Table of Content

25 July 2020, Volume 42 Issue 7 Previous Issue    Next Issue

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Study on Prediction of Preceding Vehicle's Stochastic Motion Based on Risk Scenarios Clustering Analysis Guo Jinghua, Li Keqiang, Wang Jin, Chen Tao, Li Wenchang, Wang Ban 2020, 42 (7):  847-853.  doi: 10.19562/j.chinasae.qcgc.2020.07.001 Abstract ( 482 )   PDF (3143KB) ( 583 )   Save Due to complex and changeable road situation in China, the construction of a suitable test scenario plays a decisive role in the validity of intelligent driving system test and evaluation. Based on the actual road traffic environment in China, typical scenarios with Chinese characteristics are extracted and the data fragments of risk working condition are selected from the naturalistic driving data. Then, the scenario feature elements of the comprehensive tests of intelligent driving system are extracted, and three types of typical risk scenarios are obtained by clustering analysis. Then the stochastic motion of the vehicle driven by the human driver in front of the subject vehicle is featured by the Markov chain theory and the subject vehicle data in each scenario obtained by clustering is used as the historical working condition data of the preceding vehicle. The Markov chain transfer probability is concluded and learned, and the state of the future time is predicted by Markov chain Monte Carlo simulation. Based on this, the stochastic motion prediction model of the preceding vehicle in the risk scenarios is obtained. The validity of the proposed model is verified by comparing the original working condition data, which effectively solves the problem that the preceding vehicle data is in accurate due to the low accuracy of the acquisition equipment and the stochastic motion of the preceding vehicle driven by the human driver cannot be accurately featured in test scenarios. References | Related Articles | Metrics

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Multi-Sensor Fusion Method Based on Checking Unscented Information Fusion Algorithm Liu Zhiqiang, Zhang Guanglin, Zheng Yuewen, He Xiaoyu 2020, 42 (7):  854-859.  doi: 10.19562/j.chinasae.qcgc.2020.07.002 Abstract ( 261 )   PDF (2360KB) ( 417 )   Save For the problem of low recognition accuracy for the target vehicle of single sensor, this paper proposes a target tracking method based on millimeter-wave radar and camera information fusion. Meanwhile, based on extended information fusion (EIF) and unscented information fusion (UIF), checking unscented information fusion (CUIF) algorithm is established to fuse multi-sensor information. The CUIF algorithm uses a distributed fusion structure to correlate and fuse the trajectories from different sensors to obtain the target trajectory, and applies the distributed detection system to perform real-time system state compensation on the acquired sensor delay information, thus solving the problems of single sensor signal delay and packet loss. CarSim and Simulink are used jointly to build a simulation and test platform to validate the algorithm of the established fusion model. The experimental results show that CUIF algorithm reduces the target loss rate by more than 10% compared with EIF and UIF, and reduces the time delay to 5 ms, which meets the real-time requirements of the system. References | Related Articles | Metrics

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Research on Networked-vehicle Cooperative Platoon Control System Ma Fangwu, Wang Jiawei, Yang Yu, Shen Yucheng, Liu Zhenze 2020, 42 (7):  860-866.  doi: 10.19562/j.chinasae.qcgc.2020.07.003 Abstract ( 359 )   PDF (1869KB) ( 643 )   Save In order to improve the stability, safety and ride comfort of the platoon, a multi-vehicle cooperative platoon control system is constructed based on inter-vehicle communication. The system adopts the driving behavior decision model based on nonlinear inter-vehicle distance control with sufficient consideration of the effects of real communication time delay on the system. Aiming at the stability of the platoon, the parameter constraint boundary of each controller and the influence of their changes on system stability are analyzed. Finally, Matlab/Simulink model is built and a simulation is conducted to verify the effectiveness and reasonability of multi-vehicle cooperative control under three typical conditions, including the continuous disturbance of leading vehicle, emergency braking and non-zero initial state. The results show that the platoon control system constructed can achieve the stability control of the platoon, ensure driving safety, with the phenomena of frequent acceleration and braking avoided, enhancing driving comfort to a certain extent. References | Related Articles | Metrics

