Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of...Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of cables,but the impact of alterations in the winding core structure on the mechanical–electrical behavior of superconducting cables remains unclear.This paper presents a 3D finite element model to predict the performance of three cables with different core structures when subjected to transverse compression and axial tension.The three cables analyzed are CORC(conductor-on-round-core),CORT(conductor-on-round-tube),and HFRC(conductor-on-spiral-tube).A parametric analysis is carried out by varying the core diameter and inner-to-outer diameter ratio.Results indicate that the CORT cable demonstrates better performance in transverse compression compared to the CORC cable,aligning with experimental data.Among the three cables,the HFRC cables exhibit the weakest resistance to transverse deformation.However,the HFRC cable demonstrates superior tensile deformation resistance compared to the CORT cable,provided that the transverse compression properties are maintained.Finite element results also show that the optimum inner-to-outer diameter ratios for achieving the best transverse compression performance are approximately 0.8 for CORT cables and 0.6 for HFRC cables.Meanwhile,the study explores the effect of structural changes in HTS cable winding cores on their electromagnetic properties.It recommends utilizing small tape gaps,lower frequencies,and spiral core construction to minimize eddy losses.The findings presented in this paper offer valuable insights for the commercialization and practical manufacturing of HTS cables.展开更多
This study focuses on the electrical properties and microstructure of polypropylene(PP)-based blends used for cable insulation in nuclear power plants(NPPs).The PP-based blend,comprising isotactic PP and propylene-bas...This study focuses on the electrical properties and microstructure of polypropylene(PP)-based blends used for cable insulation in nuclear power plants(NPPs).The PP-based blend,comprising isotactic PP and propylene-based elastomer(PBE)at concentrations ranging from 0 to 50 wt%,underwent a melt blending process and subsequent cobalt-60 gamma-ray irradiation with doses ranging from 0 to 250 kGy.Electrical conductivity,trap distribution,and alternating(AC)breakdown strength were chosen to assess the insulation performance.These results indicate that the addition of PBE significantly improves the electrical properties of PP under irradiation.For PP,the electrical conductivity increased with irradiation,whereas the trap depth and breakdown strength decreased sharply.Conversely,for the blend,these changes initially exhibit opposite trends.When the irradiation was increased to 250 kGy,the AC breakdown strength of the blend improved by more than 21%compared to that of PP.The physical and chemical structures of the samples were investigated to explore the improvement mechanisms.The results offer insights into the design of new cable-insulation materials suitable for NPPs.展开更多
Frost heave and thaw settlement in cold regions pose a significant threat to engineering construction.Optical frequency domain reflectometry(OFDR)based on Rayleigh scattering can be applied to monitor ground deformati...Frost heave and thaw settlement in cold regions pose a significant threat to engineering construction.Optical frequency domain reflectometry(OFDR)based on Rayleigh scattering can be applied to monitor ground deformation in frozen soil areas,where the interface behavior of soil-embedded fiber optic sensors governs the monitoring accuracy.In this paper,a series of pullout tests were conducted on fiber optic(FO)cables embedded in the frozen soil to investigate the cable‒soil interface behavior.An experimental study was performed on interaction effects,particularly focused on the water content of unfrozen soil,freezing duration,and differential distribution of water content in frozen soil.The highresolution axial strains of FO cables were obtained using a sensing interrogator,and were used to calculate the interface shear stress.The interfacial mechanical response was analytically modeled using the ideal elasto‒plastic and softening constitutive models.Three freezing periods,correlating with the phase change process between ice and water,were analyzed.The results shows that the freezing effect can amplify the peak shear stress at the cable-soil interface by eight times.A criterion for the interface coupling states was proposed by normalizing the pullout force‒displacement information.Additionally,the applicability of existing theoretical models was discussed by comparing the results of theoretical back‒calculations with experimental measurements.This study provides new insights into the progressive interfacial failure behavior between strain sensing cable and frozen soil,which can be used to assist the interpretation of FO monitoring results of frozen soil deformation.展开更多
基金supported by the National Natural Science Foundation of China(12072136).
