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Table of Content

    25 November 2023, Volume 45 Issue 11 Previous Issue    Next Issue
    Research on Integrated Thermal Management System of Hydrogen Fuel Cell Vehicle
    Zhongwen Zhu,Xin Wang,Weihai Jiang,Cheng Li
    2023, 45 (11):  1991-2000.  doi: 10.19562/j.chinasae.qcgc.2023.11.001
    Abstract ( 312 )   HTML ( 40 )   PDF (4189KB) ( 350 )   Save

    Effective thermal management is crucial for the efficient operation of fuel cell vehicles (FCVs). Fuel cell vehicle thermal management often adopts independent management methods for each subsystem, but this independent method cannot effectively utilize its own waste heat to improve thermal management efficiency and range. In this regard, a vehicle integrated thermal management (VITM) system that utilizes fuel cell waste heat is developed in this paper. The VITM uses a heat exchanger to achieve waste heat recovery of fuel cells and efficient thermal management of various components. The flexible management of each circuit decoupling is achieved through the integrated design of six-way valves. And simulation research on thermal management is conducted on the AMESim simulation platform. The results show that the VITM system developed in this paper can maintain the stability of various components of fuel cell vehicles within the specified operating temperature range. At an ambient temperature of -10 ℃, compared with direct heating mode, a heat pump air conditioner using fuel cell waste heat as a heat source to heat the power battery, the heating time is reduced by 55%.The heating time for the passenger compartment is reduced by 85%, and the energy consumption ratio (COP) value is 4, resulting in a 75% reduction in energy consumption.

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    Performance Analysis of a Thermal Management System for Electric Vehicles Based on the Three-Fluid Heat Exchanger
    Tianchan Yu,Yuan Wang,Wenxing Shi,Chenjiyu Liang,Xianting Li,Junping Cen,Min Luo
    2023, 45 (11):  2001-2013.  doi: 10.19562/j.chinasae.qcgc.2023.11.002
    Abstract ( 126 )   HTML ( 7 )   PDF (7991KB) ( 160 )   Save

    The electric vehicle can achieve energy conservation, emission reduction, energy storage and peak shaving, which is of great significance for the realization of China's "carbon peaking and carbon neutrality" goals. For the problems of the current thermal management system for electric vehicles of complex heat exchange processes, low system energy efficiency, and the difficulty in integration and lightweight, in this paper, a thermal management system based on the three-fluid heat exchanger for electric vehicles is proposed. The calculation model of the three-fluid heat exchanger is established through prototype experiments and tests, and the performance model of the thermal management system of the three-fluid heat exchanger is established by combining the load model and heat pump model. Besides, the operating performance of the proposed thermal management system under different conditions is analyzed and compared with the existing typical thermal management systems for electric vehicles. The results show that the energy consumption of the thermal management system with the three-fluid heat exchanger is 2.3% and 15.1% lower than that of the existing air-cooled condenser system and liquid-cooled condenser system respectively at 36 ℃ and 60 km/h in summer. And the energy consumption of the thermal management system with the three-fluid heat exchanger in the outdoor waste heat recovery mode and indoor waste heat recovery mode is reduced by 5.9% and 19.7% respectively compared with the system without waste heat recovery at 0 ℃ and 60 km/h in winter.

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    Research on the Preheating Strategy of Lithium Batteries Under Subzero Temperature for Electric Vehicles
    Qiao Xue,Junqiu Li,Yansheng Xiao,Yu Zhao,Yu Liu,Dongxue Han
    2023, 45 (11):  2014-2022.  doi: 10.19562/j.chinasae.qcgc.2023.11.003
    Abstract ( 194 )   HTML ( 31 )   PDF (3022KB) ( 314 )   Save

    To improve the driving range of electric vehicles under low temperatures, a battery pack heating strategy based on the optimization of heating target temperature is proposed in this paper, which can effectively enhance the battery energy efficiency to achieve the driving requirement under low temperature. Firstly, the maximum discharge capacity of the battery at different temperatures is determined by the experiment test. Secondly, based on the energy retention rate of the battery at different temperatures and considering the influence of temperature on the battery life, a nonlinear multi-objective constraint function is established and solved to obtain the optimal heating target temperature of the battery under different ambient temperatures and different SOC. Finally, the heating strategy is validated via simulation of the physical model calibrated with real world vehicle experiment data. The experimental results show that the vehicle driving range based on the optimized battery heating target temperature increases maximumly by 8.41% and 4.77% respectively at the initial temperature of -15 and -5 ℃, indicating the proposed method can effectively improve the driving range of electric vehicles at low temperature.

