This paper is concerned with the finite element technique for predicting the dynamic properties of anisotropic fiber-reinforced composite laminated plates. Considering the effect of transverse shear deformation, a higher order shear deformation theory which satisifes the zero shear stress conditions at the upper and bottom surfaces is assumed. The natural frequencies and mode shapes of a rectangular plate with all free edges are obtained by finite element method and the modal damping values by finite damped element technique. An equivalent stiffness method is introduced to reduce computation time. Four different theoretical predictions of natural frequencies and damped values of a laminated plate are compared with experimental results. Discussions on the effect of transverse shear deformation to the dynamic properties of composite plates are given.

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In the traditional design of the working equipment of the hydraulic excavator, its stress distribution was almost determined by adopting the static calculation method, and then its strength was ensured by selecting the safety factor, which is not fully considered because of the dynamic stresses resulting from shocks and vibrations in the operating process of the hydraulic excavator. Based on the finite element analysis software ANSYS, the 3D models of the main components (boom and bucket rod) of the working equipment for certain type of hydraulic excavator were analyzed. The inherent frequency and the main vibration mode were analyzed by extracting the first 6-th order modal. The research results show that with the increase of modal order, the vibrating mode form increased in complexity. The first and the second orders vibrating mode can be both a linear bending deformation or muster within a certain plane individually. From the beginning of the third order, the model deflection begins to become a mutual coupling complex vibrating type which showed multiple orders of bending and torsion deformation. The maximum deflection of boom is concentrated near the ear plate as well as the hinge point connected with boom and oil cylinder. On the other sides, the maximum deflection of bucket rod is concentrated on its middle part. i.e. between the hinge joints of rocker and the ear plate as well as near the rear supporting plate. Therefore, in order to ensure strength and working safety of the working equipment, it is necessary to improve the structure of the maximum deformation. The Modal analysis provides important modal parameters for the corresponding analysis of the boom and bucket rod of the working equipment in hydraulic excavator, and provides a basis for the optimization design of the analysis on total vibration and structural dynamic characteristics.