EQUATION OF MOTION FOR NOVEL FRICTION PENDULUM SYSTEM WITH DUAL ROLLERS

A novel friction pendulum system （FPS） with dual rollers is studied based on the multibody dynamics theory. By analyzing kinematic characteristics of the system, it is reduced to a one degree-of-freedom system. Then the equation of motion for the system is analytically derived by applying the theorem of the relative kinetic energy for a system of particles in differential form in the non-inertial reference system described as a nonlinear differential equation. In the case of the small angular displacement, the natural frequency of the corresponding undamped linear system is obtained, which is consistent with the experimental observation. The derived equation is useful for the study of dynamic characteristics of novel FPS, and its solution directly expedites the simulation of the system in a control loop, and further facilitates the semi-active control process including novel FPS.

Optimization experiment on eccentric lapping of cylindrical rollers

Cylindrical rollers are important elements of bearings,and their machining accuracy and consistency affect the bearing quality.Using a GCr15 cylindrical roller ofФ11×12 as the processing object in this study,the effects of loading pressure,abrasive concentration,and speed combination on cylindrical roller machining precision were investigated using the orthogonal experimental design method on a double-side eccentric pendulum lapping and polishing machine.The machining parameters of the lapping stage were optimized,and the lapping optimal process parameters were determined by S/N response analysis and analysis of variance(ANOVA).The results show that when the experiment was optimized using loading pressure of 10 N/roller,abrasive concentrationof 20.0 wt%,and rotational speed combination,the material removal rate(MRR)of cylindrical roller reached 0.0896μm/min;the average roughness of the batch decreased from 0.056μm to 0.027μm,51.8%lower than the original batch average roughness,and the deviation decreased from the initial 0.022μm to 0.014μm;the batch average roundness error decreased from 0.47μm to 0.28μm,40.4%lower than the original batch average roundness error,and the deviation decreased from the initial 0.19μm to 0.038μm;and the batch average diameter variation decreased from 4.5μm to about 3.6μm,20%lower than the original batch average diameter variation.The double-side eccentric lapping of cylinder rollers does not only lead to improvement in the surface quality and shape accuracy of rollers,but also improvement in the batch consistency.

A simplified approach for negative skin friction calculation of special-shaped pile considering pile-soil interaction under surcharge

A simplified approach was proposed to analyze the negative skin friction calculation of special-shaped pile considering pile-soil interaction under surcharge. Based on the concentric cylinder shearing theory, considering the changes of pile shape(such as, taper angle and diameters of pile base, etc.), the load-transfer of special-shaped pile was built. The accuracy of the developed simplified approach was verified by numerical simulation model with the same condition. Then, the influence factors, such as, taper angles, the diameter of pile base, surcharge, and pile-soil interface parameters were analyzed and discussed. The results show that the developed simplified approach can calculate NSF of special-shaped pile under surcharge effectively. A limited parametric study indicates that in many practical situations special-shaped piles(such as belled wedge pile shown in this work) offer a design option that is more economical than traditional uniform cross-section piles.

Motion mechanism analysis of two contacting rollers

Two rollers contact each other under the normal load,and when the driving roller rotates,it drives the driven roller rotate by the tangential force on contact area.Finite Element Method analysis and experimental analysis are adopted to research the motion mechanism of two rollers which elasticity has big difference both on the condition of direct contact and indirect contact.From the analysis it is achieved that the relative sliding between the two rollers is due to the tangential force on the contact area and the radial compression deformation of the soft roller which has greater elasticity.For the condition of indirect contact in which a layer of inter-medium exists between the two rollers,the relative sliding is greater than that on the condition of direct contact,and the hardness of the intermedium layer affects the relative sliding between the two rollers.And for the condition of multiple rollers in the state of pressing contact,the number of contact areas on the soft roller also affects its motion characteristics.

Design of Hard Compaction Rollers for Automated Fiber Placement on Complex Mandrel Geometries

This paper presents a methodology for designing hard compaction rollers for an AFP(automated fiber placement)head with a hot gas torch heating system for laying thermoplastic CFRP(carbon fiber reinforced plastic)tapes.Some manufacturing defects and alternative designs are reviewed to highlight the importance of AFP compaction roller conformity and surface adhesion.The formulation of a general parametric description of the design challenge is derived and adequately addresses the problem on a tow-to-tow basis.

ANALYSIS AND DESIGN OF LOAD-UNIFORMING MANGLE ROLLERS WITH AXIALLY-STAGGERED CONTACT

It is desirable to get a uniform load distribution for the pressure rollers of the mangle.In thispaper,the load uniforming principle of the axially-staggered pressure rollers and the rules for theroller design have been analysed by the theory of bending of beams.The ratio of maximum tominimum value of the distributed load in the nip being taken as a useful index to describe the uni-formity of the load distribution,the performance of the so-called load-uniforming pressure rollerswith rubber covering,under various operation conditions,has been evaluated.As a result,it isproved that the load-uniforming pressure rollers with axially-staggered contact is a pratically use-ful means of uniformizing the load distribution,which ensures that the mangle will squeeze the ma-terial to be processed uniformly over its whole width under any technological load,and needs onlysome simple regulations.The conclusions obtained in this paper can easily be extended to the pressure rollers with anysupport conditions.