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Study on Factors Affecting Thermal Regeneration of Diesel Particulate Filter Tang Dong, Liu Yang, Liu Sheng, Zhou Yiwen, Liu Ning, Wang Li 2020, 42 (7):  867-873.  doi: 10.19562/j.chinasae.qcgc.2020.07.004 Abstract ( 249 )   PDF (5109KB) ( 308 )   Save The thermal regeneration model of diesel particulate filter (DPF) is established by GT-Power software. The off-line regeneration method is used to perform the thermal regeneration test of DPF and the test result is used to verify the accuracy of the model. Combined with the simulation and test results, the effects of DPF structure and operating parameters on wall peak temperature, maximum temperature gradient and regeneration duration during regeneration are analyzed. The results show that the wall peak temperature and regeneration rate decrease with the increase of wall thickness, CPSI and filter length. The wall peak temperature increases with the increase of regeneration heating temperature and soot accumulation, and decreases with the increase of inlet flow rate. Increasing the oxygen concentration in regeneration gas will help to improve the overall regeneration rate and efficiency, but will increase wall temperature and temperature gradient during regeneration. References | Related Articles | Metrics

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Analysis of DPF Pressure Drop and Noise Characteristics of Diesel Engine Chen Guisheng, Zhou Qunlin, Ma Longjie, Lü Yu, Shen Yinggang 2020, 42 (7):  874-881.  doi: 10.19562/j.chinasae.qcgc.2020.07.005 Abstract ( 207 )   PDF (1345KB) ( 353 )   Save In order to explore the characteristics of DPF pressure drop and noise during engine operation, this paper analyzes the influence of carrier structure, carbon load, ash content and other factors on DPF performance by establishing a one-dimensional simulation model of DPF. The results show that the smaller diameter of the DPF carrier is , the greater the DPF pressure drop is , while the noise is relatively reduced, with little effect of the carrier length on the pressure drop and noise. The larger the carbon load is, the smaller the noise at the exhaust end of DPF is. When the carbon load is within the range of 4g/L, the pressure drop of deep filtration takes the dominant position. When the carbon load is more than 4g/L, the pressure drop of soot layer gradually dominates. The effect of ash content and ash distribution coefficient on DPF pressure drop and exhaust noise is similar. With the increase of the value, the DPF pressure drop increases and the noise attenuation ability increases. By revealing the influence of carrier size, carbon load and ash content on DPF pressure drop and exhaust noise characteristics, this paper provides a reference for DPF structure design to reduce pressure drop loss and exhaust noise. References | Related Articles | Metrics

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Effects of Initial Distance Between Occupant and Airbag on Occupant Mild Traumatic Brain Injury Li Haiyan, Li Xinjie, Cui Shihai, He Lijuan, Ruan Shijie, Lü Wenle 2020, 42 (7):  882-886.  doi: 10.19562/j.chinasae.qcgc.2020.07.006 Abstract ( 196 )   PDF (2785KB) ( 339 )   Save Based on a constructed and validated 50th percentile adult head FE model, the crash process with different initial distances between occupant and airbag is simulated using software LS-DYNA to investigate the effects of initial distance between occupant and airbag on the mild traumatic brain injury (mTBI) of occupant during vehicle crash. The craniocerebral response parameters of occupant including HIC15, grey matter pressure, the von Mises stress of brain tissue and the shear stress in brain are measured in simulation and the results of analysis show that when the initial distance between occupant and airbag is larger than 290 mm, the probability of leading to occupant mTBI will be less than 50%, and with the reduction of the distance between occupant and airbag, the craniocerebral response parameters and hence the probability of occupant mTBI increase. Therefore, even though occupant uses safety belt properly during crash, mTBI may also occur if occupant is too close to airbag, so it is suggested that the distance between occupant and airbag should larger than 290 mm. References | Related Articles | Metrics

