Front Axle Research Articles

Dynamic Simulation Model of Miniature Tracked Forestry Tractor for Overturning and Rollover Safety Evaluation

This study proposes a method to construct a dynamic simulation model to implement the lateral overturning and backward rollover characteristics of an actual tractor. Based on theoretical analysis, factors affecting these characteristics are identified, which include tractor weight, track width, wheelbase, location of mass center, weight distribution, heights of front and rear axles, and geometric shapes. The location of the mass center of the actual tractor is measured based on the standard test procedure set by the International Organization for Standardization, and the remaining influencing factors are derived through measurements. A three-dimensional (3D) model of the tractor is constructed to reflect all these factors. Additionally, a simulation model utilizing this 3D model is developed using a commercial dynamic simulation software program. The ability of the model to simulate the overturning and rollover characteristics of the actual tractor is verified by comparing the static sidelong falling angle and minimum turning radius with those of the actual tractor. The errors between the characteristics of the actual tractor and those of the 3D model and dynamic simulations are shown to be less than 5%, thus indicating that the proposed method can effectively simulate the overturning and rollover characteristics of the actual tractor.

Evolution of the Formula One front wing assembly

Abstract. The front wing is an important component of the F1 racing car. It is used to generate pressure on the front axle and guides the airflow around and below the vehicle. The main function of the front wing of an F1 racing car is to provide downforce and enhance the car's grip of wheels. The front wing can also bifurcate the airflow from the tires to improve backward airflow and underfloor airflow. This review will mainly discuss the historical evolution of the front wing, the advantages and disadvantages of the design and some application from the professional team. The paper will aim to put forward suggestions and improvement measures for the existing problems, which may provide new ideas for the development of high-performance racing cars.

Automatic determination of directional stability parameters of an electric vehicle with a two-motor scheme as part of the torque distribution controller

In case if the front and rear axle of the electric vehicle are not mechanically linked, the presence of automatic torque distribution to the axles or wheels becomes not only an addition to increase the level of consumer properties, but also a necessity. A method for determining the directional stability condition of an electric four-wheel drive vehicle is developed as part of the research by comparing the target and measured yaw rate, and is based on the formulated conditions of drift, skid, and counter steer registration. A method for detecting slipping of the driving wheels of an electric vehicle with a dual-motor scheme is developed, which is based on comparing the target and measured velocity differences of the front and rear axle and includes an auto oscillation detection function. A method for determining the target front and rear axle speed difference in a corner is described. Based on the tests performed, it is concluded that the proposed methods are applicable to the active torque distribution function between the axles of an all-wheel drive electric vehicle being developed by the authors of the paper, which provides improved directional stability and controllability, and counteracts slipping of the drive wheels.

Stair-Climbing Wheeled Robot Based on Rotating Locomotion of Curved-Spoke Legs.

This study proposes a new wheel-leg mechanism concept and formulations for the kinematics and dynamics of a stair-climbing robot utilizing the rotating leg locomotion of curved spokes and rolling tires. The system consists of four motor-driven tires and four curved-spoke legs. The curved-spoke leg is semicircle-like and is used to climb stairs. Once the spoke leg rolls on the surface, it lifts and pulls the mating wheel toward the surface, owing to the kinematic constraint between the spoke and the wheel. Single-wheel climbing is a necessary condition for the stair climbing of whole robots equipped with front and rear axles. This study proposes the design requirements of a spoke leg for the success of single-wheel climbing in terms of kinematic inequality equations according to the scenario of single-wheel climbing. For a design configuration that enables single-wheel climbing, the required minimum friction coefficient for the static analysis of the stair-climbing wheeled robots is demon-strated. Thereafter, the stair-climbing ability is validated through the dynamic equations that enable the frictional slip of the tires, as well as the curved-spoke legs. Lastly, the results revealed that the rotating locomotion of the well-designed curved-spoke legs effectively enables the stair climbing of the whole robot.

