20 March 2018, Volume 31 Issue 3
    

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  • Research on Technology and Engineering Application of Silt Subgrade Solidified by Lignin-based Industrial By-product
    LIU Song-yu, ZHANG Tao, CAI Guo-jun
    China Journal of Highway and Transport. 2018, 31(3): 1-11.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To investigate the feasibility of the silt subgrade solidified by lignin-based industrial by-product, a series of laboratory tests including unconfined compression strength test, water resistance test, and wetting-drying test were conducted to analyze the effect of the additive content and the curing period on mechanical properties and durability of lignin treated silt. The improvement of lignin was also compared with the lime. Based on the results of microscopic analysis, the stabilization mechanism of lignin solidified silt was explained. Moreover, the field test of subgrade silt solidified by lignin was carried out, whilst the road performance tests including California bearing capacity ratio (CBR) test, rebound deflection value test, dynamic cone penetrometer (DCP) test and evaluation of environmental impact of solidified silt were conducted. The results show that lignin can effectively improve the compression strength and durability of silt. The optimum percentage of lignin of the silt is 12%. The specimen treated with 12% lignin after 28 days of curing has a water resistance coefficient of 0.52. And after suffering 4 times wetting-drying cycle, the mass loss rate of sample is less than 20%. The durability of lignin treated silt is much better than that of lime treated silt. Hydrolysis, protonation, and electrostatic reaction between lignin and silt take place, and a more stable and compact soil structure is formed after the treatment. The road performance indicators of 12% lignin solidified silt after 15 days of curing are better than those of 8% lime treated silt, and the rebound deflection value is not more than 1mm. The penetration resistance with the variation of the curing period and depth can be employed to reflect the strength characteristics of treated silt subgrade. In addition, the environmental quality of the silt subgrade solidified by lignin meets the requirements of the secondary quality standard. The feasibility and environmental friendliness of the technology of silt subgrade solidified by lignin based industrial by-product is well verified.
  • Surface Material Properties of Slope Surface Protection Technology with Composite Layers in Silt Subgrade
    ZHANG Peng, YANG Heng-wei, WU Mi-mi, DONG Jin-mei, LI Jun-cai
    China Journal of Highway and Transport. 2018, 31(3): 12-21.
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    In allusion to failure characteristics of the slope surface erosion and the layered slipping of the silt subgrade, a new slope surface protection technology with composite layers was proposed by combining basalt fiber reinforcement and the polyacrylamide solidification, with function of planting grass, anti-scouring and improving soil strength. According to the protection mechanism of different composite layers, direct shear tests, leaching tests, permeability tests and capillary water rise tests were carried out. The variation of basalt fiber reinforcement modulus, length of basalt fiber and relative optimal dosage of polyacrylamide as well as relations of shear strength, shear deformation, quality loss ratio of soil, permeability coefficient and infiltration capacity was discussed. The relative economical dosage of basalt fiber, length of basalt fiber and relative optimum proportions of polyacrylamide were analyzed from the perspective of materials. The results show that compared with the natural silt, the strength of composite layers increases by 0.8 to 1.5 times. The performance of anti-erosion increases by about 200%, whilst the impermeability increases by three orders of magnitude. The relative optimal length of basalt fiber is 12 mm, and the relative optimal quality ratio is 0.4%. The relative optimal dosage of polyacrylamide is 1%. The surface layer material greatly has been used to improve the strength, deformation performance, erosion resistance and impermeability of the original silty soil. The strength of silt, anti-erosion resistance performance and impermeability performance of the silt can be significantly improved by dint of materials in three composite layers.
  • pF Meter-based Research on Soil Freezing Characteristic Curves（in English）
    XUE Ke, YANG Ming-bin, WEN Zhi, ZHANG Ming-li, LI De-sheng, GAO Qiang
    China Journal of Highway and Transport. 2018, 31(3): 22-29.
