Elastic Tire Research Articles

Dynamics of Heavy Mechanized Bridge During Span-Lowering Process

Heavy mechanized bridge is utilized to be rapidly deployed as a temporary bridge to facilitate the movement of vehicles and personnel across obstacles. This paper presents a dynamic model of the TMM-3M heavy mechanized bridge during the span-lowering process, including considerations of cable deformation, rear outriggers, elasticity of tire, and front suspension system. Based on the dynamic model, the authors establish a system of differential equations describing the oscillation of the system using Lagrangian equations of the second kind. The article provides a fundamental basis for studying the entire process of deploying the TMM-3M bridge and aims to improve the rear outriggers and cable winding system to reduce bridge deployment time.

The Effect of Training Model and Arm Muscle Strength on Arm Power in Judo Sport

The purpose of this study was to determine the effect of training models and arm muscle strength on arm power judo sports in Bandar Lampung City in order to determine whether there is an effect of training models and arm muscle strength on arm power in athletes. The type of research is factorial 2 x 2. The sample used was judo athletes in Bandar Lampung City totalling 50 athletes. The sampling technique used was purposive sampling. The instrument used was the Two Medicine Ball Put test. Data analysis techniques include descriptive analysis, prerequisite tests (normality and homogeneity tests), hypothesis testing using paired sample tests and independent sample tests. The data analysis technique used in this study using SPSS 20 is by using two-way ANOVA (two-way ANOVA). The results showed (1) There was a significant difference in influence between elastic training of Uchikomi tyres and push ups on arm power of judo athletes in Bandar Lampung City, with a p-value of 0.009 < 0.05. The Uchikomi elastic tyre training group was better than the push up group with an average posttest difference of 0.37 metres. (2) There is a significant difference between athletes with high and low arm muscle strength on arm power of judo athletes in Bandar Lampung City, with a p-value of 0.003 <0.05. Athletes with high arm muscle strength are better than athletes with low arm muscle strength with a posttest average difference of 0.44 metres. (3) There is a significant interaction between Uchikomi tyre elastic training and push ups and arm muscle strength (high and low) on arm power of judo athletes in Bandar Lampung City, with a p-value of 0.002 <0.05. The results showed that the Uchikomi tyre elastic training group was a more effective method used for athletes with high arm muscle strength and the push up group was more effective for athletes with low arm muscle strength.

Water displacement drag decomposition of aircraft elastic tires rolling on contaminated runways

During the taxiing of an aircraft on a water-contaminated runway, the rolling tires impact water film resulting in a considerable water displacement drag and a large amount of spray, which will affect the safety of take-off and landing. The characteristics and flow mechanism of the water displacement drag generated by an elastic tire are numerically studied based on the coupling method of Smoothed Particle Hydrodynamics and Finite Element Method. The water displacement drag is divided into wave-generated drag and film-generated drag based on flow mechanism for the first time, and the former is much larger than the latter. The water displacement drag satisfies the Gaussian distribution along the rotation axis. The longitudinal grooves cause a significant increase in the wave-generated drag and a reduction in the film-generated drag. A simple potential flow model around a semi-infinite bluff body is proposed to reveal the flow physics of film-generated drag. Two drag formulas are proposed to quickly predict the wave-generated drag and film-generated drag.

Research of features of oscillating process’ behavior in the nonlinear system of individual traction drive of an electrobus

