Kenji Hosokawa

Vibrations of clamped orthotropic rectangular plates

Abstract A solution in a double trigonometric series form is proposed for a forced vibration problem of a clamped orthotropic rectangular plate. With the increasing number of terms of the series, the solution satisfies more closely both the boundary condition and the governing equation. The accuracy of the solution is discussed numerically. As an example, the solution is applied to the iteration method for the analysis of the free vibration problem of a clamped orthotropic rectangular plate. Very accurate natural frequencies are obtained for typical plates.

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

Free Vibration Analysis of Angle-Ply Laminated Circular Cylindrical Shells with Clamped Edges

The free vibrations of angle-ply laminated cylindrical shells are studied numerically and experimentally. The material of the cylindrical shell is a carbon fiber reinforced plastic (CFRP). First, the material properties for the lamina of the cylindrical shell are measured. Secondly, using the measured material properties of the lamina, the natural frequencies and mode shapes of the angle-ply laminated cylindrical shells with clamped edges are computed by the finite element method (FEM). Finally, the vibration tests of the angle-ply laminated cylindrical shells with clamped edges are carried out. By applying the experimental modal analysis technique, natural frequencies and mode shapes of the shells are obtained. From the comparison between experimental and numerical results, one can see the good agreement between these results. Furthermore, the effects of length of the angle-ply laminated cylindrical shells with clamped edges on the natural frequencies and mode shapes are investigated numerically and experimentally. An approximate frequency equation for the shells length is proposed.

Free Vibration Analysis of Cantilevered Laminated Trapezoidal Plates

A numerical approach for analyzing the free vibration problem of a laminated FRP (fiber reinforced plastic) composite plate has already been proposed by the authors. In the present study, this approach is applied to a cantilevered laminated trapezoidal plate. First, the natural frequencies of the plate are calculated for discussion of the convergence and accuracy of the solution. Next, the effects of the plate configuration and stacking sequence on the natural frequency of the plate are studied. Furthermore, the natural frequency and mode shape of the plate are obtained experimentally. These experimental results are found to agree well with the numerical results computed using the measured material properties of the lamina.

Free Vibration Analysis of Angle-ply Laminated Shallow Cylindrical Shell with Clamped Edges

In a previous paper, the authors proposed a numerical approach for analyzing the free vibrations of a laminated FRP (fiber reinforced plastic) composite plate. In the present paper, this approach is modified for application to a symmetrically laminated shallow cylindrical shell having a rectangular planform. First, the natural frequencies of the shell are calculated for discussion of the convergence and accuracy of the solution. Next, the effects of the curvature ratio and stacking sequence on the natural frequencies and mode shapes of the shell are studied. Furthermore, to justify the numerical results, vibration tests of the clamped symmetrically laminated shallow cylindrical shell having a square planform are carried out. These experimental results are found to agree well with the numerical results computed using the measured material properties of the lamina.

Free-vibration analysis of clamped antisymmetrically laminated elliptical plates

In a previous paper, a numerical approach for analyzing the free vibration problem of an unsymmetrically laminated fiber-reinforced plastic composite plate was proposed by the authors. In the present paper, this approach is applied to the clamped antisymmetrically laminated elliptical plate. As numerical examples, the natural frequencies and the mode shapes of the circular and elliptical plates are estimated. The effects of the fiber orientation angle on natural frequency and mode shape are studied. Furthermore, the vibration tests of the clamped antisymmetrically laminated circular and elliptical plates made of carbon fiber-reinforced plastic are carried out, and the experimental natural frequency and mode shape are compared with the numerical results.

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

Study on Modification of Ski Referring Characteristic of Ski-Turn (Change of Width and Shoe Center)

An approach is proposed for automatically modifying a shape and shoe center (design valuables) of a ski. The proposed approach needs the inverse analysis method (sensitivity analysis) and two indices of the ski turn (“Locus of ski turn” and “Rotational angle of ski”) as the objective functions. Firstly, to obtain the two indices of the ski turn, the outline of the numerical approach for a ski turn is introduced. Subsequently, the sensitivity analysis is shown to estimate the change quantities for the modification of the ski. Finally, referring two indices of the ski turn, a prototype ski is modified into an objective ski by tuning the width and shoe center of the ski. From the above-mentioned numerical calculations, it follows that one can efficiently modify the prototype ski by using the proposed approach.

Study on Identification of Elastic Parameters for Skis

The elastic parameters of skis are essential for simulation on skiing. Generally, the elastic parameters of skis have not been reported. Also, the elastic parameters of skis are difficult to determine by either theoretical and experimental approach. Therefore, an inverse analysis method to identify equivalent elastic parameters of skis is very important. In the identification method, mainly, the experimental modal analysis technique, the finite element method and the sensitivity analysis method are used. First, by applying the experimental modal analysis technique to a ski with free boundary conditions, natural frequencies and mode shapes are obtained. Secondly, from the obtained natural frequencies and mode shapes, the equivalent elastic parameters of the ski are identified numerically. Finally, to justify the application of this approach, the bending stiffness and twisting stiffness in longitudinal direction calculated by the obtained equivalent elastic parameters of the ski are compared with those obtained by the other experimental method.

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.