ANCF索梁单元应变耦合问题与模型解耦

发布时间：2018-03-06 04:12

  本文选题：绝对节点坐标　切入点：索　出处：《力学学报》2016年06期 　论文类型：期刊论文

【摘要】：索粱结构在土木工程、航空航天等领域有着广泛的应用.在各类索梁动力学建模方法中,由于绝对节点坐标方法(absolute nodal coordinate formulation,ANCF)能够描述柔性体的大变形和大转动问题,因此非常适合大变形索梁结构的动力学建模.对绝对节点坐标索梁单元的应变进行分析可知,弯曲变形会引起单元内部轴向应变的不均匀分布,即单元轴向应变与弯曲应变相互耦合.这种应变耦合效应使单元产生伪应变能,导致单元刚度增大,造成单元失真.分析不同弯曲角下的单元应变及应变能可知,弯曲变形越大,单元失真越严重.通过构造等效一维杆单元重新描述轴向应变,实现了轴向应变与弯曲应变解耦.在此基础上推导广义弹性力,得到了绝对节点坐标索梁单元的应变解耦模型.对解耦前后的两种梁模型进行静力学和动力学仿真,结果表明;解耦模型消除了单元伪应变,相比原模型表现出更好的收敛性和曲率连续性,在相同单元数目下具有更高的精度.同时由于解耦模型降低了单元刚度,因此相比原模型,速度曲线中不再有高频振动.
[Abstract]:The cable beam structure has been widely used in civil engineering, aerospace and other fields. In all kinds of cable beam dynamic modeling methods, absolute nodal coordinate formation ANCFs can describe the large deformation and rotation problem of flexible body. Therefore, it is very suitable for dynamic modeling of cable beam structure with large deformation. By analyzing the strain of cable beam element with absolute node coordinate, it can be concluded that bending deformation will cause uneven distribution of axial strain in element. That is, the element axial strain is coupled with the bending strain. This strain-coupling effect causes the element to produce pseudo-strain energy, which results in the increase of the element stiffness and the distortion of the element. The analysis of the element strain and strain energy at different bending angles shows that the element strain and strain energy can be obtained. The greater the bending deformation, the more serious the distortion of the element. By constructing an equivalent one-dimensional bar element to redescribe the axial strain, the decoupling of the axial strain and the bending strain is realized. On this basis, the generalized elastic force is derived. The strain decoupling model of cable beam element with absolute node coordinates is obtained. The static and dynamic simulations of two beam models before and after decoupling are carried out. The results show that the decoupling model eliminates the pseudo-strain of the element. Compared with the original model, the model shows better convergence and curvature continuity, and has higher accuracy under the same number of elements. At the same time, because the decoupling model reduces the stiffness of the element, there is no high frequency vibration in the velocity curve compared with the original model.
【作者单位】： 哈尔滨工业大学;中国空间技术研究院;
【基金】：国家重点基础研究发展计划(973计划)(2013CB733004) 微小型航天器技术国防重点学科实验室开放基金(HIT.KLOF.MST.201508)资助项目
【分类号】：O342
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本文编号：1573267