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    Multi-parameter Optimization Analysis of Factors Influencing Thermal Comfort in Automobile Passenger Compartment
    Guohua Wang,Guohui Sang,Yingchao Zhang,Jincheng Xu
    2023, 45 (11):  2023-2033.  doi: 10.19562/j.chinasae.qcgc.2023.11.004
    Abstract ( 147 )   HTML ( 15 )   PDF (5385KB) ( 128 )   Save

    At present, the cruising range of pure electric vehicles is greatly affected by the environment. In this paper, taking SUV models as the research object, the mathematical model of the passenger compartment is constructed by computational fluid dynamics software. Coupling with the human thermophysiological model, the Berkely thermal comfort evaluation model is used to evaluate the human thermal comfort in the passenger compartment. For the high temperature working conditions, the influence of air supply temperature, air supply speed and air humidity on the thermal environment of the passenger compartment, the total load of air conditioning and the thermal comfort of human body is studied. The results show that when the supply air speed changes from low to high, the overall thermal comfort of the occupants will first increase, then decrease, and the energy consumption will also increase. Moreover, under the condition of low supply air speed, the change of supply air temperature has limited effect on the overall thermal comfort. The influence of supply air humidity on thermal comfort is weaker than that of supply air temperature and supply air speed. At the same time, in this paper, by taking the supply air temperature, relative humidity of the supply air and supply air speed as the independent variables, and taking the overall thermal sensation, overall thermal comfort index and even the total load of the air conditioning system as the research objects, the regression equation of the relationship between them is constructed. Using the multi-parameter optimization analysis, the influence of different air supply parameters on thermal comfort and air conditioning load is coupled to analyze. The target value of the overall thermal comfort index of the occupants is set to 0, the target value of the heat load reduction of the air conditioning system is set to the minimum value, and the weight of the overall thermal comfort index of the occupants and the load of the air conditioning system are set to 1, so as to find the best solution to achieve the purpose of improving thermal comfort and reducing the heat load of the air conditioning system.

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    Analysis of Differential Effect of Local Thermal Response on Overall Thermal Sensation in Non-uniform Thermal Environment
    Jiqing Chen,Xiaoting Li,Fengchong Lan,Weijian Li
    2023, 45 (11):  2034-2046.  doi: 10.19562/j.chinasae.qcgc.2023.ep.005
    Abstract ( 124 )   HTML ( 11 )   PDF (4102KB) ( 158 )   Save

    Under the trend of vehicle intelligence and electrification, it is an important optimization goal of the regionalized thermal environment management performance of the passenger compartment to meet the requirements of both human thermal comfort and vehicle energy saving. Especially in the narrow space environment with highly non-uniform heat flow characteristics, the thermal environment of the passenger compartment can be optimized efficiently only by correctly understanding and quantifying the differences and related effect of local human body heating, response and heat demand. Therefore, combing the physical and physiological thermal regulation characteristics of the human body and its relationship with the environmental heat transfer of the passenger compartment, a numerical analysis model of the thermal response of the human body is established to analyze the variation law of human skin temperature and thermal sensation under the effect of non-uniform local heat flow. The influence factor analysis method is applied to quantify the characteristics of the relationship between local and overall thermal sensation, and different key parts of the effect of local heat flow on the overall thermal sensation of the human body are obtained. The results show that under the same intensity of cold/heat excitation, the head and hands of the human body are the main parts that affect the overall thermal sensation of the human body, with the largest variation amplitudes of the skin temperature and thermal sensation response. In a high temperature environment, the key parts with requirement for local cooling are the head, hands, chest and back in turn while in a cold environment those with requirement for local heating are the head, hands and feet.

