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  • 2012, Vol. 3 No. 4 Published on:25 December 2012 Previous issue    Next issue
    Focusing on Vulnerable Populations in Crashes:Recent Advances in Finite Element Human Models for Injury Biomechanics Research
    HU Jingwen, Jonathan D. RUPP, Matthew P. REED
    2012, 3(4):  295-307.  doi:10.3969/j.issn.1674-8484.2012.04.001
    Abstract ( 2046 )   PDF (2058KB) ( 2461 )  

    Children, small female, elderly, and obese occupants are at greater risk of death and serious injuries
    in motor-vehicle crashes than the mid-size, young, male occupants. However, current injury assessment tools,
    including crash test dummies and finite element (FE) human models, generally do not account for different
    body shape and composition variations among the population. The opportunity to broaden crash protection
    encompassing all vehicle occupants lies in improved, parametric human FE models that represent a wide range
    of human attributes. In this study, a literature review demonstrates that recent studies on human anthropometry,
    finite element human modeling, mesh morphing, human tissue tests and whole-body cadaver tests have laid the
    groundwork for the new generation of human models. A framework for developing such models was proposed
    in this study. The developed models enable population-based simulations for future vehicle design optimizations
    targeting at various vulnerable populations that are not represented by current injury assessment tools.

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    Automotive Safety
    Design of a Magnesium Alloy Seat frame Using the Rear Sled Crash Test and Simulation
    Moonyoung CHOI, Younghan YOUN, Wanhee HAN
    2012, 3(4):  308-312.  doi:10.3969/j.issn.1674-8484.2012.04.002
    Abstract ( 2029 )   PDF (1667KB) ( 1992 )  

    To minimize vehicle mass is an important selection for energy safe and eco-friendly vehicles to
    reduce environmental pollution. This paper investigates the design and feasibility of a magnesium alloy seat
    frame (MASF) to substitute the existing steel seat frame and improve the seat frame strength while maintaining
    the advantages of lower density and higher vibration absorption properties. Sensitivity analysis of MASF
    parameters, including stress distribution and acceleration, was made using the finite element (FE) analysis. An
    optimization design for MASF in a rear crash test was obtained using a three-level orthogonal array approach of
    the Taguchi design matrix, as well as through the correlation of a prototype magnesium seat and an LS-DYNA
    simulation. The results show that 40% of mass reduction can be achieved using this approach compared with
    using a conventional steel seat structure.

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    Influence of Vehicle Model Year and Occupant Seating Position on Serious Injury RIsk in Near-Side Collision
    LIU Yang, LAI Xing-Hua, MA Chun-Sheng
    2012, 3(4):  313-318.  doi:10.3969/j.issn.1674-8484.2012.04.003
    Abstract ( 1830 )   PDF (1698KB) ( 1614 )  
    The crash safety of four-door sedans in near-side impacts was investigated with respect to the
    vehicle model year and the occupant seating position to predict serious injury risks, using the National Highway
    Traffic Safety Administration (NHTSA) New Car Assessment Program (NCAP) moving deformable barrier (MDB)
    tests database as the data sources. The test vehicle geometrical characteristics and the crush deformation
    were summarized with the head injury criteria (HIC), the thoracic trauma index (TTI), and the peak pelvis lateral
    acceleration (PPLA) used to evaluate serious injury risks for different body regions of occupants. The results
    show that these injury criteria all decrease with increasing vehicle model year for both front and rear seat
    occupants. Much higher risks of serious head and thoracic injury occur for rear seat occupants compared with
    the front seat occupants for newer vehicle models. Restraint effectiveness is closely related to occupant seating
    positions. Therefore, the head and thoracic injury mechanism and countermeasures should be emphasized for
    rear seat occupants.
