By measuring the pressure and piston stroke of hydraulic servo cylinders in the oscillation system of a caster mould,friction between mould and shell can be determined.The condition of solidified shell can be monitore...By measuring the pressure and piston stroke of hydraulic servo cylinders in the oscillation system of a caster mould,friction between mould and shell can be determined.The condition of solidified shell can be monitored by thermocouples fixed to the mould.Breakouts,whether caused by shell cracking,shell sticking or entrained impurities,can therefore be predicted and effectively avoided through monitoring the change characteristics of friction and thermocouples temperature during the process.展开更多
The friction sensitivity(FS) of five linear and eight cyclic nitramines has been determined.Arrhenius parameters of non-autocatalyzed thermal decomposition of these nitramines were used for comparison of the FS values...The friction sensitivity(FS) of five linear and eight cyclic nitramines has been determined.Arrhenius parameters of non-autocatalyzed thermal decomposition of these nitramines were used for comparison of the FS values with thermal reactivity.Generally,increasing values of activation energies of non-autocatalyzed decomposition of the studied nitramines are connected with decreasing FS values.A similar trend was found in the relation between FS and hypothetical initiation temperature for 5% conversion of the nitramines after 50 μs of their thermolysis,however,if in the given series of nitramines their initiation reactivity is predominantly determined by the energy content of their molecules and closer similarity of their molecular structures,then the above-mentioned trend may be opposite.The found relationships were used for prediction and verification of the activation energy of non-autocatalyzed thermal decomposition of 2,5-dinitro-2,5-diazahexane.展开更多
Some of the remarkable characteristics of natural landslides, such as surprisingly long travel distances and high velocities, have been attributed to the mechanisms of frictional heating and thermal pressurization. In...Some of the remarkable characteristics of natural landslides, such as surprisingly long travel distances and high velocities, have been attributed to the mechanisms of frictional heating and thermal pressurization. In this work, this mechanism is combined with a depth-averaged model to simulate the long runout of landslides in the condition of deformation. Some important factors that influence frictional heating and thermal pressurization within the shear zone are further considered, including velocity profile and pressurization coefficient. In order to solve the coupled equations, a combined computational method based on the finite volume method and quadratic upwind interpolation for convective kinematics scheme is proposed. Several numerical tests are performed to demonstrate the feasibility of the computational scheme, the influence of thermal pressurization on landslide run-out, and the potential of the model to simulate an actual landslide.展开更多
According to the thermodynamic characteristics in the work interface of the plastic forming of metals, a set of TCR (thermal contact resistance) experimental system under the conditions of high temperature and high pr...According to the thermodynamic characteristics in the work interface of the plastic forming of metals, a set of TCR (thermal contact resistance) experimental system under the conditions of high temperature and high pressure has been designed. The interrelations between the thermal contact resistance (TCR) and its influence factors such as contact pressure etc, are obtained. A modified coefficient E is introduced to consider the relative slide in the contact interface. Then the interfacial TCR calculating model, which suits to the special conditions of `high temperature+plastic rheology’ and frictional contact such as continuous roll casting process, is established.展开更多
A heat source model for radial friction welding was proposed, which was determined by friction pressure, friction coefficient, material properties and extrusion speed of material. A 3D model was established to analyze...A heat source model for radial friction welding was proposed, which was determined by friction pressure, friction coefficient, material properties and extrusion speed of material. A 3D model was established to analyze the continuous drive radial friction welding temperature field of 45 steel pipe. The influences of friction pressure, friction time and rotation speed on the temperature of the friction interface were analyzed. The results showed that the temperature on the friction interface rapidly rose to a peak temperature in initial friction stage and kept constant in the stable friction stage. Welding parameters of friction pressure, friction time and rotation speed had few influences on the peak temperature, while the increase of frlctlon pressure and rotation speed could shorten the time to reach the peak temperature.展开更多
文摘By measuring the pressure and piston stroke of hydraulic servo cylinders in the oscillation system of a caster mould,friction between mould and shell can be determined.The condition of solidified shell can be monitored by thermocouples fixed to the mould.Breakouts,whether caused by shell cracking,shell sticking or entrained impurities,can therefore be predicted and effectively avoided through monitoring the change characteristics of friction and thermocouples temperature during the process.
基金the project of the Ministry of Education,Youth and Sports of the Czech Republic No.MSM 0021627501
文摘The friction sensitivity(FS) of five linear and eight cyclic nitramines has been determined.Arrhenius parameters of non-autocatalyzed thermal decomposition of these nitramines were used for comparison of the FS values with thermal reactivity.Generally,increasing values of activation energies of non-autocatalyzed decomposition of the studied nitramines are connected with decreasing FS values.A similar trend was found in the relation between FS and hypothetical initiation temperature for 5% conversion of the nitramines after 50 μs of their thermolysis,however,if in the given series of nitramines their initiation reactivity is predominantly determined by the energy content of their molecules and closer similarity of their molecular structures,then the above-mentioned trend may be opposite.The found relationships were used for prediction and verification of the activation energy of non-autocatalyzed thermal decomposition of 2,5-dinitro-2,5-diazahexane.
基金supported by the National Natural Science Foundation of China (Grant No. 41790433)NSFC-ICIMOD (Grant No. 41661144041)+1 种基金Key Research and Development Projects of Sichuan Province (2017SZ0041)CAS "Light of West China" Program
文摘Some of the remarkable characteristics of natural landslides, such as surprisingly long travel distances and high velocities, have been attributed to the mechanisms of frictional heating and thermal pressurization. In this work, this mechanism is combined with a depth-averaged model to simulate the long runout of landslides in the condition of deformation. Some important factors that influence frictional heating and thermal pressurization within the shear zone are further considered, including velocity profile and pressurization coefficient. In order to solve the coupled equations, a combined computational method based on the finite volume method and quadratic upwind interpolation for convective kinematics scheme is proposed. Several numerical tests are performed to demonstrate the feasibility of the computational scheme, the influence of thermal pressurization on landslide run-out, and the potential of the model to simulate an actual landslide.
文摘According to the thermodynamic characteristics in the work interface of the plastic forming of metals, a set of TCR (thermal contact resistance) experimental system under the conditions of high temperature and high pressure has been designed. The interrelations between the thermal contact resistance (TCR) and its influence factors such as contact pressure etc, are obtained. A modified coefficient E is introduced to consider the relative slide in the contact interface. Then the interfacial TCR calculating model, which suits to the special conditions of `high temperature+plastic rheology’ and frictional contact such as continuous roll casting process, is established.
基金This work was suooorted by National Natural Science Foundation of China （Grant No. 51075174/E050803 ）.
文摘A heat source model for radial friction welding was proposed, which was determined by friction pressure, friction coefficient, material properties and extrusion speed of material. A 3D model was established to analyze the continuous drive radial friction welding temperature field of 45 steel pipe. The influences of friction pressure, friction time and rotation speed on the temperature of the friction interface were analyzed. The results showed that the temperature on the friction interface rapidly rose to a peak temperature in initial friction stage and kept constant in the stable friction stage. Welding parameters of friction pressure, friction time and rotation speed had few influences on the peak temperature, while the increase of frlctlon pressure and rotation speed could shorten the time to reach the peak temperature.
