Table of Content

25 June 2020, Volume 42 Issue 6 Previous Issue    Next Issue

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Design and Test of Driving Push Service Platform and Its Key Algorithm Liang Jun, Cong Sensen, Wang Jun, Cai Yingfeng, Jiang Haobin, Chen Long 2020, 42 (6):  709-717.  doi: 10.19562/j.chinasae.qcgc.2020.06.001 Abstract ( 249 )   PDF (4038KB) ( 424 )   Save In view of the neglect of the interaction between push service and users during the process of “active perception-automatic generation-active push” in driving active service system (DASS), a driving push service platform (DPSP), which covers storage layer, application layer and evaluation layer, is designed based on the operation behavior of driving users. The storage layer is used to classify and store the pervious and current data of user behavior. In application layer, B-Num/BT algorithm is designed based on user's operation behavior, for improving the user acceptance of DPSP, while the evaluation layer utilizes operation data to evaluate and monitor the performance of push service. A driver-in-the-loop test is conducted to verify the timeliness, safety and accuracy of typical push service scenarios. The results show that DPSP meets the performance requirements of push system. In addition, it is found that the timeliness also has the function of classifying driving users. The research has great significance for the perfection of DASS system, the strengthening of driving safety and even the popularization of autonomous driving technology References | Related Articles | Metrics

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Effect of Injection Ratio on Combustion and Emission ofCombined Injection Gasoline Engine During Warm-up Process Sun Ping, Liu Ze, Liu Shaozhen, Yu Xiumin, Cao Zhi, Yang Song 2020, 42 (6):  718-724.  doi: 10.19562/j.chinasae.qcgc.2020.06.002 Abstract ( 239 )   PDF (4443KB) ( 460 )   Save A warm-up test of different injection schemes is carried out on a combined injection gasoline engine to study the effects of different injection ratios on the combustion and emission characteristics of the combined injection gasoline engine in warm-up process. The results show that with the rise of coolant temperature, the combustion and emission performances of the gasoline engine gradually improve. When injection ratio is 80%, the engine achieves the best performance, with the peak of cylinder pressure increases by 49.1%, HC emission decreases by 14.5%, CO emission reduces by 27.1%, NOx emission rises by 56.6%, and PN emission lowers by 92.5% on average in warm-up process, compared with pure direct injection scheme. With the rise of coolant temperature in warm-up process, the combustion of engine improves, and the emissions of HC, CO and total particulates gradually reduce References | Related Articles | Metrics

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Effects of Ash Deposition on Regeneration Characteristicsof CDPF with Different Structures Chen Guisheng, Li Qing, Chen Chunlin, Lu Shenke, Lü Yu, Shen Yinggang, Huang Zhen 2020, 42 (6):  725-733.  doi: 10.19562/j.chinasae.qcgc.2020.06.003 Abstract ( 159 )   PDF (6027KB) ( 337 )   Save A bench test is conducted on the catalytic diesel particulate filter (CDPF) of a high-pressure common rail diesel engine to study the effects of different structures of CDPF on the performance of engine and the pressure drop characteristics of CDPF under different soot loadings. A 3D thermodynamic model of CDPF is established, and the influences of ash loadings and ash distribution coefficients on the regeneration characteristics of CDPF with different structures are analyzed. The results show that CDPF would lower the performance and economy of diesel engine, but the CDPF with asymmetric cell technology (ACT), i.e. asymmetric CDPF, can effectively weaken the effects of the filter on the performance of diesel engine. The pressure drop of CDPF will rise with the accumulation of soot loading in filter channels and the CDPF with ACT can effectively reduce the pressure drop of filter, and the advantage of the asymmetric CDPF becomes more obvious as the amount of soot loading increases. Ash deposition is beneficial to the reduction of the thermal conductivity of the filter to the environment and increase the heat capacity of the filter, conducive to soot oxidation regeneration. The temperature of the filter during CDPF regeneration is higher in the center and rear end and lower in the periphery and front end. The ash distribution coefficient has little effect on soot oxidation rate. The filter structure, ash loading and ash distribution coefficient also have less effects on the maximum regeneration temperature gradient of CDPF References | Related Articles | Metrics