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    Multi-objective Optimization of Lithium Battery Composite Cooling Structure Based on Heat Pipes and Liquid Cooling Plate
    Zhiyong Duan,Jing Ma
    2023, 45 (11):  2047-2057.  doi: 10.19562/j.chinasae.qcgc.2023.11.006
    Abstract ( 100 )   HTML ( 8 )   PDF (3653KB) ( 172 )   Save

    To meet the temperature consistency requirements of lithium batteries after packaging, this paper proposes a composite cooling structure based on heat pipe (HP) and liquid cooling plate (CP). Using numerical simulation to compare the cooling performance of two different channels (Channel I and Channel II) in the CPs, the results show that Channel II has better cooling performance. Then, four structural factors that exert substantial influence on the cooling performance of Channel II are selected as design variables by the orthogonal experiment method, and the battery module temperature difference and coolant pressure drop are set as the objective functions. The Kriging surrogate model between the design variables and the objective functions is established, and the NSGA-II genetic algorithm is used for the optimization. Compared to the initial structure, the optimized Channel II results in a 10.52% reduction and a 50.14% reduction in temperature difference and coolant pressure drop, respectively, with only a 0.68% increase in maximum temperature. The methods and conclusions of this paper can provide a reference for the design and optimization of lithium battery cooling structure based on HP-CP.

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    Optimized Design and Performance Study of New Liquid Cooling Plate Based on Concentric Circle Structure
    Xinglong Lu,Furen Zhang,Haibo Zhao,Shizheng Sun,Xue Li,Haodong Zhao
    2023, 45 (11):  2058-2069.  doi: 10.19562/j.chinasae.qcgc.2023.11.007
    Abstract ( 66 )   HTML ( 1 )   PDF (6258KB) ( 92 )   Save

    To improve the comprehensive performance of the battery thermal management system, a liquid-cooled plate with concentric circular structure channels is proposed in this paper. Firstly, the influence of the number and width of annular channels on the comprehensive performance of the liquid-cooled plate is discussed by using the control equation, and the optimal number and width of annular channels are selected by comprehensive evaluation indexes. Then, in order to reduce the pressure drop of the liquid-cooled plate to a greater extent, some of the curved section channels are straightened, and the angle of the straight section channels and the circle center distance are optimized. Compared with the initial model, the pressure drop of the optimal model is reduced by 62.83 Pa (67.61%) and the temperature is reduced by 1.1 ℃. Finally, in order to further improve the cooling performance of the system, nanofluids of different types and volume fractions are introduced as cooling media based on the optimal model. Compared with pure water, better overall performance can be obtained by using nanofluids as cooling media at low Reynolds number, and the overall evaluation index can be improved by up to 16.19%, with significant results.

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    The Masquerade Intrusion Detection Technique for Automotive ECUs Based on the Hybrid Feature Extraction of Frame Intervals and Bus Voltages
    Haotian Liu,Hongqian Wei,Peicheng Shi,Youtong Zhang
    2023, 45 (11):  2070-2081.  doi: 10.19562/j.chinasae.qcgc.2023.11.008
    Abstract ( 62 )   HTML ( 1 )   PDF (4764KB) ( 57 )   Save

    The development of networking and intelligence in automobiles has intensified the intrusion risk of automotive CAN (Controller Aera Network). Unlike Ethernet networks with well-established identity authentication mechanisms and encrypted transmission protocols, CAN bus adopts the plaintext means of data, making the messages easily stolen and attacked by illegal ECUs. Therefore, how to design an onboard intrusion detection system (IDS) to identify illegal tampering and disguise attacks has become a key and difficult issue. Accordingly, an automotive ECU camouflage attack recognition technology based on frame interval and bus voltage hybrid feature extraction is proposed in this paper. Firstly, the frame intervals of the message frame are obtained using the timestamp mechanism of the embedded device. Meanwhile, voltage signals of the automotive bus network are sampled, and the characteristic parameters of the bus voltage (such as voltage mode and edge time) are obtained using fast signal processing technology. Thus, the hybrid features including the frame intervals, voltage modes, bit time, edge time are formulated to construct the ECU fingerprints. Then, the lightweight Softmax learning algorithm is used to train the IDS model and identify potential illegal intrusion behaviors such as disguised attacks online. In order to verify the effectiveness of the proposed method, hardware experiments based on ECU devices are conducted in this paper, and the results show that the recognition accuracy of the proposed method for all ECUs is as high as 98.33%, with illegal intrusion identified by the sources of messages. Compared to traditional methods based on single feature fingerprints, the method proposed in this article can improve recognition accuracy by about 7%.