Numerical simulation of friction characteristics of bionic flexible contact surface of front axle rocker arm sleeve of car

Based on the finite element software ABAQUS, the friction process of the flexible friction pair of the front axle rocker bushing of a car with a convex structure similar to the mantis head is established.The finite element model of the process is constructed and its friction characteristics are verified. By selecting a suitable hyperelastic constitutive model and changing the size of the convex structure on the surface of the sleeve,The simulation analysis of the mechanical characteristics of the flexible friction pair in radial and torsional directions shows that the bionic convex hull design changes the maximum stress of the bushing when it is subjected to force.The force and strain position are adjusted to reduce the possibility of cracking of the rubber bushing; the contact friction force and friction coefficient of the bionic bushing surface are significantly reduced, and the type 2 modelThe drag reduction and wear resistance of the profiled surface are the best.

Strange nonchaotic attractors and bifurcation of a four-wheel-steering vehicle system with driver steering control

In this paper, a dynamical model is developed for the four-wheel-steering(4WS)vehicles, with nonlinear lateral tyre forces and quasi-periodic disturbances from the steering mechanism and quasi-periodic pavement external deformation. Initially, the stability and Hopf bifurcation of the 4WS vehicle system without disturbance are analyzed employing the central manifold theory and projection method. The effects of parameters on the stability and the types of Hopf bifurcation for the vehicle system are also discussed. It is shown that both Hopf bifurcation and degenerate Hopf bifurcation occur in the vehicle system. The critical speed decreases with increased driver’s perceptual time delay and distance from the vehicle’s center of gravity to the front axles, while it increases with the control strategy coefficient. However, the increase of the frontal visibility distance of the driver leads to an initial increase of the critical speed, decreasing afterwards. Subsequently, the strange nonchaotic dynamical behaviour of the disturbed 4WS system is investigated. Several routes and mechanisms for the birth of strange nonchaotic attractors (SNAs) are identified, including the torus doubling bifurcation, the torus fractalization, and the loss of transverse stability of a torus. Finally, the nonchaotic property is verified through the calculation of the maximum Lyapunov exponent, and the strange property is characterized using power spectra and rational approximation.

Influence of Immersion Orientation on Microstructural Evolution and Deformation Behavior of 40Cr Steel Automobile Front Axle during Oil Quenching.

This study employs the finite element method to investigate the microstructural evolution and deformation behavior of a 40Cr steel automobile front axle during the quenching process. By establishing a multi-physics field coupling model, the study elucidates the variation patterns of the microstructure field in the quenching process of the front axle under different immersion orientations. It is found that along the length direction, the bainite and martensite structures decrease from the center to the edge region, while the ferrite structure shows an increasing trend. Additionally, the influence of immersion orientation on the hardness of the front axle's microstructure and deformation behavior is thoroughly discussed. The results indicate that, firstly, when quenched horizontally, the hardness difference among different regions of the front axle is approximately 8.2 HRC, whereas it reaches 10.3 HRC when quenched vertically. Considering the uniformity of the microstructure, the horizontal immersion method is preferable. Secondly, due to the different immersion sequences in different regions of the front axle leading to varying heat transfer rates, as well as the different amounts of martensite structures obtained in different regions, the deformation decreases along the length direction from the center to the edge region. Horizontal immersion quenching, compared to vertical immersion, results in a reduction of approximately 56.2% and 48.9% in deformation on the representative central cross-section (A-A) and the total length of the front axle, respectively. Therefore, considering aspects such as microstructure uniformity and deformation, the horizontal immersion quenching orientation is more favorable.

Failure analysis of kingpin hole on front axle of mining truck based on finite element analysis

The axle is a critical load-bearing component of a vehicle, and its failure can lead to serious accidents. During a vertical fatigue test, the front axle of a mining truck failed prematurely. To identify the cause of this failure and enhance the structural design to meet technical requirements, a stress analysis was conducted using the finite element method. The analysis revealed areas of stress concentration on the front axle. The mechanical properties of the material were determined through tensile testing. A fatigue life analysis method, based on finite element analysis, was employed to assess the axle’s fatigue life. This method identified the location where fatigue cracks initiated and determined the minimum load cycles before the onset of fatigue cracking. The results were then compared with actual observations. Following improvements to the design based on the simulation results, another round of fatigue analysis was performed. The findings indicated a significant increase in the axle’s fatigue life, thereby meeting the required technical standards.

