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Welcome to Journal of Automotive Safety and Energy,
汽车安全与节能学报

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  • 2014, Vol. 5 No. 03 Published on:25 September 2014 Previous issue    Next issue
    Progress & Prospects
    Hybrid propulsion and hybrid braking technologies of electrified vehicles: Status and prospect
    ZHANG Junzhi, LV Chen, LI Yutong
    2014, 5(03):  209-223.  doi:10.3969/j.issn.1674-8484.2014.03.001
    Abstract ( 865 )   PDF (2350KB) ( 4145 )  

    The performances of hybrid propulsions and hybrid brakes of various electric vehicles (EVs)
    significantly affect their energy efficiency and their safety. The development statuses were worldwide reviewed
    for the hybrid propulsion and hybrid braking technologies from the aspects of the parameter matching and
    optimization, the blending energy management, and the dynamical cooperative control to conclude and analyze
    the scientific topics and generic technologies. Further researches that need to be carried out in the hybrid
    propulsion and the hybrid braking to improve EV performances include the parameter matching and optimization
    when vehicle dynamics considered, the construction of cyber-physical system which can provide a platform
    for online management of vehicle multi-source and dual-way driving and braking energy, and the investigation
    of dynamic characteristics, blended mechanisms, and cooperative control for dynamical-process of the hybrid
    propulsion and the braking systems under critical driving situations.

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    Temperature sensitivity of lithium-ion battery: A review
    LI Ping, AN Fuqiang, ZHANG Jianbo, WANG Haoran
    2014, 5(03):  224-237.  doi:10.3969/j.issn.1674-8484.2014.03.002
    Abstract ( 1390 )   PDF (3316KB) ( 3860 )  

    Temperature sensitivity statistics were collected and analyzed for lithium-ion battery (LIB) of electric
    vehicles (EV) based on survey of papers and patents. The results show that low and high temperatures have
    great effect on the performances, respectively, severely affecting the operation and the market penetration of
    EVs. To mitigate this problem, some techniques are used including changing raw material properties, optimizing
    cell designs, and using battery thermal management systems (BTMS). Further research for temperature
    sensitivity is to improve the cathode materials and anode materials of LIB to increase electric conductivities
    and ionic conductivities; to optimize electrode structures and cell structures to uniform thermal and electrical
    distribution; to develop new protocols for alternating current (AC) preheating/charging at low temperatures; and
    to incorporate the liquid cooling method.

