The free vibration of a functionally graded material hollow spheresubmerged in a compress- ible fluid medium is exactly analyzed. Thesphere is assumed to be spherically isotropic with material consta-nts being inhomog...The free vibration of a functionally graded material hollow spheresubmerged in a compress- ible fluid medium is exactly analyzed. Thesphere is assumed to be spherically isotropic with material consta-nts being inhomogeneous along the radial direction. By employing aseparation technique as well as the spherical harmonics expansionmethod, the governing equations are simplified to an uncoupledsecond-order ordinary differential equation, and a coupled system oftwo such equations. Solutions to these equations are given when theelastic constants and the mass density are power functions of theradial coordinate. Numerical examples are finally given to show theeffect of the material gradient on the natural frequencies.展开更多
A recursive formulation is proposed for the method of reverberation-ray matrix (MRRM) to exactly analyze the free vibration of a multi-span continuous rectangular Kirchhoff plate, which has two oppo- site simply-suppo...A recursive formulation is proposed for the method of reverberation-ray matrix (MRRM) to exactly analyze the free vibration of a multi-span continuous rectangular Kirchhoff plate, which has two oppo- site simply-supported edges. In contrast to the traditional MRRM, numerical stability is achieved by using the present new formulation for high-order frequencies or/and for plates with large span-to-width ratios. The heavy computational cost of storage and memory are also cut down. An improved recursive formulation is further proposed by modifying the iterative formula to reduce the matrix inversion op- erations. Numerical examples are finally given to demonstrate the effectiveness and efficiency of the proposed recursive formulae.展开更多
基金the National Natural Sciences Foundation of China(No.19872060)
文摘The free vibration of a functionally graded material hollow spheresubmerged in a compress- ible fluid medium is exactly analyzed. Thesphere is assumed to be spherically isotropic with material consta-nts being inhomogeneous along the radial direction. By employing aseparation technique as well as the spherical harmonics expansionmethod, the governing equations are simplified to an uncoupledsecond-order ordinary differential equation, and a coupled system oftwo such equations. Solutions to these equations are given when theelastic constants and the mass density are power functions of theradial coordinate. Numerical examples are finally given to show theeffect of the material gradient on the natural frequencies.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 10725210, 10832009, and 10432030)the National Basic Research Program of China (Grant No. 2009CB623204)+1 种基金 the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 20060335107)the Program for New Century Excellent Talents in University (Grant No. NCET-05-0510)
文摘A recursive formulation is proposed for the method of reverberation-ray matrix (MRRM) to exactly analyze the free vibration of a multi-span continuous rectangular Kirchhoff plate, which has two oppo- site simply-supported edges. In contrast to the traditional MRRM, numerical stability is achieved by using the present new formulation for high-order frequencies or/and for plates with large span-to-width ratios. The heavy computational cost of storage and memory are also cut down. An improved recursive formulation is further proposed by modifying the iterative formula to reduce the matrix inversion op- erations. Numerical examples are finally given to demonstrate the effectiveness and efficiency of the proposed recursive formulae.