BACKGROUND: When a vehicle is in motion, self-oscillations which properties are dependent on slip rate in a contact patch may occur in the area of tire interaction with ground surface. Oscillations frequency will vary in dependence with value of wheel slip relative to ground surface. Soft self-oscillations are excited by variable set of initial conditions at full slip in traction and driven wheel rolling modes as well as in mixed braking mode with partial slip. Hard mode of self-oscillations occurs at full wheel slip in braking mode. These processes have a negative impact on the processes in electric drive and mechanical drivetrain reducing their efficiency and may cause damage of components. Oscillations in the system are excited by interaction forces of an elastic tire with ground surface featuring vertical oscillations due to elastic behavior of its interaction with road unevenness. AIMS: Research of features of oscillating process behavior in the nonlinear system of individual traction drive of an electrobus. METHODS: Simulation of self-oscillation excitation processes in the area of contact interaction of a wheel and road was carried out in the MATLAB/Simulink software package. RESULTS: The article features the results of simulation and experimental studies of self-oscillation excitation processes of the KAMAZ 6282 electrobus moving on asphalt-concrete surface. It was found that vertical wheel displacement when moving through unevenness lead to oscillating behavior of vertical reaction forces in contact patches and, as a consequence, to oscillating behavior of longitudinal reaction forces, torque and rotation velocity of the shaft of the traction electric motor of the individual drive. It was defined that tire oscillation frequency is 67 Hz that coincides with electric motor shaft rotation oscillation frequency and this value is the same for both experiment and simulation. CONCLUSIONS: Practical value of the study lies in ability of using the study results at development of self-oscillation processes exclusion algorithms as a part of vehicle control system.

Method for detecting the loss of stability of the movement of tractors when towing a trailer or a coupled unit

BACKGROUND:Currently, combines and tractors, being the most energy-intensive transport and technological machines for agricultural purposes, largely determine the possibility of transition to an efficient and environmentally friendly agricultural economy, and also provide the technical aspect of the transformation of the agro-industrial complex into the leading sector of the countrys industry. One of the sources of dynamic loads in the units and subsystems of tractor equipment are self-oscillating modes.
 AIMS:Study of the conditions for the occurrence of self-oscillating processes in the design of wheeled tractor trains and development of methods to increase the handling and safety of their movement by means of reducing the galloping and yawing of the tractor-tractor when towing heavy loads.
 METHODS:It has been established that due to the coupling of oscillations along the longitudinal displacement of a truck tractor and a trailer with oscillations along the vertical displacement of the center of mass and with pitch angle oscillations of the truck tractor, when an auto-oscillatory mode occurs in the interaction zone of an elastic wheel with a solid surface, the same mode of self-oscillation will occur along the mentioned degrees of freedom. Moreover, it is possible to specify the sequence of occurrence of self-oscillating modes in different zones of the tractor train design.
 RESULTS:First, self-oscillations are excited in the contact patch of a wheel with a solid surface when a complete slip occurs, then self-oscillations along the pitch angle of a truck tractor body begin and after that self-oscillations along the vertical displacement of the center of mass of a truck tractor occur. Folding angle oscillations of a tractor train are associated with oscillations of the translational motion of wheel centers, which lead to the emergence of an self-oscillating mode, both with partial and full slip in the interaction zone of an elastic tire with a solid surface. Since the self-oscillations of each of the wheels occur at random times, the self-oscillations of a truck tractor along the folding angle will be chaotic.
 CONCLUSIONS:The practical value of the study lies in the possibility of using the proposed methods to identify the danger of self-oscillating processes in the design of promising types of agricultural machinery.

FORMATION OF THE LOAD FROM THE VEHICLE ON THE ROAD SURFACE AT DIFFERENT SPEED OF OVERCOMING THE ROUGHNESS

To reduce the negative impact of the vehicle on the road surface, its maximum axle load is limited to the legal level. At the same time, when the car is moving on an uneven road, its dynamic load on the road surface can both exceed the static load by several times and decrease to zero (the separation of the wheel from the supporting surface). At the same time, the elastic tire is deformed in different directions, which is accompanied by forces and moments that are transmitted to the car's steering system and its suspension through the rim, disc and hub. This can lead not only to fluctuations in the sprung and unsprung mass of the car (affecting the smoothness of the ride, fuel economy, etc.) and changing its direction of movement (loss of stability and controllability) [1], but also to further destruction of the road surface. It is worth noting that the deviation of the values of the dynamic load of car wheels on the road surface from the static one largely depends on the speed of overcoming road irregularities. The article presents the results of theoretical studies of the motion of an average passenger car that overcomes road irregularities with its left-hand wheels. Different speeds for overcoming road irregularities were studied, starting with 30 km/h and ending with a speed of 120 km/h. The dependence of the change in the normal reactions of the support surface on the wheels of the car from the traveled distance was determined. In order to understand the formation of the load from the car on the road surface, an analysis of graphical dependencies describing the working processes of the suspensions of its wheels, which overcome road unevenness, was carried out. The obtained data allow us to analyze and evaluate the influence of the working processes of the suspension of the wheels of the car and the speed of overcoming road irregularities on the formation of the load acting on the road surface.

