Keiichi Nemoto

Buckling Strength of Composite Laminated Plates under Compressive Load.

Because of their high specific strength and stiffness, fiber-reinforced plastics have been used as structural members in various fields, and hence analysis of thin laminated structures is important. Postbuckling behaviors of thin laminated plates under uniaxial compression have been discussed by many researchers. However, little research has been performed on the secondary buckling phenomenon for thin laminated plate which occurs with further increase of load. In this paper, the stability condition of CFRP cross-ply laminated plates under uniaxial compression which are simply supported along four edges is determined, using the second variation of total potential energy. The necessity of secondary buckling is proven analytically, and the effects of various factors, such as number of layers, deflection pattern and average axial shortening, are clarified.

Postbuckling Stability Analysis of Composite Laminated Flat Plates with Initial Deflection under Biaxial Compression

Postbuckling Stability Analysis of Composite Laminated Flat Plates with Initial Deflection under Biaxial Compression Keiichi Nemoto1, Hirakazu Kasuya2, Hisao Kikugawa3 and Tooru Kohiga4, 1Department of Aerospace Engineering, The Yokohama Rubber Co., Ltd., Hiratsuka 2548601 2Department of Prime Mover Engineering, School of Engineering, Tokai University, Hiratsuka 2591292 3Department of Biomedical Engineering, School of Engineering, Tokai University, Hiratsuka 2591292 4Course of Mechanical Engineering, Graduate School of Engineering, Tokai University, Hiratsuka 2591292

Dynamic Response of Composite Laminated Cylindrical Shells Subjected to Periodic External Pressure.

Advanced fiber-reinforced composite materials have been used for structural members because of their high specific strength and stiffness. A study is conducted on the stability of symmetric cross-ply laminated cylindrical shells under static and periodic external pressure of short duration. The cylindrical shell can withstand an impulsive load greater than the static buckling pressure if the loading duration is very short compared with the free vibration period of the laminated cylindrical shell in the first mode. The inevitability of dynamically unstable behaviors and the effects of various factors, such as load ratio, number of layers, stacking sequence, fundamental natural frequency, driving amplitude of the vibration and dynamic unstable mode, are analytically clarified.

Dynamic Response of Composite Laminated Cylindrical Shells Subjected to Axial Step Loading.

Advanced fiber-reinforced laminated composite materials have been used for structural members because of their high specific strength and stiffness. This paper deals with the problem of dynamic stability of laminated cylindrical shells subjected to axial step loading. First, the axially symmetric motion of the shell under the loading is determined. Subsequently, certain perturbations are superimposed on this motion, and their behavior in time is investigated. The symmetric state of motion of the shell is called stable if the perturbations remain bounded. The solutions for the prebuckling motion and the perturbated motion are obtained by the use of Galerkins method. The inevitability of dynamically unstable behaviors is proved analytically and the effects of various factors such as compressive load ratio, number of layers, dynamic unstable mode and dimension of cylinder are clarified.