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The joint forces and moments applied to the joints in an air suspension system in truck are important input loads for lightweight and fatigue analysis of bushings, air spring brackets, torque arms and trailing arms. In order to derive a reliable solution of joint forces and moments, engineers will generally use Multi Body Dynamics (MBD) simulation software, like ADAMS, which can save time in product development cycle. Taking an air suspension in truck as a study example, a 2-dimensional quasi-static model of an air suspension, whose stiffness of air spring and bushing is nonlinear, is established in ADAMS environment. After that, simulations are performed at the typical and extreme working condition respectively, and the results are compared with another three cases. Case I assumes that the stiffness of air spring is linear but the stiffness of bushings, including torsion and radial stiffness, are nonlinear.

An Inline 4-cylinder engine is equipped with second-order balance shafts.When the engine is running under full load in 5000rpm,the engine generated severe structural radiation noise.The bench test analysis shows that the main reason is the resonance of the engine near 800Hz and 1500Hz. In this paper, a method for modeling and analyzing the vibration of the engine structure is proposed, and the sound quality of the engine is evaluated and imporved by the Moore–Glasberg loudness method. Firstly, the finite element model of the engine was established, and the experimental modes of the engine casing assembly, crankshaft and balance shaft were measured. The natural frequencies and modal shapes obtained by calculation and experiment were compared, which validates the established finite element model.Secondly, a flexible multi-body dynamic model of the engine was established.

To solve the contradiction between model complexity and the warning accuracy of the algorithm of the vehicle rollover warning, a rollover state warning method based on the secondary predictive zero-moment point position for vehicles is proposed herein. Taking a sport utility vehicle(SUV) as the research object, a linear three-degrees-of-freedom vehicle rollover dynamics model is established. On the basis of the model, the lateral position of the zero-moment point and its primary and secondary rates of change are calculated. Then, the theoretical solution of time-to-rollover of the vehicles is deduced from the lateral position of the secondary predictive zero-moment point. When the rollover warning index, the lateral position of the zero-moment point, is greater than the set threshold, the active anti-rollover control system will be triggered. The active anti-rollover braking control system adopts a hierarchical control strategy.

The vehicle will produce certain shock and vibration during the braking process, which will affect the driving experience of the driver. Aiming at the problems of pitch vibration, longitudinal vibration and shock during the braking process, this paper proposes a planning and following control method for target longitudinal acceleration in post-braking phase, and designs control trigger strategies. Target longitudinal acceleration planning takes minimizing longitudinal shock as the design goal. The following control takes the brake pressure as the control object, and adopts the “feedforward +PID feedback” method to follow the target longitudinal acceleration. Besides, considering the safety of braking process, the trigger condition of control is designed which utilizes BP neural network method to judge whether the control has to be triggered. Based on Simulink software, the simulation model of straight-line braking is established.

In order to improve the ride comfort and road friendliness of heavy commercial vehicles, a lateral interconnected air suspension system is developed. Based on the theory of thermodynamics and vehicle dynamics, a Ten-degree-of-freedom vehicle dynamics model with lateral interconnected air suspension is established. Interconnected pipeline parameters’ influence on characteristics of air suspension system in whole vehicle are calculated and analyzed. Simulation results show that the stiffness of air suspension decreases gradually with the increase of interconnected pipeline diameter. The designed interconnected air spring experiments verify the simulation results. Simulation on vehicle dynamics models is carried out by building random road models with different roughness levels in MATLAB.

In order to study the effects of different factors on the static and dynamic characteristics of air springs, three models were established to calculate the static and dynamic characteristics of air springs, including modeling at the design position, modeling only considering the straight state, and modeling considering the thickness of the bellows in the straight state. Static stiffness of air springs is calculated using three different models and are compared with experiments. In the straight state model considering the thickness of the bellow, the influence of aluminum tube and bellows thickness on the static stiffness are considered, and the modeling with the straight state solved the problem of the change in cord angle after the air spring was inflated and expanded. The established model is then used to calculate static and dynamic characteristics of air springs, such as static stiffness, hysteresis loop, and dynamic stiffness.

