Kin'ya Matsumoto

Identification of Damping Parameters for Laminated Shallow Cylindrical Shells

An inverse analysis method has already been proposed by the authors to identify damping parameters of laminated composite materials using the FEM eigenvalue analysis. The purpose of this study is to apply the proposed method to a laminated shallow cylindrical shell. First, by applying the experimental modal analysis technique to the laminated shallow cylindrical shell with free boundary conditions, natural frequencies, mode shapes, and modal damping ratios are obtained. Next, by considering those obtained for the laminated shallow cylindrical shell, damping parameters for the lamina of the shell are identified

Finite Element Analysis of Vibration Damping for Woven Fabric Composites

The estimation method of the damping properties for woven composites has proposed. The proposed method has been applied to the plain woven composites. From these results, it is recognized that the computational damping properties have agreed with the experimental ones. Next, the effect of angle of fiber bundle on material damping of plain woven composites has investigated. The results show that the damping ratio is highest at angle of 45 degree.

Identification of Layer Elastic Parameters for Angle-ply Laminated Plates and Shells (Comparison of Numerical and Experimental Results)

An inverse analysis method has already been proposed by the authors to identify elastic parameters for laminated composite materials using the experimental modal analysis technique, the FEM eigenvalue analysis and the nonlinear optimization method. To investigate the application of the proposed inverse analysis method, the method is applied to an angle-ply laminated square plate and an angle-ply laminated shallow cylindrical shell made of the same composite materials and made by the same curing condition. First, by applying the experimental modal analysis technique to the angle-ply laminated square plate and shallow cylindrical shell, natural frequencies and mode shapes are obtained. Next, by using the obtained natural frequencies and mode shapes, the layer elastic parameters for the test pieces are identified. On the other hand, the layer elastic parameters are experimentally measured with prepared specimen. These identified layer elastic parameters were compared, and found to agree well, with the measured layer elastic parameters. * Corresponding Author: Associate Professor Kenji Hosokawa Faculty of Engineering, Chubu University 1200 Matsumotocho, Kasugai, Aichi 487-8501 Japan Tel:+81-568-51-1 111 Fax: +81-568-51-1194 E-mail: hosokawa@isc.chubu.ac.jp

Measurement of Material Damping Properties of Triaxial Woven Fabric Composites in Low-Pressure Condition

An effect of the air on the material damping of triaxial woven fabric (TWF) composites has been investigated. Two types of TWF composites, i.e., basic and bi-plain weave, are used as reinforcement. An excitation test of TWF composites is carried out in the atmosphere and in the low-pressure chamber, respectively. Comparing the both of experimental results, the effects of an atmosphere on the natural frequency and on the damping ratio have been discussed. As a result, it may be concluded that the aerodynamic force has a great influence on the damping properties and few influence on the natural frequencies.

Identification of Elastic Parameters for Cross-ply Laminated Plates and Shells

ABSTRACT An inverse analysis method has already been proposed by one of the authors to identifY elastic parameters of laminated composite materials using the FEM eigenvalue analysis and the nonlinear optimization method. The purpose of this study is to apply the proposed method to a laminated square plate and a laminated shallow cylindrical shell made of the same composite material. The identified elastic parameters for the lamina of the plate were compared, and found to agree well, with that for the lamina of the shell.

A Study of Vibration Analysis of Unsymmetrically Laminated Composite Plates. Eigenvalue Analysis by using a Simple FEM Plate Bending Model.

On the assumption that the neutral surface of the bending shifts toward a stiffer side in unsymmetrically laminated composite plates, a thin plate bending model is generated without using the coupling stiffness. And a new finite element for eigenvalue analysis of these composite plates is formulated. As a result of numerical works, the natural frequencies and modal shapes of unsymmetrically laminated FRP square plates are obtained. A shaking test using fixed CFRP rectangular plates is performed. The experimental results are compared with the analytical ones by the proposed method. Each results agrees well with one another.

A study on vibration analysis of symmetrically laminated composite shells. Eigenvalue analysis by use of flat triangular shell elements.

A method for FEM eigenvalue problems of symmetrically laminated composite shells is developed. A 15 d. o. f. flat triangular shell element is formulated considering the anisotropic behavior of composite materials with the assumption that the transverse normal strain is linear in symmetrical lamination. The present method enables us to analyze large scale problems by only a desktop microcomputer, using a subspace iteration algorithm and a skyline solver scheme. In order to estimate the accuracy of the program, eigenvalue problems of Donnel-type circular cylinders are calculated and compared with exact solutions.