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    Design of straight-retractable energy-absorbing beam for electic cars and its crashworthiness analysis
    WANG Qiu-Cheng, LIU Wei-Guo, GE Dong-Dong
    2012, 3(4):  319-325.  doi:10.3969/j.issn.1674-8484.2012.04.004
    Abstract ( 1419 )   PDF (2479KB) ( 1562 )  
    The insufficient mileage is one of the major bottleneck factors which affect the promotion and
    application of electric cars. To reduce the electric vehicle body mass is an effective way to improve the mileage
    of an electric vehicle. Two kinds of contraction beams, straight retractable (SR) and tapered retractable (TR)
    beams, were designed to lighten the electric car mass. A frontal crash model was established by using the
    Hypermesh and LS-DYNA to study the frontal structural component crashworthiness of an electric car during
    collisions at a low-speed of 16 km/h and a high-speed of 50 km/h. The collision energy absorption, the impact
    force, and the body acceleration, when using new energy-absorbing beams, were analyzed and compared
    with those when using the original energy-absorbing beam. Simulation results demonstrate that the straight
    retractable beam can absorb more crash energy by 18.0% at the high-speed collision and reduce the mass by
    23.6%, which optimizes both the light mass and the crashworthiness of an electric car.
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    Energy absorption characteristic simulation of cone thin-walled metal tube research in the automotive collision
    ZOU Meng, WEI Can-Gang, XU Shu-Cai
    2012, 3(4):  326-331.  doi:10.3969/j.issn.1674-8484.2012.04.005
    Abstract ( 1547 )   PDF (2109KB) ( 1643 )  
    Thin-walled metal tubes are structural parts for vehicle security when automotive collisions occur.
    This paper investigates the energy absorption characteristics of an aluminum alloy LD2 metallic thin-walled
    tube with different tapers and cell numbers to optimize the design of the tube. Hypermesh and Ls-Dyna soft
    wares were used to simulate the dynamic loads in axial and deflective directions with Initial Peak Load (IPL) and
    Specific Energy Absorption (SEA) characterizing the energy absorption characteristics. The results show that
    the IPLs of the single-, double-, and fourfold-cell conical tubes reduce with increasing taper, with the IPLs of the
    taper pipe being lower than those of the straight tube and that the SEA increases with increasing taper. Both
    the IPL and the SEA in oblique impact decrease as the collision angle increases for fourfold-cell conical tube
    with taper of 0.3. Therefore, a reasonable adjustment of the tube taper and cell number can improve the energy
    absorption characteristics of thin-walled tubes.
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    Analysis and its solution for bumper low-speed structural crash based on RCAR
    SUN Qing, GAO Bao-Cai, CHEN Xian-Ling
    2012, 3(4):  332-338.  doi:10.3969/j.issn.1674-8484.2012.04.006
    Abstract ( 2221 )   PDF (2623KB) ( 2718 )  
    Bumper low-speed structural crash tests proposed by Research Council for Automobile Repairs
    (RCAR) were added to the official insurance level assessment programs by European Commission in January
    2011. Bumper low-speed crash was simulated for a real sports utility vehicle (SUV) to analyze the effects of
    the new RCAR tests on the insurance rating evaluation adopting Oasys and Hypwork software tools, the test
    and evaluation methods of RCAR, and the design concept for vehicles in low speed crash. The results show
    low stiffness of the bumper beam with the absence of underpins between the bumper and the bumper beam
    resulting in poor support in the crash. Barrier’s deformable section center line does not align with the bumper
    beam center line, which induces heavy damage and reduces the vehicle insurance rating. Some measures are
    given to perfect vehicle passive security.
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    Simulation research and optimal analysis for small overlap frontal crashworthiness of a real car
    LIU Zhen-Hai, QIAO Lei-Lei, YUE Guo-Hui
    2012, 3(4):  339-346.  doi:10.3969/j.issn.1674-8484.2012.04.007
    Abstract ( 1932 )   PDF (2479KB) ( 1993 )  
    A crash-test protocol and rating guidelines for small-overlap frontal-crashworthiness, which
    was released by the Insurance Institute for Highway Safety (IIHS) in August 2012, is a challenge to China’s
    enterprises intending to enter the US automotive market. Small-overlap frontal barrier crash tests on a real
    vehicle in the authors' company were simulated and analyzed using the correlated FE model according to the
    protocol and guidelines. The tests were conducted at 64.4 km/h and 25% overlap, with rating based on vehicle
    structures, restraints and dummy kinematics, and dummy injury measures, and with the overall rating obtained
    by weighting of each individual rating. The original results indicate that the structure rating is “Marginal”. After
    optimizing the structure and material according to the original results, the structure obtains “Good” rating. Some
    strategies for structure crashworthiness and restraints are summarized to offer references for new car safety.