文摘Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of cables,but the impact of alterations in the winding core structure on the mechanical–electrical behavior of superconducting cables remains unclear.This paper presents a 3D finite element model to predict the performance of three cables with different core structures when subjected to transverse compression and axial tension.The three cables analyzed are CORC(conductor-on-round-core),CORT(conductor-on-round-tube),and HFRC(conductor-on-spiral-tube).A parametric analysis is carried out by varying the core diameter and inner-to-outer diameter ratio.Results indicate that the CORT cable demonstrates better performance in transverse compression compared to the CORC cable,aligning with experimental data.Among the three cables,the HFRC cables exhibit the weakest resistance to transverse deformation.However,the HFRC cable demonstrates superior tensile deformation resistance compared to the CORT cable,provided that the transverse compression properties are maintained.Finite element results also show that the optimum inner-to-outer diameter ratios for achieving the best transverse compression performance are approximately 0.8 for CORT cables and 0.6 for HFRC cables.Meanwhile,the study explores the effect of structural changes in HTS cable winding cores on their electromagnetic properties.It recommends utilizing small tape gaps,lower frequencies,and spiral core construction to minimize eddy losses.The findings presented in this paper offer valuable insights for the commercialization and practical manufacturing of HTS cables.
基金supported by the National Natural Science Foundation of China(No.52077151)the State Key Laboratory of Electrical Insulation and Power Equipment(No.EIPE23208)the Key Laboratory of Engineering Dielectrics and Its Application,Ministry of Education(No.KFM202203).
文摘This study focuses on the electrical properties and microstructure of polypropylene(PP)-based blends used for cable insulation in nuclear power plants(NPPs).The PP-based blend,comprising isotactic PP and propylene-based elastomer(PBE)at concentrations ranging from 0 to 50 wt%,underwent a melt blending process and subsequent cobalt-60 gamma-ray irradiation with doses ranging from 0 to 250 kGy.Electrical conductivity,trap distribution,and alternating(AC)breakdown strength were chosen to assess the insulation performance.These results indicate that the addition of PBE significantly improves the electrical properties of PP under irradiation.For PP,the electrical conductivity increased with irradiation,whereas the trap depth and breakdown strength decreased sharply.Conversely,for the blend,these changes initially exhibit opposite trends.When the irradiation was increased to 250 kGy,the AC breakdown strength of the blend improved by more than 21%compared to that of PP.The physical and chemical structures of the samples were investigated to explore the improvement mechanisms.The results offer insights into the design of new cable-insulation materials suitable for NPPs.
基金the National Key Research and Development Program of China(Grant No.2023YFF1303501)the National Science Fund for Distinguished Young Scholars of China(Grant No.42225702)the Open Fund of State Key Laboratory of Frozen Soil Engineering(Grant No.SKLFSE201814).
文摘Frost heave and thaw settlement in cold regions pose a significant threat to engineering construction.Optical frequency domain reflectometry(OFDR)based on Rayleigh scattering can be applied to monitor ground deformation in frozen soil areas,where the interface behavior of soil-embedded fiber optic sensors governs the monitoring accuracy.In this paper,a series of pullout tests were conducted on fiber optic(FO)cables embedded in the frozen soil to investigate the cable‒soil interface behavior.An experimental study was performed on interaction effects,particularly focused on the water content of unfrozen soil,freezing duration,and differential distribution of water content in frozen soil.The highresolution axial strains of FO cables were obtained using a sensing interrogator,and were used to calculate the interface shear stress.The interfacial mechanical response was analytically modeled using the ideal elasto‒plastic and softening constitutive models.Three freezing periods,correlating with the phase change process between ice and water,were analyzed.The results shows that the freezing effect can amplify the peak shear stress at the cable-soil interface by eight times.A criterion for the interface coupling states was proposed by normalizing the pullout force‒displacement information.Additionally,the applicability of existing theoretical models was discussed by comparing the results of theoretical back‒calculations with experimental measurements.This study provides new insights into the progressive interfacial failure behavior between strain sensing cable and frozen soil,which can be used to assist the interpretation of FO monitoring results of frozen soil deformation.
