We present a prototype vibration isolator whose design is inspired by origami-based foldable cylinders with torsional buckling patterns. The vibration isolator works as a nonlinear spring that has quasi-zero spring stiffness in a given frequency region, where it does not transmit vibration in theory. We evaluate the performance of the prototype vibration isolator through excitation experiments via the use of harmonic oscillations and seismic-wave simulations of the Tohoku-Pacific Ocean and Kobe earthquakes. The results indicate that the isolator with the current specification is able to suppress the transmission of vibrations with frequencies of over 6 Hz. The functionality and constraints of the isolator are also clarified. It has been known that origami-based foldable cylinders with torsional buckling patterns provide bistable folding motions under given conditions. In a previous study, we proposed a vibration isolator utilizing the bistability characteristics and numerically confirmed the device's validity as a vibration isolator. Here, we attempt prototyping the isolator with the use of versatile metallic components and experimentally evaluate the isolation performance.

In this paper, a novel vibration isolator based on a foldable cylinder with a torsional buckling pattern, which is also called Kresling's pattern, is proposed, and the performance of the proposed isolator in terms of preventing structural vibration is numerically evaluated. It is known that foldable cylinders with a torsional buckling pattern provide bistable folding motions under specific conditions. For simplification, a foldable cylinder with a torsional buckling pattern is modeled using horizontal, longitudinal, and diagonal truss elements connected by rotational joints and enforced by rigid frames, which are also called Rahmen, while maintaining the bistability of the structure. Additional linear springs are incorporated into the structure in order to obtain a nonlinear spring with quasi-zero-stiffness characteristics. It is numerically established that: (i) the resonance of the combined structure is effectively suppressed and (ii) the structure decreases the vibration response even at high frequencies when it is used around the equilibrium position at which the spring stiffness is quasi-zero.

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The martensitic transformation of Ni-Ti shape memory alloy was investigated by X-ray diffraction analysis aided X-ray diffraction pattern simulation. Using the wire shape samples the X-ray diffraction patterns were measured at every 10 from 0 to 80 . The software that simulated the X-ray diffraction patterns using by the data of already known lattice constants was developed on the basis of the Bragg's law and the intensity laws. First we confirmed that the X-ray pattern measured by arranging wire samples and attaching the sample holder coincided that of the powder method. Next the X-ray pattern at austenite phase (80 ) was compared with the simulated pattern of B2 crystal structure by the program and the state was identified as B2 structure. On the other hand at martensite phase (0 ) B2 and B19' structures were mixed in the crystal. Although the shape memory effect was expressed at this environmental temperature, it is considered that not only B19' structure but B2 structure is also related to the effect of shape memory effect.