Multiple Wheels Research Articles

Mechanically Interlocked Polyrotaxane Networks with Collective Motions of Multiple Main-Chain Mechanical Bonds.

Type I main-chain polyrotaxanes (PRs) with multiple wheels threaded onto the axle are widely employed to design slide-ring materials. However, Type II main-chain PRs with axles threading into the macrocycles on the polymer backbones have rarely been studied, although they feature special topological structures and dynamic characteristics. Herein, we report the design and preparation of Type II main-chain PR-based mechanically interlocked networks (PRMINs), based on which the relationship between microscopic motion of mechanical bonds on the PRs and macroscopic mechanical performance of materials has been revealed. The representative PRMIN-2 exhibits a robust feature in tensile tests with high stretchability (1680 %) and toughness (47.5 MJ/m3). Moreover, it also has good puncture performance with puncture energy of 22.0 mJ. Detailed rheological measurements and coarse-grained molecular dynamics (CGMD) simulation reveal that the embedded multiple [2]rotaxane mechanical bonds on the PR backbones of PRMINs could undergo a synergistic long-range sliding motion under external force, with the introduction of collective dangling chains into the network. As a result, the synchronized motions of coherent PR chains can be readily activated to accommodate network deformation and efficiently dissipate energy, thereby leading to enhanced mechanical performances of PRMINs.

Mechanically Interlocked Polyrotaxane Networks with Collective Motions of Multiple Main‐Chain Mechanical Bonds

AbstractType I main‐chain polyrotaxanes (PRs) with multiple wheels threaded onto the axle are widely employed to design slide‐ring materials. However, Type II main‐chain PRs with axles threading into the macrocycles on the polymer backbones have rarely been studied, although they feature special topological structures and dynamic characteristics. Herein, we report the design and preparation of Type II main‐chain PR‐based mechanically interlocked networks (PRMINs), based on which the relationship between microscopic motion of mechanical bonds on the PRs and macroscopic mechanical performance of materials has been revealed. The representative PRMIN‐2 exhibits a robust feature in tensile tests with high stretchability (1680 %) and toughness (47.5 MJ/m3). Moreover, it also has good puncture performance with puncture energy of 22.0 mJ. Detailed rheological measurements and coarse‐grained molecular dynamics (CGMD) simulation reveal that the embedded multiple [2]rotaxane mechanical bonds on the PR backbones of PRMINs could undergo a synergistic long‐range sliding motion under external force, with the introduction of collective dangling chains into the network. As a result, the synchronized motions of coherent PR chains can be readily activated to accommodate network deformation and efficiently dissipate energy, thereby leading to enhanced mechanical performances of PRMINs.

Evaluation of ride quality in a passenger car with non-uniform tyre radial stiffness

This study is dedicated to examining the influence of varying radial stiffness along the circumference of tyres on a road vehicle ride quality and with a specific focus on aspects relevant to maintenance. Computer simulations employing a three-dimensional road-vehicle model, developed within commercial multi-body software, were conducted to explore the multifaceted factors influencing vehicle behaviour. These factors encompass road unevenness, driving speed, and the range of radial force variation resulting from harmonic changes in tire radial stiffness. Furthermore, simulation tests were carried out using a model of a diagnostic wheel balancing machine, which holds significance in vehicle maintenance practices. Measurements obtained from a passenger car equipped with standard tires with minimal non-uniformity, served as reference values for assessing the car's vibration levels. Additionally, selected scenarios were examined, involving vehicle with multiple wheels exhibiting non-uniform radial stiffness. The findings underscore that non-uniform radial stiffness can magnify the detrimental effects of road irregularities, potentially leading to amplified vibration levels and a heightened need for maintenance considerations.

Analysis of soil compaction under different wheel applications using a dynamical cone penetrometer

Soil compaction is one of the major problems in modern agriculture. Thus, the workability of a soil reflects to its ability to accept the traffic of agricultural machinery and implements. Water content and compaction are factors that influence the rheological behavior of the soil. the representation of soil shows limitations regarding the behavior of the tire-soil interface and its resistance to deformation is both influenced by the different forms of loading application along a tire path on a soil particle. This paper presents a study of the impact of multiple wheel passage, the wheel velocity, and the weight applied to the wheel on the agricultural soil represented by the cone index. To do this, we were inspired to launch an investigation for soil compaction determination at three levels of wheel load, three levels of velocity and at tillage, first, second and third passages of wheel with three replications on clayey sandy mixed grain soil. The results of this study shows that the greatest soil compaction occurred at the highest wheel load (1000 N), the lowest speed (0.1 m/s) and the highest number of passes (third pass), this leads to minimize multiple passes and or follow the same path, also, keeping the load on the ground as low as possible (weight of the machines), and working at high speed in agricultural fields.

