Effect of slope inclination on step friction coefficient of human being was studied by gait friction tester developed by Henan University of Science and Technology.It is beneficial to improving the safety of human bei...Effect of slope inclination on step friction coefficient of human being was studied by gait friction tester developed by Henan University of Science and Technology.It is beneficial to improving the safety of human beings while walking on a ramp.Based on the trajectory of mass center of body(MCOB)and the mechanical analysis of human body while walking,conclusion could be drawn that the required step frictional coefficient(RSFC)exhibited an"M"shaped curve during the foot contacting with the ground and got its maximum and minimum values when MCOB of the subject was at the highest and lowest position respectively.Moreover,the first peak of RSFC decreases firstly and then increases,while the second peak of RSFC increases with the increase of slope inclination at the experimental condition.The position of pivotal point is decided by the relative size of slope inclination and the angle between the plumb line through MCOB and the line from foot to MCOB.展开更多
Impact dynamics of multi-rigid-body systems with joint friction is considered. Based on the traditional approximate assumption dealing with impact problem, a general numerical method called the sliding state stepping ...Impact dynamics of multi-rigid-body systems with joint friction is considered. Based on the traditional approximate assumption dealing with impact problem, a general numerical method called the sliding state stepping algorithm is introduced. This method can avoid difficulties in solving differential equations with variable scale and its result can avoid energy inconsistency before and after impact from considering complexily of tangential sliding mode. An example is given to describe details using this algorithm.展开更多
倾斜的海浪由放在多步底部地形学上的垂直多孔的结构抑制在线性水波浪理论的帮助下被学习。倾斜的波浪的某部分，多孔的结构上的事件，变得被多步底部反映了，多孔的结构，和剩余的宣传进跟随多孔的结构的水媒介。二个盒子被考虑：在跟...倾斜的海浪由放在多步底部地形学上的垂直多孔的结构抑制在线性水波浪理论的帮助下被学习。倾斜的波浪的某部分，多孔的结构上的事件，变得被多步底部反映了，多孔的结构，和剩余的宣传进跟随多孔的结构的水媒介。二个盒子被考虑：在跟随多孔的结构然后跟随多孔的结构的无界的水媒介的一种特殊情况的水媒介从多孔的结构在有限距离放的第一面一稳固的垂直的墙。在两个盒子中，边界价值问题在三不同媒介被建立，是的第一媒介水，是的第二媒介由 p 组成的多孔的结构在每个步骤上面的垂直区域一个和是的第三媒介水再。由沿着 virtualvertical 边界使用匹配的条件，线性方程的一个系统被推出。思考系数和播送进步波浪的无尺寸的振幅的行为由于不同相关参数被学习。由于倾斜的水的繁殖，通过多孔的结构的波浪也是的精力损失执行了。各种各样的参数的效果例如迅速凋落的模式的数字，孔，磨擦因素，结构宽度，步骤和入射角的数字，在思考以后，系数和播送波浪的无尺寸的振幅为两个盒子图形地被学习。迅速凋落的模式的数字仅仅影响散布现象。但是孔表演的更高的价值相对为更低的孔比那降低思考。在思考系数的摆动为磨擦因素的更低的价值被观察，但是它随磨擦因素的价值的增加消失。播送进步波浪的振幅独立于结构的孔。但是磨擦因素的更低的价值引起更高的传动。调查然后为第二个盒子被执行，即，当墙是不在的时。这里考虑的二个盒子之间的重要差别是思考由于薄多孔的结构很高稳固的墙什么时候作为与盒子相比存在没有墙什么时候是在场的。精力损失也由于不同的孔，磨擦因素，结构宽度和入射角被检验。我们的模型的有效性被与可得到的匹配它查明。展开更多
The aim of present study is introducing a method by subdividing friction welding phases into three steps according to the temperature change during continuous drive friction welding operation. Thermal curve allowable ...The aim of present study is introducing a method by subdividing friction welding phases into three steps according to the temperature change during continuous drive friction welding operation. Thermal curve allowable subdividing of the friction welding phase's time into three distinct periods, while the microstructure evolution during friction welding goes through three different situations. The effects of three distinct periods were achieved by macro-microscopy, microhardness HV_(0.1), tensile tests and scanning electronic microscopy(SEM).The results clearly show that the microstructure during the friction phase goes through three completely different situations which mechanically influenced on microstructure, tensile strength and ductility of the welded joint.展开更多
The effects on the local skin friction of smooth flat plate by formation of air cavity are investigated experimentally,under the conditions of several variations of air injection angle,pore size,porous surface area an...The effects on the local skin friction of smooth flat plate by formation of air cavity are investigated experimentally,under the conditions of several variations of air injection angle,pore size,porous surface area and transverse step.The experimental results show that local skin friction of downstream of the porous section could be reduced at extent ranging from 50% to 90%,by injection air through pore or slot,with free stream velocities from 2 to 6 m/s.The pore size and area of air injection surface have small effect on skin friction reduction,step has significant effect on skin friction reduction.The mechanism of the skin friction reduction is due to the formation of air cavity,mixed with air and water,between the flat plate and its water boundary layer.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.U1034002 and 51175149)
文摘Effect of slope inclination on step friction coefficient of human being was studied by gait friction tester developed by Henan University of Science and Technology.It is beneficial to improving the safety of human beings while walking on a ramp.Based on the trajectory of mass center of body(MCOB)and the mechanical analysis of human body while walking,conclusion could be drawn that the required step frictional coefficient(RSFC)exhibited an"M"shaped curve during the foot contacting with the ground and got its maximum and minimum values when MCOB of the subject was at the highest and lowest position respectively.Moreover,the first peak of RSFC decreases firstly and then increases,while the second peak of RSFC increases with the increase of slope inclination at the experimental condition.The position of pivotal point is decided by the relative size of slope inclination and the angle between the plumb line through MCOB and the line from foot to MCOB.