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Design Optimization of Vehicle Occupant Restraint System Based on Adaptive Surrogate Model Liu Xin, Liu Xiang, Zhou Zhenhua, Hu Lin 2020, 42 (7):  887-893.  doi: 10.19562/j.chinasae.qcgc.2020.07.007 Abstract ( 277 )   PDF (1918KB) ( 417 )   Save In order to enhance the occupant protection performance of vehicle occupant restraint system and reduce the injury of occupants, an optimization method of occupant restraint system based on adaptive surrogate model is proposed in this paper. Firstly, the numerical model for the occupant restraint system of a minibus is established and then validated and corrected by real vehicle crash tests. Then, the surrogate model for the occupant restraint system is built based on radial basis function and the reverse shape parameter method is also used to enhance the accuracy of surrogate model. Finally, the intergeneration projection genetic algorithm (IP-GA) are adopted to optimize the occupant restraint system of vehicle. The results demonstrate that the method proposed can speedily obtain the optimum matching parameters of vehicle occupant restraint system and ensure the safety of occupants. References | Related Articles | Metrics

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Closed-loop Position Tracking Control for Dry Clutch Considering Nonlinear Stiffness of Membrane Spring Zhang Mingyuan, Chen Li 2020, 42 (7):  894-900.  doi: 10.19562/j.chinasae.qcgc.2020.07.008 Abstract ( 142 )   PDF (3691KB) ( 344 )   Save In view of that the diaphragm spring for clutch has a nonlinear stiffness with a negative value in some travels, so may lead to system instability and the low control accuracy in clutch position, a nonlinear control scheme combining differential flatness feedforward and gain self-turning feedback is proposed. The results of simulation and experiment verify the instability phenomenon caused by the negative stiffness of diaphragm spring. Compared with the traditional control method without considering the negative stiffness characteristics of diaphragm spring, the nonlinear control scheme proposed can eliminate instability phenomenon with small tracking error. References | Related Articles | Metrics

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Study on Friction and Wear Performances of Surface Coating of Magnesium Alloy Metal Belt in Continuously Variable Transmission Liu Jingang, Xiang Hongyu, Wang Gaosheng, Zou Naiwei, Chen Jianwen, Chen Jianhua 2020, 42 (7):  901-908.  doi: 10.19562/j.chinasae.qcgc.2020.07.009 Abstract ( 162 )   PDF (5382KB) ( 377 )   Save In order to reduce the friction and wear between the friction plate and the pulley of the metal belt type continuously variable transmission (CVT) and enhance the transmission efficiency of the CVT, a magnesium alloy material with wear resistant coating by heat treatment is proposed to replace the bearing steel material for friction plate. It is founded by finite element simulation analysis that the friction plates of different materials have a significant influence on their contact stress and a certain effect on their stress distribution. The centrifugal force generated by magnesium alloy metal belt has much less effects on the system than that generated by bearing steel metal belt. The results of experimental study show that all three wear resistant coatings prepared on the surface of magnesium alloy can enhance its wear resistance, and hence reduce the friction and wear between the friction plate and the pulley and extend the service life of the metal belt of CVT. References | Related Articles | Metrics

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Research on Differential Drive Steering Control Strategy for Rear Axles of Multi-Axle Distributed Electric Drive Vehicle Peng Bo, Li Junqiu, Sun Fengchun, Zhu Xuebin, Wan Cuncai 2020, 42 (7):  909-916.  doi: 10.19562/j.chinasae.qcgc.2020.07.010 Abstract ( 241 )   PDF (4298KB) ( 557 )   Save Firstly, the dynamics model for an eight-axle distributed electric drive vehicle is established, and a two-layer control strategy for differential steering based on centroid sideslip angle is proposed. The upper controller takes the centroid sideslip angle and its change rate and the turning angle of front wheel as inputs, and adopts fuzzy control to generate the relative positions of the steering centers of mechanical steering axle and differential steering axle, to obtain the reference steering angle of rear axle. The lower controller takes the reference steering angle in upper controller as the control target, and adopts the incremental digital PI control to obtain the differential torque of rear axle motor. Finally, a hardware-in-the-loop simulation is conducted to verify the control effect and real-time performance of differential steering of rear axle under medium and high speeds conditions. The results indicate that compared with the ideal Ackerman steering strategy, the strategy proposed can effectively reduce the centroid sideslip angle of vehicle in the process of steering and ensure steering stability. References | Related Articles | Metrics

