Alshabatat Nabeel Taiseer
Mechanical Engineering Department, Tafila Technical University, Tafila 66110, Jordan.
Materials (Basel). 2022 Jan 18;15(3):698. doi: 10.3390/ma15030698.
One method to avoid vibration resonance is shifting natural frequencies far away from excitation frequencies. This study investigates optimizing the natural frequencies of circular cylindrical shells using axially functionally graded materials. The constituents of functionally graded materials (FGMs) vary continuously in the longitudinal direction based on a trigonometric law or using interpolation of volume fractions at control points. The spatial change of material properties alters structural stiffness and mass, which then affects the structure's natural frequencies. The local material properties at any place in the structure are obtained using Voigt model. First-order shear deformation theory and finite element method are used for estimating natural frequencies, and a genetic algorithm is used for optimizing material volume fractions. To demonstrate the proposed method, two optimization problems are presented. The goal of the first one is to maximize the fundamental frequency of an FGM cylindrical shell by optimizing the material volume fractions. In the second problem, we attempt to find the optimal material distribution that maximizes the distance between two adjoining natural frequencies. The optimization examples show that building cylindrical shells using axially FGM is a useful technique for optimizing their natural frequencies.
避免振动共振的一种方法是将固有频率移至远离激励频率的位置。本研究探讨使用轴向功能梯度材料优化圆柱壳的固有频率。功能梯度材料（FGM）的成分基于三角定律或通过控制点处体积分数的插值在纵向方向上连续变化。材料特性的空间变化会改变结构刚度和质量，进而影响结构的固有频率。使用Voigt模型获得结构中任意位置的局部材料特性。采用一阶剪切变形理论和有限元方法估计固有频率，并使用遗传算法优化材料体积分数。为了验证所提出的方法，给出了两个优化问题。第一个问题的目标是通过优化材料体积分数来最大化FGM圆柱壳的基频。在第二个问题中，我们试图找到使两个相邻固有频率之间的距离最大化的最佳材料分布。优化实例表明，使用轴向FGM构建圆柱壳是优化其固有频率的一种有用技术。
