G804.66 20004370肘关节角度与外负荷的关系=On the relationbetween elbow joint and external load[刊,中,A]/章旌红.严发本∥武汉体育学院学报.-2000.-34(2).-110-112表2(MYL)运动生物力学∥肘关节∥角度∥负荷∥肌肉力量肘关节在做...G804.66 20004370肘关节角度与外负荷的关系=On the relationbetween elbow joint and external load[刊,中,A]/章旌红.严发本∥武汉体育学院学报.-2000.-34(2).-110-112表2(MYL)运动生物力学∥肘关节∥角度∥负荷∥肌肉力量肘关节在做屈伸运动时,关节角度与肌力之间存在一个最佳的发力位置。当角度为90°-100°时,肌力的运动效果最佳,克服的阻力最大。这个最佳角度与阻力的方向无关。展开更多
Time-varying stiffness is one of the most important dynamic characteristics of rolling element bearings.The method of analyzing the elements in the bearing stiffness matrix is usually adopted to investigate the charac...Time-varying stiffness is one of the most important dynamic characteristics of rolling element bearings.The method of analyzing the elements in the bearing stiffness matrix is usually adopted to investigate the characteristics of bearing stiffness.Linear mapping structure of the bearing stiffness matrix is helpful to understand the varying compliance excitation and its influence on vibration transmission.In this study,a method to analyze the mapping structure of bearing stiffness matrix is proposed based on the singular value decomposition of block matrices in the stiffness matrix.Not only does this method have the advantages of coordinate transformation independence and unit independence,but also the analysis procedure involved is geometrically intuitive.The time-varying stiffness matrix of double-row tapered bearing is calculated and analyzed using the proposed method under two representative load cases.The principal stiffnesses and principal axes defined in the method together indicate the dominant and insignificant stiffness properties with the corresponding directions,and the vibration transmission properties are also revealed.Besides,the coupling behaviors between different shaft motions are found during the analysis of mapping structure.The mechanism of the generation of varying compliance excitation is also revealed.展开更多
文摘G804.66 20004370肘关节角度与外负荷的关系=On the relationbetween elbow joint and external load[刊,中,A]/章旌红.严发本∥武汉体育学院学报.-2000.-34(2).-110-112表2(MYL)运动生物力学∥肘关节∥角度∥负荷∥肌肉力量肘关节在做屈伸运动时,关节角度与肌力之间存在一个最佳的发力位置。当角度为90°-100°时,肌力的运动效果最佳,克服的阻力最大。这个最佳角度与阻力的方向无关。
基金the Joint Funds of the National Natural Science Foundation of China(Grant No.U1834202).
文摘Time-varying stiffness is one of the most important dynamic characteristics of rolling element bearings.The method of analyzing the elements in the bearing stiffness matrix is usually adopted to investigate the characteristics of bearing stiffness.Linear mapping structure of the bearing stiffness matrix is helpful to understand the varying compliance excitation and its influence on vibration transmission.In this study,a method to analyze the mapping structure of bearing stiffness matrix is proposed based on the singular value decomposition of block matrices in the stiffness matrix.Not only does this method have the advantages of coordinate transformation independence and unit independence,but also the analysis procedure involved is geometrically intuitive.The time-varying stiffness matrix of double-row tapered bearing is calculated and analyzed using the proposed method under two representative load cases.The principal stiffnesses and principal axes defined in the method together indicate the dominant and insignificant stiffness properties with the corresponding directions,and the vibration transmission properties are also revealed.Besides,the coupling behaviors between different shaft motions are found during the analysis of mapping structure.The mechanism of the generation of varying compliance excitation is also revealed.