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    Automotive Energy Efficiency & Environment Protection
    Measurementsof unregulated emissions from a methanol-gasoline blend vehicle using different methods
    ZHANG Fan, WANG Jian-Hai, YU Jin-Tao
    2012, 3(4):  347-354.  doi:10.3969/j.issn.1674-8484.2012.04.008
    Abstract ( 1572 )   PDF (2482KB) ( 1521 )  
    Unregulated emissions have become an important factor restricting the development of methanol alternative
    fuels. Type I emission tests were carried on a chassis dynamometer according to the state standard of China, GB 18352.3-
    2005, using a light-duty vehicle fuelled with pure gasoline and gasoline blend with methanol volume fractions of 10% and
    20%. High performance liquid chromatography, gas chromatography-mass spectrometry, and Fourier transform infrared
    spectrometer (FTIR) were used to measure methanol, formaldehyde, acetaldehyde, acetone, benzene, toluene, xylene and
    other unregulated emissions from a vehicle fuelled with different proportions of methanol-gasoline blends. The test results
    show that the methods of the integration of FTIR instantaneous values and the chemical analysis of bag sampling can both
    accurately measure formaldehyde, benzene, toluene and other unregulated pollutant emissions in the vehicle exhaust. With
    increasing methanol content in the fuel, CH4, unburned methanol and formaldehyde emissions increase proportionally, with
    the benzene and toluene emissions having a slight increase and acetaldehyde, acetone and xylene emissions remaining
    basically the same.
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    Driving control of IPM motors with wide-range speed-regulation for electrical vehicles
    JIA Yao-Qin, LONG Fei, CAO Hui-Min
    2012, 3(4):  355-363.  doi:10.3969/j.issn.1674-8484.2012.04.009
    Abstract ( 1663 )   PDF (2563KB) ( 2794 )  
    Interior permanent magnet (IPM) synchronous motors are widely used in electric vehicles. This
    paper investigates the driving control of IPM motors with Hall position sensors to realize large torque starting,
    wide range of speed regulation and high efficiency operation. The driving control strategy combines the
    improved Hall prediction algorithms with the first-order Hall position algorithms. Simulation and experimental
    results show that the maximum error of rotor position detection is less than 0.3 rad using the proposed strategy
    when the motor starts. The proposed flux weakening method has a better robustness compared with the
    traditional flux-weakening control. The motor efficiency is increased by 1% compared with that of the zero
    quadrature axis current control, when using table look-up control strategy and average-voltage dead-time
    compensation method.
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    Corporate average fuel consumption (CAFC)and uts limit standard of passenger vehicle in China
    MA Dong, AN Feng, KANG Li-Ping
    2012, 3(4):  364-370.  doi:10.3969/j.issn.1674-8484.2012.04.010
    Abstract ( 2329 )   PDF (1954KB) ( 5150 )  
    To promote the fuel economy level of passenger vehicle industry in China is beneficial to energy
    saving and emission reduction. The Corporate Average Fuel Consumption (CAFC) of passenger vehicles
    in China market was investigated based on the authority’s data and standards. The results show that the
    passenger-vehicle CAFC in China market in the year of 2011 is 7.5 L/(100 km), which overall meets the target
    value of Phase 2 in the "Limits of Fuel Consumption for Passenger Cars" (GB 19578-2004, 2004-09-02) of
    China, but does not meet the target of Phase 3 (GB 27999-2011, 2011-12-30). The vehicle companies with
    independent-brands have lower real CAFC values than those with the joint-venture-brands, but have a higher
    ratio of the real value to the CAFC target standard, so they have more work to do to meet the Phase 3 standard.
