波箔过渡圆角对箔片气体轴承结构刚度的影响

Effects of rounding radius in bump foil on the structure stiffness of gas foil bearing

为研究波箔过渡圆角这一结构特征对箔片气体轴承性能的影响,基于弹性变形理论,考虑摩擦力以及各波拱之间的相互作用,构建了考虑过渡圆角的波拱的弯矩方程组,推导出箔片的变形方程,得到单个波拱的变形与刚度计算公式.与既有的无过渡圆角的箔片模型进行比较,验证了模型的有效性,并研究了过渡圆角和摩擦因数对箔片气体轴承结构刚度的影响;利用三角形载荷分布形式模拟气膜力分布,研究过渡圆角和摩擦因数对气体轴承结构刚度各向异性的影响.结果表明:在固定区,随着过渡圆角半径的增大,波拱数量呈阶梯状减少,波拱刚度先增大后减小;在滑移区,波拱的刚度随过渡圆角半径的增大而降低,存在使波箔平均刚度达到最大的过渡圆角半径;随着摩擦因数增大,波拱刚度呈非线性上升趋势,有效降低了结构刚度的各向异性;随过渡圆角半径增大,结构刚度各向异性有所增强,但影响程度不如摩擦因数剧烈.研究结果可为波箔气体轴承的结构设计提供理论参考.

Considering the friction between bump foil and surrounding structure and the interaction between bumps in bump foil, the bending moment of the bump foil including a rounding between bump and bridge was established based on the elastic deformation energy theory. The foil deformation and stiffness of single bump was obtained and the validity of the proposed model was verified by comparing with previous foil models. The effects of the rounding radius on the structural stiffness of gas bearing and the anisotropy performance are studied by simulating gas film force distribution with triangular load distribution. The simulation results show that with the increase of the rounding radius the number of pinned-down bumps decreases in a step-like manner, and the stiffness of pinned-down bumps first increases and then decreases whereas the stiffness of the sliding bumps decreases. There is an optimal rounding radius at which the mean stiffness of the bump foil has a maximum value. With the increase of friction coefficient, the stiffness of foil arch presents a non-linear upward trend, which effectively reduces the anisotropy of structural stiffness. With the increase of rounding radius, the anisotropy of the stiffness of the structure increases, but the influence degree is not as severe as the friction coefficient. The results above can provide theoretical reference for structural design of gas foil bearing.