Vibration Analysis Characteristics of Coupling System Composed of Steel Strip and Air Cushion in Continuous Hot-dip Galvanizing Processes
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摘要: 为获得平衡状态下带钢变形、气垫区压力以及带钢-气垫耦合系统的动特性,将带钢近似为恒张力作用下的轴向运动Euler-Bernoulli梁,根据描述气垫区气体动力学特性的经典附壁边界理论,建立带钢和气垫区气体压力的控制方程及耦合条件。引入轴向运动带钢变形的格林函数,以压力卷积的形式显式表达带钢位移,采用Newton-Raphson法对气垫区的平衡压力和带钢平衡变形进行数值求解。将带钢和气垫区气体压力控制方程分别在其平衡位置处线性化,得到描述系统线性响应的变系数偏微分方程组。通过Galerkin法对模型进行全局离散,用广义矩阵特征值问题的数值解法得到带钢的固有频率。研究结果表明:适当减小带钢运行速度并增大带钢张力有利于带钢的稳定运行,而气垫箱供应压力对带钢动特性的影响极为有限。Abstract: In order to obtain the equilibrium state and dynamic characteristics of the steel strip, it is necessary to regard the steel strip and air cushions as a coupling system. Taking the steel strip as an axially moving Euler-Bernoulli beam under tension and using the Ground-Effect theory to describe the gas dynamics characteristics in air cushion area, the governing equations and coupling condition of the system are established. By introducing the Green's function for static deflection of the strip, the transverse deformation of the strip is represented explicitly in terms of the pressure by convolution. The equilibrium pressure in air cushion area and the strip deformation are determined by Newton-Raphson method. Then the governing equations of the system are linearized at the equilibrium state, and a set of differential equations with non-constant coefficients is obtained. Global discretization is conducted with Galerkin's method. The natural frequencies of the steel strip are determined by numerical method of generalized matrix eigenvalue problem. The results show that reducing speed and raising tension appropriately have favorable impact on the stability of steel strip; however, supply pressure impact on dynamic characteristics of steel strip is extremely limited.
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Key words:
- Green's function /
- air cushion /
- convolution /
- coupling system /
- deformation
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