Heavy Wheel Research Articles

Numerical and experimental investigation on critical stresses due to rail cant

The track integrity is significantly affected by the internal stress state of the rail. The rail cant influences the flexural stress distribution on the rail foot, thereby shifting the critical stress locations. In this study, full-scale lab testing was done for heavy equivalent wheel loads (16–40 tonne) to measure the rail foot stresses. Further, the mathematical model for track design is modified considering the effect of rail cant on stress distribution and compared with the developed finite element model (FEM) and the experimental study conducted. It was observed that the FEM and modified model calculates the rail stresses with better accuracy of around 5% for heavy wheel loads. The rail cant cause redistribution of stresses, making the gauge corner critical to rail failures. It was observed that stresses at the gauge corner are 20% higher than at the field corner of the rail foot.

An exploratory framework for accelerated airport pavement testing using the geotechnical centrifuge

ABSTRACT Full-scale Accelerated Pavement testing (APT) has been regarded as an essential step to bridge the gap between research and practice for pavement design because it can fully mimic a large number of heavy wheel loading on pavements. Despite being able to test pavements in an accelerated manner compared to Long-term Performance Monitoring (LTPM), conducting one full-scale APT experiment is still demanding in terms of monetary cost, space, time, etc., and the accessibility to APT facilities is only available in a few countries nowadays. In this study, an exploratory APT study with a down-scaled pavement model in a high-g environment created by geotechnical centrifuge was performed with up to half a million simulated aircraft load repetitions. Through this test, it was proved that the centrifuge APT can reproduce the full-scale airfield pavement responses, including rutting, cracking, material fatigue, etc. The transient and permanent deflection of the pavement surface, variations in stress and strain states within the pavement structure over its lifespan can be well captured for analysis. This framework of centrifuge APT provides a new methodology for pavement testing and can significantly save the current cost and time of full-scale APT.

EFFECTS OF LOADING MASS ECCENTRICITIES ON UNSPRUNG MASS ROTATIONAL DYNAMIC RESPONSES OF HEAVY VEHICLE ON IRREGULAR ROAD PAVEMENT

Using individual independent unsprung masses in suspension system modeling is not a realistic reflection of vehicle dynamics in response to eccentric wheel kinematics and asymmetric heavy vehicle loading. This is because the use of such masses does not accurately represent the unsprung mass system's influence on heavy vehicles' dynamics, including its impact on the sprung masses or wheel pavement dynamic loading. This study aims to examine how heavy vehicle asymmetric loading and wheels' eccentric kinematic excitation affect the rotational dynamic response of the unsprung masses. A total of 450 models were used to investigate various asymmetrical cases, from which 9 3D 24 DOF heavy vehicles' 4 DOF rear tandem drive axle suspension systems were selected for analysis using SIMWISE 4D. These vehicles were tested for a pothole depth of 25 mm and a vehicle translational speed of 60 km/h. The study found that the nature of the pavement distress factor (kinematic excitation) determines the suspension's rotational dynamic response and, consequently, the sprung mass. Moreover, the load distribution on the sprung mass also affects the rotational dynamic response of the tandem beams

Modeling of flexible metal wheel for pressurized lunar rover and traction performance prediction

AbstractThe pressurized lunar rover has become one of the most important equipment in lunar exploration and resource utilization missions. On the terrain of soft lunar regolith, the rover wheels are easy to slip, sink, or even fail to move. To improve the traction performance of the rover on soft lunar soil, it is necessary to study the interaction between the wheels and the lunar soil. The deformation of the flexible wheel provides a larger contact area, which results in greater tractive force. Moreover, flexible wheels have better comfort and stability than rigid wheels, which are needed for manned rovers. However, there are few studies on the wheel soil interaction model of the heavy flexible wheel for the pressurized lunar rover. In this paper, a metal flexible wheel soil interaction model for pressurized lunar rovers was established, and the traction performance of the flexible wheel was predicted by using this model. Then, the accuracy of the wheel soil interaction model was verified by the soil bin test. The experimental results showed that the average error between the theoretical value of sinkage and the experimental value was 13.9%, and the average error between the theoretical and experimental value of drawbar pull was 11.5%, indicating that the model has high prediction accuracy. The new model can be used to predict the traction performance of flexible wheels and the experimental results can provide a reference for the flexible wheel design lunar rovers.