    Compared with domestic vehicles, imported passenger vehicles have higher CAFC real values and a higher
    ratio of the real value to the target standard, which shows a severe challenge to the domestic vehicles.
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    Battery Thermal Management System with Liquid Cooling and Heating in Electric Vehicles
    YUAN Hao, WANG Li-Fang, WANG Li-Ye
    2012, 3(4):  371-380.  doi:10.3969/j.issn.1674-8484.2012.04.011
    Abstract ( 2059 )   PDF (2996KB) ( 5909 )  
    The performance and life of electric-vehicle battery-systems are affected by the temperature. A
    liquid cooling/heating Battery Thermal Management (BTM) with an optimum geometric structure was designed
    to keep the average battery-system temperature in the range from 20 ℃ to 45 ℃ and the temperature gradient
    within 3 ℃ . According to overall system flow balancing in a BTM, cooling/heating plates with different structure
    parameters were simulated to investigate cooling effects of the BTM. An infrared thermal imager monitored the
    cooling/heating plate temperature rises in battery-system heating experiments. Experimental and simulation
    results were shown to be the same. The results show that the structure with an inlet and an outlet on the
    same side has an even flow distribution. By combining the simulation and optimization, the obtained optimum
    combination of the inlet velocity and the temperature in the cooling/heating plate reduces the plate-surfacetemperature
    standard-deviation to 2.61 ℃ , and makes the battery system uniformly heated.
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    Multivariable control of residual-affected  HCCI engines based on model predictive control
    LI Ding-Gen, WANG Di
    2012, 3(4):  381-389.  doi:10.3969/j.issn.1674-8484.2012.04.012
    Abstract ( 1357 )   PDF (2171KB) ( 2160 )  
    A two-input and two-output physical model for pressures and combustion phases was built to realize
    the coordinated control of the peak pressures and combustion phases for a homogeneous charge compression
    ignition (HCCI) engine. This model is based on the Shaver' residual-affected HCCI engine model with the
    constant wall temperature heat transfer model suitable for HCCI combustion. A cooperative control system of
    pressure and combustion phase was designed using the model predictive control (MPC) theory with the variable
    valve timing (VVT) as the control method. The coordinated simulation experiment was done by using GT-Power
    and Matlab/Simulink. The results show that the control model satisfies the engine control demand, realizes the
    collaborative control of the pressure and combustion phase with control accuracies of ±30 kPa and ±0.6° CA,
    and the response time of 6-7 engine cycles.
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    Experimental Study on Mechanical Properties of AZ31B-H24 Magnesium Alloy Sheets uder Multi-Axial Loading Conditions
    JIA Yue-Qian, LONG Xiang, BAI Yuan-Li
    2012, 3(4):  390-400.  doi:10.3969/j.issn.1674-8484.2012.04.013
    Abstract ( 1621 )   PDF (3001KB) ( 2959 )  
    Since magnesium alloy is a promising engineering material for the automotive light-mass design, this
    paper investigates the plasticity and fracture properties of AZ31B sheets based on the experimental results from
    uniaxial, biaxial and equi-biaxial tensions. The results show that AZ31B displays remarkably anisotropy in both
    plasticity and fracture. Hill-1948, Barlat-1989 and Barlat-2003 anisotropic constitutive models were calibrated
    for plasticity. The results show that that none of the above models accurately describes both material strength
    and plastic flow at various orientations if associated flow rules are assumed. Therefore, non-associated flow is
    suggested for this material. The ductile fracture strains of AZ31B-H24 can be measured using two methods, the
    correlation Digital Imaging Correlation (DIC) system and the fracture-initiation-locations area-reduction, with
    the forecast results calculated using the fracture forming limit diagram (FFLD) and the modified Mohr-Coulomb
    criterion (MMC).
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