Analysis of Nonlinear Piezoelectric Impedance Modulation Considering Asymmetry of Stiffness and Damping at Contact Surface

2019 ◽  
Vol 2019.18 (0) ◽  
pp. 102
Author(s):  
Yuta NISHIDA ◽  
Arata MASUDA
Keyword(s):  
Contact Surface ◽  
Impedance Modulation ◽  
Piezoelectric Impedance ◽  
Stiffness And Damping

scholarly journals Estimation of the Two Degrees-of-Freedom Time-Varying Impedance of the Human Ankle

2018 ◽  
Vol 12 (1) ◽  
Author(s):  
Evandro Ficanha ◽  
Guilherme Ribeiro ◽  
Lauren Knop ◽  
Mo Rastgaar
Keyword(s):  
Degrees Of Freedom ◽  
Mechanical Impedance ◽  
Heel Strike ◽  
Time Varying ◽  
Two Degrees Of Freedom ◽  
Impedance Modulation ◽  
Ankle Stiffness ◽  
Human Ankle ◽  
Stiffness And Damping ◽  
And Inversion

An understanding of the time-varying mechanical impedance of the ankle during walking is fundamental in the design of active ankle-foot prostheses and lower extremity rehabilitation devices. This paper describes the estimation of the time-varying mechanical impedance of the human ankle in both dorsiflexion–plantarflexion (DP) and inversion–eversion (IE) during walking in a straight line. The impedance was estimated using a two degrees-of-freedom (DOF) vibrating platform and instrumented walkway. The perturbations were applied at eight different axes of rotation combining different amounts of DP and IE rotations of four male subjects. The observed stiffness and damping were low at heel strike, increased during the mid-stance, and decreases at push-off. At heel strike, it was observed that both the damping and stiffness were larger in IE than in DP. The maximum average ankle stiffness was 5.43 N·m/rad/kg at 31% of the stance length (SL) when combining plantarflexion and inversion and the minimum average was 1.14 N·m/rad/kg at 7% of the SL when combining dorsiflexion and eversion. The maximum average ankle damping was 0.080 Nms/rad/kg at 38% of the SL when combining plantarflexion and inversion, and the minimum average was 0.016 Nms/rad/kg at 7% of the SL when combining plantarflexion and eversion. From 23% to 93% of the SL, the largest ankle stiffness and damping occurred during the combination of plantarflexion and inversion or dorsiflexion and eversion. These rotations are the resulting motion of the ankle's subtalar joint, suggesting that the role of this joint and the muscles involved in the ankle rotation are significant in the impedance modulation in both DP and IE during gait.

Detection of Contact-Type Damages by Utilizing Nonlinear Piezoelectric Impedance Modulation of Self-Excited Structures

2013 ◽  
Author(s):  
Arata Masuda ◽  
Yuya Ogawa ◽  
Akira Sone
Keyword(s):  
Damage Detection ◽  
Wave Field ◽  
High Frequency ◽  
Detection Method ◽  
Piezoelectric Sensor ◽  
Frequency Wave ◽  
Contact Type ◽  
Impedance Modulation ◽  
Excited Oscillation ◽  
Piezoelectric Impedance

This paper presents an improvement of a nonlinear piezoelectric impedance modulation (NPIM)-based damage detection method, a damage-sensitive, baseline-free structural health monitoring technique proposed by the authors, by introducing self-excited oscillation. The NPIM-based damage detection utilizes the modulation of high-frequency wave field of structures caused by the contact acoustic nonlinearity at the damaged part. In this study, the high-frequency wave field is induced as a self-excited oscillation of the structure by positively feed-backing the strain signal measured by a surface-bonded piezoelectric sensor, followed by a phase-shift in 90 degrees and a nonlinear element consisting of a saturation element and a negative linear gain. The induced self-excitation can have multiple stable limit cycles at certain eigenmode frequencies, and one can switch among them by inputting an auxiliary excitation signal into the feedback loop. The current flowing through the piezoelectric sensor is measured to detect its modulation due to the stiffness fluctuation due to the existence of the contact-type damage. Experiments using a specimen with a simulated damage are conducted to examine the performance of the self-excitation circuit and its applicability to the NPIM-based damage detection method.

123 Nonlinear Piezoelectric Impedance Modulation and Its Application to Crack Monitoring

2009 ◽  
Vol 2009 (0) ◽  
pp. _123-1_-_123-6_ ◽  
Author(s):  
Arata MASUDA ◽  
Tomohiro SHINAGAWA ◽  
Junsuke AOKI ◽  
Daisuke IBA ◽  
Akira SONE
Keyword(s):  
Impedance Modulation ◽  
Crack Monitoring ◽  
Piezoelectric Impedance

scholarly journals Impedance of the Human Ankle During Standing for Posture Control

2018 ◽  
Author(s):  
G. A. Ribeiro ◽  
E. Ficanha ◽  
L. Knop ◽  
M. Rastgaar
Keyword(s):  
Mechanical Impedance ◽  
Posture Control ◽  
Resultant Force ◽  
Order System ◽  
Time Varying ◽  
Ankle Impedance ◽  
Impedance Modulation ◽  
Human Ankle ◽  
Stiffness And Damping ◽  
Antagonistic Muscles

The stiffness and damping of anatomical joints can be modulated by muscle co-contraction, where antagonistic muscles contract simultaneously, increasing both the joint’s stiffness and damping. In a second order system, the mechanical impedance, or simply impedance, is a function of the system’s inertia, damping, and stiffness. The ankle impedance can be defined as the resultant force due to an external motion perturbation. The impedance modulation of the human ankle is required for stable walking. The estimation of the time-varying impedance modulation of the human ankle is the focus of research by different groups [1,2].

The Vibration Characteristics of Steam Turbine Blades with New Friction Damping Structures

2013 ◽  
Vol 312 ◽  
pp. 268-272
Author(s):  
Jun Wu ◽  
Rui Shan Yuan ◽  
Peng Fei Zhao ◽  
Yong Hui Xie
Keyword(s):  
Finite Element ◽  
Steam Turbine ◽  
Contact Surface ◽  
Turbine Blades ◽  
Harmonic Balance Method ◽  
Equivalent Stiffness ◽  
Friction Damping ◽  
Element Analysis ◽  
Steam Turbine Blades ◽  
Stiffness And Damping

The hysteresis curves that show the relationship between the tangential friction force and relative displacement of the contact surface were measured. The equivalent stiffness and damping of the friction contact surface under different normal loads were computed by harmonic balance method (HBM). The finite element model of steam turbine blades with new friction damping structures was established. The effects of friction between the contact surfaces were considered by using spring damping elements to connect the friction damper and the blade. The equivalent stiffness and damping which were calculated by the experiment results were applied to the spring damping elements under different rotational speeds. Based on the natural frequencies which were computed by finite element analysis, the Campbell diagram of the whole blades was obtained. The results showed that there were no 3-coincide points in the working speed range.

Nonlinear piezoelectric impedance modulation induced by a contact-type failure and its application in crack monitoring

2011 ◽  
Vol 20 (2) ◽  
pp. 025021 ◽  
Author(s):  
Arata Masuda ◽  
Junsuke Aoki ◽  
Tomohiro Shinagawa ◽  
Daisuke Iba ◽  
Akira Sone
Keyword(s):  
Contact Type ◽  
Impedance Modulation ◽  
Crack Monitoring ◽  
Piezoelectric Impedance
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