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• 2015, Vol. 6 No. 02
  Published on:25 June 2015 Previous issue    Next issue
  Progress & Prospects

  Traffic congestion mechanism in the automotive social cost and the “Tokyo model”

  LI Chunli, ZHANG Zhongyun

  2015, 6(02):  103-118.  doi:10.3969/j.issn.1674-8484.2015.02.001

  Abstract ( 362 )   PDF (1951KB) ( 2233 )  

  An analysis was made over the inherent mechanism creating the automotive social cost and the
  endogenous causes of traffic congestion to explain the strategies to resolve traffic congestion problem, by
  using an explaining model based on the economic theories of social cost and supply-demand relations. A
  concept of transportation demand management was introduced to explain the problem from three dimensions:
  controlling transportation demand, changing trip modes, as well as rational planning of urban spatial distribution.
  Due to Tokyo’s comparability with Beijing, an elaboration was made on the “Tokyo Model” that derives from its
  experience of regulating its own traffic congestion, with its three major characteristics: the restriction on selfdriving
  trips, the development of three-dimensional rail transit system, and the emphasis on the construction
  of urban “sub-center”. After compared with such megalopolises as Tokyo, London, and New York, it is clear to
  highlight Beijing’s uniqueness. Therefore, theoretic explanations and specific policy advice can be proposed by
  using the experience of other countries for reference to tackle traffic congestion problem in China.

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  Recall management mechanism of defective automotive products in China: Status and development

  CHEN Yuzhong, LIU Chen, ZHANG Jinhuan

  2015, 6(02):  119-127.  doi:10.3969/j.issn.1674-8484.2015.02.002

  Abstract ( 393 )   PDF (1699KB) ( 1736 )  

  Recall of defective automotive products is internationally adopted for after-market administration by
  the government. This paper summarizes the current mechanism of automotive defective products management,
  counts up and quantitatively analyses the statistics of total recalls, the automotive defect investigations and the
  social economic benefits in China in 2004-2014. 19.8 million vehicles were recalled with 28.4 billion YUAN (RMB)
  costs saved for Chinese customers during this period. The results show that the current recall management
  mechanism is effective to China in vehicle risk-management respect. However, the current mechanism in China
  is still far from perfect in the recall rate, the recall ratio and the economic benefit, etc., comparing between
  China and USA. Therefore, the defective automotive products management mechanism needs to be continually
  improved with great effort for China.

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  Automotive Safety

  Tests of pedestrian flexible legform base on Euro-NCAP assessment protocol

  LIU Weiguo, L Xiaojiang, GU Xianguang, LU Dongmei, ZHOU Dayong, SUN Lizhi

  2015, 6(02):  128-133.  doi:10.3969/j.issn.1674-8484.2015.02.003

  Abstract ( 367 )   PDF (1780KB) ( 1733 )  

  Flexible legform impactor (Flex-PLI) impact tests were done for a type of vehicle base on the
  European New Car Assessment Program (Euro-NCAP) to reduce the impact injure onto pedestrian lower
  legform. The key factors influencing the tibia injury and knee injury were analyzed based on the scores by
  the Euro-NCAP assessment. The results show that vehicle front contact with tibia position stiffness has a
  great influence on bending moment, and knee ligament elongation is associated with upper and lower relative
  motion of knee joint. So that, the front-end structure design should avoid tibia bending moment being exceed
  the standard caused by the great stiffness of vehicle front structure; and the design should adjust the knee
  when upper and lower amount of intrusion to improve knee ligament elongation. These conclusions will provide
  practice in front-end structure design for new vehicles.

