中性线修正型变截面梁类构件压电控制

传统绝对节点坐标法(absolute nodal coordinate formulation, ANCF)在变截面梁类构件建模过程中常以几何中位线等效构造单元中性线, 难以对变截面单元位移场状态进行精确描述. 为解决此类问题, 本文以中细型变截面梁类构件为研究对象, 深入考虑变截面结构几何因素及复合材料属性对变截面梁类构件中性线位置所产生的偏差影响, 建立修正型变截面梁单元位移场描述方法. 并进一步结合负应变率压电控制策略, 通过传感型及作动型压电片提出变截面梁类构件在空间热载荷作用下的ANCF主动抑振抑变控制方法. 同时, 以变截面太阳帆桅杆在轨实际运行状态为算例, 通过所述方法分析验证了模型在动力学参数预测过程中的准确性及精确性, 并深入探究变截面梁类构件在不同压电安装策略下的动态行为参数演化规律. 据其分析结果可知, ANCF主动抑振抑变控制方法随作动型压电片与传感型压电片之间安装距离的增加, 其控制同步性将会降低; 且在一定程度内提高增益调节系数可加强控制系统的稳定性及灵敏性, 但该参数一旦发生超调亦会激励变截面梁类构件产生非稳定性振动. 

PIEZOELECTRIC CONTROL INVESTIGATION ON BEAM WITH VARIABLE CROSSSECTION AND CORRECTIONAL NEUTRAL LINE

In traditional absolute nodal coordinate formulation(ANCF) modelling method, the neutral line of the beam with variable cross-section is assumed consistent with structural median line. It will reduce predicting accuracy in flexible deformation and dynamic behaviour for the beam with variable cross-section. For solving this kind of problems, a new dynamic predicting method for slender beam with variable section is presented in this paper. The neutral line position errors of beam with variable cross-section caused by variable section structure and composite material properties are considered to establish the displacement field in this method. Combining with the strain feedback control law and the proposed method, the active vibration control strategies for this beam under space thermal load are proposed by using the sensory and actional piezoelectric patches. Meanwhile, the correctness and accuracy of the proposed method has been verified by taking the variable section solar-sail masts into numerical analysis with the proposed method. According to the numerical results, the higher prediction accuracy can be provided by the proposed method, and the flexible deformations of solar-sail mast with variable section caused by thermal load have been effectively suppressed by the strain feedback control law. For obtaining the optimized control results in flexible deformation of the beam with variable cross-section, the dynamic behaviour of it with different piezoelectric ply control strategies has been further analysed.According to the numerical results, the active vibration control will be deteriorated with the assembling distance between sensing and actuating piezoelectric plates increasing. In addition, the stability and sensitivity of the control system can be improved by raising the controller gain. However, the unsteady vibration of the beam will also be excited with the overshoot controller gain. The theoretical value and practical significance in the compositive technical performance can be provided for the beam with variable cross-section during on-orbit working process.