The outcome of the cutting blasting in a one-step shaft excavation is heavily related to the cutting parameters used for parallel cutting method. In this study, the relationships between the cutting parameters（such a...The outcome of the cutting blasting in a one-step shaft excavation is heavily related to the cutting parameters used for parallel cutting method. In this study, the relationships between the cutting parameters（such as the hole spacing L and the empty hole diameter D） and damage zones were investigated by numerical simulation. A damage state index γ was introduced and used to characterize the crushing and crack damage zones through a user-defined subroutine. Two indices, i.e., η1 and η2 that can reflect the cutting performance, were also introduced. The simulation results indicate that an optimal value of L can be obtained so that the η1 and η2 can reach their optimal states for the best cutting performance. A larger D results in better cutting performance when the L value maintains its best. In addition, the influences of the loading rate and the in-situ stress on the cutting performance were investigated. It is found that an explosive with a high loading rate is suit for cutting blasting. The propagation direction and the length of the tensile cracks are affected by the direction and the magnitude of the maximum principal stress.展开更多
Through rolling experiments and interfacial tensile strength tests of cross-wedge rolled laminated shafts of 42CrMo/Q235 composites, the influence of process parameters, including forming angle, spreading angle, area ...Through rolling experiments and interfacial tensile strength tests of cross-wedge rolled laminated shafts of 42CrMo/Q235 composites, the influence of process parameters, including forming angle, spreading angle, area reduction, rolling temperature and core material diameter on the interfacial shear strength was analyzed. The results show that the sequence of process parameters in order of greatest influence on interfacial tensile strength was rolling temperature, area reduction, core material diameter, forming angle and spreading angle. At the interface of the combined materials, tensile strength decreased as forming angle and spreading angle increased, whereas the tensile strength first increased and then decreased as area reduction, rolling temperature and core material diameter increased.展开更多
The aim of the study is to determine the optimal structural parameters for a plastic centrifugal pump inducer within the framework of an orthogonal experimental method.For this purpose,a numerical study of the related...The aim of the study is to determine the optimal structural parameters for a plastic centrifugal pump inducer within the framework of an orthogonal experimental method.For this purpose,a numerical study of the related flow field is performed using CFX.The shaft power and the head of the pump are taken as the evaluation indicators.Accordingly,the examined variables are the thickness(S),the blade cascade degree(t),the blade rim angle(β1),the blade hub angle(β2)and the hub length(L).The impact of each structural parameter on each evaluation index is examined and special attention is paid to the following combinations:S2 mm,t 2,β1235°,β2360°and L 140 mm(corresponding to a maximum head of 98.15 m);S 5 mm,t 1.6,β1252°,β2350°and L 140 mm(corresponding to a minimum shaft power of 63.06 KW).Moreover,using least squares and fish swarm algorithms,the pump shaft power and head are further optimized,yielding the following optimal combination:S 5 mm,t 1.9,β1252°,β2360°and L 145 mm(corresponding to the maximum head of 91.90 m,and a minimum shaft power of 64.83 KW).展开更多
基金Projects(2016YFC0600706,2016YFC0600802) supported by the National Key Research and Development Program of ChinaProject(2017zzts186) supported by Cultivating Excellent Doctors of Central South University,China
文摘The outcome of the cutting blasting in a one-step shaft excavation is heavily related to the cutting parameters used for parallel cutting method. In this study, the relationships between the cutting parameters（such as the hole spacing L and the empty hole diameter D） and damage zones were investigated by numerical simulation. A damage state index γ was introduced and used to characterize the crushing and crack damage zones through a user-defined subroutine. Two indices, i.e., η1 and η2 that can reflect the cutting performance, were also introduced. The simulation results indicate that an optimal value of L can be obtained so that the η1 and η2 can reach their optimal states for the best cutting performance. A larger D results in better cutting performance when the L value maintains its best. In addition, the influences of the loading rate and the in-situ stress on the cutting performance were investigated. It is found that an explosive with a high loading rate is suit for cutting blasting. The propagation direction and the length of the tensile cracks are affected by the direction and the magnitude of the maximum principal stress.
基金This project was supported by the National Natural Science Foundation of China （Grant Nos. 51405248 and 51475247）, the Key Research and Development Program of Shandong Province （Grant No. 2016ZDJQ0604）, the Natural Science Foundation of Zhejiang Province （Grant No. LY18E050006）, Natural Science Foundation of Ningbo City （Grant No. 2017A610088） and the K.C. Wong Magna Fund in Ningbo University.
文摘Through rolling experiments and interfacial tensile strength tests of cross-wedge rolled laminated shafts of 42CrMo/Q235 composites, the influence of process parameters, including forming angle, spreading angle, area reduction, rolling temperature and core material diameter on the interfacial shear strength was analyzed. The results show that the sequence of process parameters in order of greatest influence on interfacial tensile strength was rolling temperature, area reduction, core material diameter, forming angle and spreading angle. At the interface of the combined materials, tensile strength decreased as forming angle and spreading angle increased, whereas the tensile strength first increased and then decreased as area reduction, rolling temperature and core material diameter increased.
基金project of the“The University Synergy Innovation Program of Anhui Province(GXXT-2019-004)”,“Natural Science Research Project of Anhui Universities(KJ2021ZD0144)”,“Wuhu Key R&D Project:Research and Industrialization of Intelligent Control Method of Engine Energy-Feeding Hydraulic Semi-Active Mount”.
文摘The aim of the study is to determine the optimal structural parameters for a plastic centrifugal pump inducer within the framework of an orthogonal experimental method.For this purpose,a numerical study of the related flow field is performed using CFX.The shaft power and the head of the pump are taken as the evaluation indicators.Accordingly,the examined variables are the thickness(S),the blade cascade degree(t),the blade rim angle(β1),the blade hub angle(β2)and the hub length(L).The impact of each structural parameter on each evaluation index is examined and special attention is paid to the following combinations:S2 mm,t 2,β1235°,β2360°and L 140 mm(corresponding to a maximum head of 98.15 m);S 5 mm,t 1.6,β1252°,β2350°and L 140 mm(corresponding to a minimum shaft power of 63.06 KW).Moreover,using least squares and fish swarm algorithms,the pump shaft power and head are further optimized,yielding the following optimal combination:S 5 mm,t 1.9,β1252°,β2360°and L 145 mm(corresponding to the maximum head of 91.90 m,and a minimum shaft power of 64.83 KW).
