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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.

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.

In order to study the influence of engine silicone oil fan clutch on the performances of engine cooling system under different control strategies, a model of engine cooling system for light truck is established. The working characteristics of the silicone oil clutch and the measured performance parameters of the cooling system components are taken into account in our proposed model. Modeling methods for different silicone oil fan control strategies are also given. Using the established model, the performance parameters under different vehicle speeds, such as coolant temperature of engine outlet and power consumption of cooling fan, are calculated and analyzed. The in-suite measurement of the engine cooling system is carried out to get the temperatures of engine coolant inlet and outlet from engine ECU. The model is validated by the comparison between the calculation and the measured results.

To enhance the transient vibration performance of the vehicle at key on and key off, a method for optimizing mount parameters of a powertrain mounting system (PMS) is proposed. Uncertainties of mount parameters widely exist in a PMS, so a method for optimizing mount parameters of a PMS, which treats the mount parameters of a PMS as uncertain, is also proposed in this paper. Firstly, a 13 degrees of freedom (DOFs) model including car body with 3 DOFs, a PMS with 6 DOFs and unsprung mass with 4 DOFs is established, and the acceleration of the active side of mounts is calculated. An experiment is carried out to measure the accelerations located at active and passive sides of each mount and the accelerations of seat track. A comparison is made between the measured and estimated accelerations, and the proposed model is validated. Two optimization methods for the PMS are proposed based on the developed 13 DOFs model.

The ball joint with cross groove offers both angular and plunging motion. When transmitting the same torque, the cross groove ball joint is lighter than other plunging Constant Velocity Joints (CVJs). It is crucial for the design of the joint and enhancing the contact fatigue life of the raceway to accurately estimate component loads of the ball joints with cross groove. In this study, the transmission efficiency of the joint and the peak value of contact force between ball and the track are used as evaluation indexes for characterizing dynamic performance of the joint. A multibody dynamic model of the joint is established to calculate its dynamic performance. In the model, the contact properties and friction characteristics of the internal structures were modeled, and a nonlinear equivalent spring and damping model was adopted for estimating the contact force. The transmission efficiency loss of the cross groove joint was measured and compared with the calculated values.

The influence of the channels of a liquid-cooled plate on the heat dissipation performance of battery module is investigated in this paper. A topology optimization method for obtaining channel configurations of the liquid cooled plate is presented. Firstly, the battery pack cooling system test platform is built to test the flow resistance of the liquid-cooled plate under different flow rates and the maximum temperature and temperature difference of the battery under different working conditions. Secondly, the geometric model of the battery pack is established, and CFD software is used to simulate according to the test conditions. The test results validate the correctness of the model. Then, taking the average surface temperature of the liquid-cooled plate as the optimization objective, the topology optimization structure of the liquid-cooled plate is obtained by variable density method.

When the automotive engine cooling fan is actually working, there is a process of interaction and coupling between the fluid and solid domains on the blades. In order to study the influence of the "fluid structure coupling" effect on the aerodynamic and structural performance of fans during operation, a fan performance calculation model was established with and without considering the fluid structure coupling effect of fans. We conducted aerodynamic performance tests on fans, tested the relationship between fan flow rate, static pressure, transmission efficiency and fan speed, and compared and analyzed the calculated fan performance. The aerodynamic performance and structural deformation of the fan were calculated under different flow rates, rotational speeds and environmental temperatures, with and without considering the coupling of fan blades and airflow. The calculation results were compared and analyzed.

To study the heat dissipation performance of the multi-fan cooling module composed of multiple fans and a radiator, numerical models of the radiator and the multi-fan cooling module were established, and heat dissipation performance prediction analysis and application analysis were conducted. In modeling, the Effectiveness-Number of Transfer Units (ε − NTU) method is used to predict the heat dissipation performance of the radiator. The aerodynamic performance of the fan at any speed is obtained by the similarity theorem using the data obtained from the tests at a certain speed. The influence between the fan and the radiator was established by using the flow addition scheme. To validate the established model, heat dissipation performance using 36 radiators and 11 multi-fan cooling modules is measured, and the measured data are compared with the calculations.

An Inline 4-cylinder engine is equipped with second-order balance shafts. When the engine is running under no-load acceleration conditions, the gear system of the balance shaft generated whine noise. In this paper, an analysis and experiment method for reducing the whine noise is presented. First, a flexible multi-body dynamic model of the engine is established, which includes shaft and casing deformation, micro-modification of the gears. Taking the measured cylinder pressure as input, the load on each gear of balance shaft gear system is calculated. In addition, the influence of tooth surface micro-modification on the meshed noise was analyzed. The results show that the dynamic meshing force between the crank gear and the shim gear is large under the original tooth surface micro-modification parameters, which is the main reason of the whine noise.

In this paper, the influence of the decoupler-cage structure on the hitting noise of the hydraulic mount is studied, the abnormal noise of the hydraulic mount is mainly caused by the collision impact between the decoupler and the cage, the hitting noise was simulated and evaluated using calculation and experiment. a finite element model of the collision impact between the decoupler and the cage is developed, and an explicit finite element analysis is performed to obtain the time history of the vibration acceleration of the model, which is used as the boundary condition of the noise analysis. The acoustic boundary element method is used to analyze the impact noise of the decoupler-cage, and the frequency domain distribution characteristics of the impact sound pressure are obtained. The influence of different decoupler structure on the hitting noise is studied, and the recommended values for each parameter for a structure are given.

