This paper investigates Q420 dual-angle cross combined section columns under axial and eccentric compression by conducting experiments.The specimen parameters,experimental setup,and test results are presented.It showe...This paper investigates Q420 dual-angle cross combined section columns under axial and eccentric compression by conducting experiments.The specimen parameters,experimental setup,and test results are presented.It showed that local buckling occurred apparently for single internode specimens(λ<35)under axial compression,while overall bending buckling appeared for others,and no torsional buckling occurred.The theoretical formulas on stability factor were derived by the energy approach.Non-linear finite element models considering residual stress were established using ANSYS which were verified by the corresponding experimental results.The parametric study was to evaluate the effects of slenderness ratio(λ),width to thickness ratio of angles(b/t),the number of filled plate(n),load relative eccentricity(e)and the lateral support stiffness on the ultimate strengths of dual-angle cross combined section columns.Based on above analysis,the design equations are proposed by using curve fitting technique.It is shown from comparison between test results,finite element analysis and related specifications that the ultimate strength from theoretical formulas,proposed equations and finite element models are consistent with experiments results.展开更多
Wearable electronics have promising applications in human-machine interfaces due to their excellent flexibility,stretchability and human friendliness,and one of the key points of wearable electronics is to develop str...Wearable electronics have promising applications in human-machine interfaces due to their excellent flexibility,stretchability and human friendliness,and one of the key points of wearable electronics is to develop strain sensors with high sensitivity and working range.Herein,a high-performance Eco-flex@AgNW/graphite/Pt hybrid strain sensor was fabricated by suction filtrating,transferring and surface sputtering sequentially.The suction filtrating of AgNW and graphite dispersions on a wrinkle-shape Nylon filter,transferring of AgNW/graphite layer onto Ecoflex and further surface sputtering by Pt allow the construction of fingerprint bionic Ecoflex@AgNW/graphite/Pt hybrid strain sensor.The resul-tant fingerprint bionic hybrid strain sensor possesses high sensitivity of 2064.1 at the strain of 140%e155%,a wide working range of 0e155%,a short response time(111 ms and 189 ms for tensile and releasing process)and excellent cyclic stability over 5000 cycles.This study provides a universal tech-nique for the preparation of strain sensors with promising applications in the field of next-generation intelligent wearable electronics.展开更多
Silver nanowire(AgNW)has become one of the best candidates for flexible transparent electromagnetic(EMI)shielding materials,while the low corrosion resistance of AgNW hinders its application in environments with high ...Silver nanowire(AgNW)has become one of the best candidates for flexible transparent electromagnetic(EMI)shielding materials,while the low corrosion resistance of AgNW hinders its application in environments with high content of corrosive substances.Herein,an AgNW/poly(3,4-ethylene dioxythiophene)/poly(styrene sulfonate)(PEDOT:PSS)@nickel electrode was prepared through ultrasonic spray coating and electroplating methods.PEDOT:PSS is sprayed to improve the conductivity of the AgNW network,and a 9.8-16.5 nm Ni layer is deposited on the AgNW/PEDOT:PSS to protect the AgNWs from corrosion.The AgNW/PEDOT:PSS@Ni electrode shows a sheet resistance of 29 U·sq^(-1),a transmittance of 78.18%,an average EMI shielding efficiency of 19.64 dB and excellent corrosion resistance in Na2S solution.The resultant AgNW/PEDOT:PSS@Ni electrode is promisingly used in high corrosion resistance transparent EMI shielding film.展开更多
For seismic control of arch bridge,a model reduction of long-span arch bridge was implemented based on modal analysis.As for the critical mode selection,an approach based on the maximum modal displacement was presente...For seismic control of arch bridge,a model reduction of long-span arch bridge was implemented based on modal analysis.As for the critical mode selection,an approach based on the maximum modal displacement was presented.This approach takes into consideration the effect of external seismic excitation and is more reasonable than only considering dynamic bridge characteristics based on a modal contribution ratio.The time domain and frequency domain analysis method were used to verify the simplified model of the Nimu arch bridge in Tibet as an example.The numerical results show that the method of maximal modal displacement better analyze long-span arch bridge when multisupport seismic excitation must be considered.The reduced-order system also is more in line with the performance of the original model.展开更多
The axial piston pumps in aerospace applications are often characterized by high-speed rotation to achieve great power density. However, their internal rotating parts are fully immersed in the casing oil during operat...The axial piston pumps in aerospace applications are often characterized by high-speed rotation to achieve great power density. However, their internal rotating parts are fully immersed in the casing oil during operation, leading to considerable churning losses (more than 10% of total power losses) at high rotational speeds. The churning losses deserve much attention at the design stage of high-speed axial piston pumps, but accurate analytical models are not available to estimate the drag torque associated with the churning losses. In this paper, we derive the analytical expressions of the drag torque acting on the key rotating parts immersed in oil, including the cylinder block and the multiple pistons in a circular array. The calculated drag torque agrees well with the experimental data over a wide range of rotational speeds from 1500 to 12000 r/min. The presented analytical model provides practical guidelines for reducing the churning losses in high-speed axial piston pumps or motors.展开更多
文摘This paper investigates Q420 dual-angle cross combined section columns under axial and eccentric compression by conducting experiments.The specimen parameters,experimental setup,and test results are presented.It showed that local buckling occurred apparently for single internode specimens(λ<35)under axial compression,while overall bending buckling appeared for others,and no torsional buckling occurred.The theoretical formulas on stability factor were derived by the energy approach.Non-linear finite element models considering residual stress were established using ANSYS which were verified by the corresponding experimental results.The parametric study was to evaluate the effects of slenderness ratio(λ),width to thickness ratio of angles(b/t),the number of filled plate(n),load relative eccentricity(e)and the lateral support stiffness on the ultimate strengths of dual-angle cross combined section columns.Based on above analysis,the design equations are proposed by using curve fitting technique.It is shown from comparison between test results,finite element analysis and related specifications that the ultimate strength from theoretical formulas,proposed equations and finite element models are consistent with experiments results.
