Roller Support Research Articles

Examination of the contact pattern of rolling surfaces

This article provides a brief summary of the potential applications of contact pattern examinations. The examination of contact pattern is a frequently used test for gear drives, rolling bearings and checking support rollers. It is used on gear drives and support rollers to test operating conditions, whereas in the case of rolling bearings the cause of the failure has already been identified. The chapters mention the types of contact patterns, the shape and size of contact patterns. This article is an introduction to a multi-part article series that presents the computerbased capabilities of contact pattern examination.

Determination of the maximum allowable distance between the roller conveyors of a tubular belt conveyor

The article developed a mathematical model of the stress-strain state of a tubular conveyor belt filled with bulk load. In this case, the belt is considered as a thin elastic inextensible cylindrical shell, and the bulk load in the belt is in the limit state. A system of differential equilibrium equations for a tubular belt with a bulk load with respect to forces and bending moments in a belt was obtained, which, when simplified, was reduced to a fourth-order differential equation for belt deflections. Based on this mathematical model, analytical dependencies of the deflections of the tubular conveyor belt on the parameters of the conveyor, the radius and properties of the belt, as well as the properties of the bulk load are obtained and analyzed. As a result, the maximum allowable distance between the roller supports of the tubular conveyor is determined. It was found that the allowable distance between the roller bearings is directly proportional to the tension of the belt and inversely proportional to the square of the radius of the belt and the bulk weight of the load. The research results can be used in the design of tubular belt conveyors transporting bulk load.

Features of dynamics of the load-carrying body of the belt tubular conveyor

The problems of researching the dynamics of the load-carrying body of a belt tubular conveyor (BTC) are formulated. It is noted that for BTC, at which the flat belt is rolled into a pipe with the help of special roller supports, the main danger is torsional vibrations. The factors causing torsional vibrations of the tubular belt are analyzed. An estimate of the maximum angle of rotation of the belt from the suddenly applied moment is given. A comparison of the angular turns of the tubular belt of the closed and open profiles is made. The relations of the main belt’s parameters, which exclude the possibility of its significant rotation and load spills are obtained.

Analysis and Experimental Study on Pressure Characteristics of Supporting Roller Group of Pipe Belt Conveyor

Aiming at the problem in measuring the nonuniformly distributed pressure generated by the pipe belt conveyor when conveying raw coals, a hexagonal adjustable pressure measuring device for the idler group is proposed. The dynamic model of the pipe belt conveyor clamping‐type roller group is established. In order to simplify the calculation process of mechanical analysis, the modal analysis is carried out to determine the factors which will influence the pressure. The pipe diameter and filling rate are selected as the key control factors by the sensitive analysis of pressure of the pipe belt conveyor clamping type roller group. An adjustable diameter‐type supporting roller group experiment device is self‐designed, and the dynamic pressure change of the roller group and each roller pressure are tested. The results show that the average error between the simulated and tested values of the pressure of the idler group at different filling rates is 7.3%; the theoretical and simulated values of the pressure of the idler group are in good agreement with the experimental values. The study provides a theoretical basis and experimental reference for the design and application of pipe belt conveyors.

Brake force of tracked vehicles

It is commonly supposed that the slowing down and stopping of vehicle is caused by adhesion of its tracks to the dirt surface. However, force analysis shows that, although these forces play an important role during braking, the longitudinal components of the internal forces applied to the shafts of the vehicle’s braked drive wheels and the front support rollers of the tracked propulsion are directly responsible for its deceleration. The sum of these longitudinal forces directed against the motion of the tracked vehicle constitutes the braking force of the tracked vehicle. The value of this total braking force is ultimately determined by the ratio of the braking torque developed by the friction forces to the radius of the drive wheels with which the braking devices are coupled. Since when braking a tracked vehicle, the longitudinal reaction is balanced, it cannot be the direct cause of the deceleration of the vehicle, i.e. its braking force. In addition, the longitudinal reaction applied to the lower fixed part of the track does not perform mechanical work and cannot absorb the kinetic energy of a moving vehicle. This work is performed by the internal braking force Ртор, which develops negative (braking) power during braking. It turns out that during braking, the longitudinal reaction is needed not at all to cause a slowdown, but as an external force, to balance some of the internal forces of the tracked vehicle. As a result of its action, the unbalanced part of the internal forces forms the internal braking force, which directly causes the machine to slow down and stop. In this case, the longitudinal reaction of the supporting surface, without which the formation of an internal braking force is not possible, limits both the lower and upper values of the latter, and these forces themselves are numerically equal. The fact that the braking force of a tracked vehicle, like its traction force, is an internal force, does not contradict theorems on the movement of the center of mass or the change in the amount of motion of a mechanical system, which are valid only for isolated mechanical systems that do not have a source of active internal forces.

