The use of the electro-mechanical (E/M) impedance method for health monitoring of thin plates and aerospace structures is described. As a nondestructive evaluation technology, the E/M impedance method allows us to identify the local dynamics of the structure directly through the E/M impedance signatures of piezoelectric wafer active sensors (PWAS) permanently mounted to the structure. An analyt...

This paper presents a procedure to determine an element-length dependent strain and stress relation until fracture that is suitable for implementation in finite element models. This material relation is obtained experimentally with an optical measuring system. The strain until fracture is calculated from the measured surface displacements. The stress is derived from the measured force and the c...

Chronic exposure to hypoxia causes pulmonary hypertension and pulmonary arterial remodeling. Although the exact mechanisms of this remodeling are unclear, there is evidence that it is dependent on hemodynamic stress, rather than on hypoxia alone. Pulmonary supernumerary arteries experience low hemodynamic stress as a consequence of reduced perfusion due to 90° branching angles, small diameters,...

The dynamics of complex topological defects in ferroelectric materials is explored using automated experimentation piezoresponse force microscopy. Specifically, a trigger system (i.e., FerroBot) employed to study metastable domain-wall Pb0.6Sr0.4TiO3 thin films. Several regimes superdomain wall have been identified, including smooth motion and significant reconfiguration the domain structures. ...

AbstractIn this paper, we investigate effect of Fe–intermetallic compounds on plastic deformation of closed-cell composite Aluminum Foam as filler of thin-walled tubes. However, deformation of the Aluminum foam-filled thin-walled tubes as crushed-box will be presented in Part (II). Composite foams of AlSi7SiC3 and AlSi7SiC3-(Fe) as closed cell were synthesized by powder metallurgy foaming metho...

Abstract Improving the geometric accuracy of deposited component is essential for wider adoption wire arc additive manufacturing (WAAM) in industries. This paper introduces an online layer-by-layer controller that operates robustly under various welding conditions to improve deposition WAAM process. Two control strategies are proposed and evaluated this work: A PID algorithm a multi-input multi...

in this paper a new element for analysis of thin-walled structures is presented, and the effects of secondary shear stresses on longitudinal displacements are examined. since the interpolation functions are based on non-uniform torsional differential equations, the analysis of stiffness matrix is facilitated. therefore, its ability to produce accurate results with the least number of elements i...

The use of embedded piezoelectric-wafer active-sensors for in-situ structural health monitoring of thin-wall structures is presented. Experiments performed on aircraft-grade metallic specimens of various complexities exemplified the detection procedures for nearfield and far-field damage. For near-field damage detection, the electro-mechanical (E/M) impedance method was used. Systematic experim...

The capability of embedded piezoelectric wafer active sensors (PWAS) to perform in-situ ultrasonic nondestructive evaluation (NDE) is explored. Laboratory tests are used to prove that PWAS can satisfactorily perform Lamb wave transmission and reception. Subsequently, pulse-echo method for crack detection in an aircraft panel is illustrated. For large area scanning, a PWAS phased array is used t...

Embedded-Ultrasonics Structural Radar (EUSR) is a new concept and methodology for in-situ nondestructive evaluation (NDE) of thinwall structures. EUSR utilizes (a) a Piezo Wafer Active Sensors (PWAS) array embedded onto the structure; and (b) electronic modules for signal transmission/reception, processing, and interpretation. The EUSR methodology is developed as an extension of our previous wo...