Experimental investigation on the structural performance of the high-strength ring strengthened dowel connection under monotonic load

Traditional dowel connections embedded into concrete are susceptible to localised concrete crushing under heavy wheel loads. To address this issue, this paper introduces an innovative high-strength ring strengthened dowel connection to improve the bearing resistance of concrete at the joint surface. Monotonic load tests were conducted to investigate the effects of the high-strength ring concrete compressive strength, the high-strength ring thickness and length on improving ultimate load and mitigating localised concrete crushing. Test results indicated that the ultimate load and the initial stiffness of the specimen were greatly improved after applying the high-strength rings. Because of the excellent compressive resistance of the ring concrete, the initiation of the crushing zone was delayed, and the maximum compressive stress in normal strength concrete was reduced with the increase of the ring thickness. In addition, the deflection response of the dowel connection embedded into concrete could be predicted by the beam on elastic foundation (BEF) and the beam on inelastic foundation (BIF) theories. Based on the deformation of the dowel connection and surrounding concrete, the analytical solution was derived to predict the ultimate load of the high-strength ring strengthened dowel connection embedded into concrete.

Optimization of heavy haul railway wheel profile based on rolling contact fatigue and wear performance

This paper presents a methodology to develop optimal railway wheel profiles based on their rolling contact fatigue (RCF) and wear performance. The NSGA-II multi-objective optimization algorithm was employed to minimize two objective functions: the wear index and the fatigue index while satisfying objective constraints. The commercial multibody software SIMPACK® was used for modeling the railway vehicle's dynamics and macrogeometry of a Brazilian heavy haul railway. The objective functions and constraints are obtained from the dynamic simulation and used as inputs to the optimization algorithm which then provides new wheel profiles as the output. To verify the long-term performance of the new profiles, wear and fatigue analysis were performed. Wear simulation using Archard's law generated worn profiles that were used to estimate the wheel's theoretical service life and degradation rate. Fatigue simulation employing the Dang Van fatigue criterion was done to obtain the stress histories for fatigue analysis using a Finite Element Model (FEM) inside ANSYS® software. The study resulted in three optimized profiles. The first was optimal for wear, the second was optimal for fatigue, and the last presented an intermediate performance in terms of wear and fatigue. The findings show that all three optimized wear profiles reduced the wear index by at least 47% when compared to the currently used profile. Furthermore, an improvement of at least 159% was observed in the fatigue index for all new profiles. The service life increased 12% according to the current hollow wheel criterion, 3 mm.

Development of Prediction Model for Rutting Depth Using Artificial Neural Network

One of the most common pavement distresses in flexible pavement is rutting, which is mainly caused by heavy wheel load and various other factors. The prediction of rutting depth is important for safe travel and the long-term performance of pavements. Factors that are considered in this paper for the prediction of rut depth are Temperature, Equivalent Single Axle Load, Resilient modulus, and Thickness of hot mixed asphalt. The input data for all factors are collected from the Long-Term Pavement Performance Information Management System for the state of Texas. Regression analysis is performed for dependent and independent variables to obtain the empirical relationship. In various fields of civil engineering, artificial neural networks have recently been utilized to model the qualities and behavior of materials and to determine the complicated relationship between various properties. An Artificial Neural Network is used to develop a predictive model to predict the rutting depth. A total number of 70 observations were considered for the predictive model. A mathematical relation is developed and verified between rut depth and variable input data.