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    Restricted by the technology, the soil freezing characteristic curve (SFCC) in the freezing soil could only be obtained by empirical formula methods, and the research on the relationship between the soil freezing characteristic curve (SFCC) and the soil-water characteristic curve (SWCC) still rested on the theoretical assumption stage. In allusion to these problems, SFCCs of three kinds of saturated soil samples (namely, Qinghai-Tibetan red clay, Lanzhou silt and fine sand) with different particle sizes were obtained by dint of the pF meter matric potential sensor which could be used in an extreme negative temperature. The regularity of unfrozen water content and the energy change of three soil samples was acquired during the process of soil freezing. Meanwhile, the reliability of the method used to derive SFCC with tests was verified by the indirect convention on the basis of the Clapeyron-Equation. In addition, in order to verify the reasonability of the method in previous frozen soil research with regarding the ice crystal in saturated frozen soil as the gas in unsaturated soil, SFCCs and SWCCs aimed at soil samples with different sizes were compared. The results show that the SFCCs derived by Clapeyron-Equation are similar with the measured ones, so the Clapeyron-Equation can be used to calculate the SFCC. Both the SFCC and SWCC are similar in form but different in specific values. The reason is that the different phase in soil dehydration process and soil freezing process results in the different interfacial forces of phase. The difference is inversely proportional to the average particle size of soil. Therefore, the method with regarding the ice crystal in saturated frozen soil as the gas in unsaturated soil which is widely used in frozen soil is improper to simplify the relationship of ice crystal, liquid water and soil particle in the freezing process. The results provide the theoretical support for future research on the moisture migration mechanism and the moisture migration driven force in the process of frost heave.
  • Time Effect Analysis and Calculation Method of Pile-soil Stress Ratio of Rigid Pile Composite Foundation
    WU Chong-fu, JI Ye, GUO Wei-chao, QIAO Fei-fei
    China Journal of Highway and Transport. 2018, 31(3): 30-37.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to investigate the calculation method of pile-soil stress ratio in rigid pile composite foundation considering time effect, the pile bearing capacity and drainage consolidation of soil between piles were analyzed theoretically. The time effect of the pile stress and the soil stress was investigated by dint of Terzaghi's one-dimensional consolidation theory in which there were three assumptions. That is to say, the soil between piles was assumed to be homogeneous material. The piles were ignored considering soil settlement, and the vertical drainage consolidation existed only on rigid pile composite foundation. Subsequently, a single pile as well as the soil around it was selected as a calculation unit, and the deformation relations in each component of the calculation unit were obtained by the load transfer method. Based on this, the formulas of deformation relations in each component of rigid pile composite foundation were derived. By simplifying the distribution curve of pile side friction reasonably, the formulas of the pile stress and soil stress with depth were obtained, whilst the pile stress at the top of pile and soil stress were calculated combined with the deformation coordination equation. Meanwhile, the formulas of the pile-soil stress ratio considering time effect was derived by introducing a correction coefficient of the pile-soil stress ratio. The time history curves of pile-soil stress ratio under different geological conditions were obtained by the application of method in practical engineering. The researches show that there is the significant time effect of pile-soil stress ratio in the rigid pile composite foundation which can not be ignored in actual calculation, and the time effect of pile-soil stress ratio becomes more and more obvious over time. The pile-soil stress ratio increases when the compression modulus of soil between piles decreases. When pile-soil stress ratio reaches its maximum, the rigid pile is in the most disadvantageous state of stress which should be paid much attention during the design. Furthermore, the pile-soil stress ratio decreases and tends to be stable.
  • Research on Mechanical Performance of Large Perfobond Connectors with Strong Confinement（in English）
    DI Jin, ZOU Yang, QIN Feng-jiang, ZHOU Xu-hong
    China Journal of Highway and Transport. 2018, 31(3): 38-48,58.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to investigate the mechanical properties and bearing mechanism of the large perfobond connector with strong confinement, a total of 18 specimens in six groups were tested by considering various hole sizes, hole shapes and perforating rebars as parameters, and all the specimens were intensively arranged with reinforcing bars to ensure the strong confinement. Additionally, combined with the finite element analysis method, the mechanical behaviors of the perforating rebars, concrete dowel and steel-concrete interface were studied. The results of tests and finite element analysis show that the circular and wide hole connectors show the typical shear failure, while the long hole connectors present the collapse of concrete at the top of dowel. The difference of the shear stiffness of connectors with different shapes is up to 191%, but the difference of the ultimate bearing capacity is only 7.6%. Perfobond connectors show a high shear capacity and good ductility without a perforating rebar under the strong confinement. When the hole area reaches 17 850 mm2, the nominal shear strength of concrete dowel still exceeds 49.2 MPa, and the ductility of the connectors increases with the size of the hole. Therefore, the connectors with the strong confinement have a larger reasonable range of the hole size, and the elimination of perforating rebars will not cause brittle failure of the connector. Combined with the finite element analysis method, the mechanical behaviors of the perforating rebars, concrete dowel and steel-concrete interface were investigated. The results of finite element analysis show that The perforating rebars in circular and wide hole connectors provide the shear strength by means of shear. The perforating rebars in long hole provide the shear strength directly and indirectly, by dint of axial constraint of the concrete tenon. Although the perforating rebars of connectors with different hole shapes have different bearing mechanism, the shear capacities provided by perforating rebars are similar. Under the shearing load, the dilatancy effect of concrete dowel will lead to the separation of the steel-concrete interface. The interface is separated by more than 0.2 mm in the limit state. Hence, the adhesion and friction of the interface make little difference to the ultimate shear capacity of the connector.