Analysis of the resonance frequencies of multiple wheels–track coupled system based on the wave approach

Resonances of wheel and rail due to their interactions play an important role in the formation of irregular wear of wheel and rail profiles, which is the main cause of vibration and noise radiation from the wheel–rail interface and fatigue of vehicle and track structures. Although the concept of P2 resonance is widely known, other resonances due to the interaction of multiple wheels and rail above the cut-off frequency of the track system have not been studied in detail. Wave propagation in an infinite beam resting on an elastic foundation is formulated and solved analytically to illustrate the wave characteristics in railway tracks. The developed formulae can be applied to the Timoshenko beam or the Euler-Bernoulli beam with or without elastic support. The formation mechanisms and properties of the two resonance ranges of the multiple wheels–track coupled system are investigated. An important finding is the quasi-resonance frequency between 560 Hz and 610 Hz for various parameters of the vehicle and track systems, which has not been previously discovered in the literature. Although the resonances due to wave interaction are sensitive to axle spacing, the quasi-resonance frequency is independent of axle spacing. Once the resonance frequency induced by the wave interaction is close to the quasi-resonance frequency, significant resonance can be generated, which can contribute to the high-order polygonal wear of wheels as well as the short-pitch corrugation of rails. Both the model and the flexural wave solution provide a basis for more general investigation of vehicle–track interaction and other types of beams and attachments. The results can also provide guidelines for optimising of track and vehicle system to mitigate irregular wear of contact surfaces and the vibration and noise generated.

High-Frequency Resonances of Train-Track Coupled System Due to Multiple Wheels Interference

A significant resonance pattern at high frequencies around 400[Formula: see text]Hz to 1000[Formula: see text]Hz has been well observed from measured rail accelerations. Such resonances are key issues for rail noise and corrugation. Although this pattern has been noted and discussed in various papers in terms of wave reflections among multiple wheels, the aim of this study is to develop novel dynamic model and reveal generation mechanism of this resonance phenomenon with the train-track coupled system. An infinite Timoshenko beam with continuous supports is adopted for modeling the track system, and the point and transfer receptances of the rail for a moving excitation are explicitly deduced by the residue theorem together with a Fourier transform-based method. A frequency-domain method is then established to calculate the power spectral densities (PSD) of the train-track coupled system responses to stochastic irregularities with the moving vehicle model with multiple wheels. It is found that the high-frequency resonances occur when the reflected waves generated from multiple wheels on the rail are exactly in phase with the initial track irregularity. The load speed has negligible influence on the wheel–rail interaction in the lower frequency range and a small influence in the upper frequency range only for very high train speeds.

An integrated 3D dynamic FE vehicle-track model in elasto-plasticity to investigate short pitch corrugation under cyclic wheel loads

The mechanism of rail short pitch corrugation has remained elusive in the past. The damage mechanisms of the corrugation are reported to be differential wear or plastic deformation. The former has been extensively studied, while the plastic deformation, especially under multiple wheel passages has been seldom studied. To uncover the facts behind it, an integrated dynamic vehicle-track model with the rail material treated in elasto-plasticity is developed. Further, a novel method which can simulate the material deformation under cyclical axle loads is proposed. This method is used to study the rail material response at corrugation. Our research found that for the cases studied, the rail material undergoes cyclic plastic deformation at corrugation peaks only for a limited number of cycles (2–4 cycles) before reaching the elastic shakedown limit. After that, no further residual stresses and strains accumulate. The plastic deformation at corrugation peaks weakens the corrugation amplitude, serving as an early corrugation attenuation mechanism. Conversely, work-hardening at corrugation peaks increases wear resistance at those peaks, promoting corrugation in the long term. The explanation of the corrugation development process under the interplays of the plastic deformation and wear has been validated by field corrugation data. Additionally, we propose a wear coefficient in the wear model to account for the work-hardening and change in the wear resistance. Experimental results of the hardness distribution show the similar characteristics to the numerical results.