PENGARUH NORMALIZING TERHADAP BAJA 20Mn Cr6 HASIL PENGECORAN UNTUK SUPPORT ROLLER

Rotary Kiln machine is used in fertilizer plant which is function to mix the fertilizer ingredients. Part of the Rotary Kiln is support by using a roller. Support roller is made of 20MnCr6 material, AISI 5120 (0.18% C) with casting process. Normalizing phase on casting processes is using to increase strength of the material The objectives of the normalizes process is to eliminate residual stresses, softening, increasing toughness, homogenization of micro structures and to ease machining processes. The effect of normalizing can be measured by using mechanical test, ie tensile test, hardness test and microstructure analysis. Test specimens were made the same material with normalizing and without normalizing process. Normalizing process temperature at 900oC heating for 150 minutes with air cooling for 7 hours. The results has shown that normalizing material has lowest tensile strength of 41.05 kgf/mm2 is compared to 42.16 kgf/mm2. However, the ductile fracture is higher 41.2% is compared to 29.52%, the microstructure formed uniformly evenly compared without normalizing. The softening process also makes the roller support rotate due to rubbing with riding ring.

ВЛИЯНИЕ ИЗНОСА РИСУНКА ПРОТЕКТОРА БЕГОВОЙ ДОРОЖКИ ШИНЫ НА ЕЕ СЦЕПНЫЕ СВОЙСТВА ПРИ ТОРМОЖЕНИИ НА СТЕНДЕ В БЛОКОВОМ РЕЖИМЕ

The PURPOSE of the article is to carry out an experimental study of the effect of the tire tread pattern wear on the implemented coefficient of adhesion to the support surfaces of the test bench under the variation of normal load value. METHODS. The studies were performed on the test bench of modular design, which allows to measure the normal and tangential reactions of the elastic tire with support surfaces. RESULTS. It has been determined that the increase of the tire tread pattern wear from 10 to 90% reduces the adhesion coefficient of the automobile wheel elastic tire by 35.3% when braking in the locked mode on a flat support surface. When the wheel brakes on one support roller of the test bench and the tread wear is from 10% to 90% the adhesion coefficient reduces by 18%. When the wheel brakes on two support rollers of the test bench the coefficient of adhesion makes 23.8% on the front roller and 48.4% on the rear support roller of the stand, with an increase in the wear of the tread pattern from 10% to 70%. CONCLUSION. The conducted experimental studies allowed to determine the dependence of the adhesion coefficient of the elastic tire on the wear degree of the tire tread pattern and the variation of normal load under the locked wheel braking on the flat support surface and one or two support rollers.

Isochronous Beams by an Inclined Roller Support

The paper addresses the problem of isochronous beams, namely those that oscillate with a frequency that is independent of the amplitude also in the nonlinear regime. The mechanism adopted to obtain this goal is that of having, as a boundary condition, a roller that can slide on a given path. A geometrically exact Euler–Bernoulli formulation is considered, and the nonlinear analysis is done by the multiple time scale method, that is applied directly to the partial differential equations governing the motion without an a priori spatial reduction. The analytical expression of the backbone curve is obtained, up to the third-order, and its dependence on the roller path is addressed. Conditions for having a straight backbone curve, i.e., the isochronous beam, are determined explicitly. As a by-product of the main result, the free and forced nonlinear oscillations of a beam with an inclined support sliding on an arbitrary path have been investigated.

Axial-transversal coupling in the nonlinear dynamics of a beam with an inclined roller

The nonlinear oscillations of an Euler–Bernoulli beam hinged at one end and having a roller support sliding on a inclined line on the other end are investigated for the first time (to the best of the authors’ knowledge). Free and forced dynamics are studied, and the backbone curve and frequency response curve are obtained by the multiple time scale method. These results allow us to detect analytically the main features of the nonlinear dynamics, in particular the hardening/softening dichotomy, and how it is influenced by the various beam parameters. Furthermore, the analytical results are compared with finite element simulations to check their reliability. The main goal of the paper is that of investigating the coupling between axial and transversal displacements, which appears yet in the linear regime (first order solution) due to the slope of the constraint. An element of novelty consists of showing the qualitative and quantitative changes that the coupling undergoes passing from small (linear regime) to moderate and large (nonlinear regime) displacements.

