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During the operation of the ball joint, its service life and transmission efficiency are affected by the internal friction. Taking the ball joint as the research object, based on fractal theory, the friction between the steel ball and the raceway inside the ball joint of an automotive drive shaft system is studied in this paper. During the analysis, the friction between the steel ball and the arc raceway is regarded as the friction between a sphere and an arc raceway surface. In order to describe the friction state more accurately, this paper proposes a correction coefficient to modify the distribution function of contact asperities in the plane, and obtains the distribution function of contact asperities between the sphere and the arc raceway surface. The correction coefficient is related to the load, the size parameters and the material parameters of the steel ball and the raceway.

Design of powertrain mounting bracket is always challenging in achieving good NVH characteristics, sound durability and simultaneously reduced weight. Structural optimization is an effective tool to obtain an optimum design. Depending on the design status, different schemes, i.e. size, topology and shape optimization, are applied. In this paper, a case study of application of structural optimization in the design of a mount bracket has been presented. Firstly, both test and FEA (Finite Element Analysis) results expose problems of the initial design. Therefore, it is necessary to redesign the bracket. With sufficient design freedom and time in topology optimization, design space and optimization parameters are defined. Die direction and other manufacturability considerations for the casting components are vital. Shape optimization is then conducted to further decrease the weight and refine local weakness.

The trajectory planning and the accurate path tracking are the two key technologies to realize the intelligent driving. The research of the steering wheel angle plays an important role in the path tracking. The purpose of this study is to optimize the steering wheel angle input during the automated lane changing. A dynamic programming approach to trajectory planning is proposed in this study, which is expected to not only achieve a quick reaction to the changing driving environment, but also optimize the balance between vehicle performance and driving efficiency. First of all, the lane changing trajectory is planned based on the positive and negative trapezoidal lateral acceleration method. In addition, the multi-objective optimization function is built which includes such indexes: lateral acceleration, lateral acceleration rate, yaw rate, lane changing time and lane changing distance.

Because the power unit of electric vehicle has large torque, the rubber mount of electric vehicle is fully compressed under the condition of full throttle acceleration. When designing the mount of electric vehicle, the dynamic-to-static stiffness ratio of mount under the case should be as low as possible to improve the vibration isolation rate of the mount. In this paper, a method for calculating the high frequency dynamic characteristics of rubber isolators under different preloads is presented. Firstly, the dynamic characteristics of rubber specimens under various shear pre-strains were tested. The test results show that the dynamic stiffness of specimen decreases at first and then increases with the increase of shear strain. The viscoelastic parameters of rubber in frequency domain under different pre-strain were identified according to the experimental data. Secondly, a finite element modeling method was proposed.

The application of turbochargers in fuel vehicles brings high-frequency noise, which seriously affects the vehicle's ride comfort. The hiss noise of a turbocharged car is improved in this paper. Firstly, under different operating conditions and whether the air intake system is wrapped, the noise in the vehicle cabin and the driver's right ear is tested, and the noise sources and noise characteristics are identified. Then, the acoustic calculation model of the muffler is established, and the transmission loss (TL) of the original muffler behind the turbocharger (MBT) is calculated. The TL of the muffler is measured by the double-load impedance tube method. The finite element calculation model is verified by comparing the TL of muffler calculated with tested. Thirdly, the MBT is redesigned. The improved muffler significantly improves the performance of eliminating high-frequency noise, and its TL beyond 20 dB is expanded to the band of 1600 ~ 3500 Hz.

The static characteristics of solenoid valve play an important role in the performance of brake system and can indirectly reflect the response speed of the brake system. The static characteristics of the solenoid valve reflect the electromagnetic characteristics of the solenoid valve itself, revealing the maximum potential of the solenoid valve in the system work, which is one of the important characteristics to characterize the working ability of the solenoid valve. In this paper, a numerical calculation method is used to build a finite element model of the solenoid valve electromagnetic field on the Ansoft Maxwell simulation platform. The model takes into account the nonlinear magnetization characteristics of soft magnetic materials and the air gap.

Aiming at the problem of middle and low frequency noise absorption, a combined sound-absorbing structure is designed based on porous material and a coiled-up cavity resonance structure. Combined with the sound absorption principle of porous materials and coiled-up cavities, a theoretical analytical model was established. By the finite element method, the sound absorption coefficient curve of the combined structure in a frequency range of 500-2000Hz is calculated, and the correctness of the analytical calculation and the finite element simulation calculation was verified in the impedance tube experiment. The results show that the combined structure has good sound absorption performance in the 500Hz-2000Hz frequency band, and the sound absorption peak appears near the 1108Hz frequency, reaching nearly perfect sound absorption. Compared with a single porous material, the sound absorption performance of the combined structure is better.

The good mobility and large carrying capacity promote the popularity of intercity coach in mass transit, especially in the long distance passenger transport nowadays. However, accidents related to coach and bus usually involve large casualties. Higher risk of fatalities is exhibited in rollover than the other coach accident types. In order to protect the occupants when a rollover accident occurs, coach structure must have sufficient strength to resist the impact loads. This paper presents a rollover test of an intercity coach body section using both numerical simulation and experimental testing to investigate its rollover crashworthiness in accordance with ECE R66. A full scale coach body section is manufactured and a tilting bench is designed and fabricated. Displacement transducers and accelerometer are equipped to record the time history of superstructure deformation and impact acceleration. And the FE model was developed accordingly.