2D Path Following Control of Motor Graders

Optimal ground conditions in mining are crucial for operational efficiency and safety. Motor graders play a crucial role in achieving precise grading of passages; however, unlike many other mining vehicles, they have not yet been commercially automated. The redundant kinematics of motor graders, including articulation, front axle steering, and blade operations, pose significant challenges for automation. This research explores path following with a 2D kinematic model of motor graders and uses simulation to evaluate and compare the performance of these controllers in terms of step response and operational effectiveness. To address kinematic redundancy, two methods are proposed: Rear Offset Control, which defines the articulation angle using a lateral offset between the front and rear axles, and Single Track Control, which utilizes steering redundancy to adapt existing automation approaches to articulated vehicles. Simulation tests were conducted using two controllers: a Feedback Linearized PD controller (FBL+PD) and a Feedback Linearized Model Predictive Controller (FBL+MPC). Both were tuned for optimal performance on a step input path, with performance assessed based on Root Mean Square Error (RMSE) and control effort. This work introduces two methodologies—Rear Offset Control and Single Track Control—for autonomous motor grader operation. These were implemented with FBL+PD and FBL+MPC controllers on a 2D kinematic model. Future research will focus on dynamic modeling, implementing a Non-Linear Model-Predictive Controller, refining tuning methodologies for Feedback Linearized systems, and integrating these approaches with live vehicles.

Multi-objective parameter optimization of a novel hydraulically interconnected suspension for tri-axle mining dump trucks

The harsh working environment in the mining area has put strict requirements for the suspension system performance of mining dump trucks. To improve the anti-pitch and anti-roll ability of tri-axle mining dump trucks, a new type of hydraulically interconnected suspension system is proposed, including the left-right wheel interconnection in front axle and X-cross interconnection in mid-rear axle (X-HIS). The parameter sensitivity of X-HIS is analyzed, and the significant parameters are optimized. Specifically, a vehicle mechanical-hydraulic coupling model is established based on impedance matrix transfer method. The objective functions are obtained by combining the road spectral density matrix, and accuracy of the model is verified by the accumulator pressure experiment of the mining dump truck. Subsequently, the Morris method is applied to analyze the sensitivity of suspension parameters to the bounce, pitch, and roll modes vibration. The results indicate that the sensitive parameters are the initial pressure and volume of the front accumulator, the inner diameter of damping hole, the initial pressure of mid-rear accumulator, and the area ratio of upper and lower chamber of cylinder. The Pareto solution set shows that there is no conflict between the anti-pitch and anti-roll capabilities of X-HIS. The optimized X-HIS improves the ride comfort and anti-roll ability of the vehicle and balances the anti-pitch performance.

Regenerative braking fault compensation control of distributed electric vehicle considering random wheel fault degree

Distributed drive electric vehicles can reduce range anxiety through regenerative braking. However, if the wheel motor torque output fails, it will form an additional yaw moment to the vehicle, causing instability, or deviation and threatening its safety. To solve this problem, the research object is an electric vehicle driven by a four-wheel hub motor. A braking force compensation distribution strategy for front and rear axles is proposed, which combines electronic hydraulic braking (EHB) system compensation control and deviation auxiliary control. Firstly, a fault detection module is established, and the motor’s output torque is estimated by designing a torque observer to obtain the fault degree information of the motor. Secondly, to fully use the motor’s regenerative braking force, the fault-free and faulty electro-hydraulic braking force distribution strategies are designed in the coordinated distribution layer of the electro-hydraulic braking system. The corresponding electro-hydraulic braking force compensation method is selected according to the fault degree of the regenerative braking function, the position of the faulty wheel, and the braking strength. Then, a deviation auxiliary controller is designed based on the model predictive control, and the intervention time of the auxiliary controller is determined according to the vehicle’s state. Finally, the control method is verified based on CarSim/Simulink co-simulation and hardware-in-the-loop (HIL) platform. The test results show that the designed control method can effectively compensate for the regenerative braking failure of random wheel and ensure the braking safety of the vehicle.