  • Critical Condition Analysis of Overturned Bridges with Single-column-piers and Applicability of Design Standards
    XIONG Wen, LU Sheng-di, GONG Xuan, CUI Shan-shan, YE Jian-shu
    China Journal of Highway and Transport. 2018, 31(3): 49-58.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to investigate the mechanics of overturn and safety assessment of single-column-piers, a fine 3D finite element modeling, taken a certain single-column-pier bridge where the overturning accident has taken place as an example, was built by simulating the bearings with rubber elements and considering the geometric and material nonlinearities. Besides, a full-range analysis for the ultimate failure state of the overturned bridge under several types of unbalanced vehicle loading (checking loading) was conducted. Four critical overturn conditions which continuously occur were proposed to describe different mechanical behaviors during the entire overturn process. The safety factor of anti-overturn was used to quantitatively determine the anti-overturn performance of bridges with single-column-piers corresponding to different critical conditions. The rationality was verified by the overturning accidents of the bridge. Results of design standards, simulated analysis and real conditions, were compared. The results show that the design standards will highly overestimate the anti-overturn behavior based on the rigid body rotation of the bridge model with ideal supports. During the entire operation stage, the bearing disengagement needs to be avoided and the torsion angle of superstructures also needs to be limited. The ratio of dead load counter force and the maximum live load negative reaction force is calculated by dint of space calculation model of the elastomer. The calculated ratio is regarded as the safety factor of anti-overturn for the first critical overturn condition. The values of such safety factor are suggested to be more than 1.3 and 2.0, when 55 t car beam and highway-I are taken as checking loadings. All the analyses for the overturn behavior of bridges with single-column-piers need to consider the interaction between rubber bearings and bottom surface of girders.
  • Experiment on Grouting Effects of Combined Grouting Piles Under Extra-thick Fine Silty Sand Layer
    WAN Zhi-hui, DAI Guo-liang, GONG Wei-ming, CHEN Hai-jun, ZHU Ming-xing
    China Journal of Highway and Transport. 2018, 31(3): 59-67.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To investigate grouting effects of combined grouting side piles and the tip of piles in extra-thick silty fine sand layer, in-situ static load tests on six cast-in-place piles with large diameter were conducted on the basis of the engineering of Shishou Yangtze River Highway Bridge. The influence of the combined grouting on the bearing capacity properties, the tip resistance and side resistance of cast-in-place piles with large diameter was explored by comparing the test results of cast-in-place piles before and after the combined grouting.Besides,the distribution of the cement slurry and the effect of the combined grouting on the pile foundation were comprehensively analyzed by the coring tests and standard penetration tests, respectively. The empirical coefficients of side resistance in the silty fine sand layer before and after the grouting were obtained based on the statistical analysis, and the relational expression between the side resistance after the grouting and the blow counts N before the grouting was established. The results show that compared with the numerical values before the combined grouting, both side resistance and tip resistance after the combined grouting dramatically increase, and the ultimate bearing capacity of grouted piles increases by 94.25%-151.51%, which shows that the effect of combined grouting is significantly obvious. The bearing behaviors of the combined grouting pile are obviously superior to bored pile with post-grouting merely at pile tip, and significantly affect the load transfer characteristics of pile foundation. Moreover, the distribution of the cement slurry of the side pile and the tip of the pile was clarified by the coring test. The effectiveness of combined grouting was further proved. Additionally, the results of the standard penetration test show that the blow counts after the combined grouting is significantly higher than that before the combined grouting. The results can be applicable to the design of the bridge pile foundation, and can provide references for the similar bridge pile foundation projects in extra-thick silty fine sand layer.