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Study on Braking Stability of Articulated Vehicle with Eddy Current Retarder Axle Gao Zhiwei, Li Desheng, Ye Lezhi, Liu Zongqiang 2020, 42 (7):  917-924.  doi: 10.19562/j.chinasae.qcgc.2020.07.011 Abstract ( 169 )   PDF (3299KB) ( 395 )   Save In order to solve the problem of insufficient braking force and poor braking stability of main brake system in an articulated vehicle, the liquid-cooled eddy current retarder and vehicle axle are integratively designed to construct an eddy current retarder axle for avoiding “impact” and “jackknifing” phenomena during the braking of heavy-loaded trailer. Bench test on eddy current retarder axle is conducted to comparatively analyze vehicle braking stability with retarder installed on tractor and trailer under the conditions of no load and full load. The results show that in no load, especially full load condition, with retarder installed on trailer, the vehicle will have better braking stability and safety than that with retarder installed on tractor. References | Related Articles | Metrics

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Dynamic Control and Experimental Study of Active Rear Wheel Steering Considering Uncertain Disturbances Zhao Han, Deng Bin 2020, 42 (7):  925-932.  doi: 10.19562/j.chinasae.qcgc.2020.07.012 Abstract ( 240 )   PDF (3497KB) ( 661 )   Save For the problem of high precision angle tracking control and anti-interference of active rear wheel steering system under complex working conditions and uncertain disturbances, firstly, the active rear wheel steering mechanism with adjustable length electronic beam angle bar is adopted to realize the rear wheel steering action, and the non-linear dynamic model is established for the system. Then, based on the analysis of dynamic model, improved active disturbance rejection control (ADRC) tracking control method for the active rear wheel steering angle is designed. Extended state observer (ESO) is used to observe external and internal disturbances and disturbances are compensated to the controller to achieve high precision angle control and anti-interference ability. Finally, experiments show that the steering mechanism with adjustable length electronic beam angle bar and improved ADRC method can achieve high accuracy angle tracking control under uncertain load disturbances. Compared with the conventional PID control, the improved ADRC control method has strong robustness and anti-interference. References | Related Articles | Metrics

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Research on Subjective Evaluation Method of Vehicle Sound Quality Based on Interval Grey Number Theory Bi Fengrong, Huang Yu, Zhang Lipeng, Shen Pengfei, Lü Dali 2020, 42 (7):  933-940.  doi: 10.19562/j.chinasae.qcgc.2020.07.013 Abstract ( 164 )   PDF (2772KB) ( 305 )   Save In order to improve the reliability and practicability of subjective evaluation of vehicle sound quality, and to analyze the interior noise quality characteristics of pure electric vehicle under the condition of constant speed and acceleration, based on the anchored semantic differential method (ASDM) and the interval grey number theory, an improved subjective evaluation method of sound quality is proposed. Firstly, referring to a benchmark sample, the assessors use fuzzy scoring method to evaluate subjectively the noise samples in the vehicles. Secondly, the grey incidence degree is used as scorer reliability to eliminate the invalid score data. Thirdly, a certainty parameter of interval grey number is proposed as an important index for calculating the weights of scores in order to obtain the comprehensive scoring results of each sample. By comparison with the evaluation results of traditional semantic differential method (SDM) and ASDM, it is verified that the improved method can more accurately reflect people's subjective feelings about the noise in the vehicle while the workload of evaluation is not increased. The method is used to evaluate subjectively the interior noise quality of three pure electric vehicles of different positioning under different working conditions, so that the sound quality characteristics of three vehicles can be compared and analyzed. References | Related Articles | Metrics