Use of recycled tires for seismic protection of embankment dams

Earth dams are currently the main type of retaining structures designed and built in areas of high seismic activity. One of the constructive measures to improve the seismic resistance of earth dams is a solution based on the use of the principle of seismic isolation. In the course of the work, structures of embankment dams were developed with a seismic isolation layer located between the body of the dam and its soil base. The seismic isolation layer is formed using recycled metal-cord tires filled with gumbrine. The use of these new designs allows, due to the unique technical properties of the waste (tires and gumbrin), to achieve increased damping and diffraction. Soil reinforcement is one of the constructive measures used on dams of small and medium height to increase their seismic resistance. The paper presents new structures of earthquake-resistant embankment dams with reinforcing elements. These reinforcing elements are made from recycled tires of heavy vehicles and concrete blocks. When seismic forces act on the dam, the reinforcing elements take on excess tensile forces due to adhesion to the dam soil. The deformability of the soil is limited and regulated by elastic tires and reinforced concrete beams in the reinforcing elements, which, with the help of tubular connections, work as one whole system. A new design of an earthquake-resistant group dam with reinforcing elements using recycled steel cord tires of two sizes has been developed. The reinforcing element consists of concrete blocks made of two paired concrete discs. The disks of larger diameter are located below the disks of smaller diameter. Recycled tires act as a fixed formwork in the manufacture of concrete discs.

Особливості руху коліс візка автомобіля по криволінійній траєкторії

The results study of the motion along a curvilinear trajectory of a multi-axle vehicle axle group elastic wheel on a ground plane with a high coefficient of adhesion are presented. The elastic wheel is considered as an integral mechanism, which includes a hard rim, an elastic tire body and a large tire contact patch.The analysis of previous studies showed that during the elastic wheel movement along a curved trajectory, the wheel rim rotates simultaneously and its lateral offset relative to the tire contact patch. Turning the disc causes the tire body torsion and its lateral offset causes the wheel to roll with the slip angle. The torsion angle of the tire body in absolute value is equal to the slip angle and their values depend on the curvature of the trajectory, the longitudinal axis of the tire contact patch and the presence of adhesion in it.It is established that if the wheel of vehicle axle group is offset relative to the center of the portable movement during the motion along the curvilinear trajectory there will be an additional lateral offset of the wheel disk relative to the tire contact patch during the time when the wheel travels a path equal to the longitudinal axis of the tire contact patch. Dependences for determination of slip angles of a vehicle axle group wheels during movement along the curvilinear trajectory has been determined. It is established that the value of the additional slip angle caused by the lateral offset of the rim depends on the axle group wheel base, the radius of curvature of the wheel trajectory, the longitudinal axis of the tire contact patch and the presence of adhesion zones in the tire contact patch.The total slip angle of the wheel, which is shifted relative to the center of the vehicle’s portable motion, is determined by the sum of the kinematic angle of the wheel and the angle caused by the lateral offset of the wheel rim relative to the tire contact patch. If there are sliding zones in contact of the tire contact patch with the ground plane, the increase in the slip angle will be proportional to the part of the longitudinal axis of the tire contact patch, which is in a state of adhesion to the ground plane.

