K. Otomo

Bio: K. Otomo is an academic researcher from Tohoku University. The author has contributed to research in topics: Deflection (engineering) & Harmonic balance. The author has an hindex of 3, co-authored 3 publications receiving 111 citations.

Nonlinear Vibrations and Stability of Shells and Plates

Abstract: Introduction. 1. Nonlinear theories of elasticity of plates and shells 2. Nonlinear theories of doubly curved shells for conventional and advanced materials 3. Introduction to nonlinear dynamics 4. Vibrations of rectangular plates 5. Vibrations of empty and fluid-filled circular cylindrical 6. Reduced order models: proper orthogonal decomposition and nonlinear normal modes 7. Comparison of different shell theories for nonlinear vibrations and stability of circular cylindrical shells 8. Effect of boundary conditions on a large-amplitude vibrations of circular cylindrical shells 9. Vibrations of circular cylindrical panels with different boundary conditions 10. Nonlinear vibrations and stability of doubly-curved shallow-shells: isotropic and laminated materials 11. Meshless discretization of plates and shells of complex shapes by using the R-functions 12. Vibrations of circular plates and rotating disks 13. Nonlinear stability of circular cylindrical shells under static and dynamic axial loads 14. Nonlinear stability and vibrations of circular shells conveying flow 15. Nonlinear supersonic flutter of circular cylindrical shells with imperfections.

A finite element method for nonlinear forced vibrations of rectangular plates

Abstract: The finite element method has been extended to determine the response of large amplitude forced vibrations of thin plates. A harmonic force matrix of a rectangular element under uniform harmonic excitation is developed for nonlinear forced vibration analysis. Inplane deformation and inertia are both considered in the formulation. Results obtained are compared with simple elliptic response, perturbation and other approximation solutions.

Reduced-Order Models for Acoustic Response Prediction

Abstract: : This report documents an in-house research effort to evaluate, refine, and validate reduced-order methods for computing the response of air vehicle skin panels to extreme acoustic and thermal loading. These methods reduce a finite element model to a reduced-order system of nonlinear modal equations. A short historical review of acoustic response prediction methods is presented followed by a detailed discussion of the methods. Several refinements to the methods are developed. The methods are applied to several example problems ranging from a clamped-clamped beam to a curved panel. Model predictions are compared to results from full-order simulations and well-characterized experiments. Effects of nonlinear large deformation, thermal loading and acoustic coupling are included in the methods. The reducedorder methods are shown to provide accurate prediction of acoustic response with orders-of-magnitude reductions in computational cost over full-order finite element analysis.

Experimental Investigation of Single-Mode Responses in a Fixed-Fixed Buckled Beam

Abstract: The nonlinear, single-mode responses of a fixed-fixed, buckled beam are investigated under the case of a uniform, transverse, harmonic excitation. In order to avoid axial slipping and to obtain meaningful data, a clamping apparatus was designed to maximize the clamping force applied to the beam. To fully characterize the single-mode responses, data were obtained at various levels of buckling up to 3.3 times the thickness of the beam. The data demonstrate that at a low level of buckling, supercritical period doubling occurs during an amplitude sweep in which the first mode is directly excited. However, as the buckling level increases, the period-doubling bifurcation becomes subcritical during such amplitude sweeps. In addition, a period-five motion, broadband responses, and responses with an unexplained sideband structure were observed.