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    Automotive Safety
    Optimization design in developing a vehicle body in forward engineering
    SHI Guohong, WU Jinyan, SONG Zhengchao
    2014, 5(03):  238-243.  doi:10.3969/j.issn.1674-8484.2014.03.003
    Abstract ( 631 )   PDF (2083KB) ( 1750 )  
    Abstract: This paper studies how to apply the optimization design method in various stages of development
    of body in white (BIW) reasonably, with a new car BIW development in forward engineering as an example.
    Material distribution and load path of BIW were created through topology optimization technology. Parametric
    BIW geometric / finite element models were built for load path studying and BIW base model defining. BIW
    structure, passive safety, noise, vibration performance and mass were balanced through the parametric
    optimization technology based on design of an experiment and an approximation model. The detailed stamped
    rib design of the BIW parts was completed by topography optimization technology. Through 4 cases (topology
    optimization, load path studying, parametric optimization and topography optimization), using a variety of
    optimization design method reasonably, the BIW development process is optimized, the BIW development
    efficiency is improved, the structure, passive safety, noise and vibration performance of BIW are enhanced, and
    the body mass is reduced.
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    Stress and strain of Hybrid Ⅲ dummy neck under impact loading
    LAI Xinghua1,2, ZHAO Jiaqing2, ZHOU Qing1
    2014, 5(03):  244-251.  doi:10.3969/j.issn.1674-8484.2014.03.004
    Abstract ( 609 )   PDF (2881KB) ( 1302 )  
    Certificated dummy neck pendulum impacts and frontal sled tests were simulated to investigate the
    dynamic mechanical behaviors of a three-point belted soft material dummy neck under impact loading, using a
    validated Hybrid III 50th percentile male finite element model, and a non-linear dynamic explicit finite element
    method, respectively. Some dynamic mechanical behaviors such as local stresses and strains of Hybrid III neck
    were measured at two structural levels and two loading types. The results show that the loading for a Hybrid
    III neck regulated certification test is severer than that for a simulated vehicle crash test. Therefore, some
    experimental designs are needed for an accurate material characterization of dummy necks under crash-like
    impact loading while the strains in the material tests should reach 1.5 and the strain rates should reach 50 s-1,
    with the stress states including simple tension/ compression, pure shear, bi-axial tension/ compression, and bulk
    compression.
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    Influence of the safety belt collecting on chest deflection in frontal impact tests and the D-ring improvement
    SHANG Enyi, JU Chunxian, JIANG Binqing, QIN Jiajia
    2014, 5(03):  252-256.  doi:10.3969/j.issn.1674-8484.2014.03.005
    Abstract ( 538 )   PDF (2743KB) ( 1812 )  
    In vehicle frontal impact tests, the safety belt collecting, which normally appears at the upper guide
    ring (D-ring) of a safety belt height adjuster, causes severe dummy chest injuries. Two sled tests were conducted
    for a vehicle. In one test, the belt acted normally, and in the other test, the belt had collection on the D-ring.
    The friction forces, the shoulder belt forces, the chest deflections, and the chest rigidity were measured in the
    tests, and then analyzed. The results show that the safety belt collecting enhances D-ring friction force with the
    shoulder force increasing by 500 N and the shoulder belt force rising quickly, which makes dummy chest rigidity
    decrease, with the dummy chest deflection raising about 20%. Therefore, a new safety belt structural design
    should reduce D-ring friction force to prevent safety belt collecting.
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    Eco speed optimization based on real-time information of road gradient
    WANG Jianqiang, YU Qianwen, LI Shengbo, DUAN Ning, LI Keqiang
    2014, 5(03):  257-262.  doi:10.3969/j.issn.1674-8484.2014.03.006
    Abstract ( 611 )   PDF (2477KB) ( 2171 )  

    Road slopes significantly affect vehicles’ fuel economy. This paper presents a novel Eco Speed
    algorithm for vehicles on roads with up-down slopes based on road gradient information, which is the basic for
    eco-driving assistance system with connected vehicles. Based on the construction of the vehicle model and the
    fuel consumption model, the algorithm first calculated a steady eco speed, which is the most fuel economical
    cruise velocity for a vehicle on the road without slopes. When entering a road slope, with the aid of GPS (global
    positioning system) / GIS (geographic information system) information, the algorithm calculated the eco speed
    profile, using dynamic programming. The algorithm was evaluated under Carsim and Matlab/Simulink, and the
    simulation results show that the fuel consumption is reduced.