The generator is an important loaded component of an engine front end accessory drive system (EFEADS). With a huge moment of inertia and a highest running speed, the vibration and noise often occurs in operation, which has an effect on the service life. Thus an overrunning alternator decoupler (OAD) is used in the EFEADS for reducing the vibration of system. In this paper, a model of EFEADS with an OAD is established. The impact of the OAD on the dynamic responses of pulley of generator and the system are analyzed, and is verified by bench experiments. And the influence of parameters, such as spring stiffness, moment of inertia of generator and loaded torque on the dynamic performances of the system are studied. The influence of misalignment in pulleys on the dynamic performance of system is also discussed. The presented method is useful for optimizing the dynamic performance of system, such as the oscillation of tensioner arm and the slip ratio of the belt-generator pulley.

An experiment is carried out to measure creep groan of a drum brake located in a trailer axle of a truck. The noise nearby the drum brake and accelerations on brake shoes, axle and trailer frame are collected to analyze the occurring conditions and characteristics of the creep groan. A multi-body dynamics model with 1/4 trailer chassis structures is established for analyzing brake component vibrations that generates the creep groan. In the model, the contact force between brake cam and brake shoes, the contact friction characteristics between brake linings and inner circular surface of brake drum, and the properties of chassis structure are included. Dynamic responses of brake shoes, axle and trailer frame during the braking process are estimated using the established model and the responses are compared with the measured results, which validate the model.

The kinematic model of the double roller tripod joint is established in order to analyze its kinematic characteristics and provide theoretical basis for its application and improvement. By means of spatial coordinate transformation, the translational and rotational motion equations of the rollers relative to the tracks and trunnions, the motion equation of the center of the tripod and the equations of the input/output angular displacement error and bending angle are derived. The motion simulation of the double roller tripod universal joint was carried out in ADAMS so as to verify the established kinematic model. The results show that the rollers of the double roller tripod joint only have periodic translational motions relative to the tracks while the rollers have both periodic translational and rotational motions relative to the trunnions. The tripod’s center does the circular motion on the tripod plane with the angular velocity 3 times of the input angular velocity.

The fatigue prediction model of an air spring based on the crack initiation method is established in this study. Taking a rolling lobe air spring with an aluminum casing as the studying example, a finite element model for analyzing force versus displacement is developed. The static stiffness and dimensional parameters of limit positions are calculated and analyzed. The influence of different modeling methods of air springs bellow are compared and analyzed. Static stiffness measurement of an air spring is conducted, and the calculation results and the measured results of the static stiffness are compared. It is shown that the relative error of the measured stiffness and calculated stiffness is within 1%. The Abaqus post-processing stage is redeveloped in Python language.

This paper designs the important components and structure of the integrated electro-hydraulic brake system (I-EHB). Firstly, the simplified linear system is modeled, and the transfer function without considering the nonlinear disturbance such as system friction is derived, and the correctness of the linear system is preliminarily verified by AMESim. Then set up the I-EHB system test bench, and use the Stribeck friction model to identify the friction torque parameters in the static and kinetic friction stages of the system to obtain a more accurate friction model. Finally, based on the I-EHB system model of friction disturbance, a pressure-speed-current three-loop cascade PID controller is designed, and a feedforward controller based on the system model is added to form the control structure of “pressure feedforward compensation + pressure-speed-current closed-loop cascade PID”.

This paper presents an adaptive H2/H∞ control strategy for a semi-active suspension system with unknown suspension parameters. The proposed strategy takes into account the damping force characteristics of continuous damping control (CDC) damper. Initially, the external characteristics of CDC damper were measured, and a forward model and a back propagation (BP) neural network inverse model of CDC damper were proposed using the measured data. Subsequently, a seven-degree-of-freedom vehicle with semi-active suspension system and H2/H∞ controller was designed. Multiple feedback control matrices corresponding to different sprung mass parameter values were determined by analyzing time and frequency domain performance. Finally, a dual observer system combining suspension state and parameter estimation based on the Kalman filter algorithm was established.

The automatic tensioner is an important component of the engine front end accessory drive system (EFEADS). It maintains the tension of the belt steadily and reduces the slip of pulley, which is benefit for improving the life of V-ribbed belt. In this paper, an EFEADS model is established which is considering with the hysteretic behavior and the asymmetry of friction damping of a tensioner. A four-pulley EFEADS is taken as a study subject. The dynamic responses of system, such as the oscillation angle of each pulley, the slip factor of pulley, the oscillation of tensioner arm and the dynamic belt tension are analyzed with symmetric damping and asymmetric damping tensioner. Meanwhile, the influence of asymmetric damping factors of tensioner on the dynamic response of EFEADS is also investigated.

