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    25 February 2017, Volume 45 Issue 2
    Automotive Engineering
    LAN Feng-chong LIU Jin CHEN Ji-qing HUANG Pei-xin
    2017, 45(2):  1-8.  doi:10.3969/j.issn.1000-565X.2017.02.001
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    There are few researches on the collision safety of battery pack,and most of the researches emphasize on the battery box and its installation location instead of the internal security of the battery pack.In order to solve this problem,a refined model of battery pack,which takes into consideration the cell,the cell contact,the fixed structure and the inner shelf,was proposed,with an actual battery pack being used as the example.Then,by analyzing the collision results of battery pack and its internal structure in the aspects of deformation and acceleration,the deformation and response law of the battery box and the internal structure during the collision were investigated.The results indicate that the lifting lug near the impact position,the internal shelf,the bolt and the battery modules all deform in different degrees; and that,after the collision,the acceleration magnitudes are excessive at the cell contact and the installation point of attached components.

    ZANG Meng-yan SHI Fang
    2017, 45(2):  9-15.  doi:10.3969/j.issn.1000-565X.2017.02.002
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    According to the requirements of European child restraint system regulations ( ECE \ R129) ,a finite element model considering a trolley seat,a child seat,a child dummy and a safety belt is established by using the related software.Then,the collision process is simulated and analyzed with Ls-dyna according to the conditions of the front and the rear crash experiments,finding that the movement patterns as well as the dummy's head and thorax accelerations in the collision process are consistent with the experimental ones,which means that the simulation model is effective.Finally,a finite element model to describe the side impact is built by introducing a side plate instead of the vehicle side doors,which is used to analyze the side impact situations of car child safety seat.The results show that the peak accelerations of dummy's head and chest in side impact situations are both greater than those in the front and rear crash situations,which means that it is necessary to develop and implement side impact regulations for automobile child restraint systems.

    ZONG Chang-fu SUN Hao CHEN Guo-ying
    2017, 45(2):  16-22.  doi:10.3969/j.issn.1000-565X.2017.02.003
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    Aiming at the steering angle allocation of distributed independent steering system,first,the structure and operation principle of distributed steering system are expounded.Next,based on the Ackermann steering principle,a steering angle allocation algorithm suitable for both front-wheel steering ( 2WIS) and four-wheel independent steering ( 4WIS) is put forward with the consideration of the front tier cornering,and the optimization effect of the proposed algorithm on the tire wear and the vehicle stability is investigated.Then,by using a linear vehicle model with two degrees of freedom,the relationship between tire sideslip angle and vehicle speed,yaw rate as well as wheel angle is explored,and the Ackermann steering principle is modified with the obtained tire sideslip angle,which helps to reveal the steering angle allocation of each wheel.Finally,a Carsim-Simulink combined simulation is performed to verify the correctness of the proposed steering angle allocation,the improvement in tire wear pattern is determined by evaluating the optimized tire lateral force,and the vehicle stability is evaluated by using the sideslip angle.Simulated results indicate that the proposed steering angle allocation method is effective in improving the tire wear and enhancing the vehicle stability.

    SHANGGUAN Wen-bin CHEN Cheng-feng LI Li-ping YU Hong QI Zhen-ning
    2017, 45(2):  23-29,38.  doi:10.3969/j.issn.1000-565X.2017.02.004
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    In order to optimize the bushing and structure of vehicle body,a vibration isolation analysis model for the bushing and the top mount of vehicle suspension system is established,and the expressions of force and displacement vector at each join point between two substructures are decuced.Then,by using the vibration power transmission analysis method,a method is presented to calculate the power transmitting to the vehicle body under the road excitation through each bushings.Moreover,by taking a typical Macpherson suspension as the example,a multi-body dynamic model of the suspension is established with ADAMS software,and the power transmitting to the vehicle body through each bushing and top mount is calculated and analyzed,which helps to identify the maximum power transmission path.Finally,the influence of bushing characteristics on the power transmission is analyzed,and the effect of a hydraulic bushing on the vibration damping of vehicle body caused by the lateral excitation is discussed.