基金supported by the Key R&D Program of Zhejiang Province of China(No.2020C01126)the National Key R&D Program of China(2016YFB0401305).
文摘Wearable electronics have promising applications in human-machine interfaces due to their excellent flexibility,stretchability and human friendliness,and one of the key points of wearable electronics is to develop strain sensors with high sensitivity and working range.Herein,a high-performance Eco-flex@AgNW/graphite/Pt hybrid strain sensor was fabricated by suction filtrating,transferring and surface sputtering sequentially.The suction filtrating of AgNW and graphite dispersions on a wrinkle-shape Nylon filter,transferring of AgNW/graphite layer onto Ecoflex and further surface sputtering by Pt allow the construction of fingerprint bionic Ecoflex@AgNW/graphite/Pt hybrid strain sensor.The resul-tant fingerprint bionic hybrid strain sensor possesses high sensitivity of 2064.1 at the strain of 140%e155%,a wide working range of 0e155%,a short response time(111 ms and 189 ms for tensile and releasing process)and excellent cyclic stability over 5000 cycles.This study provides a universal tech-nique for the preparation of strain sensors with promising applications in the field of next-generation intelligent wearable electronics.
基金supported by the Key R&D Program of Zhejiang Province of China(No.2020C01126)and the National Key R&D Program of China(2016YFB0401305).
文摘Silver nanowire(AgNW)has become one of the best candidates for flexible transparent electromagnetic(EMI)shielding materials,while the low corrosion resistance of AgNW hinders its application in environments with high content of corrosive substances.Herein,an AgNW/poly(3,4-ethylene dioxythiophene)/poly(styrene sulfonate)(PEDOT:PSS)@nickel electrode was prepared through ultrasonic spray coating and electroplating methods.PEDOT:PSS is sprayed to improve the conductivity of the AgNW network,and a 9.8-16.5 nm Ni layer is deposited on the AgNW/PEDOT:PSS to protect the AgNWs from corrosion.The AgNW/PEDOT:PSS@Ni electrode shows a sheet resistance of 29 U·sq^(-1),a transmittance of 78.18%,an average EMI shielding efficiency of 19.64 dB and excellent corrosion resistance in Na2S solution.The resultant AgNW/PEDOT:PSS@Ni electrode is promisingly used in high corrosion resistance transparent EMI shielding film.
文摘For seismic control of arch bridge,a model reduction of long-span arch bridge was implemented based on modal analysis.As for the critical mode selection,an approach based on the maximum modal displacement was presented.This approach takes into consideration the effect of external seismic excitation and is more reasonable than only considering dynamic bridge characteristics based on a modal contribution ratio.The time domain and frequency domain analysis method were used to verify the simplified model of the Nimu arch bridge in Tibet as an example.The numerical results show that the method of maximal modal displacement better analyze long-span arch bridge when multisupport seismic excitation must be considered.The reduced-order system also is more in line with the performance of the original model.
基金the National Key R&D Program of China(Grant No.2021YFB2011902)the National Natural Science Foundation of China(Grant No.52005323)+1 种基金the National Postdoctoral Program for Innovative Talents(Grant No.BX20200210)the China Postdoctoral Science Foundation(Grant No.2019M660086).
文摘The axial piston pumps in aerospace applications are often characterized by high-speed rotation to achieve great power density. However, their internal rotating parts are fully immersed in the casing oil during operation, leading to considerable churning losses (more than 10% of total power losses) at high rotational speeds. The churning losses deserve much attention at the design stage of high-speed axial piston pumps, but accurate analytical models are not available to estimate the drag torque associated with the churning losses. In this paper, we derive the analytical expressions of the drag torque acting on the key rotating parts immersed in oil, including the cylinder block and the multiple pistons in a circular array. The calculated drag torque agrees well with the experimental data over a wide range of rotational speeds from 1500 to 12000 r/min. The presented analytical model provides practical guidelines for reducing the churning losses in high-speed axial piston pumps or motors.