A new method to derive rail roughness from axle-box vibration accounting for track stiffness variations and wheel-to-wheel coupling

Railways require frequent inspection to maintain acceptable levels of rail roughness. Accelerometers mounted on in-service railway vehicles potentially offer a cost-effective method of near-continuous roughness monitoring by using a transfer function in the frequency domain to derive rail roughness spectra from measurements of axle-box vibration. This paper addresses two phenomena that currently limit the effectiveness of such a method: the variation in track support stiffness along the track, which is the least known property of the vehicle-track system, resulting in a variable transfer function; and the vibration coupling between wheels, which limits the effectiveness of a transfer function based on a single wheel. A new method is presented that estimates the track stiffness by curve-fitting a transfer function to the peak in the axle-box acceleration spectrum associated with the so-called ‘P2’ resonance of the wheel-rail system. Wheel-to-wheel coupling is addressed by refining the transfer function to account for multiple wheels running on the same rail. Axle-box acceleration is also affected by wheel roughness, and the use of a comb filter is briefly demonstrated to mitigate this effect. The developments are evaluated by both numerical simulation and measurement trials conducted on London Underground’s Victoria line.

Murray-Darling Basin Plan mark II. What should stakeholders plan for?

ABSTRACT The revised Murray-Darling Basin Plan is scheduled for 2026. Given the Plans complexity, and issues involved in the revision it is worth asking what will be the main drivers of change? What changes can reasonably be anticipated? What preparations should stakeholders make for their engagement in the planning process? As we move towards the next Basin Plan, there are multiple wheels in motion that could shape the future. Several factors we anticipate being important are examined. Our aim is to stimulate stakeholders to think about and prepare for major contingencies that could affect their interests. We focus on those that will likely affect water availability, and changes in policy and water-governance by public agencies. We take the starting point that rivers are complex social-ecological systems, within which structural circumstances and forms of social capital will affect individuals’ and communities’ abilities to maximise what they achieve from their natural assets, and their resilience to unfavourable contingencies. We conclude with some observations about how stakeholders might strengthen their ability to respond to opportunities or threats. While the future is always uncertain and all planning processes are flawed, how stakeholders conceive of and respond to today’s challenges will substantially affect their capacity to be resilient.

Design and Characterization of a Single Lever Bicycle Brake with Hydraulic Pressure Proportioning

In 2019, the Centers for Disease Control and Prevention estimated that 329,000 Americans were injured in cycling-related incidents. Since the first bicycle brake in 1817, there has been an individual brake lever for decelerating each wheel, while on cars, there has been a single control lever for decelerating multiple wheels since 1921. To perform an emergency stop on a bicycle, the rider must proportion hand pressure on each brake lever and simultaneously vary hand pressure throughout the duration of the maneuver to match the variations of normal force on each tire. Only highly skilled riders, with years of training and practice, can correctly proportion brake pressure to maximize available traction and thus minimize stopping distances. The objective of this study is to simulate and prototype a hydraulic, single-lever bicycle brake system, integrating front and rear brake proportioning, which minimizes stopping distance compared to dual-lever simulations. A design is developed to address the brake proportioning issue. Based on the simulations and physical model, the prototype proportioning valve decreased simulated stopping distances up to 18%. Exploring a range of bike types and scenarios, stopping distances were decreased between 13% and 26%. Simulating an ideal proportioning valve, stopping distances were further decreased between 4% and 40%. These results show that there can be an advantage to brake proportioning technologies in bicycles.

Extensible Mecanum wheel intelligent car

Today, with the rapid development of robots, intelligent robots can bring us a lot of convenience in all aspects of life. Dangerous and difficult operations can make machines that can adapt to the changes in work tasks and working environments replace manual work. At the same time, they can also ensure personal safety, reduce labor intensity, improve labor productivity, and reduce production costs. As an intelligent mobile robot driven by multiple wheels, the intelligent car has the advantages of small size, lightweight, low cost, and convenient operation. When encountering complex terrain, it is particularly important to study the environmental adaptability and obstacle-surmounting ability of the car. The key technologies of terrain adaptability and obstacle surmounting include obstacle identification, azimuth and distance measurement, and wheel structure design.

Evolution of thermally induced white etching layer at rail surface during multiple wheel/train passages

A thermo-mechanical-phase transformation FEM was developed to quantitatively predict the formation process of thermally-induced white etching layer (WEL) at rail surface. A practical scenario of multiple wheel passages with two locomotives was introduced for a single train, and the evolution of martensitic WEL and the residual stress during ten train passages was reported. The results indicate that an effective heating period during wheel passage is a critical factor to influence WEL formation. For the given model parameters, the maximum volume fraction of martensite increases from 1.8% to 19.78% during the passage of ten trains. The residual stress distribution on the rail top is changed after WEL formation.