Research on coordinated control strategy for braking energy recovery of pure electric vehicles based on ESC

AbstractTaking a rear‐wheel drive pure electric vehicle as the research object, considering the safety during braking and improving energy recovery rate, a study was conducted on the distribution strategy of front and rear axle braking force. During the braking process, the feedback braking force of the motor and the hydraulic braking force with an electronic stability controller (ESC) were coordinated and controlled, to ensure that the total required braking force was met. A fuzzy logic controller has been designed, with three variables of battery state of charge, vehicle speed, and braking intensity as inputs, and a modified motor braking ratio as output variable to prevent wheel lockup. Using Cruise software, a co‐simulation model was established with Amesim and Simulink, and simulation validation was conducted on the braking process and cycling conditions. The simulation results showed that the brake recovery strategy based on fuzzy control can effectively improve the vehicle's control performance and energy recovery rate compared to the Economic Commission of Europe regulation. The NEDC (New European Driving Cycle) working condition improved by 10.41% and the CLTC‐P (China Light‐duty Vehicle Test Cycle‐passenger) working condition improved by 10.57%. Effectively improving power consumption per 100 km, NEDC decreased by 1.81% and CLTC‐P decreased by 2.62%.

Synchronized path planning and tracking for front and rear axles in articulated wheel loaders

Wheel loaders are multi-function construction equipment, yet their complex kinematics and coupled front-rear axle relationships pose significant challenges in path planning and tracking control. This paper presents a synchronous path planning method and a reinforcement learning-based tracking controller for these axles. Initially, a kinematic model and tracking error model are developed based on steering radius analysis and verified through simulations. The Reeds-Shepp curve is used to plan the V-shaped path for the front axle, with the rear axle path derived from the kinematic model. Using reinforcement learning, a path tracking controller is developed with a preview model of tracking error. Performance is validated through simulations and field tests, showing a position error reduction of 25% and 37.5% for two paths, and heading error reductions of 27.8% and 27.3%. The results also indicate improved stability in heading and articulation angles during tracking.

All-Wheel Steering Tracking Control Method for Virtual Rail Trains with Only Interoceptive Sensors

A virtual rail train (VRT) is a multi-articulated vehicle as well as a novel public transportation system due to its low economic cost, environmental friendliness and high transit capacity. Equipped with all-wheel steering (AWS) and a tracking control method, the super long VRT can travel on urban roads easily. This paper proposed a tracking control approach using only interoceptive sensors with high scene adaptivity. The kinematic model was established first under reasonable assumptions when the sensor configuration was completed simultaneously. A hierarchical controller consists of a front axle controller and a rear axle controller. The former applies virtual axles theory to avoid motion interference. The latter generates a first-axle reference path with path segmentation and a data updating method to improve storage and computational efficiency. Then, a fast curvature matching rear axles control method is developed with an actuator time delay considered. Finally, the proposed approach is verified in a hardware in loop (HIL) simulation under various situations with predefined evaluation standards, which shows better tracking performance and applicability.

Static and dynamic responses of buried steel pipe under truck load: An experimental study

The behavior of a buried pipe under static and dynamic loading conditions has been investigated through full-scale field tests. A plain steel pipe with a diameter of 762 mm was gauged at the outer surface of two pipe sections. A dump truck was employed for the static and dynamic loading tests. Under static loading, the measured pipe strains increase with increasing axle load and decreasing cover depth. The measured strains under dynamic loading show three peaks, which correspond to the times at which the front, middle, and rear axles, respectively, reach the pipe centerline. The offset loading pattern produces greater strains than the non-offset one while keeping the axle load constant under both static and dynamic loads. It is discovered that the pipe strains caused by each truck axle vary with truck speed. Since the load transfer is influenced by a number of factors, including the truck load, road roughness, truck speed, and others, a moving truck load does not always result in higher pipe strains as compared to a static load. The complexity of dynamic pipe responses can be explained in part by a single-degree-of-freedom (SDOF) model.