Placing an FRP bridge in Taijiang national park and in virtual reality

In this paper, the all-FRP composite pedestrian bridge of Taijiang National Park was investigated for its flexural-torsional behaviour under half-surface loading conditions. The bridge, which consists of four GFRP I-girders separated by three GFRP diaphragms, was loaded on half of its longitudinal surface and analysed numerically for its induced shear and flexural deformation. From finite element simulations, the parts of the FRP pedestrian bridge more susceptible to damage due to transverse shear from the torsional load were found to be at the midspan of the exterior girder (bottom flange and web) at the loaded half, the webs of the girders around the roller support, and the web of the diaphragm closer to the roller support. In addition to finite element analysis, a 3D model of the FRP bridge was placed in virtual reality (VR). Using a VR goggle, the virtual FRP bridge can be examined in an immersive virtual environment. The use of VR provides a means to deliver a better service to national park visitors and may act as a catalyst for greater public interest.

Study on the contact behavior of pipe and rollers in deep S-lay

S-lay is a widely used method for offshore pipe installation. In recent years, S-lay has gradually applied to the deepwater condition. Because of the increasing pipe weight in deep S-lay, there exist severe and complex contact problems between the overbend pipe and roller supports of the stinger. In deep S-lay design, it is difficult to solve this nonlinear mechanics problem, and there remain confusion and difficulties to predict the roller contact forces and the pipe strain level in S-lay design.The present paper develops a refined finite element model with the framework of ABAQUS, which considers the complex surface contact behaviors in the overbend section. The features of the contact state of different rollers within one roller box are discussed, and the resultant support forces from each roller box are calculated and compared with the commercial design code. The overbend strain level of five S-lay cases is investigated and the pipelaying safety is checked by DNV rules. The simulation results show that the proposed model can provide more accurate and reasonable predictions on roller forces and pipe strain distribution for deepwater S-lay design.

Analytical solution for cylindrical bending of two-layered corrugated and webcore sandwich panels

We analytically investigate infinitesimal cylindrical bending deformations of two-layered triangular corrugated and webcore linearly elastic sandwich panels by using the mechanics of materials approach and the classical plate theory. The model is validated by comparing its predictions with the solution by the finite element method of the linear elasticity equations for plane strain deformations. The model can accurately capture the secondary bending of the facesheets, manifested as changes in their curvature between the webs and the resulting changes in the axial stresses, from being tensile to possibly compressive, that the commonly-employed homogenization schemes fail to capture. Subsequently, the model is used to analyze several problems with the sandwich panel having a pinned support at the left edge and a roller support at the right edge, and a uniformly distributed load applied on the top facesheet of the panel. It is found that the core plates mostly deform in compression and bending, respectively, for corrugated and web core panels. Furthermore, a significant fraction of the work done by the external load on the structure is absorbed as strain energy of deformations of the core plates near the supports. For four hybrid combinations of corrugated and webcore configurations in two-layered panels, the combination with the upper corrugated core set-up has the least maximum face sheet deflection and axial stress. The analytical technique can be easily extended to multi-layered hybrid configurations and provides quick means of finding efficient strain-energy absorbing hybrid designs.

Reaction Forces on a Fixed Ladder in Static Equilibrium: Analysis and Definitive Experimental Test of the Ladder Problem

The development of a theoretical model to predict the four equilibrium forces of reaction on a simple ladder of non-adjustable length leaning against a wall has long remained an unresolved matter. The difficulty is that the problem is statically indeterminate and therefore requires complementary information to obtain a unique solution. This paper reports 1) a comprehensive theoretical analysis of the three fundamental models based on treating the ladder as a single Euler-Bernoulli beam, and 2) a detailed experimental investigation of the forces of reaction as a function of applied load and location of load. In contrast to previous untested proposals that the solution to the ladder problem lay in the axial constraint on compression or the transverse constraint on flexure, the experimental outcome of the present work showed unambiguously that 1) the ladder could be modeled the best by a pinned support at the base (on the ground) and a roller support at the top (at the wall), and 2) the only complementary relation needed to resolve the static indeterminacy is the force of friction at the wall. Measurements were also made on the impact loading of a ladder by rapid ascent and descent of a climber. The results obtained were consistent with a simple dynamical model of the ladder as a linear elastic medium subject to a pulse perturbation. The solution to the ladder problem herein presented provides a basis for theoretical extension to other types of ladders. Of particular importance, given that accidents involving ladders in the workplace comprise a significant fraction of all industrial accidents, the theoretical relations reported here can help determine whether a collapsed structure, against which a ladder was applied, met regulatory safety limits or not.