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  Pole impact crashworthiness of hot stamping front bumper of a car

  2015, 6(02):  134-138.  doi:10.3969/j.issn.1674-8484.2015.02.004

  Abstract ( 322 )   PDF (1407KB) ( 1413 )  

  The impact crashworthiness between front-bumper and pillars (such as telegraph poles or trees)
  was investigated. Some drop hammer impact tests were done for a car with its front-bumper being built from
  ultra-high-strength hot-stamping boron-steel to reduce the bumper mass. The impact crashworthiness were
  simulated and analyzed for the bumper with different thickness by a special finite element model with the
  deformations, the stresses, and the energy absorption conditions of a front-bumper being taken as evaluation
  indexes. The results show that the front-bumper using ultra-high-strength hot-stamping boron-steel reduces 40
  mm within the biggest deformation, increases 7 kN within the biggest stress, and increases 0.1 kJ within the
  energy absorptions compared with the original bumper from cold-stamping steel. Therefore, the hot-stamping
  front-bumper has more excellent pole impact crashworthiness.

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  Optimal design of the vehicle front-end structure stiffness for pedestrian lower leg protection

  ZHANG Zhifei, LI Xun, XU Zhongming, HE Yansong

  2015, 6(02):  139-144.  doi:10.3969/j.issn.1674-8484.2015.02.005

  Abstract ( 255 )   PDF (1461KB) ( 1298 )  

  A design method of vehicle front-end structure stiffness was proposed based on a multi-body
  dynamics model to improve pedestrian lower leg protection. The model was established in Madymo, based on
  the crash tests of the leg form impact to car and a FE (finite element) model of the vehicle front-end structure,
  according to the geometry and stiffness parameters which were obtained by the finite element analysis on
  the collision area. An optimal design was completed by the global response surface method (GRSM). The
  optimal objective was the mean square evaluation (MSE) of normalization of three injury criterion (the tibia peak
  acceleration, knee bending angle, knee shear displacement) with 4 design variables including the yield forces
  and the maximum deformations for the bumper and the auxiliary bumper. The results show that the objective
  reduces by 73.9%, the tibia peak acceleration decrease by 50.3% with the knee bending angle decreasing
  48.9%. Therefore, the optimization of the vehicle front-end structure stiffness improves the performance of
  pedestrian leg protection.

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  Numerical simulation on the influence of different front window angle of automobile stability in crosswind

  ZHANG Furen, ZHANG Jinlong, QU Xian, LE Huan

  2015, 6(02):  145-149.  doi:10.3969/j.issn.1674-8484.2015.02.006

  Abstract ( 308 )   PDF (1195KB) ( 1332 )  

  It is important for car’s stability in crosswind that the airflow separation around the different front
  window angle bodies. Car body numerical calculation models with front window angle of 20°, 25°, 30°, 35°,
  and 40°were built using a CFD software—Star-ccm+. The airflow fields around the body were simulated for 20
  m/s car speed in 8 m/s crosswind. The results show that the lateral force coefficient is large affected by front
  window angle in crosswind; and the body has better stability in crosswind when front window angle of 35°. The
  airflow separation from the bottom at the rear is postponed with reducing vortex number, as the front window
  angle getting larger. By analysis on body shear stress with 35° front window angle, it is pointed that the optimal
  analysis for the leeward side A column and for the crosswind side C column are the direction to improve the
  aerodynamic performance.

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  Discrete optimal design for crashworthiness of tailor welded blank bumper beam

  XIAO Zhi, LI Suwen, KONG Chunyu, LIU Hongbin, MO Fuhao

  2015, 6(02):  150-155.  doi:10.3969/j.issn.1674-8484.2015.02.007

  Abstract ( 348 )   PDF (1323KB) ( 1084 )  

  An optimized car bumper beam with crashworthiness and lightweight was designed applying Tailor
  Welded Blanks (TWB) structure with high-strength steel plates to a bumper beam, and combining the multiobjective
  discrete optimization method. A model for original bumper beam and a model of TWB bumper beam
  were established by using Hypermesh software, and then validated by LS-DYNA software. The outer and the
  inner plates of the TWB beam were made of 5 blanks with different thickness. The targets of iterate optimization
  were improving the energy absorbing and controlling the mass with different material parameters and different
  thickness parameters based on the Three Point Static Loading Test simulation of the TWB beam. The results
  show that the energy absorbed increases 81.66% for the optimized TWB beam with only an increase of 8.96%
  for mass. Therefore, the optimized TWB beam meets the demands of crashworthiness and lightweight with a
  better deformation mode and better collision load characteristics.