On the issue of the wheel power radius with an elastic tire

Introduction (statement of the problem and relevance). Mathematical modeling of the car units, mechanisms and systems functioning strongly depends on the used calculation parameters values, for example, on the power radius of the wheel. Nowadays to research the power radius of a wheel with an elastic tire both the radius of the driving wheel and the dynamic radius are taken into account. The article is to consider which of the two is the power radius of a wheel with an elastic tire.The purpose of the study was to evaluate the influence of the chosen wheel power radius on the longitudinal characteristics mathematical modeling results of the tire adhesion with the supporting surface.Methodology and research methods. Methods of mathematical modeling and experimental studies were applied, followed by the comparative analysis of both the experimental and analytical data.Scientific novelty and results. The experimental dependences of the tire longitudinal adhesion coefficients on slippage have been obtained and compared using both the dynamic radius and the rolling radius as the power radius of the wheel in the driven mode.Practical significance. The mathematical descriptions parameters of the tire adhesion characteristics have been refined which allowed reducing the errors of the calculation results significantly.

About Braking of Wheeled Vehicle Equipped with Automated Brake Control System

The paper proposes a method for determining a vehicle stopping distance based on a braking rate and a coefficient of using an adhesion force by an automated control system for regulating a braking force on the example of a multi-axle vehicle. The aim of the study is to calculate parameters of the braking efficiency of a multi-axle wheeled vehicle equipped with an automated braking force control system based on the adhesion between a tire and a supporting surface. A peculiarity of the considered method is the use of the calculated braking coefficient of the vehicle and the coefficient of use of adhesion forces during the operation of automated system for regulating the braking force. The presence of new mathematical relationships between the position of the coordinate of the vehicle’s gravity center, realized by the clutches of its wheels, and the braking coefficient of the vehicle makes it possible to simulate the change in the deceleration of a wheeled vehicle in various braking modes of its motion. The terms describing the interaction of an elastic tire with a supporting surface in the braking mode of a wheeled vehicle have been substantiated. Equations are written that permit to calculate: a position of the coordinate of gravity center of a multi-axle wheeled vehicle relative to its front and rear axles; a braking coefficient value of a multi-axle wheeled vehicle based on the coordinates of the position of its gravity center, clutches that are realized between its tires and a supporting surface; load distribution between the respective front and rear axles of the vehicle. To calculate the stopping distance of a wheeled vehicle, it is proposed to take a coefficient value of use of the adhesion force equal to 0.83, regardless of the change in weather and climatic conditions in which the vehicle is operated (a calculation error under an accepted assumption is not more than 5 %). In a graphical form, a design diagram of the coordinate position of a gravity center of a multi-axle wheeled vehicle is presented, which gives a general idea about the redistribution of masses between front and rear axles of the vehicle. Scientific publications on the change in the value of the realized adhesion between the tire and the supporting surface in the braking mode of the automobile wheel under various factors have been analyzed in the paper. The proposed concept for determining parameters of the braking efficiency of a multi-axle wheeled vehicle clarifies some provisions in the theory of vehicle motion, in particular, it allows to apply the calculated method for determining the deceleration of a vehicle in the problem of increasing vertical loads on the axles of a multi-axle wheeled vehicle in the braking mode. The given method for calculating coefficients of weight distribution between adjacent front or rear axles of a multi-axle wheeled vehicle increases an accuracy of determining the amount of deceleration of the vehicle by the calculation method.

НЕЛІНІЙНІ ПОПЕРЕЧНО-КУТОВІ КОЛИВАННЯ ПІДРЕСОРЕНОЇ ТА НЕПІДРЕСОРЕНОЇ ЧАСТИН КОЛІСНИХ ТРАНСПОРТНИХ ЗАСОБІВ ТА ЇХ ВПЛИВ НА СТІЙКІСТЬ РУХУ