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    Numerical simulation and test validation of automotive laminated windshield glass
    WANG Dong, WANG Yajun, SHI Yuliang, WU Shenrong, ZHAO Zheng, WU Te
    2014, 5(03):  263-269.  doi:10.3969/j.issn.1674-8484.2014.03.007
    Abstract ( 633 )   PDF (2218KB) ( 1636 )  
    The study of windshield laminated glass is important for improving the performance of pedestrian
    protection in the process of automobile development. A finite element (FE) model was established for the
    automotive windshield laminated glass. The shell elements and solid elements were used to represent the
    two layers of glass, for comparison study. The solid elements were used to represent the PVB inter layer.
    Principal strain was used to deal with the crack of glass. With this finite element model, systematic analysis was
    performed for the influence factors of pedestrian head form impacting the central area of automotive laminated
    windshield glass. The results show that the modeling method based on 5-mm shell elements and hybrid mesh
    can effectively predict the pedestrian head injury and the pattern of the glass fracture, well correlated with the
    test. The method was then applied to the head form impacting to the bottom part of the windshield glass and the
    roof crush. The analysis results of the patterns of glass cracks, the value of head injury criterion, and the roof
    resistence strength are close to the test results. This method will be helpful for automotive windshield program
    development and optimal design.
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    Product quality defects level evaluation of vehicle audit
    ZHANG Lingchao, WEI Lang, WANG Shengchang, HU Xin, WANG Peng
    2014, 5(03):  270-275.  doi:10.3969/j.issn.1674-8484.2014.03.008
    Abstract ( 485 )   PDF (1873KB) ( 1672 )  
    Currently, the auto production enterprises usually express the product quality defect levels of vehicle
    audit in terms of quantitative defect score averages. Aiming at the advantage and shortcoming of the evaluation,
    the paper takes the product quality defect levels of vehicle audit as the research object, based on the defect
    type, then builds product quality defect level evaluation system, and creatively uses fuzzy comprehensive
    evaluation method to build the evaluation model, qualitatively reflects the vehicle and primary index quality level l
    by quality grade, and finally gets the vehicle audit comprehensive evaluation as a result of defects of quantitative
    audit score and qualitative quality grade. The 5 level indicators and vehicle quality level of each car can be
    shown by 5 kinds of quality grade, such as quality good, relatively good, ordinary, relatively bad, and bad.
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    Development and validation of an offset deformable barrier and its FE model
    BAI Zhonghao, GUO Hourui, BAI Fanghua, CAO Libo
    2014, 5(03):  276-281.  doi:10.3969/j.issn.1674-8484.2014.03.009
    Abstract ( 543 )   PDF (2738KB) ( 1310 )  
    An offset deformable barrier (ODB) manufactured by honeycomb blocks was developed, which
    meets the requirements of “the protection of the occupants in the event of an offset frontal collision for
    passenger car GB/T 20913-2007” in China. A finite element model (FEM) of the developed barrier was built. A
    formula of out-of-plane compression strength was derived to guide the tests. Based on quasi-static compression
    tests, honeycomb parameters that fulfill the regular requirements were obtained. High-horizontal bar and lowhorizontal
    bar sled impact tests of manufactured offset deformable barrier were carried out. Material erosion
    was added to the barrier FEM, and spring element was applied to simulate the effect of honeycomb entrapped
    air pressure under dynamic impact. The barrier impact test results were used to validate the model. The results
    show that the model can simulate the tear effect of aluminum panel and honeycomb core, and the waveform and
    peak force of the force-displacement curve are in agreement with test results.
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    Reverse technology for dummy skin material parameters of vehicle crash test
    CAO Libo, HUA Xin, ZHANG Guanjun, ZHANG Kai
    2014, 5(03):  282-288.  doi:10.3969/j.issn.1674-8484.2014.03.010
    Abstract ( 444 )   PDF (2800KB) ( 1405 )  
    In order to provide reasonable material parameters of dummy skin for development of finite element
    model, a series of uniaxial compression tests were conducted (strain rates of 0.001 s-1, 0.01 s-1, 0.1 s-1, and 2 s-1
    engineering strain levels of 10%, 20%, and 30%) with parameters of two-term Ogden model are obtained by
    fitting the test data. Finite element simulation model of test was built and a group of optimal parameters which
    allowed the minimum error between the data of test and simulation were acquired by optimizing the material
    parameters of two-term Ogden model with Hybrid genetic algorithm. Calibration tests of dummy head with
    different velocities are conducted to validate the optimal parameters, and the error is less than 4%.
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    Static crushing analysis and test validation for foam and plastic in pedestrian lower legform impact
