary theories may differ from those obtained by using stationary theories when external conditions vary rapidly. Certain types of rail corrugation may be related to high-frequency normal or tangential forces transmitted through the contact, which may determine the effect of the temporal history on the contact parameters, and consequently on the rail wear. In order to investigate the influence of the contact process on the results of models of corrugation calculation, a methodology for estimating the rail wear depth due to a wheel running on a stretch of rail is developed. The method implements an improved contact model where non-stationary hypotheses and an exact elastic model are taken into account. The results show the influence of the more realistic hypotheses adopted in the proposed method.

Operation Characteristics of Microwave Sources Based on Slow-Wave Interactions in Rectangular Corrugations

Studies on slow-wave devices with a novel disk cathode and two types of rectangular corrugation are reported. The beam voltage is weakly relativistic, which is less than 100 kV. A disk cathode can generate a uniformly distributed annular beam in the weakly relative region. Rectangular corrugation having the ratio of the corrugation width to the periodic length of 50 or 20% is used. Using the former, output powers of about 200 kW are obtained at around 100 kV. For the latter, the effect of slow cyclotron resonance is observed in the low-energy region of around 30 kV. Output powers of slow cyclotron masers are in the range of a few hundred W. The operation mode of a slow cyclotron maser can be controlled between axisymmetric and nonaxisymmetric modes by changing the end condition of rectangular corrugation.

Deterministic and Probabilistic Calculation of the Geometric Properties of Corrugated Bulkheads

Formulae are given for the major geometric properties of corrugated bulk-heads: “Elastic” and “Plastic” section modulus, shear area, spacing, depth, etc. Four corrugation types are covered: cold-form, built-up, rounded and “combination” case corrugation. While representing the geometric properties in probabilistic terms, an assumption is made that evenly distributed corrosion is the cause of the probabilistic nature of the geometric properties. The “as-built” corrugation thickness is also presented in probabilistic terms. The corrosion wastage and the residual thickness are treated in probabilistic terms as well. Thus, the probabilistic distribution of any geometric property is built for any instant or for any time period. Then, the probability of meeting any given renewal criteria (represented in terms of geometric properties) is calculated.