Manual Production of Green Current, Green Hydrogen and Green Oxygen for the Benefit of Daily Income of Poor People of Any Country

From Kasmir to Kanyakumari, as India is having many poor people with no daily income, based on humanity, we are making an advanced technical attempt to help them with a possible daily income by manual production of green current, green hydrogen and green oxygen. To have sufficient fuel, to have an efficient fuel and to reduce pollution levels, world transportation system badly needs eco-friendly hydrogen and the whole earthy environment is in a serious quest for oxygen. To resolve the above basic issues, it is planned to produce hydrogen and oxygen by means of alkaline electrolysis with external magnetic field (IIT, Mumbai, India) for a better productivity, accomplished by electricity produced from medium capacity alternators operated by human physical energy. To fulfill this requirement, it is planned to take the help of illiterates, healthy beggars, Rikshawala like poor people and farmers having no crop field or no crop yield. With efficient pedaling and gearing mechanisms associated with heavy fly wheels, 10 of 20 persons forming as a group can be allowed to run any alternator round the clock in 8-hour shift system for 4 alternative hours without any physical strain. By considering our proposal, 1) Hydrogen fuel required for running Fuel cells and Internal combustion engines can be generated in large quantity with a de-central system having unlimited number of medium capacity alternators spread across entire India. 2) Generated oxygen can be released to atmosphere and air pollution levels can be diluted to a greater extent across India. 3) Recycled waste water or sewage water can also be used. 4) Multiple number of small scale units can be set up with 5 to 10 alternators and production of hydrogen by electrolysis can be increased from 5% to (30 to 40) % of total production of hydrogen. 5) To some extent, as long as Hydrogen is considered as a fuel, employment problem, hydrogen scarcity and air pollution issues can be resolved. With further study, research and direct involvement of state and central governments, industrialists, scientists and engineers, this proposal can be implemented a full-fledged manner from Kashmir to Kanykumari. Our proposal can be considered as one of the best coordinating schemes for-fulfilling Indian transportation fuel needs, Indian poor people struggling for getting daily wages and saving mother earth from CO2, SO2 and NOx like harmful gases. This project can be implemented in any country having poor people.

Prediction Method of Heavy Load Wheel/Rail Wear Mechanical Properties Based on GA-BP Hybrid Algorithm

Due to its large axle load and high-density operation mode, heavy haul transportation has greatly improved the cargo transportation capacity, and is receiving unprecedented attention from all countries in the world. Since the development of heavy haul freight transport in China, wheel rail wear has been paid much attention, especially the use of heavy axle load locomotives on upgraded heavy haul lines, which makes reducing wheel rail wear and damage become a technical problem to be solved urgently. Considering that there are too many mechanical parameters involved in the prediction of heavy load wheel rail wear mechanical properties, the prediction accuracy is reduced. Therefore, this paper proposes a method based on GA-BP hybrid algorithm to predict the mechanical properties of heavy load wheel/rail wear. Hertz contact theory is used to simplify the wheel rail contact relationship, and the wheel rail contact model is established. According to the wheel/rail contact model, the expressions of heavy load wheel/rail in the case of vertical, horizontal, direction and gauge irregularity are analyzed, and based on this, a mechanical model of heavy load wheel/rail wear is established. In order to solve the problems of slow convergence speed and easy to fall into local optimum of BP neural network in the prediction of heavy load wheel/rail wear mechanical properties, the global convergence of genetic algorithm is used to optimize the BP network. According to the obtained mechanical parameters of heavy load wheel/rail wear, the mechanical parameters are input into the optimized model, and the relevant prediction results are output. So far, the research on the prediction method of heavy load wheel/rail wear mechanical properties based on GA-BP hybrid algorithm has been realized. The experiment is designed from three aspects of wear degree, hardness and tensile strength, and compared with the measured value, reference [4] method, reference [5] method and reference [6] method to verify the effectiveness of the proposed method. The experimental results show that the predicted results of wear degree, hardness and tensile strength by this method are closer to the measured results. It is proved that the proposed method has higher prediction accuracy and better practical application effect.

