Ichiro Ario

Homoclinic bifurcation and chaos attractor in elastic two-bar truss

Abstract In this paper, we present a dynamic bifurcation analysis of the non-linear Duffings equation on a simple elastic structure. The structure is a two-bar elastic truss with a damper, and possesses geometrical non-linear stiffness. We consider the dynamic instability of its structure based on Duffings oscillation, which shows bifurcation behavior of the homoclinic orbit. We could numerically forecast the trajectory near the invariant saddle point of homoclinic bifurcation on this model, and we found that it is possible to solve dynamic bifurcation and strange attractors (chaos) on this non-linear structure. On this truss, we could investigate the dynamic stability of the strange attractor using Lyapunov exponents under the frequency and/or the amplitude parameter of periodic load.

Smart photonic coating as a new visualization technique of strain deformation of metal plates

We will present a simple and low cost method to visualize local strain distribution in deformed aluminum plates. In this study, aluminum plates were coated with opal photonic crystal film with tunable structural color. The photonic crystal films consist of a silicone elastomer that contains an array of submicron polystyrene colloidal particles. When the aluminum sheets were stretched, the change in the spacing of the colloidal particles in the opal film alters the color of the film. This approach could be useful as a new strain gauge having a visual indicator to detect mechanical deformation.

Theory and Design Study of a Full-Scale Scissors-Type Bridge

AbstractQuick recovery of damaged bridges following natural disasters is most vital and helpful. The authors are developing a new type of emergency bridge with the scissor mechanism of expanding equipment as a quick recovery solution. This paper proposes the design method based on the solution of the equilibrium equations for a full-scale experiment of a scissors-type bridge in static mechanics. This method can obtain the dominant sectional force for each scissor member of the bridge. The presented design method was evaluated in comparison with the experimental data of a loading test for a full-scale scissors-type bridge that can withstand the load of a light vehicle. It was confirmed that this method is useful for a recovery bridge system.

Dynamic Analysis of Folding Patterns for Multi-Folding Structures

We present the basic mechanisms for the folding of a multi-layered truss, such as a combination of pantographs under dynamic loading, from a post-buckling perspective. This problem is considered in terms of the large-deflection range that the truss is allowed to fold. It develops several element forms to be stronger for dynamic control in a mechanism reminiscent of a deployable structure. Although there are several kinds of folds at the critical points, we need to develop a new concept for a multifolding mechanism (MFM) that allows various different folds even through a simple structure. We explore dynamic critical and post-buckling effects through the concept of energy minimization and hidden symmetries. For comparisons with the final large-deflection folded patterns, we use the original dynamic program for truss analysis.We demonstrate that, as final buckling develops, the mode patterns must change depending on both the velocity of the dynamic loading and some of the imperfections of the geometry of structure through the behavior of the post-buckling aspects of the fold pattern.