Purpose-This paper aims to analyze the bearing characteristics of the high speed train window glass under aerodynamic load effects.Design/methodology/approach-In order to obtain the dynamic strain response of passenge...Purpose-This paper aims to analyze the bearing characteristics of the high speed train window glass under aerodynamic load effects.Design/methodology/approach-In order to obtain the dynamic strain response of passenger compartment window glass during high-speed train crossing the tunnel,taking the passenger compartment window glass of the CRH3 high speed train onWuhan-Guangzhou High Speed Railway as the research object,this study tests the strain dynamic response and maximum principal stress of the high speed train passing through the tunnel entrance and exit,the tunnel and tunnel groups as well as trains meeting in the tunnel at an average speed of 300 km$h-1.Findings-The results show that while crossing the tunnel,the passenger compartment window glass of high speed train is subjected to the alternating action of positive and negative air pressures,which shows the typical mechanic characteristics of the alternating fatigue stress of positive-negative transient strain.The maximum principal stress of passenger compartment window glass for high speed train caused by tunnel aerodynamic effects does not exceed 5 MPa,and the maximum value occurs at the corresponding time of crossing the tunnel groups.The high speed train window glass bears medium and low strain rates under the action of tunnel aerodynamic effects,while the maximum strain rate occurs at the meeting moment when the window glass meets the train head approaching from the opposite side in the tunnel.The shear modulus of laminated glass PVB film that makes up high speed train window glass is sensitive to the temperature and action time.The dynamically equivalent thickness and stiffness of the laminated glass and the dynamic bearing capacity of the window glass decrease with the increase of the action time under tunnel aerodynamic pressure.Thus,the influence of the loading action time and fatigue under tunnel aerodynamic effects on the glass strength should be considered in the design for the bearing performance of high speed train window glass.Originality/value-The research results provide data support for the analysis of mechanical characteristics,damage mechanism,strength design and structural optimization of high speed train glass.展开更多
High speed train(HST)is an excellent platform to perform ultra-high spatial and temporal resolution observations of atmosphere using global navigation satellite systems(GNSS).However,we find that signal attenuation ca...High speed train(HST)is an excellent platform to perform ultra-high spatial and temporal resolution observations of atmosphere using global navigation satellite systems(GNSS).However,we find that signal attenuation caused by HST window glass is a major barrier for HST-based GNSS applications inside HST chambers.A field experiment is conducted to analyze the effect of HST glass on GNSS signal propagation.In the experiment,GNSS observations are collected and analyzed from a receiver covered with an HST window glass and one with an open-sky view.The size of the HST window glass is 670 mm×720 mm,with a thickness of 34 mm.The window glass is a double-glazing glass in which each layer has an actual thickness of 6 mm,and the two layers are separated by an air gap of 22 mm.The experiment results indicate that HST window glass can cause significant degradation to GNSS signals and even loss of tracking of the signal.Based on statistical results,HST window glass causes 39%,56%,49%,and 59%loss in GPS,GLONASS,Galileo,and BDS signals,respectively.Additionally,up to 20 dB-Hz of carrier-to-noise ratio(C/N0)degradation is also observed in the remaining observations.The significant signal attenuation and loss further lead to the decrease in the number of tracked satellites and occurrence of more cycle slips.The results of the study indicate that 44-230 cycle slips are detected for the HST glass-covered receiver whereas the receiver without glass does not exhibit more than 16 cycle slips.Additionally,the number of GNSS satellites tracked by the HST glass-covered receiver is reduced by 65%owing to the loss of signal.Furthermore,GNSS positioning performances from two receivers are also tested.With respect to GPS+GLONASS static precise point positioning(PPP),HST glass causes a degradation of 1.516 m and 1.159 m in the single-frequency and dual-frequency three-dimensional positioning accuracy,respectively.With respect to the GPS+GLONASS kinematic PPP,the accuracy degradations for single-frequency and dual-frequency kinematic PPP are 2.670 m and 4.821 m,respectively.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.52072356 and 52032011)the 2019 Zaozhuang High-level Talents Project (Grant No.ZZYF-01).