Simulation and Experimental Study on Rolling Friction and Wear of Heavy Haul Wheel Tread

Rolling friction and wear testing of heavy haul wheel tread was performed. The results show that a new and dominant vibration was generated owing to the surface wear, resulting in the polygonalization wear of the wheel specimen. The slip between wheel and rail specimens accelerated the formation of polygonalization wear. The pearlite and proeutectoid ferrite in the outermost layer were completely fragmented to form a fine grain layer. There was an extreme state for the deformation of the microstructure in the outermost layer, and there was a corresponding extreme value for the hardness. The slip accelerated the surface microstructure to reach the plastic hardening limit, but it had little effect on the extreme value of hardness. The stress distribution of the wheel specimen surface was simulated. The results show that there were alternating principal tensile and compressive stresses at the contact surface of the wheel specimen and shear stresses with alternating directions in the subsurface of the contact patch. The depth of the maximum shear stress from the surface was mainly related to the normal load, while the slip has no significant effect on it. A coupling modeling method of finite-element method (FEM) and smoothed particle hydrodynamics (SPH) was used to simulate the microstructure evolution of CL70 wheel steel. The simulation results show that there was mutual mechanical interaction between ferrite and cementite in pearlite. Their deformation was inconsistent owing to their different mechanical properties, resulting in large tensile stress at the boundary between them, even in the compressive stress area below the contact patch.

Myths and Realities of the Salt Lake Temple Foundation

Myths and Realities of the Salt Lake Temple Foundation

Design and performance analysis of an adaptive omnidirectional wheel for heavy payload robot

PurposeWith the development of automation technology, the accuracy, bearing capacity and self-adaptation requirements of wheeled mobile robots are more and more demanding under various complex conditions, which will urge designers such shortcomings as the low accuracy, poor flexibility and weak obstacle crossing ability of traditional heavy haul vehicles and improve the wear resistance and bearing capacity of traditional omnidirectional wheels.Design/methodology/approachThe optimal configuration for heavy payload transportation is obtained by building sliding friction consumption model of traditional wheels with different driving types based on Hertz tangential contact theory. The heavy payload omnidirectional wheel with a double-wheel steering and a coupled differential wheel driving is designed with the optimal configuration. The wheel consists of a differential gear train unit and a nonindependent suspension unit. Kinematics model of the wheel is established and relative parameters are optimized.FindingsThe prototype experiments show that the wheel has higher motion accuracy and environment adaptability. The results are consistent with the theoretical calculation, which show that the accuracy is more than 50% higher than that of differential prototype. The motion stability and the accuracy of the coupled differential omnidirectional wheel are better than those of the traditional omnidirectional wheels during the moving and obstacle crossing process under complex conditions, which verifies the correctness and advantages of the design.Originality/valueAiming at the specific application of heavy payload omnidirectional transportation, a new omnidirectional mobile mechanism with a two-wheel coupling drive structure and an adaptive mechanism is proposed. The simulation and experimental results show that it can realize the high-precision heavy-load omnidirectional movement, the effective contact with the ground and improve the adaptability to the rugged ground. It is flexible, simple and modular and can be widely applied to transportation, exploration, detection and other related industrial fields.

Deterioration and Failure Rates of Maintained Roads in Nigeria

This study evaluated failure rates of roads maintained by FERMA in Delta state and its effects. The three roads investigated are: Benin-Asaba dual carriage way (266km), Warri-Sapele-Benin dual carriage way and Asaba -Allah-Ebu Edo state border road(47km). Road condition survey was carried out on the three roads to ascertain the extent of deterioration. Sieve analysis, liquid limit, compaction and CBR tests were conducted on the material used for the maintenance works for quality control purpose. Liquid limit, optimum moisture content, unsoaked CBR values were 21%, 8.5% and 117% respectively. These were observed to be within the FMW highway manual guidelines. It was observed that beyond 12months, Benin-Asaba and Warri-Benin roads experienced 2% and 5% failure rates while Asaba-Illah recorded 30% failure rate within a 12month period. These failures were attributed to heavy traffic with heavy duty wheel. Challenges of road maintenance in the field and remedial measures for highway maintenance is also discussed. The authors recommend that FERMA should seek redress and go back to the establishing blue print for operations and funding and also refers to Federal Roads Authority bill (2015) for backups. These tools have been provided to equip the agency to carry out her mandate effectively keeping the road infrastructures in good condition.