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    Cross-Domain Object Detection for Intelligent Driving Based on Joint Distribution Matching of Features and Labels
    Zhengfa Liu,Ya Wu,Peigen Liu,Rongqi Gu,Guang Chen
    2023, 45 (11):  2082-2091.  doi: 10.19562/j.chinasae.qcgc.2023.11.009
    Abstract ( 76 )   HTML ( 14 )   PDF (4083KB) ( 55 )   Save

    Current cross-domain adaptive object detection methods primarily focus on reducing domain shift by learning domain-invariant features through feature distribution alignment. However, they often overlook label distribution shift issues caused by variations in object combinations and class imbalances in real-world scenarios, resulting in poor generalization performance. To address this, this paper proposes a novel domain adaptive object detection algorithm that simultaneously aligns domain distributions at both feature and label levels. Firstly, an image-level classification embedding module is introduced to enhance the transferability and discriminability of global features through contrastive learning. Next, a class-level distribution alignment module is presented to achieve inter-domain multimodal structure alignment through multi-level feature alignment. Finally, an enhanced consistency regularization module is proposed to achieve cross-domain label distribution alignment through region-based consistency regularization. Experimental results across multiple datasets demonstrate that the proposed domain alignment algorithm effectively improves semantic consistency both before and after cross-domain data adaptation. This provides a valuable solution for the effective deployment of autonomous vehicles in cross-domain scenarios.

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    Path Tracking Control of Autonomous Truck Based on RMPC
    Jie Hu,Ruipeng Chen,Zhihao Zhang,Bowen Xiang,Haoyan Liu,Qi Zhu,Qixiang Guo
    2023, 45 (11):  2092-2103.  doi: 10.19562/j.chinasae.qcgc.2023.11.010
    Abstract ( 113 )   HTML ( 9 )   PDF (5127KB) ( 140 )   Save

    For the problem of insufficient path tracking accuracy of autonomous trucks compared to ordinary passenger cars, which are caused by greater model uncertainty, actuator deviation and external influencing factors such as curvature disturbances, a hierarchical control method based on Robust Model Predictive Control (RMPC) is proposed in this paper. Firstly, based on the incremental steering control error model, according to the deviation between the actual vehicle system and the nominal model, a robust control law is designed and the upper-level multi-objective constraint RMPC controller is constructed to improve the tracking accuracy. Then, to solve the problem of insufficient steering and positioning error of the autonomous trucks, the lower-level steer compensator and the state estimator based on median filter are designed to improve the steering response and the vehicle stability. Finally, the results of TruckSim/Simulink co-simulation and real vehicle tests show that the proposed control method can effectively deal with model mismatch and uncertain disturbances, and has good robustness and adaptability.

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    Research on Handling Stability Control Strategy for Distributed Drive Electric Vehicle Based on Multi-parameter Control
    Qiang Song,Guanfeng Wang,He Shang,Nianzhong Zhang
    2023, 45 (11):  2104-2112.  doi: 10.19562/j.chinasae.qcgc.2023.11.011
    Abstract ( 116 )   HTML ( 5 )   PDF (2612KB) ( 174 )   Save

    In order to enhance the vehicle dynamics performance under high speed and low adhesion road conditions, a multi-parameter-control-based handling stability control strategy for distributed drive electric vehicle (DDEV) is proposed in this paper, which incorporates both an upper trajectory tracking controller and a lower torque distribution controller. In the upper controller, a model predictive control (MPC) trajectory tracking controller based on the 2-DOF reference model of DDEV and driver preview error model is developed, enabling multi-parameter control of lateral displacement deviation, yaw angle deviation, sideslip angle, and yaw rate. The lower controller is responsible for optimal torque allocation for the four-wheel motors, taking minimizing tire load rate as the optimization target. Based on the 7-DOF dynamics model, experimental verification is conducted on the CarSim-Simulink joint simulation platform under double line change and snake shape conditions. The results show that the proposed control strategy effectively improves the handling stability performance and trajectory tracking accuracy of DDEVs under high speed and low adhesion road conditions.