    ZENG Xiao-hua LI Guang-han SONG Da-feng LI Sheng ZHU Zhi-cheng
    2017, 45(2):  30-38.  doi:10.3969/j.issn.1000-565X.2017.02.005
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    Proposed in this paper is a rollover warning control strategy based on the genetic algorithm-optimized BP neural network ( GANN) for hydraulic in-wheel motor hybrid heavy truck.In the investigation,first,a rollover reference model of the heavy truck with three degrees of freedom was established,and the rollover warning indicator was selected.Next,based on the rollover reference model,an observer of rollover warning indicator was presented.Then,a new rollover warning algorithm named GANN-TTR was proposed by introducing genetic algorithm-optimized BP neural network to optimize the traditional TTR ( Time-To-Rollover) algorithm.Moreover,a system model was conducted on the Trucksim platform,a hydraulic system model was presented on the AMESim platform,and a rollover warning algorithm was achieved on the Matlab /Simulink platform.Finally,a co-simulation platform was constructed on the basis of Matlab /Simulink,AMESim and Trucksim platforms to simulate the truck under step steering and hook steering conditions,and the warning precision of the traditional TTR algorithm,the BP algorithm and the proposed GANN-TTR algorithm were compared.Simulated results show that,with the proposed GANN-TTR rollover warning algorithm,the warning precision effectively improves,and the minimum error between the revised warning curve obtained through vertical velocity and driver steering angle and the ideal warning curve is low to 5%.

    FAN Li LI Gang-yan CHEN Ran HU Da-wei ZHAO Li MENG Li-hang
    2017, 45(2):  39-45,51.  doi:10.3969/j.issn.1000-565X.2017.02.006
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    In order to avoid the sideslip or rollover under extreme turn conditions of bus with fast turning or too fast changing,first,a formula to calculate the lateral force coefficient considering the suspension movement effect is deduced by using the lateral force coefficient as an evaluation index of cornering stability under extreme turn conditions.Next,by analyzing the influence of the lateral force coefficient on the driving stability,the early warning threshold and the risk threshold of the lateral force coefficient under extreme turn conditions are both defined,and the relationship between the two thresholds and the vehicle speed is reveled.Then,in order to implement the active safety control of steering stability,a turning radius calculation model of cornering stability based on the lateral force coefficient threshold under extreme turn conditions is put forward.The proposed calculation model is finally verified through a comparative analysis by selecting some typical bus parameters.The results show that the calculation model is correct and effective,and that it helps to obtain a turning radius with a safety factor of 1. 15 to 1. 3,which is close to the limit value obtained by the simulation software IPG TruckMaker.This research provides a theoretical foundation for the cornering stability evaluation and active safety control of bus under extreme turn conditions.

    ZHOU Zhao-yao CAO Xiao-bing QIN Jie XIAO Zhi-yu
    2017, 45(2):  46-51.  doi:10.3969/j.issn.1000-565X.2017.02.007
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    In this paper,the effects of mechanical vibration on the microstructure and mechanical properties of A356 aluminum alloy were experimentally investigated,and the mechanism of dendrite breaking under the action of mechanical vibration was explored.The results show that ( 1) mechanical vibration helps to effectively eliminate material's shrinkage hole and section crack during the squeeze casting,reduce or even eliminate the micro casting pores in aluminum alloy and refine the grain structure,thus resulting in more compact microstructure; ( 2) in the initial solidification stage of the squeeze casting,to a large extent,mechanical vibration can break the secondary dendrite arms and increase the nucleation rate of materials; ( 3) the Kirkword model is of higher accuracy which is proved by a comparison between the experimental and the theoretical results; and ( 4) as compared with the gravity casting and the squeeze casting without mechanical vibration,the casting with mechanical vibration significantly improves the mechanical properties of aluminum alloy and achieves higher tensile strength as well as more elongation.