Calculation and Analysis of Vibration Stress of Guangxi Nanning Subway during Operation

In this study, based on the Mindlin solution in elastic half‐space, the stress calculation formula was determined with consideration of any point in the foundation under the dynamic amplification effect. The train load was simplified as a concentrated force moving in the direction of the train, and the stress of the soil under a single wheel load was analyzed. In the state, σz reached a maximum value of 0.56 kPa when the axle was directly above the soil, and the stress decreased until it approached zero as the distance from the soil unit increased. Then, taking the Nanning Metro Line 1 as an example, the load was regarded as the superposition of several single‐wheel loads, and the law of the soil stress change at a point directly below the moving line of the train load at different axle loads, speeds, and burial depths was studied. From the analysis of the results, it could be seen that the soil stress under different working conditions was always proportional to the train axle load, speed, and burial depths. The peak stress ratio corresponding to the depths of 9 m, 12 m, and 15 m was 1:2:11, indicating that the closer the load to the soil, the more significantly the stress of the soil element increased. Under multiple wheel loads, the soil stress always exhibited continuous cycle characteristics. The cycle period was related to the time it took for the metro to pass through the point in the soil, and the cycle period was the ratio of the distance between each axle and the vehicle speed.

Wave interference in railway track due to multiple wheels

A resonance pattern at frequencies from around 400 Hz to 1000 Hz has often been observed from measured rail accelerations. Such resonances are important for rail noise and corrugation. Although this pattern has been reported and discussed in several papers in terms of wave reflections between multiple wheels, the aim of this study is to investigate the generation mechanism of this resonance phenomenon in detail, and to give both mathematical and physical insight. An infinite Timoshenko beam with continuous supports is adopted for modeling the track system, and the point and transfer receptances of the rail for a stationary harmonic excitation are explicitly obtained by the residue theorem. A frequency-domain method is then presented to calculate the power spectral densities of the wheel-track coupled system responses to stochastic irregularities with the moving irregularity model. It is found that the multiple peaks can be explained by using the phase closure principle. Moreover, total reflection between the two wheels may occur at around 700 Hz, which results in the highest peak in the response.

The Influence of Wheel Rotations to the Lateral Runout of a Hybrid Material or Dimensionally Reduced Wheel Bearing Flange

<div class="section abstract"><div class="htmlview paragraph">The automotive industry is continuously striving to reduce vehicle mass by reducing the mass of components including wheel bearings. A typical wheel bearing assembly is mostly steel, including both the wheel and knuckle mounting flanges. Mass optimization of the wheel hub has traditionally been accomplished by reducing the cross-sectional thickness of these components. Recently bearing suppliers have also investigated the use of alternative materials. While bearing component performance is verified through analysis and testing by the supplier, additional effects from system integration and performance over time also need to be comprehended.</div><div class="htmlview paragraph">In a recent new vehicle architecture, the wheel bearing hub flange was reduced to optimize it for low mass. In addition, holes were added for further mass reduction. The design met all the supplier and OEM component level specifications. Vehicle testing, however, revealed that the wheel bearing developed high assembled lateral runout (ALRO) and judder. This was due to the tires and wheels being rotated multiple times during a durability schedule. Excessive ALRO will generate high disc thickness variation (DTV) which will lead to pulsation or judder complaints.</div><div class="htmlview paragraph">The root cause of the vehicle level judder was determined to be caused by excessive ALRO and DTV in the brake corner. The major contributor to this LRO issue was plastic deformation of the bearing wheel flange that occurred with use and multiple tire/wheel rotations.</div><div class="htmlview paragraph">This vehicle was validated in multiple regions of the world. Regional differences in vehicle service procedures were observed on the same architecture. Further investigation showed that the regions which performed more wheel rotations and other maintenance observed the vehicle judder, while the other region that did less maintenance did not.</div><div class="htmlview paragraph">To better understand the effect of bearing wheel flange geometry on ALRO in this condition, a lab evaluation was performed. Multiple wheel flange designs were evaluated, including bearing designs with different wheel flange thicknesses and versions with and without weight saving holes. Additionally, bearings with a hybrid aluminum/steel wheel flange were tested.</div></div>

Distributed Iterative Learning Formation control for Nonholonomic Multiple Wheeled Mobile Robots with Channel Noise

In this paper, we studied the robust formation control issue of multiple non-holonomic wheel mobile robots (WMRs) with nonlinear characteristics and considered the channel noise and switching communication topology, a distributed iterative learning formation control (DILFC) scheme using information interaction between robots is proposed. Firstly, the formation tracking error with consensus information is constructed, and the relationship between formation error and channel noise is obtained from the nonlinear system model of mobile robot. Next, the controller is designed based on the prediction and the current learning term between robots, and the switching topology is introduced into the formation algorithm in the form of piecewise function. The sufficient condition and norm upper bound for the formation tracking stability of the system are obtained by theoretical analysis. The results show that although the channel noise accumulates in both the time domain and iteration domain, the validity of formation tracking can be guaranteed by adjusting the sampling time of the system. To illustrate the effectiveness of the proposed scheme, numerical simulation results of a group of WMRs are presented.