A road test on semi-trailers is carried out, and accelerations of some characteristic points on the braking system,axles,and truck body is measured,also brake pressure and noise around the support frame is acquired.The measured data was analyzed to determine the causes of the brake noise, and the mechanism of the noise of the drum brake of semi-trailers during low-speed braking was investigated. The following conclusions are obtained: (1) Brake noise of the drum brake of the semi-trailer at low-frequency is generated from vibrations of the brake shoes, axle, and body, and the vibration frequency is close to 2nd natural frequency of the axle. (2) Brake noise is generated from stick-slip motion between the brake shoes and the brake drum, where the relative motion between the brake drum and the brake shoes is changed alternately with sliding and sticking, resulting in sudden changes in acceleration and shock vibration.

As the main power source of new energy vehicles, the durability and fatigue characteristics of the battery pack directly affect the performance of the vehicle. The battery pack system was modelled using multi-body dynamics software, with 7 and 13 degree of freedom models developed. Using the established model, the intrinsic properties of the battery pack are computationally analyzed. To calculate the dynamic characteristics, a sinusoidal displacement excitation is applied to the wheel centre of mass, and the displacement and acceleration of the battery pack centre of mass are calculated for both models.The displacement and acceleration curves at the centre of mass of the battery pack of the two models are compared. The results show that the amplitude of the displacement and acceleration curves at the centre of mass of the 13 degrees of freedom model of the battery pack has decreased significantly.

Sliding mode control with a disturbance observer (SMC-DO) is proposed for suppressing the sprung mass vibration in a quarter-car with double-wishbone active suspension system (ASS), which contains the geometry structure of the upper and lower control arms. The governing equations of double-wishbone ASS are obtained by the balance-force analysis of the sprung mass in ASS. Considering uncertainties in damping, stiffness, and external disturbance acting on the sprung mass, we design a disturbance observer based on a sliding mode control (SMC) to estimate these uncertainties under the unknown road excitation. By the Lyapunov minimax approach, the uniform boundedness and the uniform ultimate boundedness of ASS with the proposed control are rigorously proved. Through co-simulation of ADAMS software and MATLAB/Simulink software, the sprung mass acceleration of ASS can be obtained with and without the proposed control.

A fourth-order mathematical model for I-EHB (integrated electro-hydraulic brake) system was derived from its mechanical and hydraulic subsystems. The model was linearized at equilibrium state and then was verified by AMESIM software. The friction model of the system was analyzed based on static friction and viscous friction. A bench test was designed to identify the parameters of friction model. As the I-EHB system worked at different braking conditions, a PID-based switching controller was designed to track the target servo cylinder pressure. Both simulations and experiments results showed that, the response time of pressure was less than 120ms, and there was no overshoot, which helped handling different braking conditions and improving the braking safety and comfort.

The durability road test of a vehicle is an important test to verify the reliability of vehicle components. In order to carry out the durability bench test for drive shaft systems of all-terrain vehicles, a method for acquiring time domain signals of articulation angles of the CVJ, input torque, and rotational speeds of drive shaft systems is proposed. The acquired load spectrum of drive shaft systems is preprocessed including deleting small amplitudes, de-drifting, deburring, filtering, etc. Peaks and valleys are extracted from the preprocessed load spectrum. Based on the graphic method and the estimator stabilization method, the upper and lower thresholds of the time domain extrapolation of the load spectrum are determined, and then the peaks and valleys excesses that exceed the upper and lower thresholds are extracted. The generalized pareto distribution function is used to fit the distribution of peaks and valleys excesses.

This paper proposes a new evaluation method of analyzing stability and design of a controller for an electric power steering (EPS) system. The main purpose of the EPS system’s control design is to ensure a comfortable driving experience of drivers, which mainly depends on the assist torque map. However, the high level of assist gain and its nonlinearity may cause oscillation, divergence and instability to the steering systems. Therefore, an EPS system needs to have an extra stability controller to eliminate the side effect of assist gain on system stability and attenuate the unpleasant vibration. In this paper, an accurate theoretical model is built and the method for evaluating system quality are suggested. The bench tests and vehicle experiments are carried out to verify the theoretical analysis.