The uniaxial compressive response of steel-polypropylene hybrid fiber reinforced concrete（HFRC） and steel fiber-reinforced concrete（SFRC） was analyzed under high strain rate loading with a 74 mm diameter split Hop...The uniaxial compressive response of steel-polypropylene hybrid fiber reinforced concrete（HFRC） and steel fiber-reinforced concrete（SFRC） was analyzed under high strain rate loading with a 74 mm diameter split Hopkinson pressure bar（SHPB）.The experimental investigation focused on recorded data and resulted in distinguishing the strain rate that mobilized different ductility of steel-polypropylene hybrid fiber reinforced concrete（HFRC） and steel fiber-reinforced concrete（SFRC）.64 specimens of HFRC and SFRC with higher static compressive strength were tested at the strain rates changing from 20 to 120 s-1.The static compressive strength and dynamic stress-strain curves of the two materials were obtained at 4 different strain rates and the failure stress,and peak strain and peak toughness were also analyzed.The results show that HFRC has quite good dynamic mechanical property and clear strain-rate effect,and the failure mechanism of HFRC and SFRC was also compared based on the specimens＇ failure modes in static and dynamic compressive tests.展开更多
Understanding the mechanical behavior of hybrid fiber-reinforced concrete(HFRC),a composite material,is crucial for the design of HFRC and HFRC structures.In this study,a series of compression experiments were perform...Understanding the mechanical behavior of hybrid fiber-reinforced concrete(HFRC),a composite material,is crucial for the design of HFRC and HFRC structures.In this study,a series of compression experiments were performed on hybrid steelpolyvinyl alcohol(PVA)fiber-reinforced concrete containing fly ash and slag powder,with a focus on the fiber content/ratio effect on its compressive behavior;a new approach was built to model the compression behavior of HFRC by using an artificial neural network(ANN)method.The proposed ANN model incorporated two new developments:the prediction of the compressive stress-strain curve and consideration of 23 features of components of HFRC.To build a database for the ANN model,relevant published data were also collected.Three indices were used to train and evaluate the ANN model.To highlight the performance of the ANN model,it was compared with a traditional equation-based model.The results revealed that the relative errors of the predicted compressive strength and strain corresponding to compressive strength of the ANN model were close to 0,while the corresponding values from the equation-based model were higher.Therefore,the ANN model is better able to consider the effect of different components on the compressive behavior of HFRC in terms of compressive strength,the strain corresponding to compressive strength,and the compressive stress-strain curve.Such an ANN model could also be a good tool to predict the mechanical behavior of other composite materials.展开更多
High Temperature Superconductor(HTS)materials can operate at higher magnetic fields up to 20 T with high critical current and higher operating temperature,compared to low temperature superconductors(LTS).A Highly Flex...High Temperature Superconductor(HTS)materials can operate at higher magnetic fields up to 20 T with high critical current and higher operating temperature,compared to low temperature superconductors(LTS).A Highly Flexible REBCO Cable(HFRC)is introduced at the Institute of Plasma Physics,Chinese Academy of Sciences(ASIPP);a cabling method that is suitable for REBCO HTS tape having anisotropic material properties in its thin REBCO layer.This type of HTS superconducting cable shows high potential for applications in nuclear fusion.The alternating currents and magnetic fields in tokamak type of fusion magnets,cause AC power losses in such cables,which can provoke instability of the conductor by induced currents and increase the temperature.As a first step in characterizing the electromagnetic(EM)performance of an HFRC cable,the AC loss and contact resistance of the HFRC prototype cable were measured at the University of Twente.The measurements were done in liquid helium(4.2 K)with AC magnetic fields,applied perpendicular to the cable's long axis.The AC loss was measured simultaneously by a calibrated gas flow calorimeter utilizing the helium boil-off method,and by the magnetization method using pick-up coils.For the applied test conditions,no coupling loss could be distinguished as a part of the overall AC loss.It is suggested that this might be explained by the shielding of the conductor interior from the applied magnetic field by the outer tape layer due to the high critical current density of the REBCO tape,leading to a high penetration field.展开更多
Due to the high current capability and excellent flexibility,High Flexible REBCO Cables(HFRC)have emerged as an important candidate for composite high‐temperature superconducting conductors.The REBCO six around one C...Due to the high current capability and excellent flexibility,High Flexible REBCO Cables(HFRC)have emerged as an important candidate for composite high‐temperature superconducting conductors.The REBCO six around one Cable‐In‐Conduit Conductor(CICC)concept has been designed for application in the Central Solenoid(CS)coil of the China Fusion Engineering Test Reactor.In the application of fusion devices,the performance of CICC under electromagnetic(EM)loading and thermal stress is very important for reliable and economic operation.Therefore,a 1.22 m long sub‐cable with HFRC design for CICC was manufactured and tested at 4.2 K in a background magnetic field up to 5.8 T.The aim is to investigate the stability of the current‐carrying properties of the HFRC cable under electromagnetic and thermal cyclic loading.The test results show that the critical current(I_(c))of the HFRC cable reached 17.3 kA in a background magnetic field of 5.8 T at 4.2 K.Furthermore,no performance degradation was observed after 24 cycles of 80 kN/m peak load with a background field of 5.8 T and 8 warm‐up‐cool‐down cycles between 77 K and room temperature.The test results provide a good basis for the development of full‐size conductors in future magnet applications.展开更多
基金Funded by the Self-determined and Innovative Research Funds of WUT
文摘The uniaxial compressive response of steel-polypropylene hybrid fiber reinforced concrete（HFRC） and steel fiber-reinforced concrete（SFRC） was analyzed under high strain rate loading with a 74 mm diameter split Hopkinson pressure bar（SHPB）.The experimental investigation focused on recorded data and resulted in distinguishing the strain rate that mobilized different ductility of steel-polypropylene hybrid fiber reinforced concrete（HFRC） and steel fiber-reinforced concrete（SFRC）.64 specimens of HFRC and SFRC with higher static compressive strength were tested at the strain rates changing from 20 to 120 s-1.The static compressive strength and dynamic stress-strain curves of the two materials were obtained at 4 different strain rates and the failure stress,and peak strain and peak toughness were also analyzed.The results show that HFRC has quite good dynamic mechanical property and clear strain-rate effect,and the failure mechanism of HFRC and SFRC was also compared based on the specimens＇ failure modes in static and dynamic compressive tests.