Numerical study using stiffness parameters on the nonlinear behavior of RCA pavements under heavy traffic loads

The use of the recycled concrete aggregates (RCA) obtained from construction and demolition wastes not only reduces the demand for natural aggregate, which ultimately leads to economical and eco-friendly designs, but also improves the long-term performance of a conventional flexible pavement. This study aims to investigate the effects of using 100% RCA in the pavement subbase and base courses on the mechanical behavior of the flexible pavement. This study is divided into two stages, i.e., a laboratory study characterizing the properties of RCA and a numerical analysis evaluating the long-term performance of RCA under heavy traffic load conditions. In the laboratory study, along with the determination of the classical geotechnical properties of base and subbase samples, the stiffness properties of the samples were obtained by applying the resilient modulus test (RMT) and permanent deformation test (PDT). Then, by comparing the results of the three different constitutive models, the result of the more appropriate model was selected. In the second stage, the plastic deformation (rutting) of the pavement courses and the maximum value of deflection when subjected to multiple wheel loads were determined using a 3D nonlinear numerical method. Based on the experimental results, RCA demonstrated higher resilient modulus and lower plastic deformation compared to that of conventional base and subbase materials. Regarding the long-term behavior, the permanent strain rate of the samples was reduced at an approximately constant level during the first load cycles. Additionally, the numerical analysis results indicated that the mechanical performance and rutting values of the base and subbase courses constructed using 100% RCA met the specified requirements.

EDVWDD: Event-Driven Virtual Wheel-based Data Dissemination for Mobile Sink-Enabled Wireless Sensor Networks

Despite the several advantages of mobile sink-enabled wireless sensor networks, the data dissemination to mobile sink is challenging for resource-constrained sensor nodes due to sink mobility. Sensor nodes need to be aware of current location of the mobile sink to successfully transmit their data. However, network-wide updation of mobile sink’s location would cause high communication overhead and undermine the energy conservation goal. In this paper, we propose an event-driven virtual wheel-based data dissemination (EDVWDD) scheme that constructs multiple wheels in the sensor field with the aim of reducing the cost of updating the mobile sink location. Furthermore, EDVWDD provides easy-accessibility of wheel to each sensor node in order to reduce the delay while transmitting the data to mobile sink. Simulation results reveal improved performance of EDVWDD in terms of energy consumption, and data delivery delay as compared to state-of-the-art mechanisms at varying node density and sink speed.

Super cyclic antimagic covering for some families of graphs

Graph labeling plays an important role in different branches of sciences. It gives useable information in the study of radar, missile and rocket theory. In scheme theory, coding theory and computer networking graph labeling is widely employed. In the present paper, we find necessary conditions for the octagonal planner map and multiple wheel graph to be super cyclic antimagic cover and then discuss their super cyclic antimagic covering.

A mathematically-based study of the random wheel-rail contact irregularity by wheel out-of-roundness

The wheel-rail rolling contact finite element model has been generally considered to be a better choice for solving the high-frequency wheel-rail responses and local stress/strain states, compared to the traditional multi-body dynamics model. However, some thorny issues in the wheel-rail finite element analysis need to be solved or avoided, such as difficulties in geometry modelling especially for describing those multiple irregular wheel tread defects, possible computation termination by mesh distortion, and the balance between the computational efficiency and accuracy. Thus, an innovative computational method was proposed in this study, to transform the geometric irregularities induced by wheel out-of-roundness (wheel flat, tread spalling and wheel polygonization) to the randomly irregular displacement excitation of the wheel-rail contact, where the randomisation of the size, shape and distribution of wheel tread defects were considered. Based on geometrical relationships of the wheel-rail contact, the formulas of the wheel-rail contact displacement irregularity caused by various wheel tread defects, which was equivalent to the corresponding wheel-rail geometrical irregularity, were derived. And then the randomly irregular wheel-rail displacement satisfied to several various random distribution functions were generated by pseudo-random number sequence. Finally, the proposed method is demonstrated to facilitate applications of the explicit wheel-rail contact finite element model.