High-performance fiber fabrics and composites experienced transverse compression deformation at ultrahigh strain rates near the impact point when subjected to high-velocity impacts,which significantly affected their b...High-performance fiber fabrics and composites experienced transverse compression deformation at ultrahigh strain rates near the impact point when subjected to high-velocity impacts,which significantly affected their ballistic limits.In this paper,a fiber-scale experimental method for characterizing ultrahigh strain-rate transverse compression behavior was proposed.To begin with,in order to measure the extremely low stress and strain in small specimens,the conventional Hopkinson bar was reduced to the hundred-micron scale,thereby achieving wave impedance matching with single fibers.In addition,tangential and normal laser Doppler velocimetry(LDV)methods were employed to realize non-contact,high-precision,and high-speed axial velocity measurements of micron-scale incident and transmission bars,respectively.Meanwhile,a microscopic observation system was used to facilitate the installation of miniature fiber samples.The experimental setup and procedures were introduced,and the system accuracy was verified through sample-free loading tests based on one-dimensional stress wave propagation theory.Dynamic compression experiments on Graphene-UHMWPE fibers were carried out,followed by post-compression microstructural characterization via scanning electron microscopy(SEM).Results demonstrated that successful mechanical characterization was achieved at strain rates exceeding 105,an order of magnitude higher than the previously reported maximum rates.Furthermore,during the loading process,the fibers underwent uniform compression deformation while exhibiting pronounced strain-rate effects.This method offers a novel approach for dynamic mechanical characterization of microscale single fibers,enabling the development of comprehensive strain-ratedependent material models to guide the design of advanced composites and high-performance fibers.展开更多
This paper proposed the split short Hopkinson pressure bar(SSHPB)with short incident and transmission bars to investigate the dynamic compression characteristics of sandstone under different strain rates.The SSHPB was...This paper proposed the split short Hopkinson pressure bar(SSHPB)with short incident and transmission bars to investigate the dynamic compression characteristics of sandstone under different strain rates.The SSHPB was constructed to carry out impact tests to obtain superimposed stress waves in short bars.The separated stress waves(incident,reflected and transmitted waves)were determined by the proposed wave separation method and further used to determine the stress-strain relationship of sandstone.The SSHPB was validated by comparing the dynamic properties of sandstone determined by the SSHPB with those determined by the traditional split Hopkinson pressure bar(SHPB).The effect of the strain rate on the accuracy of the SSHPB was discussed.The results show that the stress-strain relationship of sandstone determined by the SSHPB agrees well with that determined by the traditional SHPB.The variation in the dynamic properties of sandstone with strain rate determined by the SSHPB is similar to that determined by the traditional SHPB.Under different strain rates,the relative error between the dynamic properties of sandstone determined by the SSHPB and traditional SHPB is less than 5%.Compared with the traditional SHPB,the SSHPB can reduce the length of the incident and transmission bars by 50%,which is an alternative to the traditional SHPB.展开更多
基金financial support provided by the National Natural Science Foundation of China(Grant No.12302472)the Science and Technology Support Program of Jiangsu Province(Grant No.BK20230874)+2 种基金the Aeronautical Science Fund(ASF)(Grant No.2023Z057052005)the Research Fund of State Key Laboratory of Mechanics and Control for Aerospace Structures(Nanjing University of Aeronautics and Astronautics)(Grant No.MCAS-I-0124G02)the funding received from Jiangsu Hanvo Safety Product Co.,Ltd。
文摘High-performance fiber fabrics and composites experienced transverse compression deformation at ultrahigh strain rates near the impact point when subjected to high-velocity impacts,which significantly affected their ballistic limits.In this paper,a fiber-scale experimental method for characterizing ultrahigh strain-rate transverse compression behavior was proposed.To begin with,in order to measure the extremely low stress and strain in small specimens,the conventional Hopkinson bar was reduced to the hundred-micron scale,thereby achieving wave impedance matching with single fibers.In addition,tangential and normal laser Doppler velocimetry(LDV)methods were employed to realize non-contact,high-precision,and high-speed axial velocity measurements of micron-scale incident and transmission bars,respectively.Meanwhile,a microscopic observation system was used to facilitate the installation of miniature fiber samples.The experimental setup and procedures were introduced,and the system accuracy was verified through sample-free loading tests based on one-dimensional stress wave propagation theory.Dynamic compression experiments on Graphene-UHMWPE fibers were carried out,followed by post-compression microstructural characterization via scanning electron microscopy(SEM).Results demonstrated that successful mechanical characterization was achieved at strain rates exceeding 105,an order of magnitude higher than the previously reported maximum rates.Furthermore,during the loading process,the fibers underwent uniform compression deformation while exhibiting pronounced strain-rate effects.This method offers a novel approach for dynamic mechanical characterization of microscale single fibers,enabling the development of comprehensive strain-ratedependent material models to guide the design of advanced composites and high-performance fibers.
基金support from the National Natural Science Foundation of China(Grant Nos.12172019 and 42477210).
文摘This paper proposed the split short Hopkinson pressure bar(SSHPB)with short incident and transmission bars to investigate the dynamic compression characteristics of sandstone under different strain rates.The SSHPB was constructed to carry out impact tests to obtain superimposed stress waves in short bars.The separated stress waves(incident,reflected and transmitted waves)were determined by the proposed wave separation method and further used to determine the stress-strain relationship of sandstone.The SSHPB was validated by comparing the dynamic properties of sandstone determined by the SSHPB with those determined by the traditional split Hopkinson pressure bar(SHPB).The effect of the strain rate on the accuracy of the SSHPB was discussed.The results show that the stress-strain relationship of sandstone determined by the SSHPB agrees well with that determined by the traditional SHPB.The variation in the dynamic properties of sandstone with strain rate determined by the SSHPB is similar to that determined by the traditional SHPB.Under different strain rates,the relative error between the dynamic properties of sandstone determined by the SSHPB and traditional SHPB is less than 5%.Compared with the traditional SHPB,the SSHPB can reduce the length of the incident and transmission bars by 50%,which is an alternative to the traditional SHPB.
