Papers by Keyword: Vibration Characteristics

Abstract: This study presents a finite element investigation of the vibration characteristics of a laminated carbon fiber reinforced polymer (CFRP) composite plate with a centrally surface-bonded piezoelectric (PZT-5H) patch under classical boundary conditions. A square CFRP plate of dimensions 300 × 300 × 3 mm with a [0/90/0/90] layup is analyzed with and without an active piezoelectric patch, considering clamped–clamped–clamped–clamped (CCCC), clamped–free–clamped–free (CFCF), clamped–free–free–free (CFFF), and simply supported–simply supported–simply supported–simply supported (SSSS) boundary conditions. Linear piezoelectric theory and steady-state harmonic excitation are employed using Abaqus/CAE 2025 Learning Edition. Modal characteristics are obtained from the first six natural frequencies, while harmonic response is evaluated in terms of peak out-of-plane displacement at the plate center under combined mechanical loading and open-loop electrical actuation. The results demonstrate that the presence of the PZT patch induces boundary-condition-dependent modifications in both natural frequencies and harmonic response amplitudes. For highly constrained configurations (CCCC and SSSS), the active PZT patch leads to a reduction in peak harmonic displacement, whereas for less constrained cases (CFCF and CFFF), a slight amplification of the response is observed. These findings highlight the strong coupling between structural boundary conditions and piezoelectric actuation effectiveness, and they establish a validated baseline for future investigations involving closed-loop control, multi-patch configurations, and data-driven optimization strategies.

Abstract: Based on the theories of rotor dynamics, a dynamic model of rotating blade was built. Taking account of the effect of spin softening, the research on vibration characteristics of high-speed rotating blades was carried out under different speeds. The results had shown that frequency of blade vibration increased with rising rotating velocity, whilst the frequency of all orders declined with the influence of spin softening. Meanwhile, the change of each mode shape of blade was not very large at different speed. The conclusion derived from this paper had both theoretical and empirical value on retrofitting, optimal-designing, as well as engineering application for high-speed rotating blades.

Abstract: A significant amount of research on the vibration and sound radiation of the cylindrical shell has been carried out and reported. The cylindrical shell was usually assumed to be submerged in an infinite fluid. However, the fluid region surrounding the cylindrical shell is bounded. Free vibration and forced vibration characteristics of finite cylindrical shells semi-submerged are studied in this paper, based on energy functional variational principle. The combined form of the triangular series and the Fourier series is used for the displacement of the cylindrical shell, then the orthogonality can be used to eliminate the other two directions after the variation, and only the radial displacement is kept. The relationships between the amplitudes of fluid load and the amplitudes of the radial displacement are established by the orthogonal processing of the continuous conditions of the solid-liquid coupling contact surface and the boundary conditions of the free liquid surface. Finally, the fluid structure coupling control equation is obtained. The results show that the method is correct and effective, in addition, providing a new thought for solving similar problem.

Abstract: A semi-analytical method was proposed to analyze the vibration characteristics of an elastic cavity. Combining the precise integration method and bent theory of the beam, the transfer relationship of the ends of the beam was derived. Based on the displacement continuity conditions and equilibrium equations of the junction, the conversion relation of the beams was also established. Then, the dynamics control equations of an elastic cavity were assembled by the above relationship and boundary conditions. The comparison with the FEM had verified the accuracy of the present method. This method avoids the shortage that the calculation accuracy over-depends on the element types and the mesh dividing methods, which is existed in the finite element method. In addition to this, the process of this method is efficient, so it is a useful method to the structural design and optimization of the cavity.

Abstract: Aerodynamic heating will be caused when a hypersonic vehicle is in flight, so it should be taken into account when a structural dynamic analysis is carried out. A method for structural dynamic analysis under thermal environment is presented in this paper. Firstly, Computational Fluid Dynamic (CFD) method which is based on solving the three-dimensional compressible Navier-Stokes (N-S) equations is employed to perform aerodynamic heating analysis. Secondly, Finite Element Method (FEM) is used to assess structural heat conduction and get temperature field. Lastly, based on the quasi-linear structural model, a structural dynamic analysis is analyzed under thermal environment. A hypersonic composite wing is investigated as a numerical example. Compared with the case without considering aerodynamic heating, major modes and frequencies of the wing change a lot because of the decrease of the elastic modulus and the alteration of structural stiffness distribution. The results indicate that the aerodynamic heating has a high influence on the vibration characteristics. Therefore, aerodynamic heating should be considered in hypersonic structural dynamic analysis.

Abstract: A torsional dynamic model and testing model for planetary geared systems are established to study the effects on its vibration characteristics as substituting plastic gears for steel ones successively. The dynamic model is solved by using variable step Runge-Kutta method and the vibration testing experiments for four kinds of combined planetary geared systems are carried out under different rotation speed and load torque. The numerical and experimental results show that the high frequency spectra are suppressed effectively as substituting plastic gears for steel ones. The gear mesh dynamic load and vibration intensity caused by the meshing fundamental frequency and side-frequency reduce markedly when the plastic ring and planet gear substitute for steel ones together. The numerical simulations have a better consistency with the experimental results, which verifies the correctness of the conclusions.

Abstract: In order to study air-suction when tillage planter in the field farming, Vibration due to the surface roughness of the resulting excitation tillage effects on seed planter of the device, Derivation of the air-suction device tillage planter seeder vibration characteristics of the mathematical model, Vibration characteristics of the mathematical model derived gas suction device tillage seeder seed planter primarily by structural properties, Forward speed when operating, Seed row distance between the soil surface, Soil roughness and soil sticky decision. Can predict and analyze working condition tillage planter seed quality through the establishment of the vibration characteristics of the mathematical model.

Abstract: The wing structures of long-range, high-speed flight vehicles bear vibration during the flying time. The high temperatures caused by aerodynamic heating can greatly change the elasticity properties of the materials in a high-speed flight vehicle, leading to an alteration in the vibration characteristics of high-speed flight vehicle structures. In this paper, the high-temperature environment test system and vibration test system were combined to conduct a thermal-vibration test for the composite trilaminated wing structure that comprised composite materials and metallic materials. The vibration characteristics of the composite trilaminated wing structure, such as natural frequency and vibration mode, were obtained in 200°C, 300 ^oC and 400 ^oC environments. The results provide an important basis for the dynamic characteristics analysis and safety and reliablity design of wing structures comprised composite materials and metallic materials under a thermal-vibration environment.

Abstract: High speed and large capacity belt conveyor is the main development trend. In the design, calculated and used of belt conveyor must be considered the high speed, large capacity, dynamic load. This paper starts from the analysis of conveyor belt transverse vibration. Through calculate transverse vibration natural frequency of conveyor belt, and analyze the lateral stability of belt conveyor.

Abstract: Applying the method of finite element to research the composite damping vibration reduction effect of circular saw blade. Based on the structure of composite damping circular saw blade, contrast a composite saw blade and ordinary saw blade, to design and compare their vibration characteristics. Through research the vibration characteristics on the three kinds of saw blades found that the each order natural frequency of composite damping saw blade and composite saw blade is smaller than the corresponding order natural frequency of ordinary saw blade, and the each order natural frequency of composite damping saw blade slightly smaller than the corresponding order natural frequency of composite saw blade; The maximum displacement deformation of composite damping saw blade and composite saw blade is smaller than the corresponding order of ordinary saw blade. Through study the damping characteristics found that the modal damping ratio of composite damping saw blade is greater than others; and research the dynamics characteristics found that composite damping blade's vibration attenuation faster than others, and it illustrate the good effect of damping saw blade.