基金Project supported by the National Natural Science Foundation of China(Nos.51978515 and 52090083)the Shanghai Sailing Program(No.19YF1451400)the Shanghai Municipal Science and Technology Major Project(No.2017SHZDZX02),China。
文摘Understanding the mechanical behavior of hybrid fiber-reinforced concrete(HFRC),a composite material,is crucial for the design of HFRC and HFRC structures.In this study,a series of compression experiments were performed on hybrid steelpolyvinyl alcohol(PVA)fiber-reinforced concrete containing fly ash and slag powder,with a focus on the fiber content/ratio effect on its compressive behavior;a new approach was built to model the compression behavior of HFRC by using an artificial neural network(ANN)method.The proposed ANN model incorporated two new developments:the prediction of the compressive stress-strain curve and consideration of 23 features of components of HFRC.To build a database for the ANN model,relevant published data were also collected.Three indices were used to train and evaluate the ANN model.To highlight the performance of the ANN model,it was compared with a traditional equation-based model.The results revealed that the relative errors of the predicted compressive strength and strain corresponding to compressive strength of the ANN model were close to 0,while the corresponding values from the equation-based model were higher.Therefore,the ANN model is better able to consider the effect of different components on the compressive behavior of HFRC in terms of compressive strength,the strain corresponding to compressive strength,and the compressive stress-strain curve.Such an ANN model could also be a good tool to predict the mechanical behavior of other composite materials.
基金supported by the Strategic Priority Research Program of Chinese Academy of Science under Grant No.XDB25000000Comprehensive Research Facility for Fusion Technology Program of China under Contract No.2018-000052-73-01-001228+2 种基金the National Nature Science Foundation of China(No.52077212)the Youth Innovation Promotion Association,Chinese Academy of ScienceChina Scholarship Council.
文摘High Temperature Superconductor(HTS)materials can operate at higher magnetic fields up to 20 T with high critical current and higher operating temperature,compared to low temperature superconductors(LTS).A Highly Flexible REBCO Cable(HFRC)is introduced at the Institute of Plasma Physics,Chinese Academy of Sciences(ASIPP);a cabling method that is suitable for REBCO HTS tape having anisotropic material properties in its thin REBCO layer.This type of HTS superconducting cable shows high potential for applications in nuclear fusion.The alternating currents and magnetic fields in tokamak type of fusion magnets,cause AC power losses in such cables,which can provoke instability of the conductor by induced currents and increase the temperature.As a first step in characterizing the electromagnetic(EM)performance of an HFRC cable,the AC loss and contact resistance of the HFRC prototype cable were measured at the University of Twente.The measurements were done in liquid helium(4.2 K)with AC magnetic fields,applied perpendicular to the cable's long axis.The AC loss was measured simultaneously by a calibrated gas flow calorimeter utilizing the helium boil-off method,and by the magnetization method using pick-up coils.For the applied test conditions,no coupling loss could be distinguished as a part of the overall AC loss.It is suggested that this might be explained by the shielding of the conductor interior from the applied magnetic field by the outer tape layer due to the high critical current density of the REBCO tape,leading to a high penetration field.
基金supported by the National Key R&D Program of China(No.2022YFE03150200)the Strategic Priority Research Program of Chinese Academy of Science under Grant No.XDB25000000+2 种基金Comprehensive Research Facility for Fusion Technology Program of China under Contract No.2018‐000052‐73‐01‐001228the National Nature Science Foundation of China(No.52077212)the Youth Innovation Promotion Association,Chinese Academy of Science(Grant No.2021444).
文摘Due to the high current capability and excellent flexibility,High Flexible REBCO Cables(HFRC)have emerged as an important candidate for composite high‐temperature superconducting conductors.The REBCO six around one Cable‐In‐Conduit Conductor(CICC)concept has been designed for application in the Central Solenoid(CS)coil of the China Fusion Engineering Test Reactor.In the application of fusion devices,the performance of CICC under electromagnetic(EM)loading and thermal stress is very important for reliable and economic operation.Therefore,a 1.22 m long sub‐cable with HFRC design for CICC was manufactured and tested at 4.2 K in a background magnetic field up to 5.8 T.The aim is to investigate the stability of the current‐carrying properties of the HFRC cable under electromagnetic and thermal cyclic loading.The test results show that the critical current(I_(c))of the HFRC cable reached 17.3 kA in a background magnetic field of 5.8 T at 4.2 K.Furthermore,no performance degradation was observed after 24 cycles of 80 kN/m peak load with a background field of 5.8 T and 8 warm‐up‐cool‐down cycles between 77 K and room temperature.The test results provide a good basis for the development of full‐size conductors in future magnet applications.