A method of analytical study of the nonlinear transverse-angular oscillations influence of the sprung-unsprung part system on the traffic stability of a wheeled vehicle along curved road sections has been developed. A system of nonlinear differential equations describing the dynamics of the relative motion of this system has been obtained and a first approximation of its analytical solution has been constructed. The peculiarity of the oscillations of the specified parts is that their natural frequencies depend on the amplitudes. Therefore, the dynamic interaction between the sprung and unsprung parts, as well as the road surface and elastic tires are determined by the vibrations amplitude-frequency characteristics of the specified parts, which are caused by road irregularities. Using the kinetostatics equation of the unsprung-sprung part system, the forces of dynamic interaction of elastic wheels with the road surface were determined – the basic ratios for evaluating traffic stability. It has been established: the relative oscillations of the sprung and unsprung parts of a vehicle significantly reduce the critical speed values of stable motion for overturning; the critical speed value of stable motion for overturning is greater for larger static deformation values of elastic shock absorbers and tires, as well as the progressive characteristic of elastic shock absorbers. The obtained main results can serve as a basis for the creation of a software product of adaptive suspensions, and their reliability is confirmed by obtaining results in the extreme case, which apply to simpler - linear calculation models of vehicle dynamics.

Процесс взаимодействия эластичной шины c опорной поверхностью дороги, покрытой противогололедным материалом на основе технической соли

When studying the traction properties of the elastic tire, it should be kept in mind that it is the investigation of the lateral reaction formation in the wheel contact patch with the supporting surface when it is moving with a lateral drifting that is particularly important for the researcher. In spite of numerous publications on this problem, there are practically no studies of lateral traction of the elastic wheel tire with a winter slippery road treated with chemical de-icing agent. The purpose of this study is to analyze the process of interaction of the elastic tire with a road surface covered with snow glaze and sand-salt mixture. As a result of this research, three variants of interaction of the elastic tire with the winter road have been revealed based on the different models of friction, namely, boundary, mixed and viscous models of friction, depending on the melting ability of technical salt. When mixed and viscous friction occurs between the tire and the road surface, a «third» body is formed, consisting of a mixture of particles of snow-ice deposits, salt and sand, which is able to slide on the layer of liquid salt solution formed on the supporting road surface, and significantly reduce the tire traction properties when driving with lateral drifting. The obtained results contribute to enlarging new scientific knowledge regarding lateral traction of elastic tires with the supporting surface of the road with winter slipperiness, which is important for increasing the active safety of vehicles on the roads in the cold season.

METHODS FOR MONITORING THE TECHNICAL CONDITION OF THE SUSPENSION OF VEHICLE UNDER OPERATING CONDITIONS

Suspension faults can reduce wheel traction and therefore reduce vehicle stability. Existing diagnostic methods for the suspension do not take into account the stability of the vehicle. To control stability, it is proposed to use road and bench methods, characterized by suspension vibrations and constant lateral force. Theoretical studies were carried out using mathematical models based on the description of the functioning of sprung and unsprung vehicle masses, as well as elastic tires. Experimental studies include bench tests of tires, shock absorbers and silent blocks of various technical conditions, as well as road studies of the kinematic parameters of the M1 category vehicle. As a result, a road method for monitoring the technical condition of shock absorbers was developed, taking into account their influence on stability indicators.
 Purpose – Theoretical substantiation and experimental confirmation of the method for diagnosing suspension systems by parameters related to the stability of the vehicle movement.
 Methodology includes experimental methods, mathematical modeling methods and numerical methods for solving differential equations.
 Results: experimental methods and mathematical apparatus were developed to study the influence of the parameters of the suspension system on the stability of the movement of vehicles.
 Practical implications: the results can be used by organizations and institutions involved in the development of diagnostic methods for vehicles.

