Rolling Cylinder Research Articles

Recent Advances in Needleless Electrospinning of Ultrathin Fibers: From Academia to Industrial Production

Electrospinning (e‐spinning) has been extensively explored as a simple, versatile, and cost‐effective method in preparing ultrathin fibers from a wide variety of materials. Electrospun (e‐spun) ultrathin fibers are now widely used in tissue scaffold, wound dressing, energy harvesting and storage, environment engineering, catalyst, and textile. However, compared with conventional fiber industry, one major challenge associated with e‐spinning technology is its production rate. Over the last decade, compared with conventional needle e‐spinning, needleless e‐spinning has emerged as the most efficient strategy for large‐scale production of ultrathin fibers. For example, rolling cylinder and stationary wire as spinnerets have been commercialized successfully for significantly improving throughput of e‐spun fibers. The significant advancements in needleless e‐spinning approaches, including spinneret structures, productivity, and fiber quality are reviewed. In addition, some striking examples of innovative device designs toward higher throughput, as well as available industrial‐scale equipment and commercial applications in the market are highlighted. image

Viscoelastic frictional properties of rubber-layer roller bearings (RLRB) seismic isolators

This paper deals with the behavior of a rubber-layer roller bearing (RLRB) isolation system. This system consists of steel cylinders interposed between steel plates padded with high damping rubber layers. When the cylinders start to roll, a partial decoupling is achieved between the superstructure response and the ground motion. However, the presence of rubber layers in RLRB isolators aims at dissipating part of the seismic energy, thus reducing the relative motion between the base and the superstructure (building). To better understand this phenomenon, we proceeded to a mechanistic study of the viscoelastic contact interaction between the rolling cylinders and the rubber layers. The analysis is led in the framework of continuum mechanics and linear viscoelasticity by means of a numerical strategy, belonging to the class of boundary element methods, able to take into account the viscoelastic layer thickness. The results show that, depending on the design parameters, a strong reduction of the viscoelastic friction can be achieved, useful to uncouple the motion of the superstructure from the motion of the base and then of the ground, without negatively affecting the amount of energy dissipation per unit time. The simulations allow determining the optimal sizes and dimensions to the component parts of the isolator.

Research on the rolling moment in the symmetrical and asymmetrical rolling process

Research distribution the rolling moments symmetrical and asymmetrical report presents great importance both in theory and to introduce clarifications to the calculation of rolling resistance line assemblies. Clarifying individuals of metallic material deformation between the rolls single cylinder diameters act of any difference of work and analysis of advance and delay phenomena. Torque drive value for each of the rolling cylinders was done by reducing the thickness of the laminate samples, an experimental facility located in the laboratory of plastic deformation of the Faculty of Engineering Hunedoara. The analysis of research results show that in terms of power consumption for deformation and safety equipment in operation is rational for mills which require such a difference between the work rolls to execute about one cylinder operated.

INFLUENCE OF SURFACE PROFILE MODIFIED WITH FINE SHOT PEENING ON SCUFFING IN ROLLING-SLIDING CONTACT ELEMENT

Recently, the gear is required of high strength, reliability, and surface damage resistance under severe service condition to achieve the weight saving and downsizing of a product. It is necessary to understand the influence of the surface profile on the scuffing resistance. The shot peening is able to form the arbitrary surface profile with the changes of peening conditions to the metal surface. When the effective surface profile will be found to increase the lubrication property, the metal surface will be obtained with both the surface strength and the surface lubricity. In this paper, the influence of surface profile with the fine shot peening, which is able to form the arbitrary surface profile, on the scuffing resistance in the rolling-slipping contact machine element was investigated. The scuffing test using the two cylinder rolling contact test machine was carried out. The test rollers processed with shot peening were used in the scuffing test.

Investigation of the rolling motion of a hollow cylinder using a smartphone

This paper describes the use of smartphone’s gyroscope sensor to analyse a hollow cylinder rolling down an inclined plane. The smartphone (iPhone 4s) was attached to the end of hollow cylinder and was equipped with the Sensorlog application (Sensorlog app) to record the angular speed of rolling down an inclined plane. The experimental results agree with the theoretical model that is familiar to students for the rolling motion on an inclined plane. Moreover, the coefficients of static friction and kinetic friction were determined to be 0.205 ± 0.011 and 0.178 ± 0.003 from the measurements, respectively. This experiment demonstrated an alternative way to teach the rolling motion in a physics laboratory.