    Mechanical Engineering
    WU Shang-sheng YU Zhong-ming
    2017, 45(2):  52-58.  doi:10.3969/j.issn.1000-565X.2017.02.008
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    By taking into consideration the special requirements for function and property of flexspline,the traditional cold rolling process model is analyzed and optimized based on the double-circle-arc model for flexspline.Then,a finite element model describing the cold rolling process is established according to the modified Johnson- Cook constitutive model and is finally verified.Simulated results show that,with the help of the established model,clear double-circle-arc tooth profile and uniform equivalent strain distribution can both be obtained.Moreover,by analyzing the influences of such parameters as feed rate,roller's rotation rate and friction coefficient on the residual stress distribution on gear tooth surface,it is found that ( 1) increasing the feed rate may reduce the maximum residual stress on tooth surface,but excessive feed rate may result in“bulge”on the surface; ( 2) properly reducing the rotation speed and feed rate of the roller may improve the uniformity of residual stress distribution; and ( 3) the friction coefficient positively correlates with the distribution depth of residual compressive stress.

    CHEN Shou-yan ZHANG Tie
    2017, 45(2):  59-65.  doi:10.3969/j.issn.1000-565X.2017.02.009
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    In order to improve the quality of robotic surface machining,deferent robotic machining states are analyzed,and an adaptive force control scheme? is presented.In the investigation,first,the effects of robot stiffness and feed rate on the machining quality are explored,and a machining kinetic model including both impact part and stable grinding part is constructed.Next,a fuzzy PID-based force control model is established according to the relationship between the machining deformation and the feed rate.Then,the machining deformation is calculated according the force feedback,and the machining quality is controlled by adjusting the feed rate in real time.Finally,the proposed method,the open-loop method and the PID control method are compared,and the results show that the fuzzy PID-based surface force control method helps implement high-precision surface machining force control because it can effectively decrease the amplitude of rigid force fluctuation and impact force value.

    SHI Wan-kai XU Lang HAN Zhen-hua CHANG Shuai
    2017, 45(2):  66-74.  doi:10.3969/j.issn.1000-565X.2017.02.010
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    By using the composite cycloid with good adjustable geometric feature as the internal gear tooth profile and on the basis of differential geometry and gear conjugate engagement theory,a meshing equation and a conjugate profile equation of composite cycloid planetary driving with small teeth difference are established,and the line of action,the contact ratio,the mesh boundary as well as the non-undercutting condition are all derived.Then,the induced normal curvature and the pressure angle are analyzed,and the influence of tooth profile adjustment coefficient on the pressure angle is discussed.Finally,a three-dimension solid model of the composite cycloid gear pairs is established,and a dynamic simulation is performed to reveal the meshing relationship as well as the transmission efficiency under certain conditions.The results show that the composite cycloid planetary driving with small teeth difference may result in excellent meshing properties such as multi-teeth meshing,small pressure angle,small induced normal curvature and high transmission efficiency.

    GUO Yi-ming WEI Yu-ming SHANGGUAN Wen-bin
    2017, 45(2):  75-83,107.  doi:10.3969/j.issn.1000-565X.2017.02.011
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    In this paper,first,the dynamic characteristics of rubber-type torsional vibration damper are described by using the fractional derivative model.Next,according to the equivalent principle of system energy consumption,the fractional derivative model is simplified as a mass-spring-damping model,and a lumped parameter model of crankshaft system with rubber-type torsional vibration damper is established.Then,the design parameters are preliminarily optimized by using the genetic algorithm,and the robust optimal matching of rubber-type torsional vibration damper is performed by means of the Taguchi method.Finally,rubber-type torsional vibration dampers with different design parameters are manufactured on the basis of the optimization results,and the torsional vibration damping effect of the crankshaft with different rubber-type torsional vibration dampers is tested and verified.The results show that the fractional derivative model is effective in analyzing the dynamic characteristics of rubber-type torsional vibration dampers,and that robust optimal matching helps to obtain the best damping effect of rubber-type torsional vibration dampers.