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  Optimization of body structure crashworthiness in side pole impact for a car

  XIAO Haitao, DONG Jiangtao, WANG Yue, GUANG Lingling, SUN Lizhi, ZHOU Dayong, LIU Weiguo

  2015, 6(02):  156-163.  doi:10.3969/j.issn.1674-8484.2015.02.008

  Abstract ( 334 )   PDF (1886KB) ( 1796 )  

  A car body structure was optimized and improved to avoid excess driver chest compression
  caused by excess intrusion in side rigid pole barrier crash. A reliable and credible body structure was set up
  with a restraint system model in side pole impact based on the test results which had seriously distorted seat
  installed beam and floor with insufficient occupant living space. The body structure and the material grades
  were modified by the design principles for lateral structure crashworthiness. The results show that the final side
  body strength is effectively promoted, the maximum intrusion of front door in side pole impact decreases by 13%
  with increasing the lateral restraint system buffer space, and reducing dummy chest damage. Therefore, these
  improvements meet the safety goals of body structure in side impact.

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  Femur injury assessing and performance improving according to the Euro-NCAP frontal impacting tests

  LIU Zhenhai, LIU Songmei, QIAO Leilei, LI Ning, YUE Guohui, CHEN Xianling

  2015, 6(02):  164-170.  doi:10.3969/j.issn.1674-8484.2015.02.009

  Abstract ( 399 )   PDF (1593KB) ( 1309 )  

  Femur injurie modifier assessments were investigated and Knee Mapping assessment procedure
  was summarized to avoid over-modifiers due to femur injuries. The performances of a vehicle were assessed
  according to the assessment method for femur protection in the front offset impact test in the Euro New Car
  Assessment Program (Euro NCAP), and an evaluation process of femur injury was designed. Simulation
  optimize analysis was done by a Knee Mapping Finite Element method for femur injuries at some potential hard
  points (possible injuring femur). The results show that the femur injuries are efficiently reduced by providing
  sufficient deformation space in the internal structure of instrument panel, and by designing energy absorbing
  structure with foam and metal sheet behind the cover. Therefore, the optimized method satisfies the femur force
  requirements of Knee Mapping and can avoid femur over-modifiers.

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  Automotive Energy Efficiency & Environment Protection

  Off-cycle fuel consumption test and evaluation on start-stop light duty vehicles in China

  QIAN Guogang, LI Jingyuan, LU Hongyu

  2015, 6(02):  171-178.  doi:10.3969/j.issn.1674-8484.2015.02.010

  Abstract ( 347 )   PDF (1447KB) ( 2125 )  

  Real world fuel saving potential and pollutant emission were tested and analyzed for some typical
  start-stop vehicles for 3 light duty vehicle (LDV) passenger cars. The fuel consumptions when start-stop
  function ON and OFF were tested in lab and on road in different driving cycles. The results show that the fuel
  savings potentials for every car tested both in lab and on road in two driving cycles representing China city
  traffic conditions are better than that in New European Driving Cycle (NEDC) cycle. Real-world road tests data
  in several cities in China comes to a same conclusion. The overall pollutants are comparable between startstop
  function ON and OFF in the emission tests for LDV passenger cars in different driving cycles. Start-stop
  off-cycle credit should be evaluated and granted by means of lab tests taking account of the traffic characters
  and environment temperature in China while referring to US’s off-cycle/EU’s Eco-innovation test and evaluation
  method. This approach is able to evaluate start-stop technology’s additional fuel saving in real world in China.