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.

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.

In the field of low-frequency noise control, the acoustic metamaterials have received extensive attention from researchers. However, the existing work mainly focuses on small structures with fixed boundaries, which is quite different from engineering applications. Based on the membrane-type acoustic metamaterials, this paper uses a rigid thin plate to replace the tensioned membrane, design and manufacture of two new types of local resonance structure and studies their sound insulation properties. First, the metamaterial samples with a small size of 100mm in diameter and a large-size square with a side length of 506mm were produced, and the sound TL of the two was tested through the impedance tube and the reverberation chamber-anechoic chamber, respectively. The results show that the new structure can form an obvious sound insulation frequency band at low frequencies. Based on the finite element method, a metamaterial acoustic transmission loss calculation model is established.

A test bench is proposed to be developed to measure relevant mechanics responses of lithium-ion batteries during different charge and discharge processes. It primarily consists of two parts: a mechanical structure part and a measurement and control part. The test system composed of an upper/lower battery fixing spacer and a battery is the core part of the mechanical structure part. This measurement and control part mostly contains an environmental control, an acquisition as well as a charge discharge system.

Welding deformation of aluminum alloy is an urgent problem to be solved, it affects the performance and service life of welding products. In this research, in order to compute welding deformation and residual stress, a finite element model of 6061-T6 aluminum alloy was established. The efficiency and the accuracy of the welding residual stress calculation and the welding deformation were significantly improved. By comparing the temperature field and the displacement field of simulation and experiment, the finite element model was validated. Through finite element analysis, Heat input and welding times have important effects on welding deformation and residual stress was found. The welding deformation law and the residual stress distribution law were proposed, after cooling of the welding seams, the plates collapsed to the other side of the heat source along the vertical direction, the welding deformation tendency was heightened by double-sided welding.

Taking a closed airbag suspension system as studying objects, the nonlinear dynamic model of the reservoir, compressor, solenoid valve, pipeline and air spring is established. The compressor exhaust volume, solenoid valve flow rate and air spring charging and discharging rate are calculated and compared with experiment to validate the model. Taking pressure difference and height adjustment rate under different working conditions of an airbag suspension as control measures, a control strategy is developed based on the established nonlinear dynamic model. The result indicates that when the vehicle is in curb weight, design weight and GVW (gross vehicle weight), the working time of the compressor can be reduced by 13.6%, 15.1% and 46.5%, respectively, compared with the conventional mode, during a height adjustment cycle. Then a state observer is proposed to estimate the steady-height for reducing the disturbance of measured height from road excitation.

Bumper systems are vital to improving automotive passive safety and reducing the maintenance cost in low-speed collision. Automotive companies need to develop bumpers with adequate strength, high energy absorption rate, minimum weight and least expense. To shorten the product development period and lower the development cost, four evaluation conditions were proposed to assess the behaviors of car front bumpers based on the three main low-speed collision regulations of the US Part 581, the Canadian CFVSS215 and the European ECE-R42. A finite element method was put forward to model the car front bumper and to analyze the low-speed collision performance of the bumper system. A drop hammer impact test was carried out to verify the validity of the method, and experiment results indicated the correctness of the finite element model.

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.

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.

An automatic tensioner used in an engine front end accessory drive system (EFEADS) is taken as a study example in this paper. The working torque of the tensioner, which consists of the spring torque caused by a torsional spring and the frictional torques caused by the contact pairs, is analyzed by a mathematic analysis method and a finite element method. And the calculation and simulation are validated by a torque measurement versus angular displacement of a tensioner arm. The working torques of the tensioner under a loading and an unloading process are described by a bilinear hysteretic model, and are written as a function with a damping ratio. The rule of the action for the damping devices is investigated based on the simulation and a durability test of the tensioner. A finite element method for the tensioner without damping device is established. Then the radial deformation for the torsional spring under an unconstrained state is obtained.

There is the possibility of decoupler’s impact noise in hydraulic engine mount (HEM) with a free decoupler, but there is little research on this aspect. As for how to solve the problem of decoupler’s impact noise, most of the papers are only improved through trial and error. This article uses three HEMs with different decoupler plates and cages as the research object for the experiment. First, calculate the contact force between the decoupler plate and cage of the HEM through the finite element method, to determine whether the decoupler’s impact noise problem will occur. Then design the bench test of the abnormal noise of the HEMs to verify the conclusion obtained by the calculation of the contact force. Next, deduce the relationship between the transmitted force at the chassis side of the HEM and the impact force of the decoupler, and propose a test method for evaluating the decoupler’s impact noise based on the transmitted force at the chassis side of the HEM.

During the operation of the automotive drive shaft system, the ball-type universal joint will generate a secondary torque, which will affect the torque transmission of the automotive drive shaft system and the comfort of the automobile. Under the influence of the internal friction of the ball-type universal joint, the secondary torque generates a torque component on the plane where the working angle is located and the plane perpendicular to the working angle. To effectively calculate and analyze the secondary torque, this paper establishes a multi-body dynamic model of the ball-type universal joint. At the same time, the secondary torque of the ball-type universal joint is measured by the NVH multi-function test bench, which verifies the validity of the multi-body dynamic model. In order to improve the analysis efficiency of the secondary torque, a proxy model of the secondary torque of the ball-type universal joint is established based on the multi-body dynamic model.