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    Collaborative Design Optimization of Pure Electric Vehicle Drivetrain and Motor Structure Parameters
    Zhicheng He,Zejun Xie,Kan Liu,Enlin Zhou,Qian Tang,Yuanyi Huang
    2023, 45 (11):  2113-2122.  doi: 10.19562/j.chinasae.qcgc.2023.11.012
    Abstract ( 120 )   HTML ( 9 )   PDF (2377KB) ( 198 )   Save

    A collaborative design optimization method of pure electric vehicle drive train and motor structure parameters is proposed in this paper to improve the power and economy of pure electric vehicles, while reducing the cogging torque of permanent magnet synchronous motor to reduce vibration noise of motor. Firstly, with the motor structure parameters as input and rated torque and cogging torque as output, a study on the accuracy of multi-parameter simulation and different machine learning prediction models for motors is carried out, and a high-precision machine learning prediction model for rated torque and cogging torque of permanent magnet synchronous motors is established. Secondly, the basic motor design parameters (rated torque, peak torque, rated speed, peak speed) and peak efficiency are used to construct a mathematical model for fast prediction of the PM synchronous motor efficiency map. Thirdly, based on the motor cogging torque prediction model and the fast prediction mathematical model of motor efficiency map, the mapping relationship between the structural parameters of the motor and the efficiency characteristics is established. Finally, multi-objective optimization is carried out using the genetic algorithm with motor structure parameters and transmission ratio as optimization variables, and overall vehicle dynamics, economy and motor cogging torque as optimization objectives. Simulation results show that compared with that before optimization, the optimized vehicle performance is improved with 0-100 km/h acceleration time reduced by 27.3%, the maximum climbing degree of 15 km/h increased by 40.5%, the WLTC working condition energy consumption reduced by 1.6%, and the motor cogging torque reduced by 42.2%.

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    An Experimental Study on Low Temperature Shutdown and Purging of Vehicle Fuel Cell Stack
    Lü Ping,Xin Sun,Youwei Xu,Bao Zhang,Jiahui Xu,Danmin Xing
    2023, 45 (11):  2123-2129.  doi: 10.19562/j.chinasae.qcgc.2023.11.013
    Abstract ( 66 )   HTML ( 0 )   PDF (2597KB) ( 77 )   Save

    Gas purging during shutdown is an important method for proton exchange membrane fuel cells to ensure the safe storage and normal cold start in a low temperature environment. In order to achieve the quick shutdown purging, and meet the requirement of -40 ℃ non-destructive storage and cold start, relevant research is carried out in this paper. Firstly, a water balance model is established to analyze the generation and removal of water during the purge process. Secondly, the sensitivity analysis of the main parameters of shutdown purge is carried out, and it is determined that the cell temperature is a strong sensitive parameter, the humidification temperature is a medium sensitive parameter, and the gas flow is a weak sensitive parameter. Thirdly, 30 freezing/thawing cycles at -40 ℃/60 ℃ are carried out on the purge results, and the physical morphology and electrochemical analysis of the fuel cell after the test are carried out. Finally, the -40 ℃ cold start is carried out to verify whether the purging results can meet the requirements of -40 ℃ start-up. The results show that the low temperature purge time during shutdown is greatly shortened by optimizing the purging parameters. The performance of the fuel cell stack does not degrade and the physical morphology does not change significantly after storage at -40 ℃, and the fuel cell stack can achieve cold start at -40 ℃.

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    Development and Application of A Spark-Assisted Compression Ignition Quasi-Dimensional Combustion Model
    Yaodong Wang,Yan Su,Maochun Lang,Xiaoping Li,Fangxi Xie
    2023, 45 (11):  2130-2138.  doi: 10.19562/j.chinasae.qcgc.2023.11.014
    Abstract ( 39 )   HTML ( 2 )   PDF (3076KB) ( 75 )   Save

    In this paper, the turbulent flame propagation speed model is used to describe spark ignition (SI) combustion. For a single self-ignition point, the turbulent flame propagation speed model is still used, the sum of the equivalent turbulent flame speed of all self-ignition points is considered as the total equivalent turbulent flame speed, which is used to describe compression ignition combustion and then a spark-assisted compression ignition (SACI) quasi-dimensional combustion model is established. The air and external exhaust gas recirculation (EGR) dilution SACI based on this model is studied, and the simulation and experimental results match well. The calculation shows that the flame propagation speed of SACI is higher than that of SI, which increases with ignition advanced., with the flame propagation speed of external EGR dilution lower than that of air dilution. Delaying ignition or increasing external EGR can lead to an increase in the peak area of the flame front, a slowing down of the decay rate and a weakening of the isovolumetric combustion. The thermal efficiency of air dilution is higher when the dilution ratio is comparable, but the exhaust aftertreatment of external EGR dilution is easier.