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Influence of Background Gas Density on GDI Spray Characteristics Li Qinwei, Hou Zhigang, Zhang Jingyu, Li Yanfei, Shuai Shijin 2020, 42 (6):  734-740.  doi: 10.19562/j.chinasae.qcgc.2020.06.004 Abstract ( 175 )   PDF (4569KB) ( 252 )   Save In a constant volume combustion bomb, three different background gases (He, N2, CO2) are used to study the influence of background gas density and fuel temperature on the spray characteristics of a five-hole gasoline direct injection (GDI) injector under non-flash-boiling conditions by high-speed photography. The results show that background gas density is the key factor affecting spray collapse. With the increase of background gas density, the spray collapse shows a trend of strengthening first and then stabilizing, with the turning point around 4 kg·m-3. When the background gas density is lower than 4 kg·m-3, the spray plumes would become wider and resultantly the gap between jets becomes narrower with the increase of background gas density, further preventing the external gas from entering the enclosed low-pressure zone. The internal and external pressure difference of spray increases, resulting in the increase of spray collapse degree. When the background gas density is higher than 4 kg·m-3, the gap between jets disappears, and the spray external and internal gas exchange is blocked. The internal and external pressure difference of spray tends to be stable, which leads to the stability of spray collapse. The change of fuel temperature has little effect on spray width References | Related Articles | Metrics

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Experimental Study on Thermal Balance of GDIEngine with Integrated Exhaust Manifold Xu Xiang, Liu Shuangxi, Mu Liansong, Wang Yuan, Zhao Liang 2020, 42 (6):  741-745.  doi: 10.19562/j.chinasae.qcgc.2020.06.005 Abstract ( 255 )   PDF (2177KB) ( 473 )   Save The effects of different engine bench test schemes and test conditions on thermal balance performance test resultsare studied experimentally on a GDI engine with integrated exhaust manifold. The test results show that compared with the traditional engine heat balance bench test method, the heat balance test scheme based on the real vehicle radiator, cooling system tubes, intake and exhaust pipes and accessories, can reduce the adverse impact on the heat balance test caused by pipes change, such as system flow resistance increase, heat transfer losses increase , uncontrollable coolant flow, too small temperature difference between the inlet and outlet of the engine, etc., and the test results are closer to the real vehicle state. The inlet air temperatures after intercooling, coolant temperatures and on-offcooling fan have a significant impact on the results of heat balance test. The exhaust manifold of the engine with integrated exhaust manifold is built into the cylinder head, which results in a significant increase in heat dissipation of the engine cooling water jacket. As a result, the cooling system must also provide greater cooling capacity to meet the needs of the engine heat balance References | Related Articles | Metrics

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Study on Aerodynamic Drag Reduction of a HeavyTruck Based on Aerodynamic Accessories Wang Qingyang, Huang Wenpeng, Lai Chenguang, Zhu Xijia, Wang Yong 2020, 42 (6):  746-752.  doi: 10.19562/j.chinasae.qcgc.2020.06.006 Abstract ( 259 )   PDF (3449KB) ( 541 )   Save For reducing the aerodynamic drag of heavy trucks to achieve the goal of energy saving and emission reduction, based on the sensitive regions in aerodynamic drag reduction, ten single aerodynamic drag reduction accessories for a cab-over-engine heavy truck is designed, with their drag reduction effects and mechanism studied by CFD simulation. The results show that 10 single accessories all have drag reduction effects, in which a bionics-based accessory has an obvious drag reduction effect with a drag reduction rate of 15.0% and a small installation space required. Finally, through the optimum combination of aerodynamic accessories, a best drag reduction scheme is obtained with a drag reduction rate reaching 27.4% References | Related Articles | Metrics

