Continuous Control of Modes of Vibration

设计了一种通过施加受控多个激振力来沿结构上的指定路径移动结构振动节点位置的方法。假定在结构上取三个点1、2和3，在点1和点2施加两个激振力，观察点3的振动，如果点1的力引起的点3的振动与点2的力引起的点3的振动幅度相同、相位相反，则点3的振动将因叠加而停止。然后，如果我们可以通过控制激振力来连续移动点3的位置，那么节点将沿着结构上的路径移动。如果我们需要阻止结构上某一点的振动，我们只需在那里设置点3。首先，推导出了一种阻止结构上某一点振动的理论。用两端由两个激振器简单支承的梁进行了实验，以验证该理论。在此基础上，提出了通过控制激振力的幅值比、频率和相位来实现节点位置移动的理论。在两种控制条件下对该理论进行了实验验证。

A method was devised to shift the position of a node of the structural vibration along a designated path on the structure by applying controlled multiple exciting forces.This method is based on the following idea. Assume that we take three points 1, 2 and 3 on the structure, apply two exciting forces at point 1 and 2 and observe the vibration at point 3. If the vibration of point 3 caused by the force applied at point 1 and the vibration of the point 3 caused by forceapplied at point 2 are the same in amplitude and opposite in phase, the vibration at point 3 will be stopped as a result of superposition. Then, if we can shift the position of point 3 continually by controlling exciting forces, a node will move along a path on the structure. If we need to stop the vibration of a particular point on the structure, we can simply allocate point 3 there.First, a theory was derived to stop the vibration of a designated point on the structure. Experiments were made to test the theory using a beam simply supported at both ends by two exciters. Then, a theory was derived to shift the position of a node by controlling amplitude ratio, frequency and phase of exciting forces. Experiments were made to test the theory under two control conditions.