An analysis of vibration and damping of composite spherical shells with a constrained visco-elastic core are presented. The vibration damping properties are analyzed by means of the Ritz method. Displacement functions satisfied with boundary conditions are expressed by a power series. The elastic modulus of the core is treated as a complex quantity to take account of structural damping. The complex eigenvalue problem, which is derived by means of minimizing the energy functional, is solved to determine the natural frequencies, modal loss factors and mode shapes. The accuracy and validity of the present results are confirmed by the convergence study and comparison with published data. Numerical results are presented for different parameters, such as circumferential wave numbers, opening angles, ratios of core thickness to total shell one and the shear moduli of the core.
In this paper, examples of design and research education using the general-purpose structural analysis tool (3D-CAD/CAE) are introduced. As an example of design education, performance verification ( Static analysis, Eigenvalue analysis, Buckling ) for parts of the handwinches is presented. The example of research education presents the vibration characteristic analysis of circular cylindrical shells, the comparison with other approximate method and the problem of a boundary condition are discussed. As a conclusion, the validity of the general-purpose structural analysis tool in the design and research education for the mechanical and structural engineering is considered.
An analysis for vibration of cylindrical shallow shells with a constrained viscoelastic layer and metal layers is presented. In this paper, vibration damping properties of three layer type shallow shells with viscoelastic material are analyzed from both of SEM (Strain energy method) and CEM (Complex eigenvalue method). Furthermore, behavior and accuracy of each solution are examined. Eigenvalue and eigenvector (displacement functions) are analyzed based on the Ritz method, when natural frequency, modal loss factor and strain energy are obtained. In method (CEM), the elastic modulus of viscoelastic material is dealt with complex quantity considering material loss factor. The eigenvalue problem that is derived by means of minimizing the energy functional, is solved to determine the natural frequencies and modal loss factors. In method (SEM), modal loss factor is defined as a ratio of damping energy (strain energy consumed in viscoelastic layer) dissipated during a vibration cycle and total strain energy of the shell. The accuracy and validity of the present results from two methods are illustrated through investigation of convergence and comparison with the established results from the literature. From thebehavior of the solution, consideration and interpretation are tried with respect to accuracy and characteristic of each solutionmethod.
Students in mechanical engineering are required faculty of mechanical design. In conventional mechanical design education, the students spend much time on drawing the plan, they do not have enough time to study mechanical design. On Ichinoseki National College of Technology, due to improve their faculty of mechanical design, 3D-CAD system were introduced and mechanical design curriculum using 3D-CAD were reconstructed. This paper show our new curriculum of mechanical design education using 3D-CAD and the executing case in department of mechanical engineering.
Abstract In the field of structural dynamics of large space structure (LSS), control/structure interaction technologies have been attracting much attention of researchers, and various types of control theory have beer, proposed. Meanwhile, it is important to develop actuators for the use of structural control. Piezoelectric device has some advantages characteristics such as compact size, high frequency response, low energy consumption over the other devices. With this background a uniquely designed piezoelectric actuator both for active dumping and shape adjustment has been preliminarily developed for experimental use. This paper describes the experimental results of the actuator for active dumping of planar truss and for statical or dynamical shape adjustment. And numerical simulations of planar truss with minimum numbers of pairs of collocated actuators and sensors show that a state observer can estimate truncated modes precisely and that the excited vibration can be dumped out rapidly.
The energy absorption of a polymer particle due to the dynamic load of SH-wave is discussed based on the linear theory of elastodynamics. It is shown that the ability of the energy absorption in the range of the practical use is governed by the deformation mode of the particle, when the frequency of the incident wave is lower. It is shown that the first mode of the circumferential deformation is the best for absorbing energy in the particle. The present and previous papers completes the discussion on the energy absorption in a polymer particle for the three types of the dynamic loading.