Urban playgrounds as potential green infrastructure: The case of Thessaloniki

In Greek cities and towns, playgrounds, which represent a significant portion of open public space available in high density compact urban areas, fail to positively impact the sustainability of the urban environment, as they are made of artificial materials and generally lacking in natural elements. Designed around safety from accidents, a typical urban playground is equipped with prefabricated play structures, surrounded by an extensive area of rubber protective floor providing a surface safe from falls etc. This water-sealed surface does not absorb rainwater and has a very hazardous behaviour in hot temperature climates, such as Greece has. This “toxic turf,” a product of recycled elastic tires, contains chemicals suspect for cancer. In addition, trees and vegetation are usually insufficient or absent, thus worsening the overheating due to lack of shade. Although this model continues to prevail in Greece, around the world there is a significant shift towards natural playgrounds – play spaces that are designed to incorporate trees, shrubs, dirt, sand, grass, and play elements that are not industrially manufactured but constructed in situ, using stone, wood, reed, and other natural materials. From a pedagogical point of view, a stereotypical playground offers a rather dull and uninteresting environment for children to play, compared to the rich experience of a natural playground. Therefore, if designed as green infrastructure, playgrounds can considerably contribute to urban climate adaptation and a cooler microclimate and at the same time provide opportunities for urban children to come to contact with nature and benefit from free play. The scope of the paper is to present the multiple environmental benefits of natural playgrounds and to calculate the potential positive effects by the transformation of playgrounds into green spaces in a compact urban area. The field study examines the existing playgrounds in the municipality of Thessaloniki and their potential to become part of the city’s green infrastructure.

Graphic analytical optimization of design and operating parameters of tires for drive wheels of agricultural machinery

Historically, machinery with wheels and tires has dominated the agricultural machinery market, despite the rapidly growing popularity of rubber tracks. However, notwithstanding the rather long development history of wheels, unresolved problems remain. Most of these are associated with a reduction in the harmful effects on the soil. The aim of this study was to reduce the levels of load on agricultural soils by the drive wheels of agricultural machinery through optimization of the geometric dimensions of the flat and deformed soil surface contact areas of an elastic wheeled vehicle. The tire used for agricultural machinery was modeled mathematically, principally using the properties of Cassinian curves. Some tire dimensions and materials do not satisfy the folding condition, which specifies that the ratio of distances used in specifying Cassinian ovals, a/c, should not exceed 1.41. Based on the geometric definition of a Cassinian oval, the shape of the contact profile surface of an elastic tire–soil interaction is determined by the ratio a/c. Different a/c ratios correspond to different tire shapes. When a/c = 1.2, the profile shape of the undertread of the tire does not satisfy the folding condition. Using the geometric properties of a common circle and Cassinian ovals, it was possible to determine a value of angle α≈48°. This angle is optimal for the tire–soil contact surface and, also satisfies the without folding condition. The presented method may be applicable to bias-ply and radial-ply tires, so it is not specifically applicable for one of these over the other.

Исследование автоколебательных процессов в зоне взаимодействия эластичной шины с твердым опорным основанием

When two bodies interact in contact, self-oscillations or relaxation vibrations can occur, which are vibrations of parts of bodies relative to each other. The study of the processes occurring in the zone of an elastic tire interaction with a solid support base is of particular interest, since they directly affect the safety of movement of wheeled vehicles. The aim of the work is to study the conditions for the occurrence of self-oscillating processes in the zone of interaction of an elastic tire with a solid support base in three rolling modes: traction, driven, and braking. It has been established that the appearance of a self-oscillating mode in the zone of interaction of an elastic tire with a solid support base is a useful diagnostic feature providing recognition of the development of the process of losing adhesion of a wheel with a support base when the rear axle skids at early stages.

A method for regulating modes of motion of a wheeled vehicle with installed thermal and reactive energy converters

Understanding the interaction between an elastic tire and a bearing surface is important not only for studying motion of wheeled vehicles, their controllability and running smoothness, but also necessary for creating systems for car motion automatic control. At the same time, the interaction forces between wheels and the bearing surface attract special attention since they have a decisive effect on vehicle’s controllability and stability. Indeed, all effects, including aerodynamic ones, are reflected in forces and moments arising in the wheel/bearing surface contact area, which, in turn, determine car motion parameters. Consequently, in creating a control system for vehicle motion, the primary task is to establish patterns of changes in force factors depending on characteristics of the bearing surface and parameters of the operator’s control in order to develop a criterion for controlling signal formation. The analysis of experimental and theoretical studies of wheel rolling showed that all research results are reduced to establishing patterns of change in force factors (indirect parameters) in the wheel/bearing surface contact patch depending on the parameters that indirectly characterize the kinematic parameters. Meanwhile, establishing a regular pattern of changes in force factors in the wheel/bearing surface interface is the most important task in developing a criterion for the formation of control signals for active safety systems based on force analysis. The paper presents a method for increasing vehicle’s traction and braking dynamics by partially converting thermal energy of the car into reactive tractive force (air propeller, gas turbine).

