基于绝对节点坐标法,考虑变截面梁单元的几何边界特征,利用非线性介质力学方法推导其刚度矩阵,进而建立柔性梁结构动力学方程.基于梁结构运动过程中状态空间方程和Lyapunov理论,提出变截面柔性梁结构运动及稳定性判定方法,研究了材料属性与变截面对梁结构空间运动过程中稳定性的影响.结果表明:当材料弹性模量较小时,变截面梁的稳定性略优于等截面梁;当材料的弹性模量增大,等截面梁单元稳定性大大增加,而变截面梁单元所受影响甚微;当弹性模量的增加达到一定值后,等截面梁的运动也趋于稳定.
The boundary features of the variable crosssection beams are taken into consideration and the stiffness matrix is derived based on the nonlinear continuum mechanics. A dynamic model of the beam is established by using the absolute nodal coordinate formulation. The statespace equation of the beam during motion is developed. Based on the Lyapunov theory a criterion of the motion stability of the flexible beams is proposed, and the effects of material properties and variable crosssections are investigated. The results indicate that with a small elastic modulus, the variable crosssection beam shows a better stability than the constant crosssection beam. As the elastic modulus increases, the stability of the constant crosssection becomes better than that of the variable crosssection beam. When the elastic modulus reaches a certain value, the motion of constant crosssection beam becomes stable.
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