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Reliability-based Design Optimization of Car Body Based on Dimension Reduction Method Wei Tonghui, Zuo Wenjie, Zheng Hongwei, Li Feng 2020, 42 (7):  941-948.  doi: 10.19562/j.chinasae.qcgc.2020.07.014 Abstract ( 196 )   PDF (1071KB) ( 331 )   Save Based on dimension reduction algorithm, a novel car-body reliability optimization model is established, with minimizing car body mass as the optimization objective and the reliability degree of bending and torsional stiffness of car body as constraints. By using dimension reduction algorithm, a new model with n one-dimensional functions is established to approximate the original function. With the aid of Taylor series and statistical moment theory, the first four-orders of moment of the car body function are solved, and by using the fourth order moment method, the reliability degree of car-body is obtained. By means of improved adaptive genetic algorithm-based optimization scheme and reliability assessment, the nested optimization problem is decoupled into a single-layer optimization problem, the penalty function method is used to modify and improve the fitness function. Compared with traditional reliability-based optimization methods, with this method, neither using multiple integration to solve the statistical moment of functional function nor iteration for searching the most probable failure points are required, and can also avoid the defect of the population falling into local optimum. The results of numerical calculation show that the method proposed has higher accuracy and better adaptability. References | Related Articles | Metrics

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Model-based Modification Technique of Low-frequency Radiation Emission in Electric Vehicle Wang Zilong, Gao Feng, Xiong Yu 2020, 42 (7):  949-955.  doi: 10.19562/j.chinasae.qcgc.2020.07.015 Abstract ( 170 )   PDF (4345KB) ( 490 )   Save Radiated emission, or electromagnetic interference (EMI) is a prominent problem of electric vehicle due to its high voltage and large current of power system, and it is hard in source location, high in cost and time-consuming when using experiment technique for modification and improvement. To enhance the efficiency of EMI issue improvement, a model-based approach for the analysis, location and modification of EMI issue is proposed. According to the shielding level of target vehicle, the vehicle is divided into multiple subsystems for separated modelling with less difficulty. Then a topology matrix is constructed based on the relationship of port connections to predict the EMI level of vehicle. After the validation of model accuracy, a comprehensive analysis on sensitivity and contribution is conducted to locate the source of EMI with the EMI filter selected, so as for the target vehicle to meet the requirements of GB 18387. References | Related Articles | Metrics

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Study on the Influence of Tread Pattern on Noise Radiation of Truck Tire Cao Jinfeng, Huang Wei, Zhang Chunsheng, Hou Dandan, Xiang Dabing, Wei Yintao 2020, 42 (7):  956-964.  doi: 10.19562/j.chinasae.qcgc.2020.07.016 Abstract ( 368 )   PDF (5636KB) ( 279 )   Save Tread pattern is one of the important factors affecting the noise radiation of truck tires. In this paper, three tires with typical tread pattern are selected to conduct the near-field noise test, with test data analyzed in terms of dispersion and correlation for revealing the differences between the noises at the front and rear ends of tire footprint. The results show that longitudinal groove tire and smooth tire have a better linear correlation between the sound pressure level of noise and speed compared with transverse groove tire, but reasonable design and layout of pattern pitch can significantly improve the linear correlation of transverse groove tire in medium-high speed conditions. The directional noise difference is negatively correlated with the width of transverse groove, but is positively correlated with the width of base surface, while the number of longitudinal groove has less influence on the directional noise difference. The directivity of noise for three typical treads of tires according to the order from weak to strong are transverse groove tire, longitudinal groove tire and smooth tire, with their directional noise difference being 9.5 dB(A), 11dB (A) and 14 dB(A) respectively. The transverse groove and the longitudinal groove are the main causes of that the noise at the rear-end of footprint is louder than that at the front-end of footprint, with their directional noise difference being -0.35 dB(A) and 1.73 dB(A), respectively. The smooth surface is the main cause of that the noise at the rear-end of footprint is quieter than the front-end of footprint, with its directional noise difference being 2.76 dB(A). References | Related Articles | Metrics