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  Method to realize multi-point ignition based on the microwave resonant of transverse magnetic resonant mode (TM010)

  ZHANG Guixin, HOU Lingyun, WANG Qiang, LIU Yongxi, WANG Zhi, HUANG Jian

  2015, 6(02):  179-183.  doi:10.3969/j.issn.1674-8484.2015.02.011

  Abstract ( 361 )   PDF (1382KB) ( 1770 )  

  A method to realize multi-point ignition was introduced to solve problems of low combustion speed
  and low energy utilization rate in traditional spark plug ignition system. A primary design of a transverse
  magnetic resonant mode (TM010) was used for calculation and optimization based on theoretical analysis and
  stimulation to determine the size of resonant cavity and to determine the electromagnetic field distribution in the
  cavity. A high speed camera and some pressure sensors were used for visualization analysis and combustion
  pressure characteristic analysis. The results show that this method shortens the time by 15% when the pressure
  arrived at the maximum, and increases the maximum pressure by 5% at the experiment pressure of 200 kPa
  compared to the conventional spark plug ignition. Therefore, this method can realize the multi-point ignition.

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  Effects of the ignition fuel quantity and compression ratio on the combustion characteristics of a methanol/F-T diesel engine

  ZHU Jianjun, AN Qiaoqiao, GAO Conghui, WANG Tie

  2015, 6(02):  184-190.  doi:10.3969/j.issn.1674-8484.2015.02.012

  Abstract ( 288 )   PDF (1462KB) ( 1155 )  

  The effects of the Fischer-Tropsch synthetic (F-T) diesel proportion and the engine compression
  ratio on the combustion characteristics in combustion mode were investigated by using bench tests to improve
  the rough combustion running at heavy load for a dual-fuel engine. In the tests, an F-T diesel with high cetane
  number was adopted to ignite the premixed methanol-air gas in a whole coal based dual-fuel engine with F-T
  diesel and methanol. The results show that the combustion of dual-fuel engine is more gentle compared that of
  original engine, the combustion duration declines obviously, and the economy becomes worse with increasing
  F-T diesel portion and decreasing compression ratio. The decrease of compression ratio is conducive to reduce
  the combustion rough degree under low F-T diesel portion. Therefore, by using a low F-T portion and a suitable
  small compression ratio can improve the combustion performance and economy for methanol/F-T diesel dualfuel
  engine.

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  Combustion and emission characteristics of diesel engines fuelled by polyoxymethylene dimethyl ethers (PODEn)

  WANG Zhi, LIU Haoye, ZHANG Jun, WANG Jianxin, SHUAI Shijin

  2015, 6(02):  191-197.  doi:10.3969/j.issn.1674-8484.2015.02.013

  Abstract ( 425 )   PDF (1673KB) ( 1308 )  

  How to use the Polyoxymethylene Dimethyl Ethers (PODEn) was investigated, which is a new fuel
  having high oxygen contents and high cetane number, to reduce particulate matter (PM) from diesel engines.
  The combustion, the emission characteristics, and the thermal efficiency were tested for a diesel, a fuel with
  10% PODE3-4/diesel blend, and a fuel with 20% PODE3-4/diesel blend both in a light-duty (LD) single cylinder
  diesel engine and in a six-cylinder heavy-duty (HD) production diesel engine. The results show that by adding
  20% PODE3-4, soot emissions decreases by 90% for the LD diesel engine, the thermal efficiency increases by
  2% at high load; PM emissions decreases by 36.2% for the HD engine in European Stationary Cycle (ESC), the
  average thermal efficiency increases by 0.85% in ESC. At 0.2-0.6 MPa Indicated Mean Effective Pressure (IMEP),
  adding PODE3-4 has no significant effects on heat release curves; at 0.8 MPa IMEP, adding PODE3-4 increases
  ignition delay and increases the main heat release peak. Therefore, PODEn is a promising blending component
  of diesel fuel.

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