To study the rock breaking method under the free surface induced by disc cutter,the rock breaking simulations were first conducted based on the discrete element method,and the dynamic process of rock breaking under th...To study the rock breaking method under the free surface induced by disc cutter,the rock breaking simulations were first conducted based on the discrete element method,and the dynamic process of rock breaking under the free surface was studied including stressed zone,crush zone,crack initiation and propagation.Then the crack propagation conditions,specific energy,etc.under different free surface distance(S)were also investigated combined with linear cutting experiments.The results show that the rock breaking process under the free surface induced by disc cutter is dominated by tension failure mode.There exists a critical S to promote crack propagation to free surface effectively.And this rock breaking method can improve the rock breaking force and breaking efficiency significantly when proper.展开更多
Rolling resistance of tires is one of the most important factors influencing energy consumption of road vehicles, especially on rural roads. For practical reasons, most of rolling resistance measurements are usually p...Rolling resistance of tires is one of the most important factors influencing energy consumption of road vehicles, especially on rural roads. For practical reasons, most of rolling resistance measurements are usually performed for dry road conditions. Based on the fact that roads are wet during a considerable time over the year and as part of the projects MIR/AM, ROLRES and ROSANNE, the TUG （Technical University of Gdafisk） in Poland and VTI （Swedish National Road and Transport Research Institute） in Sweden carried out trailer rolling resistance measurements on wet road surfaces to investigate water film influence on rolling resistance on different pavements. A specially-designed trailer to measure rolling resistance has been used. The test sections were both rural roads and an abandoned airfield equipped with water film sensors mounted in the pavement. Results indicate strong influence of test speed and water film depth, as well as influence of surface texture. The increase of rolling resistance on wet surfaces is caused by both hydrodynamic phenomena and cooling effect of water that decreases tire temperature thus increasing rolling resistance.展开更多
基金Project(2013CB035401)supported by the National Basic Research Program of ChinaProject(2012AA041803)supported by the National High-Technology Research and Development Program of China+2 种基金Project(51475478)supported by the National Natural Science Foundation of ChinaProject(2015GK1029)supported by the Science and Technology Project of Strategic Emerging Industry in Hunan Province,ChinaProject(CX2017B048)supported by the Hunan Provincial Innovation Foundation For Postgraduate,China
文摘To study the rock breaking method under the free surface induced by disc cutter,the rock breaking simulations were first conducted based on the discrete element method,and the dynamic process of rock breaking under the free surface was studied including stressed zone,crush zone,crack initiation and propagation.Then the crack propagation conditions,specific energy,etc.under different free surface distance(S)were also investigated combined with linear cutting experiments.The results show that the rock breaking process under the free surface induced by disc cutter is dominated by tension failure mode.There exists a critical S to promote crack propagation to free surface effectively.And this rock breaking method can improve the rock breaking force and breaking efficiency significantly when proper.
文摘Rolling resistance of tires is one of the most important factors influencing energy consumption of road vehicles, especially on rural roads. For practical reasons, most of rolling resistance measurements are usually performed for dry road conditions. Based on the fact that roads are wet during a considerable time over the year and as part of the projects MIR/AM, ROLRES and ROSANNE, the TUG （Technical University of Gdafisk） in Poland and VTI （Swedish National Road and Transport Research Institute） in Sweden carried out trailer rolling resistance measurements on wet road surfaces to investigate water film influence on rolling resistance on different pavements. A specially-designed trailer to measure rolling resistance has been used. The test sections were both rural roads and an abandoned airfield equipped with water film sensors mounted in the pavement. Results indicate strong influence of test speed and water film depth, as well as influence of surface texture. The increase of rolling resistance on wet surfaces is caused by both hydrodynamic phenomena and cooling effect of water that decreases tire temperature thus increasing rolling resistance.