  • Displacement-based Simplified Calculation on Soil-pile Interaction of PHC Pipe-piles
    HUANG Fu-yun, QIAN Hai-min, FU Cui, ZHUANG Yi-zhou
    China Journal of Highway and Transport. 2018, 31(3): 68-79,88.
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    On the basis of the reciprocating low-cycle pseudo-static test on pile-soil interaction of prestress high concrete (PHC), the regularities of distribution as well as calculating methods of pile-soil pressure and lateral displacement were investigated. The calculating methods of displacement-based pile-soil interaction under the shear equilibrium were presented and compared with the traditional M method and p-y curve method, etc. The results show that there exists a large error in the results of lateral displacement of embedded pile calculated by the strain transform method, M method and p-y curve method. The pile-soil pressure along the pile depth increases at first and then decreases. Meanwhile, pile-soil pressure reverses under the certain depth. With the increase of displacement load, the pressure of shallower soil dramatically increases, nearly reaching up to passive earth pressure. However, the deeper soil slightly increases with the increase of displacement load. The internal force and the lateral displacement calculated by M method demonstrate the linear correlation. Unfortunately, the M method overestimates the capacity of piles and lowers the safety in the seismic design and calculation. The internal force and lateral displacement calculated by p-y curve method tend not to show the significant damage or descent trajectory. The p-y curve method overestimates the ductility of pile-soil system and lowers the safety in the seismic design and calculation. Furthermore, the values calculated by dint of p-y curve method are different from experimental results. The displacement-based interaction of pile-soil simplified calculating method is applicable to the calculation of internal forces, lateral displacement and pile-soil pressure. The proposed method provides a reference for the relevant specification.
  • Matrix Analysis of Composite Box Girder with Corrugated Steel Webs Considering Shear Deformation and Shear Lag Effect（in English）
    MA Chi, LIU Shi-zhong, WU Ming-qiang
    China Journal of Highway and Transport. 2018, 31(3): 80-88.
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    In order to accurately investigate the mechanical properties of the composite box girder with corrugated steel web plates, based on the consideration of the effect of shear lag and shear deformation, the governing differential equation of the composite box girder with corrugated steel web plates was derived by dint of the energy variation principle, whilst the analytic solution was given. On the basis of the analytical solution, the element stiffness matrix and node load array were obtained, and then finite element programs of FORTRAN were written on the basis of the corresponding equations. Taking a simply supported beam and a continuous beam with corrugated steel web plates for examples, measured results, calculated results based on the theory of the derived equations and calculated results of the ANSYS solid element model were analyzed and compared. The results show that deflection values are identical with coefficients of shear lag and deformation obtained by dint of the proposed theory, the model test and finite element simulation. Moreover, the theoretical values of the coefficient of shear lag and deflection are closer to tested results of the model experiment. The shear lag effect of simply supported beams is largely affected by concentrated load, rather than uniformly distributed load in the identical section. Under the condition of concentrated load, the shear lag effect of continuous beams has a greater influence on the section near the support than the mid-span section. In addition, the negative shear lag of continuous beams in the area close to zero bending moment is manifested. The coefficients of shear lag of simply supported girder or continuous beam with corrugated steel web plates decrease with the increase of span-to-width ratios. The complicated problem of corrugated steel web plates considering double effect can be conveniently included into ordinary truss structure matrix displacement system. The shear and bending moment for structure design can be gained directly, so as to avoid the establishment of complicated ANSYS finite element model.
