主动桁架结构的有限元建模研究

将传感器、作动器和控制器等元件置于桁架结构中,构成主动桁架结构,并分别采用杆单元和梁单元方法,对主动桁架进行有限元建模,给出了两种建模条件下主动桁架的前八阶模态。比较两种建模方法得出的相应的模态,可以看出,如果采用梁单元建模,结果将出现局部模态,而不是桁架的真实模态。因此,主动桁架宜采用杆单元建模。

Study on Modeling of the Active Truss with the Finite Element Method

The active truss is constructed from the corresponding passive one and sensors,actuators and the controller.Two finite element models of the truss are presented by using a rod element model and a beam ele- ment model,respectively.The modal analysis is performed to obtain the frequencies and mode shapes of sys- tem.Comparing the first four modes of the beam element model with those of the rod element model,several observations can be made.The seventh and eighth modes of the beam element model do not appear in the rod element model.These modes involve some local bending of the truss members,which cannot be modeled by the rod element model.From this analysis one can conclude that the rod element model is suited for use in the modeling and control design of the miss structure.