Ultrasonic Pulse-Echo Signal Analysis for Damage Evaluation of Metallic Slit-Plate Hysteretic Dampers

A cyclic two-surface thermoplastic damage model with application to metallic plate dampers

The objective of this study is to develop a new constitutive model for cyclic response of metals with much broader applicability. Accordingly, a two-surface damage thermoplasticity model is proposed to understand inelastic behavior and to evaluate a potential damaged state of the metals. This model, which derived from small strain theory, is formulated through a thermodynamic approach to damage...

A Design Methodology for Hysteretic Dampers

This research proposes a design methodology for hysteretic dampers in buildings under high levels of seismic hazard. Developments in structural materials have led to designs that satisfy strength requirements but are often very flexible. This trend, along with increasingly stringent building performance criteria, suggests a philosophy of controlling structural motion as opposed to merely design...

Matching pursuit for decomposition and approximation of ultrasonic pulse-echo wavelet and its application in ultrasonic nondestructive evaluation.

The estimation of the time of arrival (TOA) and/or time of flight of the ultrasonic echoes is essential in ultrasonic nondestructive evaluation. In this paper, matching pursuit method has been used to analyze noisy ultrasonic pulse-echo wavelet and decompose the noisy pulse-echo wavelet into unit-norm vectors. The error ratio of the mean square is used to monitor the acceptability of the unit-n...

Ultrasonic Pulse-Echo Subwavelength Defect Detection Mechanism: Experiment and Simulation

The ultrasonic pulse-echo backscattered amplitude integral (BAI)-mode imaging technique [IEEE Trans. UFFC, 45:30 (1998)] has demonstrated sensitive detection of subwavelength channel defects (38m diameter reliably and 6m diameter occasionally) in flexible 220m-thick food package seals (17.3 MHz, 86 m). However, the underlying subwavelength defect detection mechanism is poorly understood. In thi...

Near Real Time Ultrasonic Pulse Echo Holographic Imaging System