Explication of Noise Generation Mechanism of Rotating Automobile Tyre

首先，研究了具有强各向异性层合结构的旋转汽车轮胎的建模。在壳体一阶剪切变形理论的基础上，采用基于有限元方法的截锥壳单元对回转轮胎这一回转壳进行了有限元模拟。在此基础上，建立了回转壳体在内压、扭矩和面内压力等预紧力作用下的瞬态响应数值计算方法，并对旋转部分球壳和截锥壳的受迫瞬态响应进行了分析，验证了该方法的有效性；其次，在轮胎模型中考虑了阻尼效应，计算了受迫稳态振动响应。也就是说，根据模态阻尼比的实验数据构造不旋转的阻尼阵[C]，然后将陀螺项加到矩阵[C]上。然后，将基本方程重新排列到状态空间中，并利用左、右特征向量进行模态分析，截断高阶振动模式。在此基础上，建立了汽车轮胎受迫稳态响应的数值计算方法。为了验证该方法的有效性，对旋转各向异性层合圆柱壳的受迫稳态响应进行了分析，提出了振动位移形态的可视化方法。从现在起，将在实际旋转汽车轮胎与地面接触的振动分析基础上，进行基于边界元方法的声辐射分析。因此，将对汽车轮胎旋转时的噪声产生机理进行研究。

First, the modeling of rotating automobile tyre with strong anisotropic laminated structure was examined. And, the rotating tyre which is a kind of shell of revolution was modeled by the assembly of truncated conical shell element based on the Finite Element Method on the ground of first-order shear deformation theory of shells. Depending on the above-mentioned model, the numerical calculation method of transient response of shells of revolution subjected to such the preloads as internal pressure, torque and in-plane compression force was developed and the forced transient responses of rotating partial spherical shell and truncated conical shell were analyzed to ascertain the validity of the method.Next, the damping effect was included into the tyre model to calculate the forced steady-state vibration response. That is, the damping matrix [C] with no-rotation is constructed from the experimental data of modal damping ratio and then the gyro-terms are added to the matrix [C]. Then, the fundamental equations are rearranged to those in the state space, and by using right and left eigen vectors modal analysis is applied and higher-order vibrational modes are truncated. Depending on the above concept, the numerical calculation method of forced steady-state responses of automobile tyre was developed. And, in order to examine the validity of the method, the forced steady-state response of a rotating anisotropic laminated circular cylindrical shell was analyzed and the method of visualization of vibrational displacement configuration was developed.From now on, the acoustic radiation analysis based on the Boundary Element Method will be carried out after analyzing the vibration of the real rotating automobile tyre contacting the ground. Thus, the noise generation mechanism of the rotating automobile tyre will be examined.