The Mechanical Resistance of Asphalt Mixture with Steel Slag to Deformation and Skid Degradation Based on Laboratory Accelerated Heavy Loading Test.

Steel slag is a main form of solid waste. Using this component to replace part of the aggregate in an asphalt mixture is an effectively way of treating solid waste. To study the performance degradation of asphalt mixture with various content of steel slag under heavy loading, some large-sized basalt hot mixed asphalt mixture (BHMA) and steel slag hot mixed asphalt mixture (SHMA) in a form of specimens were prepared and a heavy loading wheel tracking test was conducted. The aggregate characteristics of basalt and steel slag were measured. The deformation and skid resistance of the asphalt mixture with different content of steel slag was tested and analyzed. Due to the particle characteristics of steel slag aggregate, it was found that a low content of steel slag can effectively improve the resistance to deformation and skid resistance of the asphalt mixture under heavy loading. The response of SHMA can still meet the pavement technical requirement after long-term heavy loading service. The main change in the mixture under heavy loading is the crushing of the 9.5–16 mm aggregate, and the content of this part also significantly affects the deformation. This study explains the mechanism of degradation of SHMA under heavy loading: the large aggregate is crushed and forms a new aggregate skeleton structure.

Mechanistic approach to predict service life of flexible pavements subjected to heavy traffic loads

Operation of specialty trucks with heavy axle and wheel loads can result in significant loss of service life of pavements. This study aimed to propose a mechanistic framework for the characterisation of the remaining service life (RSL) of pavements with heavy truck traffic operations. A field testing plan was devised to collect relevant information on traffic and pavement structural properties in ten heavily trafficked roadways in Texas. Portable Weight-in-Motion devices and Non-Destructive Testing were deployed to collect site-specific axle load spectra and pavement layer configurations, respectively. Furthermore, a novel methodology was developed for the mechanistic quantification of the loss of pavement life due to the recent changes in traffic characteristics, considering demanding loading conditions and environmental effects. The results underscored the importance of roadway type and its role in damage assessment procedures. Further comparison of the analysed results, using the developed framework, with field measurement records also showed sound agreements.

Physical and economic impacts of studded tyre use on pavement structures in cold climates

ABSTRACT In cold regions like Alaska of USA, Canada and the northern parts of Europe, using studded tyres is common among the public when driving in icy and snowy conditions. However, studded tyres cause extensive wear to asphalt pavement, reducing pavement life. This study addresses the physical and economic impacts of winter studded tyres on the roadway system to better inform decision makers as they develop alternative solutions and future polices. The approach is applied in a case study from a sample of Alaska statewide road segments. Surveys were employed to examine the extent of the use of studded tyres and cost-effective alternatives. A pavement life-cycle cost review was established considering several variables to discover a realistic cost of roadway resurfacing and rehabilitation. Wear rates due to studded tyres and rut rates due to wheel loads were found for different highway classes. The results indicate higher average wear rates due to studded passenger vehicles on freeways than average rut rates due to heavy wheel loads. The results also indicate lower average wear rates on arterial and collector roads. The estimates show that studded tyre use reduced asphalt surface life by about 7 years on the selected freeway sample in the case study, which is about 47% loss in pavement life based on the initial design life of 15 years. Other road classes experienced lower reductions in service life. Finally, cost analysis was provided to reflect the impact of studded tyres on the state's budget. Countermeasures were suggested, which in turn may help other cold regions develop strategies on the use of new winter tyre technology.