  • Safety Factors Assessment of Resistant Overturning Stability of Long-span Continuous Girder Bridges in Cantilever Construction
    LIU Jie, YANG Ji-xin, DONG Feng-hui
    China Journal of Highway and Transport. 2018, 31(3): 89-95.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to estimate the safety of continuous girder bridges in the cantilever construction, a calculating method of safety factors of the resistant overturning stability of long-span continuous girder bridges in the cantilever construction was proposed based on the inverse reliability analysis theory. In the premise of the given target reliability indices and the randomness of structural parameters, safety factors of the resistant overturning stability of continuous girder bridges were solved by the inverse reliability analysis theory. Safety factors as well as the sensitivity of parameters of resistant overturning stability of long-span continuous girder bridges in the cantilever construction were analyzed by the proposed method. The rationality of safety factors of the longitudinal resistant overturning stability was discussed. The results show that the randomness of parameters has a major effect on safety factors of the resistant overturning stability of long-span continuous girder bridges in the cantilever construction, and ignoring the randomness of parameters will result in the overestimation of safety factors of the resistant overturning stability of long-span continuous girder bridges in the cantilever construction. The reasonable safety factors should be selected based on the target performance, and the rationality of interim consolidated facilities in the cantilever construction, as well as form traveler dropping, should be focused in order to assure the resistant overturning stability of long-span continuous girder bridges. The distribution type of the random variable has a great influence on safety factors. In the actual construction, the actual variable parameters should be sampled and statistically analyzed to determine a reasonable type of random variable distribution. Based on this, safety factors of resistant overturning stability will be more consistent with the actual situation. The choice of the initial safety factor has no influence on the accuracy of the result of the calculation method, and only has a little influence on the convergence rate of results. The inverse reliability analysis method proposed is well applicable to the determination of the safety factors of the resistant overturning stability based on target reliability indexes.
  • Parking Resource Sharing and Matching Methods for Appertaining Parking Facilities Based on Space-time Capacity（in English）
    CHEN Jun, WANG Bin, ZHANG Chu
    China Journal of Highway and Transport. 2018, 31(3): 96-104,115.
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    In order to improve the utilization efficiency of multi-type appertaining parking facilities in downtown area, on the basis of the time-space occupancy characteristics of the parking demand, the concept of the parking capacity of muti-type appertaining parking facilities was proposed, whilst time-space resource consumption models were established. Based on the parking sharing concept, the optimization process of time-space resource matching of combined parking facilities was designed. The theoretical models and the calculation process of the overflow parking demand, shared parking supply and time-space resource allocation were established. Subsequently, through taking the minimum time-space occupancy rate of the combined parking areas as a goal, the user equilibrium theory was adopted to establish the optimization model to achieve the time-space matching of the supply and demand. The proposed methods were applied to the researches on five different types of appertaining parking facilities including residential communities, administrative offices, shopping malls, hotels and hospitals.The results show that the allocation of all appertaining parking facilities, which satisfies the parking demand in residential communities, is determined by the space and parking duration of the parking demand. In other words, the efficiency of some parking lots with available spots tends not to be improved via sharing. Among all types of land use, the administrative office parking facilities (with the sharing occupancy of 39%) are best fit for matching the overflow night parking demand in the residential communities, followed by shopping malls (with the sharing occupancy of 16%), hotels (with the sharing occupancy of 15%) and hospitals (with the sharing occupancy of 0), respectively. The parking resource matching methods proposed in this paper can precisely calculate the parking sharing allocation scheme corresponding to the time-space characteristics of different parking demands, and provides the quantitative support for the refinement of shared parking strategies.
  • Driver's Intention Identification Based Lane Departure Avoidance Bounded Control
    WANG Qi-dong, WANG Xuan-yao, HUANG He
    China Journal of Highway and Transport. 2018, 31(3): 105-115.
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    In order to prevent traffic accidents resulted from the lane departure, and to avoid unnecessary intervention on driver's behavior for lane departure avoidance systems (LDAS), identifying criteria of the driver's intention for the lane departure were proposed based on method of threshold value of on-center handling characteristics and D-S evidence theory. And the effectiveness of the two identification criteria were compared by dint of CarSim/Simulink combined simulation. A vehicle-road dynamic model taking steering wheel angular rate as an input was established, whilst a sliding mode steering controller was designed for LDAS. A desired yaw rate observer was designed based on the lateral deviation at look-ahead point and yaw rates, and the performance of LDAS of desired yaw rates based on the road curvature and lateral deviation at look-ahead point was compared. The maximum value of the front wheel steering angle for guaranteeing the vehicle lateral stability of LDAS was determined based on the phase plane method. The effectiveness of driver's intention decision algorithm based on the BP neural network training was verified based on CarSim/LabVIEW RT hardware in loop test to get initial probability assignment of the D-S evidence theory. The proposed identifying criteria can timely identify driver's intention when lane departure occurs, and it gains valuable time for the controller intervention of LDAS. The designed yaw rate observer presents good stability. Furthermore, the proposed method can effectively avoid the lane departure.