Расчетная оценка возможности применения подшипников скольжения из пористого стеклопластика в составе опорного катка гусеничного движителя

Currently, antifriction bushings for sliding bearings made of expensive non-ferrous metal alloys are used in low-speed caterpillar track rollers. Composite bushings based on porous GFRP obtained by radial winding is a cheap alternative for metal ones. They can withstand high radial compressive loads and successfully work without lubrication supply system using only selflubricating modifiers in their open porosity. The bushings have a low stiffness in the radial direction due to the porous structure. Low stiffness contributes to the formation of a significant contact area between interacting surfaces. Low contact normal and tangential stresses lead to a shaft wear reduction. Low interlaminar strength is the main factor limiting the use of composite bushings. Determination of the maximum radial and shear stresses emerging in the operational process of a friction unit is a very important problem. First part of the work is devoted to determination of the static and sliding friction coefficients for composite bushing. Combination of static tests up to fracture and numerical analysis was used to determine the critical interlayer shear stress. In the second part of the work, numerical model of a support roller with antifriction bushing was developed. This model was used to determine the stress-strain state of antifriction bushings of the support roller of pipe-laying machine TR-20. Distribution of normal stresses on the contact surface with the shaft for GFRP and bronze bushings were found. The relations between the maximum normal stress value and the radial clearance in pair “shaft-bushings” were obtained for both types of bushings. It was shown, that the value of the local normal stresses is significantly affected by the skew-symmetry of the roller support, clearance in pair “shaft-bushings” after assembly and after exploitation. The maximum reasonable value of the radial clearance between the shaft and the bronze and GFRP bushings were0.25 mm and 1 mm respectively. The use of antifriction composite bushings allows increasing the value of the maximum permissible clearance of friction unit more than two times in comparison with metal one. The paper shows the possibility of replacing antifriction bronze bushings on porous GFRP bushings.

Experimental investigation on a passive auto-tuning mass damper for vibration control

Presented in this paper is an experimental investigation of a passive auto-tuning mass damper with Pulley connections (PATPD). It is a passive vibration control device that consists of a box filled with silica sand on roller supports. The silica sand provides the mass of the damper. The PATPD is connected to the structure to be controlled by a group of inelastic ropes and pulleys; it is free to move in any translational direction. The pulleys and rope transfer a driving force, resulted from the movement of the structure under control, to the damper. The inertial force from the damper mass, via the connecting rope and pulley, acts on the structure in the direction opposite to any movement and thus providing the vibration control of the structure. Free and forced vibration tests are performed on six MDOF test structures with and without the PATPD as the natural frequencies of the test structures are varied by changing its mass or stiffness whilst keeping the PATPD constant. The test results reveal that the proposed damper, without any tuning or specific adjustment, produces effective control on translational, torsional and coupled vibration of the MDOF structure—even if the vibration frequencies or natural frequencies of the structure that is being controlled changes significantly. The PATPD is simple, effective, robust and adaptive which renders this proposed damper appealing for engineering applications.

Frictional contact behaviors between beam and cylinder under cyclic loading

Finite element results are presented for frictional contact behavior between a beam and rigid cylinder with either a pinned or roller support under cyclic loading. In the case of a pinned support, a new type of rolling contact is initiated and a steady contact state is achieved owing to frictional shakedown; thus, a certain slope of frictional energy dissipation becomes dominant with respect to the ratio of the mean load to load amplitude. A similar contact behavior is observed when the beam thickness varies and maximum frictional energy dissipation occurs at a certain thickness. For the roller support, only a stick region is observed for all ranges of the loading and unloading phases regardless of the beam thickness, which causes no frictional energy dissipation. These contact behaviors are verified through the consideration of a practical grid-to-rod fretting model.

