To explore the influence of spatially varying ground motion on the dynamic behavior of a train passing through a three-tower cable-stayed bridge,a 3D train–track–bridge coupled model is established for accurately si...To explore the influence of spatially varying ground motion on the dynamic behavior of a train passing through a three-tower cable-stayed bridge,a 3D train–track–bridge coupled model is established for accurately simulating the train–bridge interaction under earthquake excitation,which is made up of a vehicle model built by multi-body dynamics,a track–bridge finite element model,and a 3D rolling wheel–rail contact model.A conditional simulation method,which takes into consideration the wave passage effect,incoherence effect,and site-response effect,is adopted to simulate the spatially varying ground motion under different soil conditions.The multi-time-step method previously proposed by the authors is also adopted to improve computational efficiency.The dynamic responses of the train running on a three-tower cablestayed bridge are calculated with differing earthquake excitations and train speeds.The results indicate that(1)the earthquake excitation significantly increases the responses of the train–bridge system,but at a design speed,all the running safety indices meet the code requirements;(2)the incoherence and site-response effects should also be considered in the seismic analysis for long-span bridges though there is no fixed pattern for determining their influences;(3)different train speeds that vary the vibration characteristics of the train–bridge system affect the vibration frequencies of the car body and bridge.展开更多
Coupled extensional and flexural cylindrical vibrations of a corrugated cylindrical piezoelectric shell consisting of multiple pieces of circular cylindrical surfaces smoothly connected along their generatrix are stud...Coupled extensional and flexural cylindrical vibrations of a corrugated cylindrical piezoelectric shell consisting of multiple pieces of circular cylindrical surfaces smoothly connected along their generatrix are studied. To validate the results for the case of relatively thick shells or equivalently high-frequency modes with short wavelengths, existing analysis is extended by considering shear deformation and rotatory inertia. An analytical solution is obtained. Based on the solution, resonant frequencies and mode shapes are calculated.展开更多
The non-metallic lightning strike protection film covering carbon fiber reinforced polymers(NM-LSP covering CFRP)can reduce the weight and thus the fuel consumption of aircraft by replacing the traditional lightning s...The non-metallic lightning strike protection film covering carbon fiber reinforced polymers(NM-LSP covering CFRP)can reduce the weight and thus the fuel consumption of aircraft by replacing the traditional lightning strike protection(LSP)materials.In the present study,in order to study the environmental influence of utilizing NM-LSP covering CFRP in an aircraft elevator,a new elevator was designed and manufactured,replacing the aluminium net and glass fiber reinforced polymers(GFRP)with NM-LSP covering CFRP,with the same mechanical and LSP abilities.A comparative life cycle assessment was conducted between the two kinds of aircraft elevators,including material extraction,transportation,elevator manufacturing phase,service phase,and end-of-life procedures.Additionally,the environmental impacts of producing two LSP materials were compared by considering the environmental effects of different buy-to-fly ratios and recycling strategies on the production of aluminium net.The analysis indicates that the new elevator achieved reduction for all the environmental impact categories used,such as human toxicity potential and marine aquatic ecotoxicity potential(3.83%and 3.20%reduction).Furthermore,it is found that the service phase makes the greatest contribution to the environmental impact of the elevators under investigation.When recycling is excluded,NM-LSP covering CFRP is more environmentally friendly than the traditional material.At the same time,CFRP prepreg and electricity from the production of NM-LSP covering CFRP contribute to a higher environmental impact compared to the NM-LSP film.From the sensitivity analysis,it is believed that NM-LSP covering CFRP can reduce environmental impact compared with traditional LSP materials.展开更多
基金the National Natural Science Foundation of China(Grant No.51678576)the National Key R&D Program of China(Grant No.2017YFB1201204)+1 种基金China Railway Corporation R&D Project(Grant No.2015G001-G)the Fundamental Research Funds for the Central Universities of Central South University(Grant No.2018zzts031).
文摘To explore the influence of spatially varying ground motion on the dynamic behavior of a train passing through a three-tower cable-stayed bridge,a 3D train–track–bridge coupled model is established for accurately simulating the train–bridge interaction under earthquake excitation,which is made up of a vehicle model built by multi-body dynamics,a track–bridge finite element model,and a 3D rolling wheel–rail contact model.A conditional simulation method,which takes into consideration the wave passage effect,incoherence effect,and site-response effect,is adopted to simulate the spatially varying ground motion under different soil conditions.The multi-time-step method previously proposed by the authors is also adopted to improve computational efficiency.The dynamic responses of the train running on a three-tower cablestayed bridge are calculated with differing earthquake excitations and train speeds.The results indicate that(1)the earthquake excitation significantly increases the responses of the train–bridge system,but at a design speed,all the running safety indices meet the code requirements;(2)the incoherence and site-response effects should also be considered in the seismic analysis for long-span bridges though there is no fixed pattern for determining their influences;(3)different train speeds that vary the vibration characteristics of the train–bridge system affect the vibration frequencies of the car body and bridge.
基金supported by the National Natural Science Foundation of China(Nos.60302001 and 10872074)Major State Basic Research Development Program of China(973 Program)(No.2009CB724205).
文摘Coupled extensional and flexural cylindrical vibrations of a corrugated cylindrical piezoelectric shell consisting of multiple pieces of circular cylindrical surfaces smoothly connected along their generatrix are studied. To validate the results for the case of relatively thick shells or equivalently high-frequency modes with short wavelengths, existing analysis is extended by considering shear deformation and rotatory inertia. An analytical solution is obtained. Based on the solution, resonant frequencies and mode shapes are calculated.
基金supported by the National Key Research and Development Program of China(No.2017YFC0703007)the Chinese MIIT Special Research Plan on Civil Aircraft(No.MJ-2015-H-G-103)+1 种基金the National Natural Science Foundation of China(No.52008137)the China Postdoctoral Science Foundation(Nos.2019TQ0079 and 2019M661288)。
文摘The non-metallic lightning strike protection film covering carbon fiber reinforced polymers(NM-LSP covering CFRP)can reduce the weight and thus the fuel consumption of aircraft by replacing the traditional lightning strike protection(LSP)materials.In the present study,in order to study the environmental influence of utilizing NM-LSP covering CFRP in an aircraft elevator,a new elevator was designed and manufactured,replacing the aluminium net and glass fiber reinforced polymers(GFRP)with NM-LSP covering CFRP,with the same mechanical and LSP abilities.A comparative life cycle assessment was conducted between the two kinds of aircraft elevators,including material extraction,transportation,elevator manufacturing phase,service phase,and end-of-life procedures.Additionally,the environmental impacts of producing two LSP materials were compared by considering the environmental effects of different buy-to-fly ratios and recycling strategies on the production of aluminium net.The analysis indicates that the new elevator achieved reduction for all the environmental impact categories used,such as human toxicity potential and marine aquatic ecotoxicity potential(3.83%and 3.20%reduction).Furthermore,it is found that the service phase makes the greatest contribution to the environmental impact of the elevators under investigation.When recycling is excluded,NM-LSP covering CFRP is more environmentally friendly than the traditional material.At the same time,CFRP prepreg and electricity from the production of NM-LSP covering CFRP contribute to a higher environmental impact compared to the NM-LSP film.From the sensitivity analysis,it is believed that NM-LSP covering CFRP can reduce environmental impact compared with traditional LSP materials.