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Study on Drag Reduction of Square-back AhmedModel Based on Plasma Flow Control Wang Jingyu, Geng Yalin, Hui Zheng, Hu Xingjun, Li Tianhong, Liu Zicheng, Li Jiuchao 2020, 42 (6):  753-758.  doi: 10.19562/j.chinasae.qcgc.2020.06.007 Abstract ( 202 )   PDF (3150KB) ( 357 )   Save The control effects of the surface dielectric barrier discharge-based plasma actuator on the wake flow separation of squire-back Ahmed model are studied by wind tunnel test in this paper. Firstly, the aerodynamic characteristics of ion wind induced by plasma actuator under static state environment are revealed through particle image velocimetry. Then according to the changes in the surface pressure and wake flow field of the model, the drag reduction rates of the model at different actuating voltages are analyzed with the mechanism of drag reduction expounded: plasma actuator can effectively control wake flow, increasing the wake pressure and hence leading to the reduction of aerodynamic drag. Test results show that the control effects of actuator weaken with the rise of wind speed and the induced speed of actuator reaches maximum at a peak voltage of 17 kV. Thus, the best drag reduction effect is achieved in a condition of a wind speed of 10 m/s and a peak voltage of 17 kV with an active drag reduction rate of -4.58% and a total drag reduction rate of -9.02% References | Related Articles | Metrics

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Study on the Correlation Between Digital Wind TunnelSimulation and Open Road Simulation Song Xin, Li Shuya, Yan Jie, Liu Zheng, Yang Hui, Guo Xiquan 2020, 42 (6):  759-764.  doi: 10.19562/j.chinasae.qcgc.2020.06.008 Abstract ( 271 )   PDF (4001KB) ( 348 )   Save In order to study the influence of computational domain on aerodynamic drag, a digital wind tunnel model is established based on the parameters of real vehicle wind tunnel. Taking the DrivAer model, a generic open source vehicle geometry, as the research object, a comparative analysis between digital wind tunnel simulation and open road simulation on 12 different vehicle patterns is carried out. The results show that difference of the aerodynamic drag obtained by two different simulations is relatively small, about 6~12 counts for smooth underbody, while the difference increases to 17~22 counts for detailed underbody. The changing trends of aerodynamic drag between two different vehicle patterns obtained by two different simulations are basically the same, but when underbody and airdam change, the difference in aerodynamic drag obtained by two different simulations reaches 9~15 counts References | Related Articles | Metrics

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Study on Aerodynamic Optimization of Rear Spoiler in a MPV Qin Peng, Zhan Jia, Li Zhengzheng 2020, 42 (6):  765-770.  doi: 10.19562/j.chinasae.qcgc.2020.06.009 Abstract ( 267 )   PDF (2191KB) ( 374 )   Save An optimization scheme combining wind tunnel test and the design of experiment is adopted to optimize the aerodynamic performance of a MPV by multi-parameter optimization on rear spoiler itself and side trim panel. By optimization through wind tunnel test, the aerodynamically optimum styling scheme of rear end is obtained, leading to a drag reduction of around 2.9%. Then, a CFD simulation is conducted on the styling schemes both before and after optimization, their differences of tail-flow field and pressure distribution are compared and the cause of drag reduction is analyzed. Finally, the contributions of each region and part to drag change are compared, which further verifies the reason of drag reduction, providing the orientation of optimization for the aerodynamic development of the rear-end of MPV References | Related Articles | Metrics

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Optimization of Active Safety Airbag for 12-year-old Children Ge Ruhai, Cui Yizhong, Hong Liang, Xiao Xuan 2020, 42 (6):  771-777.  doi: 10.19562/j.chinasae.qcgc.2020.06.010 Abstract ( 224 )   PDF (1973KB) ( 353 )   Save The child occupant restraint system is an important means of protecting the child occupants in vehicles, in particular, school bus. In this paper, the active airbag for 12-year-old child is optimized. Firstly, the effects of seven parameters, i.e. the lengths of the upper, middle and lower straps, the opening percentage of vent valve, the mass flow rate of gas, the installation height and the opening pressure of airbag on the protection results of airbag on 12-year-old child are studied. Then by sensitivity analysis, three key control parameters of active airbag are found to be the length of upper strap, the opening percentage of vent valve and the opening pressure of airbag. Finally, by using the technique of the design of experiment with Latin hypercube sampling, combined with the construction of response surface model with second-order polynomial for the relationship between weighted injury criterion (WIC) and three key parameters of airbag, an optimization is conducted on the three key parameters of airbag. The results show that with an upper strap length of 0.205 m, a vent valve opening percentage of 1.8 and an opening pressure of 1.16×105 Pa, the WIC of a 12-year-old child can reach the minimum value of 0.240 5. Compared with original airbag parameters, i.e. an upper strap length of 0.235 m, a vent valve opening percentage of 1.0 and an opening pressure of 1.25×105 Pa, the optimized airbag achieves a 24.75% reduction in WIC for 12-year-old child References | Related Articles | Metrics