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Research on Optimized Processing Method for Vehicle Load Spectra Measured Based on Wavelet Transform Theory Yu Jiawei, Qian Chunlei, Zheng Songlin, Huang Chong, Liu Kai 2020, 42 (7):  965-971.  doi: 10.19562/j.chinasae.qcgc.2020.07.017 Abstract ( 177 )   PDF (3735KB) ( 346 )   Save In view of that vehicle road load spectra collected in engineering practices are easily disturbed by outer environment leading to noise and abnormal spike signal, while the traditional Fourier transform-based filtering method may remove true signals together with noise signals simultaneously, a denoising method for vehicle road load spectrum measured based on wavelet transform theory is studied. The Daubechies wavelet function is selected, combined with various wavelet threshold denoising criteria to conduct denoising processing on the road load spectra measured from a test vehicle and systematically study the denoising performance of different wavelet threshold denoising criteria and wavelet vanishing moments for noise-containing random load signals measured. Results show that the wavelet transform-based denoising method can effectively remove disturbing noise signals, in which Heuristic SURE criterion has the best result in retaining all load characteristics of original load spectra. In addition, an automatic inspection method for abnormal spike signals in load spectrum measured is studied based on wavelet transform theory, providing certain reference for optimized processing of vehicle road load spectra measured. References | Related Articles | Metrics

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Application of Probabilistic Neural Network to Typical Fault Diagnosis of Vehicle Gearbox Zhang Yangyang, Jia Yunxian, Wu Weiyi, Su Xiaobo, Shi Xiaowen 2020, 42 (7):  972-977.  doi: 10.19562/j.chinasae.qcgc.2020.07.018 Abstract ( 201 )   PDF (2820KB) ( 320 )   Save In order to enhance the diagnosis efficiency and accuracy of the typical faults of automotive gearbox, a fault diagnosis method of gearbox based on probabilistic neural network (PNN) is proposed. The vibration signals of the gearbox under normal state, tooth root cracks and broken tooth are collected through an experiment on a gearbox. After data processing, the sample data are obtained and input into PNN model. The results of cross-validation and comparison with the BP neural network (BPNN) show that PNN can accurately identify the typical faults of the gearbox and has higher diagnostic accuracy and faster diagnostic speed compared with BPNN. References | Related Articles | Metrics

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Research on the Application of CFRP in Automobile Panels Gao Yunkai, Liu Zhe, Xu Yanan, Xu Xiang, Feng Zhaoxuan 2020, 42 (7):  978-984.  doi: 10.19562/j.chinasae.qcgc.2020.07.019 Abstract ( 200 )   PDF (3678KB) ( 364 )   Save In this paper, carbon fiber reinforced plastics (CFRP) and epoxy resin matrix materials are used for topology optimization, sample manufacturing and performance analysis of the engine hood of an SUV hybrid car. According to the actual working condition of the engine hood, with the mass minimization as the objective function, with the performance index (torsional stiffness, anterior and posterior bending stiffness, lateral stiffness, first-order torsion and bending mode) measured by the steel engine hood tests as the constraint function, the equivalent alternative topology optimization of the CFRP engine hood is carried out. The test results for various working conditions show that the performance of CFRP engine hood compared to steel engine hood is improved by more than 10% and the weight is reduced by 45.56%. References | Related Articles | Metrics

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Study on Durability of Adhesively Bonded CFRP-Aluminum Alloy Joints Exposed to Extreme Temperatures Mu Wenlong, Na Jingxin, Qin Guofeng, Tan Wei, Gao Yuan, Shen Hao 2020, 42 (7):  985-992.  doi: 10.19562/j.chinasae.qcgc.2020.07.020 Abstract ( 184 )   PDF (3924KB) ( 300 )   Save The durability of adhesively bonded carbon fiber reinforced polymer (CFRP) joints under extreme temperatures is studied. The effects of CFRP surface roughness on bonding strength are analyzed, the AL-AL and CFRP-AL single-lap joints are manufactured with their failure loads measured at 80℃ and -40℃ in different aging periods. The results show that the bonding loads of CFRP can be increased effectively through surface roughening with sandpapers. But with the roughness further increases, the load-bearing capacity of CFRP-AL joint gradually falls. Under high temperature condition, the bonding performance of AL-AL joint is determined by post-curing of adhesive, while the durability of CFRP-AL joint is affected by both the post-curing of adhesive and the aging of CFRP. Low temperature aging has no obvious effects on the performances of AL-AL joints, while the failure loads of CFRP-AL joints reduce under the ef-fects of thermal stress. In the end, the cohesion model of CFRP-AL joint is established, with the temperature degradation factors defined, achieving the joint failure prediction under the continu-ous action of extreme temperatures. References | Related Articles | Metrics