Design of a Wireless Monitoring System for Vibration Characteristics of the Wheeled Tractor at Idle Speeds

To enhance the precision and efficiency of the tractor-failure-rate and equipment-quality inspection, the present study introduces a wireless rapid detection method for assessing tractor quality. For this study, which was based on the symmetrical structural characteristics of tractors, we designed a magnetic suction accelerometer. The test system was composed of a wireless router, a magnetic suction accelerometer sensor, a data-acquisition terminal, and other components. This test system aimed to test the equipment quality of the tractor at idle speed before leaving the factory. The experiment found that the vibration characteristics of the tractor had a symmetrical pattern on the left and right sides of the front and rear axle at idle. When the idle speed of the tractor was 800 r/min and 1000 r/min, the predominant vibration direction of both sides of the front axle of the tractor was the Y direction, while the predominant vibration direction of the rear axle was the Z direction. The experimental results showed that the proposed wireless rapid detection method of tractor quality and the designed acceleration sensor had good testing accuracy. The present study could provide a novel rapid detection method for the failure detection of power machinery in the agricultural field and for inspection before leaving the factory. The implementation of the method could improve the detection efficiency, and reduce the detection cost and the incidence of failure during actual use.

Vibrating roller with compacted soil interaction modelling

Introduction. Vibrating rollers are the most common means of compacting soils in construction. The nature of stress development on the contact surface of the roller with the ground depends on the technical characteristics of the vibrating roller (the mass of the roller, the mass of the roller frame, the frequency and driving force of vibrations, the number and characteristics of the roller shock absorbers) and the properties of the soil.Materials and methods. Simulation of the interaction of a vibrating roller with compacted soil was carried out using a three-mass rheological model of the frame-roller-soil system. Differential equations of mass motion in contact and separation modes were solved numerically. To determine the numerical values of the loading time (increase in contact stresses from zero to the maximum value) and the unloading time (decrease in contact stresses from the maximum value to zero), as well as the maximum reaction force of the soil, a computational experiment was conducted on a rheological model. The mass of the vibrating roller module (the mass of the front axle) and the relative driving force were used as independent parameters of the vibrating roller. The coefficients of elastic and viscous resistance of the soil were chosen as independent parameters of the soil. The total number of combinations of factors was 192. The values of the time of loading and unloading of the soil, as well as the maximum strength of the soil reaction, were determined by oscillograms of changes in the strength of the soil reaction over time.Results. Using the STATISTICA program, regression equations, to calculate the numerical values of the loading and unloading time of the soil, as well as the maximum reaction force of the soil and the corresponding values of the reliability coefficients of the multiple approximation, were obtained.Discussion and conclusion. The rheological model reproduces the asymmetric nature of changes in contact stresses during soil compaction by a vibrating roller, observed in experimental stress oscillograms obtained during field experimental studies. The results obtained are important for calculating the depth of stress propagation in the ground and the distribution of stresses in the ground after the passage of a vibrating roller using a wave approach to describing stress propagation in the ground. In the future, it is advisable to conduct a computational experiment with an expanded list of independent parameters of the roller, including the oscillation frequency.