    JIN Yan LIU Shao-jun
    2017, 45(2):  84-90.  doi:10.3969/j.issn.1000-565X.2017.02.012
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    In order to reveal the effects of thermal elastohydrodynamic lubrication ( EHL) on the fatigue reliability of rolling bearings,a method combining the response surface method ( RSM) with the secondary-order polynomial as well as the first-order second moment method ( FOSM) is proposed.In the investigation,first,by considering the temperature field influenced by the EHL effect,the thermal stress is mapped into the Hertz contact zone of the rolling bearing,and a model to analyze the contact stress of rolling bearing under the action of thermal EHL is established.Then,by taking into consideration the thermal EHL effect,the material properties and the randomness of fatigue strength correction factors,the fatigue reliability analysis of rolling bearing under the action of thermal EHL is implemented based on the stress-strength interference theory.As compared with the traditional Monte Carlo method with 1. 5 × 105 simulations,the proposed method gives a difference in failure probability of 2. 1 × 10 - 4,a relative error of 24. 4% and a relative time consumption of only 0. 15%.Moreover,the sensitivity analysis results agree well with the practical cognition,which means that the proposed method correctly reflects the influence of thermal EHL effect on the contact fatigue reliability of rolling bearings.

    CAI Hui-kun ZHANG Yin-liang LIAO Yi-dai HE Tian-fu
    2017, 45(2):  91-98.  doi:10.3969/j.issn.1000-565X.2017.02.013
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    In order to reveal the effect of altitude on the performance of vehicle radiator fins,the simulation program for tubular radiator is developed in Matlab environment.After verifying the correctness of the simulation program,the air-side and water-side outlet temperatures,the air-side pressure drop,the air-side heat transfer coefficient and the heat dissipation of radiators with four common fins ( namely louver,straight,wavy and serrated fins) are calculated under different thermal physical conditions at different altitudes.Then,the cooling capacity of different radiator fins are analyzed under the influence of various altitudes,and the heat transfer performance as well as the wind resistance performance of different radiator fins at various altitudes are analyzed in a comparative way.It is found from the obtained comprehensive heat transfer coefficient that louver fin is of the strongest cooling capacity,while serrated fin is of the best adaptability to altitude.

    YE Guo-qiang LI Wei-guang WAN Hao
    2017, 45(2):  99-107.  doi:10.3969/j.issn.1000-565X.2017.02.014
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    Proposed in this paper is an improved image moment-based visual servoing method with learning features for planar target,which helps to overcome the singularity of interaction matrix for classical invariant moment features.In the investigation,first,based on the TRS ( 2D translation,2D rotation and scale transformation) -invariant properties of invariant moment features,the nonlinear support vector machine regression algorithm is used to reveal and model the relationship between a set of specific invariant moment features and the rotational angles around the X-axis and Y-axis of the camera.Then,the estimators of regression models,namely the learning features,are used to control the rotational motions around X-axis and Y-axis.The interaction matrix of learning features possess total decoupling and linear properties and has no singularity for any shape of planar objects.Finally,in combination with the normalized centre of gravity features,the normalized area feature and the object orientation feature,a visual servoing controller is designed to conduct the 6-DOF motion control of a camera.Simulated results show that the proposed method is effective.