    LV Xiaojiang, SUN Lizhi, ZHU Linkai , ZHOU Dayong, LIU Weiguo
    2014, 5(03):  289-293.  doi:10.3969/j.issn.1674-8484.2014.03.011
    Abstract ( 430 )   PDF (2239KB) ( 1333 )  
    Energy absorption performance of vehicle front-end material was studied when pedestrian legform
    impacts the vehicle. On foams of three different densities and one kind of plastic, static crushing performance
    experiment was carried out. On this basis, the density of 30 g/dm3 foam and the plastic were chosen which have
    better energy absorption. In a certain kind of sport utility vehicle (SUV) car, energy absorption performance of
    the pedestrian protection test samples was measured. The results show that at the static crushing experiments,
    overall performance of this kind of plastic is better than that of the foam. The plastic peak load, average load,
    total energy absorption are increased more than 4 times the foam, and the energy absorption per mass is also
    higher than the foam. Therefore, under the condition of the same energy absorption space, using plastic as the
    vehicle front-end energy absorption material can reduce the pedestrian leg tibia acceleration and knee bend
    angle, in favor of the pedestrian lower legform impact safety performance.
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    Automotive Energy Efficiency & Environment Protection
    Analysis on the progress of energy saving and new energy vehicle industrialization in China based on a database
    WANG Hewu, SHI Hong, CHEN Ping, OUYANG Minggao
    2014, 5(03):  294-297.  doi:10.3969/j.issn.1674-8484.2014.03.012
    Abstract ( 528 )   PDF (1881KB) ( 1708 )  
    The industrialization progress of energy-saving and new-energy vehicles was analysed from year
    of 2005 to June 2014 based on a database named the China Electric Vehicle Market Database developed by
    authors of the State Key Laboratory of Automotive Safety and Energy of Tsinghua University. The database
    contents the monthly production of hybrid, the pure electric vehicles or/and plug-in hybrid electric passenger
    vehicles or/and commercial vehicles, and the power battery type mounted. The results show that the vehicle
    technologies demonstration was carried out between 2005 to 2009, more than 8 000 hybrid or/and battery
    electric buses or/and passenger cars were put into several demo cities; the market cultivating period began
    from year of 2010, with 100% annual increasement in fleet number, and the total energy-saving and new-energy
    vehicles in the stock passed 156 thousand by the end of June of 2014. The Chinese market in public transport
    field is successful with a market share rate of 19.3%, but the passenger car market is just started up with only 0.4%
    market share rate.
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    Mathematical analysis and numerical simulation for thermo-stress in a square lithium-ion battery
    LU Shigang, SHI Qitong, TANG Haibo
    2014, 5(03):  298-303.  doi:10.3969/j.issn.1674-8484.2014.03.013
    Abstract ( 557 )   PDF (2619KB) ( 1971 )  
    The temperature rise and thermal stress in lithium-ion battery charging and discharging processes
    may affect battery performances. This paper gives the temperature field and thermal stress field for a square
    lithium-ion battery using theoretical calculation and simulation method, and analyzes relationship factors. The
    results show that the highest temperature in the geometric center increases linearly with the heat generation
    rate. The maximum temperature difference increases linearly the square of battery sizes. The battery center
    area, the high-temperature region, has compressive stress; battery side center has tensile stress. Thermal
    stress concentration occurs at the center of the sides. The maximum compressive stress is 2 times the
    maximum compressive stress.
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    Experimental study on the characteristics of particulate emissions from GDI engines
    SHUAI Shijin, ZHENG Rong, WANG Yinhui, FU Haichao, XU Hongming
    2014, 5(03):  304-310.  doi:10.3969/j.issn.1674-8484.2014.03.014
    Abstract ( 485 )   PDF (2251KB) ( 1523 )  
    Particulate emission experiments were conducted on two gasoline direct injection (GDI) engines to
    study the influence of engine load, excess air ratio, and ignition advanced angel on the emission characteristics
    such as particulate mass (PM), particulate number (PN), and size distribution after three way catalyst (TWC). The
    component of soluble organic fractions (SOF) was analyzed using gas chromatograph-mass spectrometer (GCMS).
    The results show that the PM and PN increase with the engine load, and the magnitudes of the increase
    are significant at high load. The PM and PN both decrease with the increase of excess air ratio and the delay of
    ignition timing. The catalyst reduces the SOF in the particulate matter and the concentration of the nucleation mode
    particles. The peak diameter of the nucleation mode particles is between 10 and 20 nm; and the peak diameter of
    the accumulation mode particles is between 50 and 70 nm. The engine load, TWC, excess air ratio and ignition
    timing have small influences on the particle diameter range.
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