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    An Experimental Study on the Effect of Triple Spark Plug Ignition System on the Lean Combustion Performance of Dedicated Hybrid Engine
    Bowen Yan,Waters Benjamin,Pendlebury Ken,Tiegang Hu,Jiaxiang Zhang,Xiaoqian Yang,Yunping Pu
    2023, 45 (11):  2139-2147.  doi: 10.19562/j.chinasae.qcgc.2023.11.015
    Abstract ( 51 )   HTML ( 3 )   PDF (4629KB) ( 67 )   Save

    A study is conducted on a three-cylinder 1.5TGDI turbocharged direct injection engine, in terms of the effect of triple spark plug (TSP) ignition on the lean combustion performance. The results show that TSP can effectively extend the lean burn limit, with compression ratio of 15, the TSP can achieve stable combustion at lambda 1.95 for the specific operating condition of 2 000 r/min 8 bar BMEP, with the minimum brake specific fuel consumption (BSFC) reduced by 5 g/(kW·h) compared with that of the single spark plug, and raw NO x emission reduced to about 50×10-6. At this condition, the limit for a further lambda increase is mainly due to the boost capability. When the compression ration increases to 16, the minimum BSFC improvement is not obvious compared with that of the compression ratio of 15, and the lean burn limit decreases. The TSP has little benefit for reducing the knock tendency, but can increase the lean mixture combustion rate obviously, at the same lambda condition, its combustion duration can be 3-6°CA shortened compared to single spark plug, and increase by only 2°CA at lambda 1.95 compared to stoichiometric combustion. Through a further investigation on the potential maximum thermal efficiency, it shows that with the compression ratio of 15, the TSP can finally achieve 45.02% maximum brake thermal efficiency.

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    Control of Gas Supply System of High Power Fuel Cell Engine for Vehicle
    Chenxu Shi,Changqing Du,Chao Wang,Xingyi Li,Jiaming Zhang
    2023, 45 (11):  2148-2156.  doi: 10.19562/j.chinasae.qcgc.2023.11.016
    Abstract ( 65 )   HTML ( 5 )   PDF (4325KB) ( 97 )   Save

    In order to meet the gas supply demand of 100 kW high power hydrogen fuel cell engine, the control strategy of supply system is developed. Firstly, the fuel cell stack and the gas supply system are modeled. Based on the controlled object model, the cathode and anode gas supply control strategy of MAP feedforward and PID feedback is designed and developed. The anode purge time is calibrated using the weighted sum of single chip voltage state and system efficiency, the control effect of which deployed in the actual controller is verified through bench test. The results show that rapid response to pressure and flow rate has been achieved in both steady-state and transient operating conditions, resulting in increase in current loading rate to 120 A/s and -170 A/s, with the steady-state and transient control accuracy of anode pressure of 98.93% and 95.10%, and the average range of full power cell voltage of 15 mV, with good consistency. Based on the test data, the state equation of the cathode air supply system is calibrated and established. An air supply scheme with integrated nonlinear disturbance observer and nonlinear controller based on Lyapunov direct method is developed. The MIL test shows that the precise control of the air supply control target is achieved, which provides a theoretical basis for further improving the response accuracy of the control system.