    Materials Science & Technology
    CHEN Gang WANG Chen-chen YAN Zhi-yuan FANG Zhi-qiang ZHU Peng-hui
    2017, 45(2):  108-115.  doi:10.3969/j.issn.1000-565X.2017.02.015
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    Polyimide fiber /epoxy paper-based composite materials were prepared from polyimide chopped fibers and polyimide fibrid fibers by means of wet papermaking combined with hot pressing and resin impregnation,and the effects of hot-pressing temperature,hot-pressing pressure and epoxy resin impregnation increment on the properties of polyimide fiber paper-based composite materials were investigated.The results show that ( 1) after the hot pressing,the contact area of polyimide fibers increases,which results in the improvement of mechanical and electrical properties of the polyimide fiber paper; ( 2) resin impregnation further improves the mechanical and electrical properties of polyimide fiber paper-based composite,concretely,the tensile index increases by 1. 25 fold and the dielectric strength increases by 17%; and ( 3) at a hot-pressing temperature of 210 ℃,a hot-pressing pressure of 120 N/mm and an impregnation increment of 20%,the composite possesses good mechanical and electrical properties,namely a tensile index of 57. 5 N·m/g,a tear index of 6. 86 mN·m2 /g and a dielectric strength of 12. 3 kV/mm,which means that the composite is potentially useful in such fields as aerospace,insulation barrier and environmental protection.

    XIAO Xin-yan ZHANG Deng-ke
    2017, 45(2):  116-121.  doi:10.3969/j.issn.1000-565X.2017.02.016
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    Acidified montmorillonite ( HMMT) was modified with isophorone diisocyanate ( IPDI) ,and the obtained IPDI-HMMT was used as a chemical modifier to modify asphalt via melt blending.Then,the physical properties,UV aging resistance and thermal stability of the modified asphalt were investigated.The results show that ( 1) IPDI-HMMT grafted with —NCO can react with the hydroxy in asphalt to produce urethane and to form an exfoliated structure; ( 2) after the incorporation of IPDI-HMMT,the initial decomposition temperature of the modified asphalt increases by 9℃,the softening point is up to 57.0℃,and the segregation softening point difference,the mass change rate,the softening point increment and the residual penetration ratio all change more slightly than those of Na-MMT modified asphalt; and ( 3) the chemical reaction between IPDI-HMMT and asphalt enhances the interaction of the internal components,which helps to form a stable colloidal structure,so that IPDI-HMMT has greater enhancement effect on the asphalt performance than Na-MMT.

    GU Ju HUANG Shi-wen WAN Peng XIAO Hai-yan
    2017, 45(2):  122-129.  doi:10.3969/j.issn.1000-565X.2017.02.017
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    Clubbed wood cellulose nanocrystals ( WNC) were prepared via the acid hydrolysis of wood powders and were co-coagulated with natural rubber ( NR) latex to form a NR/WNC mixture.Then,the mixture was blended with butadiene-styrene rubber ( SBR) ,butadiene rubber ( BR) and carbon black ( CB) to obtain WNC /CB /NR/ SBR/BR composites,and the influence of the partial replacement of CB with WNC on the properties of NR/SBR/ BR blends was investigated.The results show that ( 1) as compared with the blends reinforced by 45 phr CB,the Payne effect of the composites with WNC weakens apparently,the processability improves obviously,the mechanical properties maintain well,the heat build-up decreases by 18. 4%,and the permanent set due to compression fatigue is generally lower than 5%; ( 2) the resistance to flex cracking of the composites filled with 5 ~ 10 phr WNC keeps constant,and the abrasion resistance of the composites filled with 5 phr WNC keeps consistent; ( 3) with the increase of WNC dosage,the loss tangent ( tan δ) value of the composites at 0℃ first increases and then decreases,while the one at 60 ℃ gradually decreases; ( 4) the temperature corresponding to 5% mass loss decreases,while that corresponding to the maximum mass loss rate changes slightly; and ( 5) the addition of WNC helps to maintain the aging performance of the composites.Moreover,SEM results demonstrate that the added WNC with a small quantity displays good homogeneity and strong interfacial interaction with the rubber matrix.