Microstructure and wear behaviour of plasma transferred arc (PTA)-deposited FeCrC composite coatings on AISI 5115 steel

Plasma transferred arc (PTA) cladding was used to produce composite coatings on the surface of AISI 5115 steel using five different energy inputs and ferrochromium (FeCrC) powder. The effects of different energy inputs and of ferrochromium powder on the microstructure, hardness, and wear behaviour were investigated. The dry-sliding wear properties of the samples were determined using the ball-on-disk wear test method. The alloyed surfaces exhibited increases in hardness and wear resistance and a decrease in the coefficient of friction. The increase in hardness was explained by the presence of hard phases, such as the martensitic phase, Cr7C3, C3Cr7, Fe23C6 and iron carbides, in the microstructure. The average coefficient of friction value of the substrate was determined to be 0.83, whereas these values for the composite layers varied between 0.62 and 0.73. The lowest wear rate (2.88×10−6mm3/N/m) was observed for the 100A PTA cladding sample. The industrial coating process was applied to an AISI 5115 steel rolling cylinder using the optimum parameters (100A), which were determined after experimental studies. The PTA cladding process on the rolling cylinder improved the useful life by approximately 2.5-fold compared to the actual rolling cylinder.

粒状体を用いた転動型制振装置の開発

Passive vibration dampers are very efficient solution for vibration control in structures with low natural frequencies. However, conventional dissipative elements used in their dampers require maintenance due to their nature of their function. Therefore, it is necessary to develop a virtually maintenance-free dissipative element. In this study, a tuned rolling-granular damper is presented. This damper consist of a cylinder partially filled granular materials, which rolls in a cylindrical surface attached to a primary system. In this damper, the granular materials is the energy dissipating agent. Granular motion induced inside the cylinder, consists of intermittent contacts with other particles and the wall of the cylinder. It results in the rapid energy consumption. The effect of the particle size and mass ratio on the damping performance was investigated experimentally. The granular materials used in this study were steel particles and are of uniform size. By means of the discrete element method (DEM), an analytical solution is provided to estimate the damping performance. The contact force acting on the rolling cylinder is modeled by the sum of the spring force based on Hertzian contact theory and the damping force introduced by Tsuji. Comparison between the theory and the experiment was found to be good.

Tactile Manipulation With a TacThumb Integrated on the Open-Hand M2 Gripper

Tactile manipulation will be essential for automating industrial and service tasks currently done by humans. However, the application of tactile feedback to dexterous manipulation remains a challenging unsolved problem, with robot capabilities lagging far behind those of humans. Here, we present the tactile thumb (TacThumb): a cheap, robust, 3-D-printed optical tactile sensor integrated on the Yale GrabLab model M2 gripper. To test tactile manipulation capabilities, a cylinder is rolled along the TacThumb using the opposing nontactile finger. The tactile information permits localization of the test cylinder along the TacThumb to submillimeter accuracy over most of the movement range. In consequence, the M2 gripper can perform accurate inhand tactile manipulation, by providing information that can be used to control the location of the test object within the hand. Tactile manipulation is demonstrated by rolling cylinders with a range of diameters up and down the TacThumb along a target trajectory, using only tactile data to update its current position and move it toward a target. This model-free approach gives a demonstration of basic tactile manipulation without the need for a kinematic model of the hand, in a manner that should generalize to other tactile manipulation tasks.

Effects of lubricant viscoelasticity on film thickness in elastohydrodynamic line contacts during start-up

By means of numerical simulation the elastohydrodynamic lubricating film formation during start-up of motion of a line contact from rest is studied. The transition from solid contact to lubricated contact is of importance in investigating the start-up process and its effects on bearing performance. The numerical results of Holmes et al. (2002) and others, concerning point contact and Newtonian lubricant, are not in good agreement with the known experimental data. The numerical film thickness is significantly smaller than the experimental values and the experimental velocity at which lubricant travels through the conjunction does not equal the entrainment velocity of numerical results. In the current paper, a lubricant with viscoelastic properties is considered. The Maxwell model of a lubricant at pure rolling of elastic cylinders is used. Also, as well as in work of Usov (2008) the model assumes the division of the whole area of contact into three zones: the dry contact of surfaces, the transient zone and the zone in which the surfaces are separated by a liquid lubricant layer. The rigid body model is assumed for the lubricant in the transient zone. The effects of viscoelasticity and size of transient zone on film thickness and the velocity at which the lubricant moves through the contact are studied. It is shown that viscoelasticity raises film thickness in a start of the motion and lowers the velocity at which the lubricant moves through the contact. This velocity is lower than the entrainment velocity in the first half of the contact, as in the experimental results with point contact. In the second half of the contact, this velocity may be lower or higher than the entrainment velocity depending on the size of the transient zone. The film thickness may increase considerably at the start of motion when the size of the transient zone increases.

Angular velocity direct measurement and moment of inertia calculation of a rigid body using a smartphone

In this paper, we focus on smartphones as experimental tools; specifically we use the gyroscope sensor of a smartphone to study the turning motion of a rigid body. Taking into consideration recent work concerning that topic, we try to use the gyroscope sensor in studying the complex motion of a rolling cylinder on a slope.