Research on Roll Expanding Technology with Double Rollers

A new roll expanding technology with double rollers is developed for workpiece with local expanding shape. Feasible device is designed and some experiments are carried out. The inner stress and strain fields are analyzed by means of elastoplactic FEM, which provides theoretical basis for the application of this technology.

A unified computational model for surface texturing process of strip casting rollers

A new unified computational method is proposed for modeling the relationship between the parameters of the high-speed particle-impact texturing process and the final surface morphology of the casting roller. The whole surface-texturing process is divided into three parts. The first part is the acceleration process of particles inside and outside the nozzle,which can be analyzed using the computational fluid dynamics method to obtain the particle impact velocities. The second part is a simulation of the bombardment process of particles onto the roller surface using the LS-DYNA software as the analysis tool and the results obtained in the first part as input parameters. The last part is the continuously random impact process of particles on the casting roller surface to form a functional surface,which is characterized by a simplified roughness model. Finally,the above three parts are combined to establish a unified computational model,the performance of which is successfully verified in a series of experiments.

Surface morphology and mechanical properties of the nanocrystalline tensile-straightening rollers treated by the ultrasonic particulate peening

Tensile-straightening rollers of a pickling line at Baosteel are surface nanocrystallined by the ultrasonic particulate peening(USPP)method.Surface morphology and mechanical properties of the rollers were characterized by scanning electronic microscope(SEM),a roughness meter and a microhardness tester.Results have indicated that there are a lot of randomly distributed impact pits on the surface after the USPP and that surface roughness can be adjusted within a range of Ra 1.5-2.5.The grain size in the surface layer is refined significantly.The microhardness of the surface layer can reach 920 HV after the nanocrystalline treatment.The dependency of the two main influencing factors,i.e.the working gas temperature and pressure,on the surface roughness and microhardness is presented.

Research on Yarn Tension under Positive Guiding by Feed Rollers

In the carpet tufting machine,feed rollers are used to guide the yarns positively.After deducing the general Euler formula of yarn tension under positive guide of rollers,a conclusion is got that the tension of yarns at the output side of each roller tends to decrease one by one.Afterwards,a computing formula of wrap angle of yarn passing through the feed roller is deduced by application of triangle geometry method.By analyzing the effect of each parameter on the yarn tension,values of the space between rollers and the roller diameter are proposed for design reference,and relations between the yarn tension and the two key parameters,the friction coefficient of roller surface and the speed of rollers,are illustrated in detail.Consequently,a policy is drawn out to control the yarn tension.The results of this paper provide not only theory foundation for empirical settings of the operational parameters of tufting machine,but also theory support for further research on yarn tension-control methods.

Low-frequency ride comfort of vibratory rollers equipped with cab hydro-pneumatic mounts

Based on the advantages of hydraulic and pneumatic mounts,a new hydro-pneumatic mount(HPM)is proposed to improve the low-frequency ride comfort of vibration rollers.Through the experiment of the vibratory roller,a nonlinear vehicle dynamic model working on off-road soil grounds is then established to assess the HPM's ride comfort in the low-frequency region.Two indices,the power spectral density(PSD)acceleration and root mean square(RMS)acceleration of the operator vibration and cab shaking,are chosen as objective functions in both the frequency and time regions.The research results show that when the cab isolations are equipped with the HPM,the RMS values of the operator's seat,cab's pitch and roll angles are reduced by 35%,42%and 53%;and the maximum PSD of the operator's seat,cab's pitch and roll angles are decreased by 39%,59%and 65%,respectively.Consequently,the characteristics of the nonlinear damper and high-static stiffness of HPM can greatly reduce the operator vibration and cab shaking in the low-frequency region when compared to the vibratory roller's cab using the rubber mounts.

Structural Optimization of Metal and Polymer Ore Conveyor Belt Rollers

Ore conveyor belt rollers operate in harsh environments,making them prone to premature failure.Their service lives are highly dependent on the stress field and bearing misalignment angle,for which limit values are defined in a standard.In this work,an optimization methodology using metamodels based on radial basis functions is implemented to reduce themass of twomodels of rollers.From a structural point of view,one of the rollers ismade completely of metal,while the other also has some components made of polymeric material.The objective of this study is to develop and apply a parametric structural optimization methodology to minimize the mass of the two models of rollers.To represent the mechanical behavior of the rollers,simulations were performed using the finite element method.During the numerical optimization process,the variable parameters were the dimensions of the shaft and external tube.The geometric configuration that corresponded at the same time to the lowest mass and acceptable ranges for the stress and bearingmisalignment angle was determined.With the proposed methodology,a 32.3% reduction in mass was obtained for a metal roller design and an 18.9% reduction for a polymer roller.In both cases,the constraints were not violated.For the all-metal roller,the safety factors for the maximum stress and bearingmisalignment angle were 1.44 and 1.75,respectively,while for the polymer roller the corresponding figures were 1.50 and 2.23.This work describes a low-computational-cost optimization methodology for roller designs that have been little studied in the literature.Furthermore,the methodology could be adapted for use with other types of rollers and rollers made of different materials.