文摘Purpose-This paper aims to analyze the bearing characteristics of the high speed train window glass under aerodynamic load effects.Design/methodology/approach-In order to obtain the dynamic strain response of passenger compartment window glass during high-speed train crossing the tunnel,taking the passenger compartment window glass of the CRH3 high speed train onWuhan-Guangzhou High Speed Railway as the research object,this study tests the strain dynamic response and maximum principal stress of the high speed train passing through the tunnel entrance and exit,the tunnel and tunnel groups as well as trains meeting in the tunnel at an average speed of 300 km$h-1.Findings-The results show that while crossing the tunnel,the passenger compartment window glass of high speed train is subjected to the alternating action of positive and negative air pressures,which shows the typical mechanic characteristics of the alternating fatigue stress of positive-negative transient strain.The maximum principal stress of passenger compartment window glass for high speed train caused by tunnel aerodynamic effects does not exceed 5 MPa,and the maximum value occurs at the corresponding time of crossing the tunnel groups.The high speed train window glass bears medium and low strain rates under the action of tunnel aerodynamic effects,while the maximum strain rate occurs at the meeting moment when the window glass meets the train head approaching from the opposite side in the tunnel.The shear modulus of laminated glass PVB film that makes up high speed train window glass is sensitive to the temperature and action time.The dynamically equivalent thickness and stiffness of the laminated glass and the dynamic bearing capacity of the window glass decrease with the increase of the action time under tunnel aerodynamic pressure.Thus,the influence of the loading action time and fatigue under tunnel aerodynamic effects on the glass strength should be considered in the design for the bearing performance of high speed train window glass.Originality/value-The research results provide data support for the analysis of mechanical characteristics,damage mechanism,strength design and structural optimization of high speed train glass.
基金The authors acknowledge grant supports from the National Natural Science Foundation of China(NSFC,No.41730109)the Hong Kong Research Grants Council(RGC)General Research Fund(GRF)(B-Q52W RGC/Gov No.PolyU 152149/16E,B-Q61L RGC/Gov No.PolyU 152222/17E)+1 种基金the support from the Emerging Frontier Area(EFA)Scheme of Research Institute for Sustainable Urban Development(RISUD)of the Hong Kong Polytechnic University(No.1-BBWJ)The authors also appreciate funding support by the Innovation and Technology Commission of Hong Kong SAR Government to the Hong Kong Branch of National Rail Transit Electrification and Automation Engineering Technology Research Center(Project No.1-BBYH).
文摘High speed train(HST)is an excellent platform to perform ultra-high spatial and temporal resolution observations of atmosphere using global navigation satellite systems(GNSS).However,we find that signal attenuation caused by HST window glass is a major barrier for HST-based GNSS applications inside HST chambers.A field experiment is conducted to analyze the effect of HST glass on GNSS signal propagation.In the experiment,GNSS observations are collected and analyzed from a receiver covered with an HST window glass and one with an open-sky view.The size of the HST window glass is 670 mm×720 mm,with a thickness of 34 mm.The window glass is a double-glazing glass in which each layer has an actual thickness of 6 mm,and the two layers are separated by an air gap of 22 mm.The experiment results indicate that HST window glass can cause significant degradation to GNSS signals and even loss of tracking of the signal.Based on statistical results,HST window glass causes 39%,56%,49%,and 59%loss in GPS,GLONASS,Galileo,and BDS signals,respectively.Additionally,up to 20 dB-Hz of carrier-to-noise ratio(C/N0)degradation is also observed in the remaining observations.The significant signal attenuation and loss further lead to the decrease in the number of tracked satellites and occurrence of more cycle slips.The results of the study indicate that 44-230 cycle slips are detected for the HST glass-covered receiver whereas the receiver without glass does not exhibit more than 16 cycle slips.Additionally,the number of GNSS satellites tracked by the HST glass-covered receiver is reduced by 65%owing to the loss of signal.Furthermore,GNSS positioning performances from two receivers are also tested.With respect to GPS+GLONASS static precise point positioning(PPP),HST glass causes a degradation of 1.516 m and 1.159 m in the single-frequency and dual-frequency three-dimensional positioning accuracy,respectively.With respect to the GPS+GLONASS kinematic PPP,the accuracy degradations for single-frequency and dual-frequency kinematic PPP are 2.670 m and 4.821 m,respectively.