基金the National Natural Science Foundation of China(No.10532050)the Na-tional Science Fund for Distinguished Young Scholars(No.10625211)the Science Development Foundation of Shandong University of Science and Techonogy(No.05g017)
文摘Impact dynamics of multi-rigid-body systems with joint friction is considered. Based on the traditional approximate assumption dealing with impact problem, a general numerical method called the sliding state stepping algorithm is introduced. This method can avoid difficulties in solving differential equations with variable scale and its result can avoid energy inconsistency before and after impact from considering complexily of tangential sliding mode. An example is given to describe details using this algorithm.
文摘倾斜的海浪由放在多步底部地形学上的垂直多孔的结构抑制在线性水波浪理论的帮助下被学习。倾斜的波浪的某部分，多孔的结构上的事件，变得被多步底部反映了，多孔的结构，和剩余的宣传进跟随多孔的结构的水媒介。二个盒子被考虑：在跟随多孔的结构然后跟随多孔的结构的无界的水媒介的一种特殊情况的水媒介从多孔的结构在有限距离放的第一面一稳固的垂直的墙。在两个盒子中，边界价值问题在三不同媒介被建立，是的第一媒介水，是的第二媒介由 p 组成的多孔的结构在每个步骤上面的垂直区域一个和是的第三媒介水再。由沿着 virtualvertical 边界使用匹配的条件，线性方程的一个系统被推出。思考系数和播送进步波浪的无尺寸的振幅的行为由于不同相关参数被学习。由于倾斜的水的繁殖，通过多孔的结构的波浪也是的精力损失执行了。各种各样的参数的效果例如迅速凋落的模式的数字，孔，磨擦因素，结构宽度，步骤和入射角的数字，在思考以后，系数和播送波浪的无尺寸的振幅为两个盒子图形地被学习。迅速凋落的模式的数字仅仅影响散布现象。但是孔表演的更高的价值相对为更低的孔比那降低思考。在思考系数的摆动为磨擦因素的更低的价值被观察，但是它随磨擦因素的价值的增加消失。播送进步波浪的振幅独立于结构的孔。但是磨擦因素的更低的价值引起更高的传动。调查然后为第二个盒子被执行，即，当墙是不在的时。这里考虑的二个盒子之间的重要差别是思考由于薄多孔的结构很高稳固的墙什么时候作为与盒子相比存在没有墙什么时候是在场的。精力损失也由于不同的孔，磨擦因素，结构宽度和入射角被检验。我们的模型的有效性被与可得到的匹配它查明。
文摘The aim of present study is introducing a method by subdividing friction welding phases into three steps according to the temperature change during continuous drive friction welding operation. Thermal curve allowable subdividing of the friction welding phase's time into three distinct periods, while the microstructure evolution during friction welding goes through three different situations. The effects of three distinct periods were achieved by macro-microscopy, microhardness HV_(0.1), tensile tests and scanning electronic microscopy(SEM).The results clearly show that the microstructure during the friction phase goes through three completely different situations which mechanically influenced on microstructure, tensile strength and ductility of the welded joint.
文摘The effects on the local skin friction of smooth flat plate by formation of air cavity are investigated experimentally,under the conditions of several variations of air injection angle,pore size,porous surface area and transverse step.The experimental results show that local skin friction of downstream of the porous section could be reduced at extent ranging from 50% to 90%,by injection air through pore or slot,with free stream velocities from 2 to 6 m/s.The pore size and area of air injection surface have small effect on skin friction reduction,step has significant effect on skin friction reduction.The mechanism of the skin friction reduction is due to the formation of air cavity,mixed with air and water,between the flat plate and its water boundary layer.
