The RHT model has 34 parameters,among which 19 parameters can be obtained by experiments or theoretical calculations and the remaining 15 parameters are difficult to acquire.In this study,firstly,10 Hopkinson impact t...The RHT model has 34 parameters,among which 19 parameters can be obtained by experiments or theoretical calculations and the remaining 15 parameters are difficult to acquire.In this study,firstly,10 Hopkinson impact tests were conducted to acquire the typical stress-strain curves of granite under dynamic loads.Through the sensitivity analysis,it is found that 13 of the 15 difficult-acquired parameters are effective to affect the shape of the stress-strain curve,and the other two parameters have no effect.Following the initial determination of model parameters with reference to the concrete RHT model,a new approach is proposed to optimize the 13 influential parameters through the LS-DYNA numerical simulation and orthogonal experiments.Finally,the determined granite RHT model parameters are verified by the results of Hopkinson impact tests conducted in this study and the bullet penetration test by Wang et al.Both results of the numerical simulations are in a good agreement with the tested results,which validates the suitability of the proposed method to acquire RHT model parameters for granite and the other rocks.展开更多
To study the dynamic mechanical behavior of C 60 concrete at high temperatures,impact tests under different steady-state temperature fields（ 100,200,300,400 and 500 ℃） were conducted under a variety of durations at...To study the dynamic mechanical behavior of C 60 concrete at high temperatures,impact tests under different steady-state temperature fields（ 100,200,300,400 and 500 ℃） were conducted under a variety of durations at the corresponding constant high temperature,namely 0,30,60,90 and 120 min,employing split H opkinson pressure bar（ SH PB） system. In addition,the impact tests were also conducted on the specimens cooled fromthe high temperature to the roomtemperature and the specimen under roomtemperature. Fromthe analysis,it is found that C 60 concrete has a time-dependent behavior under hightemperature environment. U nder 100,200,300,400 and 500 ℃ steady-state temperature fields respectively,as the duration at the corresponding constant high temperature increases,the dynamic compressive strength and the elastic modulus decrease but the peak strain generally ascends. After cooling to the roomtemperature,the dynamic compressive strength and the elastic modulus descend as well,but the peak strain increases first and then decreases slightly,when the duration increases. For specimens under and cooled fromthe high-temperature,as the temperature increases,the dynamic compressive strength and the peak strain raise first and then reduce gradually,and the dynamic compressive strength of specimen under high temperature is higher than that of the specimen cooled fromthe same high temperature.展开更多
基金Supported by the Talent Indroduction Research Start-up Fund Project of Kunming University of Science and Technology(KKSY201756009)
文摘The RHT model has 34 parameters,among which 19 parameters can be obtained by experiments or theoretical calculations and the remaining 15 parameters are difficult to acquire.In this study,firstly,10 Hopkinson impact tests were conducted to acquire the typical stress-strain curves of granite under dynamic loads.Through the sensitivity analysis,it is found that 13 of the 15 difficult-acquired parameters are effective to affect the shape of the stress-strain curve,and the other two parameters have no effect.Following the initial determination of model parameters with reference to the concrete RHT model,a new approach is proposed to optimize the 13 influential parameters through the LS-DYNA numerical simulation and orthogonal experiments.Finally,the determined granite RHT model parameters are verified by the results of Hopkinson impact tests conducted in this study and the bullet penetration test by Wang et al.Both results of the numerical simulations are in a good agreement with the tested results,which validates the suitability of the proposed method to acquire RHT model parameters for granite and the other rocks.
文摘To study the dynamic mechanical behavior of C 60 concrete at high temperatures,impact tests under different steady-state temperature fields（ 100,200,300,400 and 500 ℃） were conducted under a variety of durations at the corresponding constant high temperature,namely 0,30,60,90 and 120 min,employing split H opkinson pressure bar（ SH PB） system. In addition,the impact tests were also conducted on the specimens cooled fromthe high temperature to the roomtemperature and the specimen under roomtemperature. Fromthe analysis,it is found that C 60 concrete has a time-dependent behavior under hightemperature environment. U nder 100,200,300,400 and 500 ℃ steady-state temperature fields respectively,as the duration at the corresponding constant high temperature increases,the dynamic compressive strength and the elastic modulus decrease but the peak strain generally ascends. After cooling to the roomtemperature,the dynamic compressive strength and the elastic modulus descend as well,but the peak strain increases first and then decreases slightly,when the duration increases. For specimens under and cooled fromthe high-temperature,as the temperature increases,the dynamic compressive strength and the peak strain raise first and then reduce gradually,and the dynamic compressive strength of specimen under high temperature is higher than that of the specimen cooled fromthe same high temperature.