Effects of turbocharger rotational inertia on engine and turbine performance in a turbocharged gasoline direct injection engine under transient and steady conditions

The effects of turbocharger (T/C) rotational inertia on engine and turbine performance under transient and steady engine conditions were analyzed in a 2.0 L 4-cylinder turbocharged-gasoline direct injection (T-GDI) engine. The test T/Cs consisted of heavy and light compressor wheels (C/W) and turbine wheels (T/W). The study was conducted in two research stages. First, transient engine load tests were conducted to evaluate the effect of T/C rotational inertia on transient response of the T/C, combustion performance, and fuel consumption. Seconds, steady engine load tests were conducted to find out if a light inertia T/C can run at higher efficiency under the same exhaust pulsating flow conditions within one engine cycle. In order to evaluate the engine on-board turbine instantaneous performances in the units of crank angle degree (CAD), T/C rotation speed and pressure data were measured in the experiment. The instantaneous exhaust gas mass flow rate and the temperature of upstream and downstream of the turbine were extracted by 1-D simulation. Turbine efficiency and mass flow rate parameters were calculated by combining these data. In the results, there existed positive effects of light inertia T/C on response and specific fuel consumption under transient conditions. It was also found that the light inertia T/C could show higher T/C speed fluctuation under the same exhaust pulsating flow conditions. Consequently, blade speed ratio (BSR) and turbine efficiency of light inertia T/C were partially higher than that of conventional one. However, it was not led to higher engine efficiency.

A thermal braking model of the entire heavy vehicle wheel assembly

Overheating of heavy vehicle brakes and surrounding components can have fatal consequences. The design specifications of the entire heavy vehicle wheel assembly including the rim material and wheel configuration impact the brake, axle, rim and tyre temperatures. Consequently, it is important to model the entire heavy vehicle wheel assembly. In this study, a thermal model to predict the temperatures of the brake, axle, rim and tyres is developed and validated using experimental braking results for single and dual wheels using steel and aluminium rims. The use of the model is illustrated by analysing the component temperature responses of a conceptual carbon fibre reinforced polymer (CFRP) rim to 2.5 kW of continuous braking. A CFRP rim would reduce the conduction of heat from the brakes into the tyres, resulting in a tyre temperature reduction of up to 35%. This positive benefit is at the expense of higher brake and rim temperatures.

A thermal braking model of the entire heavy vehicle wheel assembly

A thermal braking model of the entire heavy vehicle wheel assembly

Design and mechanical behavior evaluation of flexible metal wheel for crewed lunar rover

In lunar exploration, flexible metal wheels are designed because the pneumatic tires and rigid wheels are not suitable for crewed lunar rovers. However, the load capacity of the existing flexible metal wheels cannot meet the requirements of heavy load. In this work, an innovative flexible metal wheel consisting of a single rim and twin carcasses was proposed. Firstly, the design method and the detailed structure of this wheel was described. In order to analyze its mechanical performance under different heavy loads, Finite Element Method simulations were conducted based on lunar environment. By vertical load simulation, sheet thickness (1.5 mm) was determined considering elasticity and stiffness. By tangential force and side force simulation, the maximum stresses were respectively obtained as 715.5 MPa and 433.2 MPa, which were less than the yield strength of the spring steel, thus no plastic deformation would occur. Impact simulation showed that the maximum stress of the flexible wheel on the rigid ground exceeded the yield strength of the spring steel, resulting in plastic deformation, while the maximum stress on the soft ground was less than the yield strength and no plastic deformation occurred. Based on these simulations, the flexible metal wheel was fabricated and tested to verify its strength, stiffness, and impact resistance. The wheel exhibited excellent load capacity and elasticity. Finally, the relationship between the test and simulation was analyzed. It is believed that the structure and design process of this new flexible metal wheel are valuable for the subsequent development of heavy flexible metal wheel.