Finite element simulation of bulge deformation for slab continuous casting

This paper aims to provide an investigation of the bulge deformation rules by using finite element analysis software, ABAQUS/Standard. A three-dimensional thermo-mechanical coupling model, considering the dynamic contact between the slab and rolls, has been established to study the temperature and bulge deformation distributions of the slab over the casting process. The simulated results of temperature profile were compared with the measured temperatures during the continuous casting process, the results of which showed a high agreement. Moreover, the bulge deformation rules of the slab were investigated systematically, especially at the thickness direction of the cross section which is the bulge deformation of the slab on the narrow side. A wave motion was found in the bulge deformation on the wide side of the slab cross section due to the joint effect of the ferrostatic pressure and the roller supporting force. The bulge deformation on the narrow side without the constraint from the roller support was cumulative, which was greater than the recovery count and compensated the bulge deformation on the wide side. In addition, the influences of various casting process parameters on bulge deformation were studied systematically in this paper. The results showed that bulge deformation on the narrow side and the wide side both increased with an increase in casting speeds and roll pitch. The method of fixed-gap and variable-diameter was suggested to be applied in the manufacture process in order to reduce the bulge deformation.

Tracked Vehicle Performance Evaluation using Multi Body Dynamics

The objective of the study was to shorten the design cycle and evaluate the performance of infantry fighting vehicle using advanced multi body dynamics (MBD) environment before physical prototypes built. The MBD model is built with tracked vehicle module consisting of tracks (Links), sprocket, Support rollers, and hydro pneumatic suspension with suitable connections. Hull, turret are characterised by mass and inertial properties. The dynamic analysis was carried out for different field conditions i.e. trench crossing, step and ramp climbing, etc., to extract the hull forces at joints, power required to manuever, track tension forces to determine overall vehicle stability and look for possible design modifications. Recommendations were then suggested for power train, number of track segments, tensioner force, etc to ensure proper behavior during different manuevers. The MBD results are used in FEA to determine structural response in terms of stress, deformation, fatigue etc., and reflects in design modification before physical prototype made and are validated with base level analytical results.

Evaluation of Additional Rail Stress for Partial Application of Sliding Slab Track

CWR(continuous welded rail) on railway bridges should be carefully examined and installed due to additional rail stress caused by track-structure interaction. The additional rail stresses are caused by longitudinal displacement of bridge due to temperature change and train vertical load and traction/braking force. Design codes limit the additional rail stress less than or equal to 92 MPa. Previous researches showed that the additional rail stress generated through track-bridge interaction can be reduced significantly up to 80% by applying sliding slab track system. This study evaluates the effectiveness of partial application of the sliding slab track system, in which the sliding slab track is applied only at bridge roller support region rather than applying it to the entire bridge span. The proposed system has been verified here through track-bridge interaction analysis for 60 m or 70 m long simple span bridges and suggested proper application length of the partial sliding slab track.

EXPERIMENTAL STUDY OF THE DYNAMICS OF CENTRIFUGAL CASTING MACHINES FOR PRODUCTION OF MILL ROLLS

Purpose. The main purpose of experimental studies is to establish the adequacy of the developed mathematical models of machine fluctuations and the actual parameters of machine vibration. Almost all casting machines for the production of mill rolls have a unique design and performances. The additional aim of this work is to compare the vibration level of the casting machine with the requirements of the current vibration standards for new technological machines. Frequency analysis of the oscillations allows establishing defects in workmanship, errors of rotating parts installation and their influence on the dynamics of the machine. Methodology. Measurement of vibration parameters was performed on the moving parts of roller bearings of the machine. To measure the amplitudes of accelerations in three mutually perpendicular directions piezoelectric sensors with magnetic mount were used. Electrical signals from the sensors were recorded on magnetic tape. Further analysis of the oscillations was carried out and visualized using specialized frequency analyzer. The frequency analyzer implements the algorithm of fast Fourier transformation and/or integration of sensor input signal. After the first integration the data for plotting the vibration velocity spectrogram were obtained and as a result of the second integration there are the data of vibration displacements spectrogram of the machine supports. Findings. The results of experimental studies of centrifugal casting machine vibrations for the production of two-layer rolls were presented. There were obtained and analyzed the spectrograms of accelerations, velocities and displacements of moving parts of the upper and lower roller supports. The work of the machine is associated with the calculated values passing of critical frequencies and the short-term development of resonance oscillations of the rotor and roller bearings. Originality. For the first time the author obtained the frequency spectra of vibration of an industrial sample of a casting machine. The oscillations with frequencies that differ from the basic rotor frequency were detected. Practical value. Based on the results of the experiment, the actual vibration parameters of the machine in steady state when testing without die-casting the metal were determined. The adequacy of mathematical models of the dynamics of the machine and its industrial model was established. Using the method of one tone the coefficients of vibration velocity distortion of the rotor harmonic, indicating the nonlinear transformations in the system "rotor - bearings" were obtained. It was experimentally established that the vibration parameters of the machine are within the acceptable ranges, regulated by standards for vibroactive machines.