  • Occlusion Probabilities of Road-side Traffic Sign of Multilane Expressway
    HU Shao-rong, MA Rong-guo, LI Miao-miao, DENG Ya-juan
    China Journal of Highway and Transport. 2018, 31(3): 116-122,150.
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    In order to calculate the dynamic occlusion probabilities of road-side traffic signs of multilane expressways with different traffic volume and speed, and the maximum and minimum critical occlusion distances of multilane within the area of car drivers' sight were calculated based on the geometrical relationship of visual range. The vertical distance between car on inside lane and truck on outside lane was taken as a judgment of the road-side traffic sign occlusion. The road-side traffic sign occlusion model was established. The dynamic data bases including the vehicle location coordinate and the following distance of car and truck were obtained by dint of VISSIM simulation software with the simulation step size of 0.1 s. The simulation length of the inside and outside lane was decided by the recognition distance. The results show that the vehicle type, traffic volume in outside lane and inside lane, recognition distance and the speed of truck and car have an impact on occlusion probabilities. The probabilities of missing the traffic sign increase with the increasing truck volume on outside lane and the car volume on inside lane, when the traffic volume is constant. Occlusion probabilities of car drivers' sight decrease with the increasing speed of truck but increase with the increasing speed of car.
  • Hydraulically Interconnected Suspension Anti-roll Control Research（in English）
    WU Xiao-jian, ZHOU Bing, WEN Gui-lin
    China Journal of Highway and Transport. 2018, 31(3): 123-132.
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    In allusion to the needs for reducing energy consumption and improving anti-roll stability for vehicles,an anti-roll control method which can be switched between the passive hydraulically interconnected suspension(HIS)mode and the active HIS mode was put forward. Taking the coupling volume-flow-pressure characteristics of accumulator, cylinder and hydraulic pump into account, the time-domain control model for the HIS system was established based on a 9 degree-of-freedom (DOF) vehicle model. A roll stability region, and the HIS roll stability control criterion of intervention and exit, were proposed by combining the phase-plane method of body roll angle and the body roll rate with the lateral acceleration. Subsequently, an active anti-roll controller for the HIS system was designed by the backstepping nonlinear control algorithm. Finally, an evaluating indicator of anti-roll stability was analyzed and improved, the numerical simulations including double-lane change in high speed and fishhook test in the MATLAB/Simulink environment were carried out to verify whether the anti-roll performance can be improved by the active and passive switched HIS systems with lower energy consumption. The results show that the proposed control system can improve the anti-roll performance of vehicles. If the vehicle roll states are beyond the roll stability region, the HIS system will switch from the passive mode to the active mode to control vehicle roll states back to the stability region, with the purpose of improving roll stability of vehicles. Besides, the HIS system will switch back to the passive mode when satisfying the exit condition so as to reduce the energy consumption.
  • Research on Stamping Die Wear Life Based on Dynamic Model
    NIE Xin, NING Min-qing, QIAO Xiao-yong
    China Journal of Highway and Transport. 2018, 31(3): 133-141.
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    In order to accurately predict the die wear depth and to improve the service life of the stamping die, a dynamic mixed wear model was established by investigating the stamping die wear mechanisms, whilst a new method for predicting die wear life was proposed. On account of the significant influence of the previous stamping on the die wear of the after stamping, the relationship between the gross die wear depth and the single stamping die wear depth is not simple linear. The influence of wear coefficient and roughness coefficient of the chromium plating layer and flame hardening along the thickness direction, and the material hardness gradient change from the mould surface to the core were taken into consideration. The wear parameters of stamping die material with processing methods of flame hardening and electroplating chromium were obtained through the wear experiments. Such parameters were applied to the dynamic mixed wear model. The new parameters of the current wear depth which acquired by constantly updating the wear geometric profile via moving mesh nodes were used to calculate the wear depth of current stamping, to ensure that with the increase of wear, the wear parameters can be constantly updated and the wear prediction can be more accordant with the actual physical process. The deployment of new parameters made up for the shortage of the classical Archard's model in which the contact stress and sliding speed changed due to the ignorance of the wear. The finite element model was established through extracting contact surface by shell elements instead of expressing the whole stamping die. Hence, with the low complexity of the problem, the computational efficiency was improved. In this project, on the basis of an accurate relationship between wear depth and stamping times, a quantitative prediction method of the stamping die wear depth was acquired. The wear analysis on the stamping die of a certain hood outer was carried out, and the results were compared with values predicted by the classical Archard method and the actual die wear pattern. The result shows that the value predicted by the new method is close to the actual wear, and the deviation is 18.60% lower than the value predicted by classical Archard method. The accuracy of the new method is obviously higher than that of the classical Archard method.
