The double degrees-of-freedom（DOFs）parallel model is adopted to analyze static vertical human-induced vibration with the finite element analysis（FEA）method.In the first-order symmetric vibration mode,the periods o...The double degrees-of-freedom（DOFs）parallel model is adopted to analyze static vertical human-induced vibration with the finite element analysis（FEA）method.In the first-order symmetric vibration mode,the periods of the spring-mass model gradually decrease with the increase in K1 and K2,but they are always greater than the period of the add-on mass model.Meanwhile,the periods of the spring-mass model decrease with the decrease in m1 and m2,but they are always greater than the period of the hollow bridge model.Since the human＇s two degrees-of-freedom vibrate in the same direction as that of the bridge mid-span,the existence of human＇s rigidity leads to the reduction in the rigidity of the spring-mass model.In the second-order symmetric vibration mode,the changes of rigidity K2 and mass m2 result in the disappearance or occurrence of some vibration modes.It can be concluded that compared with the spring-mass model,the results of the add-on mass model lean to lack of safety to the structure;besides,the DOF with a smaller ratio of mass to rigidity plays the chief role in the vibration of the structure.展开更多
A real-time animation technique for a kind of non-rigid objects, flexible and thin objects, is proposed, which can update with stability the state of n mass points of the mass-spring (MS) modei with time complexity of...A real-time animation technique for a kind of non-rigid objects, flexible and thin objects, is proposed, which can update with stability the state of n mass points of the mass-spring (MS) modei with time complexity of O (n ). The new implicit numerical integration technique of the authors, which is based on a simple approximation of the linear system, has great advantages over the existing implicit integration methods. Moreover, experiment shows that the new technique is highly efficient in animating a kind of non-rigid objects, and suitable for the draping module of the 3D garment CAD system.展开更多
The objective of model updating is to improve the accuracy of a dynamic model based on the correlation between the measured data and the analytical (finite element) model. In this paper, we intend to update the mass a...The objective of model updating is to improve the accuracy of a dynamic model based on the correlation between the measured data and the analytical (finite element) model. In this paper, we intend to update the mass and stiffness matrices of an analytical model when only modal frequencies or spatially incomplete modal data are available. While the proposed method is systematic in nature, it also preserves the initial configuration of the analytical model, and physical equality and/or inequality constraints can be easily incorporated into the solution procedure. Numerical examples associated with a simple 5-DoF (degree of freedom) mass-spring system are chosen to illustrate the detailed procedure and the effectiveness of the proposed method. Numerical scenarios ranging from the updating for stiffness terms only to that for all mass and stiffness terms based on various kinds of incomplete modal data are studied. The obtained model updating results are excellent when the measured modal data are noise-free. Uncertainty studies are also conducted based on simulations of corrupted modal data, but a thorough theoretical analysis of the noise effect on the proposed method is still needed.展开更多
文摘The double degrees-of-freedom（DOFs）parallel model is adopted to analyze static vertical human-induced vibration with the finite element analysis（FEA）method.In the first-order symmetric vibration mode,the periods of the spring-mass model gradually decrease with the increase in K1 and K2,but they are always greater than the period of the add-on mass model.Meanwhile,the periods of the spring-mass model decrease with the decrease in m1 and m2,but they are always greater than the period of the hollow bridge model.Since the human＇s two degrees-of-freedom vibrate in the same direction as that of the bridge mid-span,the existence of human＇s rigidity leads to the reduction in the rigidity of the spring-mass model.In the second-order symmetric vibration mode,the changes of rigidity K2 and mass m2 result in the disappearance or occurrence of some vibration modes.It can be concluded that compared with the spring-mass model,the results of the add-on mass model lean to lack of safety to the structure;besides,the DOF with a smaller ratio of mass to rigidity plays the chief role in the vibration of the structure.
文摘A real-time animation technique for a kind of non-rigid objects, flexible and thin objects, is proposed, which can update with stability the state of n mass points of the mass-spring (MS) modei with time complexity of O (n ). The new implicit numerical integration technique of the authors, which is based on a simple approximation of the linear system, has great advantages over the existing implicit integration methods. Moreover, experiment shows that the new technique is highly efficient in animating a kind of non-rigid objects, and suitable for the draping module of the 3D garment CAD system.
基金supported by the National Natural Science Foundation of China (Grant No. 51079134)the NSFC Major International Joint Research Project (Grant No. 51010009)
文摘The objective of model updating is to improve the accuracy of a dynamic model based on the correlation between the measured data and the analytical (finite element) model. In this paper, we intend to update the mass and stiffness matrices of an analytical model when only modal frequencies or spatially incomplete modal data are available. While the proposed method is systematic in nature, it also preserves the initial configuration of the analytical model, and physical equality and/or inequality constraints can be easily incorporated into the solution procedure. Numerical examples associated with a simple 5-DoF (degree of freedom) mass-spring system are chosen to illustrate the detailed procedure and the effectiveness of the proposed method. Numerical scenarios ranging from the updating for stiffness terms only to that for all mass and stiffness terms based on various kinds of incomplete modal data are studied. The obtained model updating results are excellent when the measured modal data are noise-free. Uncertainty studies are also conducted based on simulations of corrupted modal data, but a thorough theoretical analysis of the noise effect on the proposed method is still needed.