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    Correction Method of Static Stiffness and Multi-level Topology Optimization for Subframe
    Yonglei Su,Zhifei Zhang
    2023, 45 (11):  2157-2164.  doi: 10.19562/j.chinasae.qcgc.2023.11.017
    Abstract ( 103 )   HTML ( 14 )   PDF (2238KB) ( 139 )   Save

    Based on the construction of the parallel simulation process of the static stiffness and K&C performance of the subframe, a correction method for static stiffness of subframe considering the coupling of performance is proposed, and a hierarchical design optimization method for the aluminum hollow subframe is systematically established. Firstly, a subframe calculation model is established and the loading method is improved, with a new static stiffness calculation method in a local coordinate system proposed. Three subcases including static stiffness analysis, flexibility model analysis and the K&C performance analysis are integrated and synchronously driven, and an ensembled surrogate model of K&C performance and static stiffness performance is constructed based on the multi-sample analysis and experimental design matrix conversion. The ensembled surrogate model is used to modify the static stiffness target according to the K&C performance index. Secondly, the multi-level topology optimization of the subframe under multi-performance constraints is carried out, using the first-level topology optimization to complete the main structure design with equal wall thickness, and the second-level topology optimization to complete the structure design with variable wall thickness. The results show that the first order and second order torsion modal increases by 39.3% and 14.9% respectively after multi-level topology optimization, with the static stiffness and K&C performance meeting the target requirements, on the premise of ensuring lighting-design and the other performance indicators significantly improved, which can provide a reference for the formulation of static stiffness performance targets of the subframe, the improvement of K&C performance and the optimization of the subframe structure.

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    Experimental Analysis and Numerical Simulation Study of Heat Dissipation Characteristic of Carbon-Ceramic Disc Brake
    Rongrong Zhang,Sirui Sun,Jie Fan,Sujun Liu,Qinchao Yang,Fengli Zhang
    2023, 45 (11):  2165-2174.  doi: 10.19562/j.chinasae.qcgc.2023.11.018
    Abstract ( 88 )   HTML ( 8 )   PDF (4169KB) ( 202 )   Save

    The heat dissipation capacity of the brake is closely related to the service braking performance of the passenger vehicles, in which the high-performance car has a higher demand for the heat dissipation capacity of the brake in the process of drastic driving. In this paper, a bench test is carried out for a certain carbon ceramic ventilated disc brake assembly. And a general fitting relation is proposed to represent the comprehensive heat transfer of convection and radiation through the calculation of the cooling coefficient of the brake disc in the cooling-down condition, which has important reference value for the quantitative description of the heat dissipation performance of the brake. Subsequently, the computational fluid dynamics (CFD) simulation is conducted in this paper, which discusses the influence of different variables on the heat dissipation characteristics of the brake, and reveals the mechanism of the influence of the dust shield on the heat dissipation of the brake. The results show that the convection heat transfer accounts for more than 75% of the total heat transfer in the cooling-down condition of the brake disk at the mean temperature of 500 ℃ without dust shield, and the convection heat transfer on the outer surface of the brake disc plays a leading role. In addition, when the brake disc is covered by the dust shield, the cooling capacity of the brake decreases significantly due to the increase of the air temperature around the brake disc surface close to the dust shield and the decrease of the mass flow rate in the ventilation channel inside the brake disc. The analysis results of this paper have important guiding significance for the optimization design of the brake cooling duct.

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    Design Method for Vehicle Body Joints Based on Load-Bearing Characteristics of Thin Plates
    Chao Wang,Wanyuan Yu,Aiguo Cheng,Zhicheng He
    2023, 45 (11):  2175-2186.  doi: 10.19562/j.chinasae.qcgc.2023.11.019
    Abstract ( 123 )   HTML ( 17 )   PDF (9731KB) ( 171 )   Save

    As a key structure of the Body-in-White (BIW), a reasonable joint design is of great significance for the improvement of the load-bearing capacity of the BIW. Taking the lower joint of the B pillar as the research object, a universal structure design method for body joints based on the load-bearing characteristics of thin plates is proposed in this paper. Firstly, the load type, force transmission mode and load-bearing characteristics of the thin plate structure are described to provide a theoretical basis for the subsequent universal joint structure. Secondly, the load conditions of joints are identified through sensitivity analysis, which is used to analyze the load-bearing characteristics of the thin plate of the joint. Then the design rules for the thin plate of T-joints are established and the universal structure design of the joint is summarized. Application examples and tests show that the joint stiffness and BIW torsional stiffness is increased by 35% and 8.5% respectively, while the weight is only increased by 0.16%. The method can quickly and effectively improve joint structure design and enhance body stiffness.

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