变截面交叉簧片柔性铰链的力学建模与变形特性分析

Static Modelling and Analysis of Cross-spring Flexure Pivots with Variable Cross-section

交叉簧片柔性铰链是一种应用广泛的柔性转动关节。依靠簧片的分布式柔度可以产生较大的转动角度,但是与此同时铰链转动过程中的中心漂移大、抗干扰能力较差,这些都影响了铰链的传动精度和稳定性。通过采用非等直簧片构造的变截面交叉簧片柔性铰链可以使弹性元件的变形主要集中于铰链的交叉点附近,从而改变铰链的转动性能。基于Euler-Bernoulli梁理论建立了考虑几何非线性的变截面交叉簧片柔性铰链的末端载荷与铰链变形之间的关系。通过与有限元仿真进行对比,验证了文中建立的变形模型的准确性。利用柔性铰链的静态变形模型,分析了铰链的转动范围、转动刚度、中心漂移和抗干扰性能与簧片截面系数之间的关系。分析结果表明,对比传统交叉簧片柔性铰链,变截面交叉簧片柔性铰链具有更高的转动精度。

The cross-spring flexure pivot is a type of flexure joint which has been widely used in long stroke compliant mechanisms. Due to the distributed compliance, the flexure pivot can generate a large rotation angle, however, this structure also has some disadvantages, i.e., large center shift and low support stiffness. The concept of variable cross-section flexure pivot is proposed. The performance of the flexure pivot can be changed by applying non-prismatic spring leaves since they will concentrate the deformation of the leaves near the ration center of the flexure pivot. A static deformation model of the variable cross-section flexure pivot which considered the geometric nonlinearity of the spring leaves is proposed based on the Euler-Bernoulli beam theory. The model is verified by finite element simulations, the results obtained from those two methods agree with each other very well. Moreover, the relationship between the section factor of the spring leaves and the static deformation performances of the proposed flexure pivot, i.e., rotation range, rotation stiffness, center shift and anti-interference ability are discussed by using the deformation model. The results show that the flexure pivot with variable cross-section has higher rotational accuracy compared with the conventional one.