  • Parameter Matching and Control Strategies of Hybrid Energy Storage System for Pure Electric Vehicle（in English）
    HU Jian-jun, ZHENG Yong, HU Zhi-hua, XIAO Jun
    China Journal of Highway and Transport. 2018, 31(3): 142-150.
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    In order to solve problems of low power density, poor ability of heavy current charge and discharge and short cycle life of power battery used in the electric vehicle, a new hybrid energy storage system(HESS) composed of battery and ultracapacitor(UC) was taken as an object of research. The optimal approach of parameter matching for HESS was proposed under the typical cycle condition. Under the premise of satisfying the energy demandand power demand of HESS, the multiple objective optimization of the total cost and the total mass was carried out by taking the power battery capacity and the UC capacity as the optimization variables. On this basis, considering motor demand power and UC state of charge, the filtration-based rule control strategy was established to reduce output current of power battery. And the hybrid fuzzy control strategy was put forward to better adapt to different cycle conditions.The primary power distribution coefficient of power battery was obtained by the main fuzzy controller on the basis of the motor power demand, power battery state of charge and UC state of charge. Meanwhile, the modified power distribution coefficient of power battery was obtained by the sub-fuzzy controller based on the motor power demand and the difference between the current state of UC and the target value. That is to say, the optimal power coefficient of power battery was obtained by dint of two controllers. The vehicle power performance, economy, and power battery current and temperature characteristics were simulated and analyzed. The results show that, compared with the pure electric vehicle equipped with the conventional battery energy storage system, the proposed HESS with the two control strategies has the better performance. The acceleration time within 100 kilometers decreases by 6.89% and 9.85%, respectively, whilst the total energy consumption under NYCC condition decreases by 14.15% and 19.08%. The maximum battery output current under NYCC decreases by 63.4% and 65.17% respectively, and power battery temperature rise decreases by 22.87% and 61.53%, respectively.
  • Investigation on Pressure Control of Shifting Clutch for High-power Automatic Transmission
    WANG Er-lie, WANG Xian-hui, CHEN Hui-yan, GU Hong-tao
    China Journal of Highway and Transport. 2018, 31(3): 151-158.
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    In order to improve the control level of oil pressure which regulates the performance of shifting clutch (including wet brake and wet clutch) for high-power automatic transmission and to improve the shift quality of vehicles, the balance piston was designed to balance the centrifugal effect for the rotating clutches, and the exhaust backfill valve was also designed for the oil discharge loop to eliminate the uncertainty caused by air in the piston cavity. The low pressure can keep the shifting clutches free of air due to the exhaust backfill valve. The shift execution system of the testing automatic transmission was analyzed, and the model calculation was administered for the piston motion, the electro-hydraulic pressure regulation and the slipping process of the shifting clutch. And the pressure regulating of inertia phase during the gear shift is characterized as a one-order control based on the end of the torque phase. Combined with phased parameter calibration, the sliding mode control was presented to overcome the external disturbance and parametric uncertainties. Simulation analysis for the effectiveness of control strategy was conducted on the basis of MATLAB. The power-on 1st-2nd up-shift with B2 brake oil-charging and the power-on 3th-4th up-shift with C2 clutch oil-charging test were considered respectively. The simulation curves show that the duration time, the shift jerk and the wear power loss of the inertia phase are effectively controlled within a reasonable range. Finally, the proposed control strategy is thoroughly verified on a heavy-duty off-road vehicle equipped with a high-power automatic transmission, and the good shifting quality has been achieved in the inertia phase which is demonstrated by the experimented data.
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