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Research on High Precision Accident ReconstructionMethod Based on Video Information Wu He, Han Yong, Shi Liangliang, Xu Wei 2020, 42 (6):  778-783.  doi: 10.19562/j.chinasae.qcgc.2020.06.011 Abstract ( 243 )   PDF (4285KB) ( 291 )   Save In order to improve the accuracy of accident reconstruction, the method of combination of multi-body system and finite element is used in this paper for reconstruction of two VRUs accident cases with clear video information and a high-precision accident reconstruction method is proposed and verified. Firstly, the video information is analyzed and vehicle collision speed is obtained based on the direct linear transformation (DLT) theory; then the VRUs kinematic response is accurately reconstructed by using the PC-Crash and MADYMO coupling method; finally, the intracranial kinematics and kinetic parameters are deeply analyzed based on the human body finite element model THUMS (Ver 4.0.2). The results show that the reconstructed vehicle VRU collision position, the kinematic response, rotation angle, landing posture and landing body of the collision process are completely consistent with the video information. The absolute error between VRU and vehicle final position is less than 7%, and the head injury position and injury severity of VRU are consistent with the injury report References | Related Articles | Metrics

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Annoyance Evaluation Model of Vehicle Interior Noise Based onTime-series Smoothed Excitation Level Spectrum CNN Model Feng Tianpei, Sun Yuedong, Wang Yansong, Zhang Boqiang, Liu Ningning, Guo Hui 2020, 42 (6):  784-792.  doi: 10.19562/j.chinasae.qcgc.2020.06.012 Abstract ( 197 )   PDF (3444KB) ( 275 )   Save Excitation level time-frequency spectrum can be used to establish the convolution neural network (CNN) model of vehicle sound quality evaluation (SQE). However, due to the discrepancy between the fluctuation characteristic of time-varying sound and the smooth characteristic of the instantaneous subjective evaluation curve of vehicle interior sound quality, the time-varying SQE model produces a fluctuating response to an input of fluctuating sound feature sequences. The performance of the CNN model of the overall annoyance evaluation of vehicle interior noise will be limited by directly using the fluctuating excitation level spectrum in time domain. In this paper, the Savitzky-Golay filter is used to smooth the excitation level spectrum in time domain, and CNN is used to build the mapping relationship between the overall subjective evaluation results of the comprehensive annoyance degree of vehicle interior noise and the time-series smoothed excitation level spectrum so that the overall annoyance CNN evaluation model based on the time-series smoothed excitation level spectrum is established. The leave-one-out cross-validation results indicate that compared with the excitation level spectrum CNN model, the time-series smoothed excitation level spectrum CNN model has better performance in overall annoyance evaluation of vehicle interior noise, with improvement in prediction accuracy (mean error decreased by 10.43%), stability (prediction variance decreased by 44.26%) and consistency (the Pearson correlation coefficient increased by 4.13%). The time-series smoothed excitation level spectrum can better represent the overall annoyance of vehicle interior noise than the excitation level spectrum References | Related Articles | Metrics