    ZHAO Er-nian QU Wei-lian ZHOU Qiang
    2017, 45(2):  130-136,152.  doi:10.3969/j.issn.1000-565X.2017.02.018
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    In order to verify the applicability of four widely-used critical plane models ( including the maximum shear strain amplitude model,the KBM model,the FS model and the MKBM model) to the multiaxial fatigue life prediction of metallic materials,a comparison of these models were performed according to the statistical data of multiaxial fatigue test of the thin-walled tubular specimens with 8 kinds of metallic materials under 173 straining conditions.Additionally,some major problems existing in the fatigue damage evaluation and the fatigue life prediction based on critical plane parameters are discussed.The results show that both the maximum shear strain amplitude model and the KBM model accurately predict the fatigue life of the specimen under multiaxial proportional loading conditions,while non-conservative fatigue life is obtained when the specimen is under the action of multiaxial non-proportional load.Moreover,it is found that both the FS model and the MKBM model work well for the multiaxial non-proportional fatigue life prediction due to the introduction of the maximum normal stress acting on the critical plane which can reflect the effect of material's non-proportional additional hardening on the multiaxial fatigue damage.

    Environmental Science & Technology
    ZHANG Yong-li TANG Jia ZHANG Jing
    2017, 45(2):  137-143.  doi:10.3969/j.issn.1000-565X.2017.02.019
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    In order to improve the efficiency of the activated carbon-activated persulfate process for organic wastewater,Ni /GAC catalyst was prepared by loading nickel on granular activated carbon ( GAC) via an impregnation- calcination process.Then,the catalyst was characterized by means of SEM,FT-IR and XPS,and the effects of sodium persulfate ( PDS) dosage,Ni /GAC dosage and pH value on the degradation of acid orange 7 ( AO7) by PDS activated with Ni /GAC were investigated.Finally,some main oxide radical species existing in the reaction system were discussed.The results show that ( 1) after the impregnation-calcination process,the Ni specie loading on the catalyst is NiO,and there are much more carboxyl,lactone and phenolic hydroxyl groups on Ni /GAC catalyst surface,so that the catalyst is of high catalytic activity; ( 2) with the increase of PDS dosage,the removal of AO7 first increases and then decreases; ( 3) the catalytic degradation effect on AO7 increases with the increase in Ni /GAC dosage; ( 4) the catalytic degradation efficiency decreases when the pH value changes from neutral to alkaline and then to acidic; and ( 5) in the optimal reaction conditions,namely,a PDS dosage of 2 mmol /L,a Ni / GAC dosage of 2 g and a pH value of 7,93.9% of AO7 can be removed in 90 min.In addition,it is found that hydroxyl radical ( HO·) and sulfate radical ( SO4- ·) are two main oxidizing substances of the catalytic system.

    MO Li-huan Tan Jin-qiang WANG Cong-cong XU Jun LI Jun
    2017, 45(2):  144-152.  doi:10.3969/j.issn.1000-565X.2017.02.020
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    In this paper,a comparison was carried out between the ozone oxidation and the γ-Al2O3 -catalyzed ozonation for the treatment of bagasse pulping effluent.The results show that ( 1) γ-Al2O3 has a certain catalytic effect on ozone and can significantly improve the removal rate of CODCr ; ( 2) with the increase of pH value,reaction temperature,ozone concentration and catalyst dosage,the removal rate of CODCr first increases and then decreases; ( 3) the catalytic ozonation by γ-Al2O3 can also effectively remove the content of AOX ( Absorbable Organic Halogen) in the pulping effluent; and ( 4) in laboratory conditions,the removal rate of AOX reaches 80. 4% after a treatment for 30 min.Moreover,it is demonstrated by the UV and GC-MS results before and after the advanced treatment that γ-Al2O3 -catalyzed ozonation can significantly reduce the type and content of organic matters in the effluent and effectively degrade hard biodegradable organic matters; and that γ-Al2O3 is of good stability and repetition,concretely,after being reused for eight times,it still keeps 88. 5% of the catalytic activity.

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