Jinkyu Yang

Origami has recently received significant interest from the scientific community as a method for designing building blocks to construct metamaterials. However, the primary focus has been placed on their kinematic applications by leveraging the compactness and auxeticity of planar origami platforms. Here, we present volumetric origami cells-specifically triangulated cylindrical origami (TCO)-with tunable stability and stiffness, and demonstrate their feasibility as non-volatile mechanical memory

A concept demonstrator of the structural health monitoring (SHM) system was developed to autonomously detect the degradation of the mechanical integrity of the standoff carbon–carbon (C–C) thermal protection system (TPS) panels. This system enables us to identify the location of the loosened bolts, as well as to predict the torque levels of those bolts accordingly. In the process of building the proposed SHM prototype, efforts have been focused primarily on developing a trustworthy diagnostic sc

We study the interaction of highly nonlinear solitary waves propagating in granular crystals with an adjacent linear elastic medium. We investigate the effects of interface dynamics on the reflection of incident waves and on the formation of primary and secondary reflected waves. Experimental tests are performed to correlate the linear medium geometry, materials, and mass with the formation and propagation of reflected waves. We compare the experimental results with theoretical analysis based on

The research presented in this paper is motivated by the need for reliable inspection technology for the detection of bolt loosening in carbon–carbon (C–C) thermal protection system (TPS) panels using minimal human intervention. Based on the diagnostic scheme proposed in part I of the study, a new PZT (lead zirconate titanate)-embedded sensor washer was developed to constitute the sensor network. The sensor suite was included in the C–C TPS prototype without jeopardizing the integrity of the ori

It is recent that the emergence of topological insulators in condensed matter physics has inspired analogous wave phenomena in mechanical systems, mostly in the setting of discrete lattice models. Here we report a numerical and experimental demonstration of topological waveguiding in a continuum plate. We take a ubiquitous design of a bolted elastic plate and show that such a design allows us to invoke the pseudo-spin Hall effect at remarkably low frequencies. We harness the complex interaction

Abstract Demonstration of topological boundary modes in elastic systems has attracted a great deal of attention over the past few years due to its unique protection characteristic. Recently, second-order topological insulators have been proposed in manipulating the topologically protected localized states emerging only at corners. Here, we numerically and experimentally study corner states in a two-dimensional phononic crystal, namely a continuous elastic plate with embedded bolts in a hexagonal

We propose a new biomedical sensing technique based on highly nonlinear solitary waves to assess orthopaedic implant stability in a nondestructive and efficient manner. We assemble a granular crystal actuator consisting of a one-dimensional tightly packed array of spherical particles, to generate acoustic solitary waves. Via direct contact with the specimen, we inject acoustic solitary waves into a biomedical prosthesis, and we nondestructively evaluate the mechanical integrity of the bone–prost

The lifetime of the stator winding insulation is reduced when operated with pulsewidth-modulation inverters, since insulation degradation is accelerated due to increased thermal and electrical stresses on the motor. This paper focuses on a new approach for monitoring the condition of the stator insulation for failure-prone inverter-fed machines. The main concept of the proposed technique is to apply a dc and/or variable-frequency ac test voltage to the stator insulation using the inverter and to

Stator insulation quality assessment is an important issue for pulsewidth modulation inverter-fed machines, since the stator insulation is exposed to increased thermal/electrical stresses. In this paper, a new approach for monitoring the condition of the stator insulation for inverter-fed machines is proposed. The main concept of the proposed approach is to apply various types of test voltages to the motor stator insulation using the inverter, to perform standard offline insulation tests wheneve

The discovery of topologically nontrivial electronic systems has opened a new age in condensed matter research. From topological insulators to topological superconductors and Weyl semimetals, it is now understood that some of the most remarkable and robust phases in electronic systems (e.g., quantum Hall or anomalous quantum Hall) are the result of topological protection. These powerful ideas have recently begun to be explored also in bosonic systems. Topologically protected acoustic, mechanical

Recently, there have been significant efforts to guide mechanical energy in structures by relying on a novel topological framework popularized by the discovery of topological insulators. Here, we propose a topological metamaterial system based on the design of the Stewart Platform, which can not only guide mechanical waves robustly in a desired path, but also can be tuned in situ to change this wave path at will. Without resorting to any active materials, the current system harnesses bistablilty