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Research on Multi-Agent Game Control System of an Electronic Air Suspension Li Zhongxing, Shen Ancheng, Jiang Hong 2020, 42 (6):  793-800.  doi: 10.19562/j.chinasae.qcgc.2020.06.013 Abstract ( 235 )   PDF (3468KB) ( 396 )   Save In order to coordinate the coupling relationship between the interconnection state control and the vehicle height control, an electronic air suspension multi-agent game control system is built by combining the multi-agent theory and game theory. First, the vehicle model that matches with the test vehicle is established and the accuracy of the model is verified. On this basis, the multi-agent game control system consisting of information collecton intelligent agent, vehicle height control agent, interconnected state control agent and game agent is constructed. The effectiveness of the system's learning behavior is verified under a single working condition, and the system control effect is verified under mixed conditions. The results show that under the control of the system, the root mean square value of the total weighted acceleration at the driver's position decreases by 7.77% and the roll factor decreases by 17.87% when driving in a straight line. Steering stability of the vehicle is improved by sacrificing partial ride comfort under cornering conditions. Under mixed conditions, the overall performance of the vehicle is greatly improved References | Related Articles | Metrics

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Research on ESC Adaptive Sliding Mode Control for CommercialVehicles Based on Nonlinear Disturbance Observation Shi Qiujun, Li Jing, Liu Peng 2020, 42 (6):  801-807.  doi: 10.19562/j.chinasae.qcgc.2020.06.014 Abstract ( 170 )   PDF (3659KB) ( 316 )   Save For problems of the commercial vehicle ESC control such as various disturbances existing for the actual vehicle, difficulty to establish an accurate vehicle model, large chattering of traditional sliding mode control, an adaptive sliding mode control (ADSMC) algorithm based on nonlinear disturbance observer (NDOB) is proposed in this paper. Firstly, the disturbances of vehicle modeling is estimated by nonlinear disturbance observer. Then, the radial basis neural network is used to adaptively adjust the key parameters of the sliding mode controller, so as to simplify the parameter adjustment process, reduce sliding mode chattering, and improve control accuracy. Finally, the vehicle model is built in TruckSim and the control strategy model is established in MATLAB. The control algorithm is tested and verified on the electronically controlled pneumatic hardware-in-the-loop test bench. The test results show that the NDOB-ADSMC algorithm has good control precision and can meet the requirements of vehicle ESC control References | Related Articles | Metrics

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Research on Complexity Evaluation Method of Dangerous Driving Scenes Dong Han, Shu Wei, Chen Chao, Sun Can, You Chao 2020, 42 (6):  808-814.  doi: 10.19562/j.chinasae.qcgc.2020.06.015 Abstract ( 273 )   PDF (1893KB) ( 556 )   Save A method of the collection of dangerous driving scene data and the evaluation of their complexity is proposed. Different from the collection method of natural driving data in large-scale real vehicle road test, the data before and after giving warning are collected as the data of dangerous driving condition for study based on advanced driving assistance system. On the basis of analyzing the dangerous driving scene data and their influence factors, the complexity evaluation indicator system of dangerous driving scenes is constructed in terms of environment, traffic flow and vehicle related factors. Based on the results of expert rating and applying analytical hierarchy process, the weights of indicators are determined and the model and method of evaluating the complexity of dangerous driving scenes are obtained and can be used for the simulation and test of intelligent vehicle References | Related Articles | Metrics

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Research on Vehicle Fault Prediction Scheme Based on Improved LightGBM Model Yan Shixuan, Zhu Ping, Liu Zhao 2020, 42 (6):  815-819.  doi: 10.19562/j.chinasae.qcgc.2020.06.016 Abstract ( 223 )   PDF (1545KB) ( 561 )   Save In view of the defects of slow model training and low recall rate caused by the large scale and class imbalance of vehicle fault data in the application of machine learning technique to automotive industry, the improvements in two respects are conducted on LightGBM model: firstly, the setting of class weights and the loss function of correction model for L1 normalization in model training, with the value of correction coefficient obtained by Bayesian optimization; secondly, the lowering of model classification threshold by threshold moving scheme in model prediction. The results of verification on Scania truck fault dataset show that the improved LightGBM model proposed has fast training speed, high recall rate and great engineering application significance References | Related Articles | Metrics