The Planar Wide-Frequency Vibration Characteristics of Heavy-Load Radial Tires

This paper investigates the planar wide-frequency vibration characteristics of heavy-load radial tires with a large aspect ratio. A proposed tire model with a piecewise flexible beam on an elastic foundation is investigated and validated using experimental modal analysis and theoretical modeling method. The reproducibility of frequency response functions below 400 Hz is discussed. The experimental modal analysis particularly assesses the coupling of features across the circumferential and cross-sectional directions of heavy-load radial tire carcass. Piecewise circumferential modal characteristics were investigated experimentally, leading to the suggestion of a piecewise flexible beam on an elastic tire foundation. Using a genetic algorithm (GA), the structural parameters EI, ρ A , and kr and damping coefficients η and cr for the proposed tire model are identified, and the piecewise transfer functions and the planar transfer functions for a heavy-load radial tire are compared with planar hammer test. Experimental and theoretical results show the following: (1) the sectional vibration characteristics for a heavy-load radial tire with a large aspect ratio result from the cross-sectional vibration of the tire carcass; (2) the piecewise transfer function is mainly influenced by the circumferential vibration of the flexible carcass, and this is consistent with a model where a flexible beam is placed on an elastic tire foundation; (3) the analytical transfer functions calculated for the proposed tire model, drawing on the identified structural parameters and damping coefficients, agree well with the experimental results.

Best Practice for De-Vulcanization of Waste Passenger Car Tire Rubber Granulate Using 2-2'-dibenzamidodiphenyldisulfide as De-Vulcanization Agent in a Twin-Screw Extruder.

De-vulcanization of rubber has been shown to be a viable process to reuse this valuable material. The purpose of the de-vulcanization is to release the crosslinked nature of the highly elastic tire rubber granulate. For present day passenger car tires containing the synthetic rubbers Styrene-Butadiene Rubber (SBR) and Butadiene Rubber (BR) and a high amount of silica as reinforcing filler, producing high quality devulcanizate is a major challenge. In previous research a thermo-chemical mechanical approach was developed, using a twin-screw extruder and diphenyldisulfide (DPDS) as de-vulcanization agent.The screw configuration was designed for low shear in order to protect the polymers from chain scission, or uncontrolled spontaneuous recombination which is the largest problem involved in de-vulcanization of passenger car tire rubber. Because of disadvantages of DPDS for commercial use, 2-2-dibenzamidodiphenyldisulfide (DBD) was used in the present study. Due to its high melting point of 140 °C the twin-screw extruder process needed to be redesigned. Subsequent milling of the devulcanizate at 60 °C with a narrow gap-width between the mill rolls greatly improved the quality of the devulcanizate in terms of coherence and tensile properties after renewed vulcanization. As the composition of passenger car tire granulate is very complex, the usefulness of the Horikx-Verbruggen analysis as optimization parameter for the de-vulcanization process was limited. Instead, stress-strain properties of re-vulcanized de-vulcanizates were used. The capacity of the twin-screw extruder was limited by the required residence time, implying a low screw speed. A best tensile strength of 8 MPa at a strain at break of 160% of the unblended renewed vulcanizate was found under optimal conditions.

Using the kinematic radius in the mechanics of elastic wheel rolling

As you know, in the mechanics of a wheel with an elastic tire, both dynamic (rd) and kinematic (rk) radius are widely used. At the same time, specialists in the theory of the motion of wheeled vehicles still do not have a clear understanding of the scope of their application. Keywords: elastic wheel, kinematic radius, circumferential force, dynamic radius, wheel traction force, instantaneous center of speeds, torque, solid, rolling resistance