The influence of engine cooling fan on the working state of engine cooling system under different driving forms and control strategy is studied, and a simulation model of engine thermal management system of a commercial vehicle is established. The model takes into account the measured performance parameters of the cooling system components, the gear shift logic of the transmission, the effect of vehicle speed on the airflow rate of the radiator, and proposes a modeling method for different cooling fan driving forms. The performance parameters such as engine outlet coolant temperature and corresponding cooling fan speed under different vehicle speeds and engine loads are calculated and analyzed by using the established model. The road measurement test of the engine thermal management system under the same working condition was carried out to read the relevant data from the engine ECU and confirm the reliability of the data.

Considering the interaction between fan blades and the surrounding air when a cooling fan rotates, the Fluid-Structure Interaction (FSI) model of the fan is established, and flow rate, static pressure, efficiency versus speed of the fan are calculated and analyzed. The aerodynamic performance of the fan is carried out, and the measured performance parameters are compared with calculated to validate the developed model. Using the established model, the performance of fans with different rotating speeds, diameters and blade installation angles is calculated. The effects of fan speed, diameter and blade installation angle on blade deformation and aerodynamic performance are studied.

A battery cooling system model of electric vehicle was established. The system model consists of a battery pack, a pump, a radiator, and a fan. A cooling plate was used to cool the battery pack, and the coolant flow rate in the cooling plate was controlled by the pump. The heat in the battery cooling system was released into the ambient air through the radiator. A finite element analysis model of the cooling plate was established to calculate the pressure drop of the cooling plate. A coupled dynamics model of the battery pack-radiator cooling system was established to simulate the temperature of the battery pack during charging and discharging. Tests were carried out to obtain the pressure drop of the cooling plate and the temperature of the battery pack under different working conditions. The simulation results and test results were compared and analyzed, and the accuracy of the models were verified.

Robust data association is a core problem of visual odometry, where image-to-image correspondences provide constraints for camera pose and map estimation. Current state-of-the-art visual semantic odometry uses local map points semantics, building semantic residuals associated with all classes to realize medium-term tracking of points. Considering the problem of inefficient semantic data associations and redundant semantic observation likelihood model in the visual semantic odometry, we propose a visual odometry, Local Semantic Odometry (LVSO), which is integrated with medium-term semantic constraints based on local nearest neighbor distance model.

Because autonomous vehicles (AVs) equipped with active front steering have the features of time varying, uncertainties, high rate of fault, and high burden on the in-vehicle networks, this article studies the adaptive robust control problem for improving lateral stability in steer-by-wire (SBW) vehicles in the presence of abrupt nonlinear faults. First, an upper-level robust H∞ controller is designed to obtain the desired front-wheel steering angle for driving both the yaw rate and the sideslip angle to reach their correct values. Takagi-Sugeno (T-S) fuzzy modeling method, which has shown the extraordinary ability in coping with the issue of nonlinear, is applied to deal with the challenge of the changing longitudinal velocity. The output of the upper controller can be calculated by a parallel distributed compensation (PDC) scheme.

Electromagnetic semi-active hydraulic engine mount (HEM) with double inertia tracks can realize the opening and closing of the inertia tracks through the control of electromagnetic actuator, so as to meet the needs of vibration isolation in different working conditions, but the cost is high. In this paper, without using electromagnetic actuator, a mechanical semi-active HEM with double inertia tracks is designed and manufactured with simple structure and low cost. In this study, the feature of mechanical semi-active HEM with double inertia tracks is that a baffle-current limiting column structure is added in the inertia track. Under different excitation amplitudes, the baffle-current limiting column structure can open and close the inertia track passively. Several mechanical semi-active HEM with double-inertia tracks samples and conventional inertia tracks HEM samples are manufactured and the dynamic characteristics of these samples under low frequency excitation are tested.

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 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.

For the improvement of the vehicle yaw stability, this paper studies the control problem of the active front steering (AFS) system with actuator input delay. A novel sliding mode predictive control method to handle actuator input delay is proposed for the AFS system. Firstly, considering the nonlinearities of the vehicle system, a linear parameter varying vehicle system model with two-level structure is proposed to capture the vehicle dynamic behaviors. Secondly, to deal with the issues of actuator input delay and system constraints, a novel sliding mode predictive control method is put forward. In the process of controller design, a sliding mode control algorithm is employed for the improvement of the robustness of the control system, and then a model predictive control algorithm is employed to deal with system constraints.

Turbulence caused by the blade tip of engine cooling fan is one of important noise generating factors. Existing theoretical researches show that the bionic serrated designs applied at the front and rear edges of fan blades can effectively improve the airflow characteristics and reduce the aerodynamic noise. However, the effect of its application at the blade tip needs to be explored and verified. In this research, vehicle engine fans whose tips are designed and remodeled with different size of triangular serrated edge have been tested on airduct, to explore the fan static pressure and noise that caused by changing of period and amplitude size. The large eddy simulation (LES) and FW-H acoustic analogy method are adopted to calculate the transient noise of each designed fan.