Simple Model of a Rolling Water-Filled Bottle on an Inclined Ramp

We investigate a water-filled bottle rolling down an incline and ask the following question: is a rolling bottle better described by a model ignoring all internal motion where the bottle is approximated by a material point sliding down an incline, or is it better described by a rigid solid cylinder rolling down the incline without skidding? The measurements presented here represent a special case of similar experiments described by K.A. Jackson et al. (see Ref. 1 and references within). There exists also a report by Kagan describing the motion of soda cans rolling on an incline. In our case we investigate motion of the fully filled bottle. We demonstrate that within accuracy of our experiment the motion of the bottle can be described by a simple “frictionless water” model. The analysis of the dynamics of the bodies sliding and rolling on a ramp is a standard component of introductory physics classes, and a required component of the Advanced Placement (AP) Physics curriculum.

Preparation of aligned polyimide-based carbon nanofibers by electrospinning

Polyimide( PI) is a good carbon precursor owing to its high carbon yield and easy graphitization. PI nanofibers prepared by electrospinning were carbonized and graphitized to prepare aligned carbon nanofibers. Pyromelliticdianhydride and 4,4'- diaminodiphenyl ether were dissolved in N,N- dimethylacetamide at room temperature and stirred for 2 h to obtain a polyamide acid( PAA) solution,which was electrospun into aligned PAA nanofibers at 20 k V and collected by a rolling cylinder 18 cm belowthe needle with a rolling speed of 2 800 r / min. The PAA nanofibers were first imidized into the PI nanofibers at 350 ℃,then carbonized at 900 ℃ at a heating rate of 5 ℃ / min and finally graphitized at 3 000 ℃ to obtain continuous and aligned polyimide- based carbon nanofibers. The PAA solution with a concentration of 20% was the most suitable for electrospinning. SEMcharacterization shows that the average diameter of the carbon nanofibers is around 100 nm. The carbon nanofibers after graphitization at 3 000 ℃have a typical graphite structure.

Walking indoors, walking outdoors: an fMRI study.

An observation/execution matching system for walking has not been assessed yet. The present fMRI study was aimed at assessing whether, as for object-directed actions, an observation/execution matching system is active for walking and whether the spatial context of walking (open or narrow space) recruits different neural correlates. Two experimental conditions were employed. In the execution condition, while being scanned, participants performed walking on a rolling cylinder located just outside the scanner. The same action was performed also while observing a video presenting either an open space (a country field) or a narrow space (a corridor). In the observation condition, participants observed a video presenting an individual walking on the same cylinder on which the actual action was executed, the open space video and the narrow space video, respectively. Results showed common bilateral activations in the dorsal premotor/supplementary motor areas and in the posterior parietal lobe for both execution and observation of walking, thus supporting a matching system for this action. Moreover, specific sectors of the occipital–temporal cortex and the middle temporal gyrus were consistently active when processing a narrow space versus an open one, thus suggesting their involvement in the visuo-motor transformation required when walking in a narrow space. We forward that the present findings may have implications for rehabilitation of gait and sport training.

Residual Stresses Due to Rigid Cylinder Indentation and Rolling at a Very High Rolling Load

In this paper, residual stresses due to indentation and rolling of a rigid cylinder on a finite plate at a very high rolling load with a relative peak pressure of 22 are examined by two-dimensional plane strain finite element analyses using abaqus for the first time. In the finite element analyses, the roller is modeled as rigid and has frictionless contact with the finite plate. The geometry of the finite plate and its boundary conditions are assigned to correspond to those of fillet rolling of crankshafts with the constraint in the rolling direction. Finite element analyses with different meshes for single indentation on an elastic flat plate under plane strain conditions are first carried out, and the results are benchmarked with those of the elastic Hertzian solutions to establish the requirement of the finite element meshes for acceptable numerical results. The results show that the accuracy of computational results is limited by the discretization of the finite element analysis by a plot of the contact width as a function of the load. For accurate peak pressure, a total of at least eight linear elements are needed. Finite element analyses with different meshes for single indentation on an elastic–plastic flat plate under plane strain conditions are then carried out. The plate material is modeled as an elastic–plastic power-law strain hardening material with a nonlinear kinematic hardening rule for loading and unloading. The computational results are compared to establish the requirement of the finite element meshes for acceptable numerical results within 4 mm distance to the rolling surface for the crankshaft fatigue analyses. The computational results for rolling at the relative peak pressure of 22 show that the symmetric Hertzian or modified Hertzian pressure distribution should not be used to represent the contact pressure distribution for rolling simulation, while the computational results for rolling at the relative peak pressure of 5 show that the symmetric Hertzian or modified Hertzian pressure distribution may be used to represent the contact pressure distribution for rolling simulation. The computational results for the rolling case also show a significantly higher longitudinal compressive residual stress and a lower out-of-plane compressive residual stress along the contact surface when compared to those for the single indentation case. The results suggest that the effects of rolling must be accounted for when two-dimensional finite element analyses of crankshaft sections are used to investigate the residual stresses due to fillet rolling of the crankshafts under the prescribed roller loads. Due to the boundary conditions of the finite plate, the compressive residual stresses are larger when compared to those when the boundary conditions of the finite plate are fully relaxed.