Experimental Study on Seismic Behavior of Exterior Joints of Special-shaped Columns with Different Lengths of Limbs

Four exterior joints with special-shaped columns which have different lengths of limbs are tested under low cyclic loading. Speeial-shaped columns adopted are L- and T-shaped in section. It can be concluded that crack pattern, failure mode and shear strength of joints are affected by the length of limb, and that shear strength and ductility increase with the length of limb; the joints with the flexural failure of the beam have better seismic behavior than those with the shear failure of the joint core.

Differences in Brake Data Results on Ministry of Transport Roller Bank Testers Such as： Maha, Ryme, with Different Distance between Rollers and Roughness of Rollers

This study gives a comparison between what occurs when braking on a MOT （Ministry of Transport） brake tester. The results from this research and the exhaustive comparative study carried out by the mechanical engineering staffs at the mechanical laboratory at MOT stations in cities such as： Elche, Pilar de la Horadada and Orihuela from Alicante region [2] have led to the following main conclusions： this paper demonstrates that MOT brake testing results can vary depending on parameters variation such as： distance between rollers, roller diameter, roughness of rollers and velocity of the brake test.

Analysis of ink flow channel between two rotating ink rollers

In order to research how the size of the ink flow channel is affected by the interaction of adjacent ink areas,according to the method of fluid-solid interaction,this paper analyzes the size of the ink flow channel of two ink rollers' rotation.Firstly,this paper simulates the situation of only one ink area.Secondly,this paper simulates the situation of five adjacent ink areas.Then,through comparing the simulation results of two above situations,it' s obvious that the interaction of adjacent ink areas has big effects on the ink pressure and the size of ink flow channel.At last,this paper gets the main factor that affects the size of ink flow channel in the different situations.

Influence of the Number of Rollers on a Tapered Roller Bearing

In roller bearings, the outer ring is usually fixed and the inner ring has the rolling motion. Concerning TRB （tapered roller bearings）, this motion generates forces that are transmitted to the outer ring by the tapered rollers. Thus, contact stresses occur and the number of rollers plays a major role with respect to the load distribution. This influence is analyzed in this study by the FEM （finite element method） with commercial code ABAQUS, where two models were evaluated： a common TRB and the same one but with fewer rollers. As an application, a manual automotive transmission was considered for the input loads.

Design of Special-shaped Interchange between Expressway and Urban Road in Mountainous Cities

Driven by the rapid economic development,the development of transportation in China has begun to move towards mountainous areas.The climate environment,topography and landform of mountainous cities are different from those of plain areas.In mountainous cities,the area of opposite interchanges between expressways and urban roads is generally large,which has a certain contradiction with the topographic conditions of mountainous cities.Therefore,it is necessary to reasonably design the opposite interchanges between expressways and urban roads in mountainous cities.The author explores and analyzes the factors restricting the special-shaped interchange between expressway and urban road in mountainous cities and the main fbnns of special-shaped interchange,and puts forward a reasonable design scheme,hoping to make a smooth development of the special-shaped interchange in mountainous cities.

Roller Screw and Threaded Chain Speed Reducer: An Experimental Evaluation

We are developing a speed reducer that can be considered a transformation of a worm gear reducer: the worm is replaced by an inverted roller screw, and the gear is replaced by a threaded chain drive. This configuration lessens wear, increases load capacity, and improves efficiency. The threaded chain consists of nut-shaped links. This paper presents the results of tests carried out on a prototype with a reduction ratio of 46.

ROLLING CONDITION FOR ROLLERS ALONG CAMS IN COLD DOUBLE-SET MULTI-ROLLER TUBE ROLLING

The necessary condition of pure rolling for the rollers moving along its individual cams are obtained by the analysis of the loading status of the rollers and it provides a theoretical basis for adjustment of rolling stand.

Nonlinear Dynamics Behaviors of a Rotor Roller Bearing System with Radial Clearances and Waviness Considered

A rotor system supported by roller beatings displays very complicated nonlinear behaviors due to nonlinear Hertzian contact forces, radial clearances and bearing waviness. This paper presents nonlinear bearing forces of a roller bearing under four-dimensional loads and establishes 4-DOF dynamics equations of a rotor roller bearing system. The methods of Newmark-β and of Newton-Laphson are used to solve the nonlinear equations. The dynamics behaviors of a rigid rotor system are studied through the bifurcation, the Poincar è maps, the spectrum diagrams and the axis orbit of responses of the system. The results show that the system is liable to undergo instability caused by the quasi-periodic bifurcation, the periodic-doubling bifurcation and chaos routes as the rotational speed increases. Clearances, outer race waviness, inner race waviness, roller waviness, damping, radial forces and unbalanced forces-all these bring a significant influence to bear on the system stability. As the clearance increases, the dynamics behaviors become complicated with the number and the scale of instable regions becoming larger. The vibration frequencies induced by the roller bearing waviness and the orders of the waviness might cause severe vibrations. The system is able to eliminate non-periodic vibration by reasonable choice and optimization of the parameters.