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Research on Sensitivity Evaluation Method Based on SpotWelds-Adjacent Elements Integrated Strain Energy Song Haisheng, Yang Na, Yang Changhai, Chen Zhiyong, Shi Wenku 2020, 42 (6):  820-825.  doi: 10.19562/j.chinasae.qcgc.2020.06.017 Abstract ( 144 )   PDF (2869KB) ( 277 )   Save Spot-welds have great influence on dynamic stiffness of structure, and the evaluation of the sensitivity of structure to spot-welds is very important in the spot-welds optimization with the dynamic stiffness of structure as objective. In view of that in some cases the traditional sensibility evaluation method for spot welds may get a wrong result, a sensibility evaluation method based on spot welds-adjacent element integrated strain energy is proposed and a comparative verification with traditional one is conducted. The results show that the method proposed can more accurately reflect the influence extent of spot welds on the dynamic stiffness of structure References | Related Articles | Metrics

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Study on Properties of Cr8 Stamping Die Steel for Automobile High Strength Plate Wei Wei, Zhou Jiangqi, Li Hengbai, Li Kaiwen, Zhao Liang, Yuan Sha 2020, 42 (6):  826-831.  doi: 10.19562/j.chinasae.qcgc.2020.06.018 Abstract ( 177 )   PDF (3841KB) ( 383 )   Save A new type of Cr8 cold working die steel HNC53has been developed in this project. The chemical composition analysis, metallographic analysis and mechanical performance test are carried out. Then samples are designed for heat treating as well as thermal diffusion treating (TD) The results show that the control accuracy of harmful impurities like P and S is of high standard, which is below 0.03% and 0.005% respectively. The carbides are dispersed in pearlite , with maximum size of 25 μm×12 μm. The maximum change rate of the three-dimensional dimensions is 1.58‰ after heat treating and surface treatment. The hickness of TD coating is 10 μm and the matrix structure is uniform. Compared with materials of the same kind , the performance indexes of HNC53 have reached the standard of imported materials References | Related Articles | Metrics

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Lightweight and Crashworthiness Design of Vehicle BodyFront-end Based on Multi-cell Structure He Liangguo, Zhao Jie, Gu Xianguang 2020, 42 (6):  832-839.  doi: 10.19562/j.chinasae.qcgc.2020.06.019 Abstract ( 220 )   PDF (3285KB) ( 434 )   Save In order to meet the requirements of lightweight and crashworthiness of vehicle body, its front-end is optimized by combining material replacement with structural improvement. Based on the vehicle frontal crash model verified by test, an aluminum front-end model is established with its crashworthiness compared with steel counterpart. For enhancing the crashworthiness of aluminum front-end, various multi-cell cross sections with different cell numbers are designed, and their energy absorption characteristics are analyzed under three-point bending and axial crushing conditions. A multi-objective optimization scheme is used to optimize the parameters of multi-cell front end structure. The results show that the aluminum multi-cell structure optimized can improve vehicle crashworthiness while significantly reducing the mass of front-end References | Related Articles | Metrics

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Study on Crashworthiness Optimization of Carbon-fiberSandwich Panel Structure with Polypropylene Foam Core Cui An, Xu Xiaoqian, Sun Wenlong, Yang Weili, Huang Xianqing, Liu Tianci 2020, 42 (6):  840-846.  doi: 10.19562/j.chinasae.qcgc.2020.06.020 Abstract ( 200 )   PDF (1677KB) ( 369 )   Save In view of the requirements of vehicle lightweight and crshworthiness, a carbon fiber sandwich panel composite structure with polypropylene foam core is manufactured, tested and simulated to study its mechanical performance. Then a multi-objective optimization is carried out on the thickness of facial sheets and foam core and the density of foam core to get the optimum scheme of thickness and density. Finally, the structure is applied to a car roof, with a topology optimization based on desity method conducted on the distribution of foam core for reducing roof mass while assuring its energy-absorbing characteristics. The results of roof crush test show that the stiffness and energy absorption performance of the car roof structure with optimized sandwich panel are obviously improved with a significant reduction in mass, meeting the crashworthiness and lightweight requirements of the vehicle. References | Related Articles | Metrics