Influence of run-in procedures and thermal surface treatment on the anti-wear performance of additive-free lubricant oils in rolling bearings

When rolling bearings are operated in the boundary and mixed friction regime, there is a risk of wear which can be minimized by the application of suitable lubricants with anti-wear additives. These lubricants form surface-bound additive-based tribolayers under tribological strain. The trend towards a reduction of additive concentration requires new methods of effective wear protection. In this study, two additive-free lubricants were investigated using highly wear-critical cylinder roller thrust bearings. The results show that both oils exhibit insufficient wear protection. This protection can be increased for one of the oils by an iron oxide-based tribolayer which is built up during a suitable run-in procedure. Furthermore, it is shown how the run-in tribolayer can be reproduced by a thermal treatment of the bearings. The increase in wear protection can be explained by a better lubricant–surface interaction due to the tribolayers, which leads to a better separation of the steel surfaces. The tribolayers are characterized using EPMA, FIB–TEM, and nano-indentation analyses.

Upward planar graphs and their duals

We consider upward planar drawings of directed graphs in the plane (UP), and on standing (SUP) and rolling cylinders (RUP). In the plane and on the standing cylinder the edge curves are monotonically increasing in y-direction. On the rolling cylinder they wind unidirectionally around the cylinder. There is a strict hierarchy of classes of upward planar graphs: UP⊂SUP⊂RUP.In this paper, we show that rolling and standing cylinders switch roles when considering an upward planar graph and its dual. In particular, we prove that a strongly connected graph is RUP if and only if its dual is a SUP dipole. A dipole is an acyclic graph with a single source and a single sink. All RUP graphs are characterized in terms of their duals using generalized dipoles. Moreover, we obtain a characterization of the primals and duals of wSUP graphs which are upward planar graphs on the standing cylinder and allow for horizontal edge curves.

Experimental study on surge shape of woody debris flow model utilized rolling cylinder

Experimental study on surge shape of woody debris flow model utilized rolling cylinder

Numerical simulations of two-dimensional floating breakwaters in regular waves using fixed cartesian grid

ABSTRACT The wave attenuation by floating breakwaters in high amplitude waves, which can lead to wave overtopping and breaking, is examined by numerical simulations. The governing equations, the Navier-Stokes equations and the continuity equation, are calculated in a fixed Cartesian grid system. The body boundaries are defined by the line segment connecting the points where the grid line and body surface meet. No-slip and divergence free conditions are satisfied at the body boundary cell. The nonlinear waves near the moving body is defined using the modified marker-density method. To verify the present numerical method, vortex induced vibration on an elastically mounted cylinder and free roll decay are numerically simulated and the results are compared with those reported in the literature. Using the present numerical method, the wave attenuations by three kinds of floating breakwaters are simulated numerically in a regular wave to compare the performance.

Rolling Friction: Comparison of Analytical Theory with Exact Numerical Results

We study the contact mechanics of a smooth hard cylinder rolling on a flat surface of a linear viscoelastic solid. Using the measured viscoelastic modulus of unfilled and filled (with carbon black) nitrile rubber, we compare numerically exact results for the rolling friction with the prediction of a simple analytical theory. For the unfilled rubber, the two theories agree perfectly while some small difference exists for the filled rubber. The rolling friction coefficient depends nonlinearly on the normal load and the rolling velocity.

Simple and effective method to prepare microfiber reinforced nanofiber film with significant improvement of mechanical properties

Microfiber reinforced nanofiber films were prepared with the help of two nozzles technology. We designed a new device via placing two nozzles on the opposite sides of a rolling cylinder, with a piece of thin insulation board with a certain size of hole in the middle part installed to accommodate the cylinder so as to form two entirely independent electric fields. Playing the role of support, microfiber may be favorable for enhancing the mechanic performance of the nanofiber. Compared with that of single nanofiber, the tensile strength of the composite micro/nanofiber prepared by this method has been increased by a factor of 4.5. After the further improvement of the fiber orientation, the tensile strength is 7.96 times that of non-oriented composite micro/nanofibers film, 30 times that of the single nanofiber film.