Dynamic Load Analysis of Mine-Truck Using Multibody Dynamic Analysis Method

Abstract: Vehicle load distributed on front & rear axle assembly during various working conditions is one of the most important factors influencing working performance and service life of drive axle assembly. The dynamic load on axle assembly is higher compared to the rated load because of variations in vehicle speed and road surface conditions. Early failure of structural components is caused because of higher dynamic reaction forces due to uneven road profiles. The dynamic load calculation of axle assembly is presented in this paper for a Mine-truck with various road conditions and vehicle speeds. The road load conditions consist of grade, bump & path hole. Mine-truck with payload capacities of 63 Ton is considered for the study. The behaviour of vertical force is calculated for different vehicle speeds (3 - 12 km/hr.) of the machine on the front & rear axle assembly during running conditions. Multi-body dynamic Analysis tool ADAMS is used for this study. ADAMS helps to study the dynamics of moving parts and load distribution throughout mechanical systems during motion. The Mine-truck3D model was created with the help of computer-aided design (CAD) software. Major units of Mine trucks are considered to prepare 3D models like Cabin-engine mass, Bucket, front axle assembly, rear Axle assembly & tires. Multi-body vehicle models are prepared in simulation software ADAMS by importing 3D models prepared by computer-aided design (CAD) software. This provides guidelines for selecting dynamic load factors while designing structural parts of the vehicle.

Improving a methodology for estimating the cross-country ability of all-wheel-drive vehicles

The object of this study is the cross-country ability of four-wheel drive vehicles under off-road conditions. Based on the results of analysis of known studies, it was determined that the procedures of experimental assessment of the load-bearing capacity of bearing surfaces (BS), based on the use of the cone index, are used in NATO member countries. They take into account the characteristics of the surface of the theater of operations and make it possible to determine the approximate speeds of all-wheel drive vehicles with the help of standardized computer software. In the procedures for assessing the load-bearing capacity of BSs, which use the soil deformation module E, there is no possibility for calculating the speed of the car with known axle loads. In addition, they provide for the determination of a number of parameters of the bearing surface, such as the coefficient of adhesion, the angle of internal friction in the soil, and the shear modulus during the formation of a track. This makes them much more difficult compared to the procedures used by NATO. Therefore, the problem that is solved in this work is to improve the methodology for assessing the reference cross-country ability of four-wheel drive vehicles. Based on the results of scientific research, motion modeling was carried out in the MATLAB Simulink environment to determine parameters of reference cross-country ability of four-wheel drive vehicles. In order to determine the cross-country ability of samples of wheeled military vehicles (WMV) based on the indicator of the maximum pressure value (mean measure pressure – MMP), the conducted experimental studies were analyzed. They showed a difference in the speed modes of vehicles of the same gross weight but different layout schemes, within 11–12 %. Therefore, the methodology for assessing the cross-country ability based on MMP has been improved to take into account the features of the layout of WMV samples. Specifically, taking into account the different values of loads on the front axle of vehicles with hoodless and hood layouts at the same gross weight. In general, the improved procedure makes it possible to give a quantitative assessment of the movement mobility of WMV samples with various layout schemes and an assessment of their potential cross-country ability on the basis of the proposed refinement of MMP calculation

Comparison of finite element analysis results with strain gauge measurements of a front axle housing

Abstract. The strength of the front axle of tractors used on rough terrain is crucial in countries in which agriculture is widespread. Rough agricultural fields, rugged village roads, and ground irregularities cause unexpected reaction forces on the axles. Thus, it is important to analyze the front axle of a tractor with respect to stress, which eventually leads to cracks and premature failure. In this study, ANSYS 13.0 finite element analysis (FEA) software (ANSYS, 2010) was used to predict the strength of a design under loading conditions. ANSYS 13.0 allows products to be tested in a virtual environment and helps to prevent problems that may arise later and accordingly improve them. This study aims to investigate the stresses that occur on the housing of the front axle of a tractor. The reaction forces acting on the front axle housing can cause cracks near the middle of the housing. The study applies a static load of 30 000 N to both hubs at the end of the front axle housing and uses the FEA method to predict and evaluate the maximum stress areas on the housing. Strain gauges are bonded to these locations to measure the real-life stresses on the axle housing in these areas. The results of the FEA and strain gauge measurements were compared, and a correlation was found with 98 % accuracy.