Advanced composites, particularly high modulus laminates, are often susceptible to transverse impact loading. Major damage introduced due to low velocity impact include matrix cracking, fiber break and delaminations. Such flaws tend to reduce residual strength of the material and may cause catastrophic failure when the material is subjected to higher operating loads [1,2]. Unfortunately, these ...

Abstrac t Pulsed eddy current (PEC) is a new technique of non-destructive material evaluation (NDE). In comparison with other eddy current techniques, PEC uses pulsed excitation that is characterized by wide frequency content and thus the response carries more complex information about a tested object. PEC method is used in many NDE common applications such as inspection of defects, measurement...

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

This paper is concerned with the use of leaky Lamb waves for the nondestructive evaluation (NDE) of damage in anisotropic materials such as fiber-reinforced composites. Two fundamental acoustic properties of the material, namely, the wave speed and attenuation have been measured. Stiffness is deduced from the wave speed. The damage mode selected for this study is matrix cracking. As expected, t...

A numerical study is presented of the influence of plate curvature and taper on the transport of ultrasound guided wave signals for nondestructive evaluation (NDE) and structural health monitoring (SHM) applications. Model formulations for transmission at sharp transitions in plate curvature and thickness taper are summarized. Results are presented showing that transitions in plate curvature an...

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...

The capabilities of embedded piezoelectric wafer active sensors (PWAS) to perform insitu ultrasonics for active structural health monitoring (SHM) and nondestructive evaluation (NDE) are explored. The paper shows that PWAS, though low-power, lightweight, and small, can successfully perform Lamb wave transmission and reception, pitch-catch and pulse-echo, as well as large area scanning using the...

Nondestructive evaluation (NDE) methods are being developed at Argonne National Laboratory for thermal barrier coatings (TBCs) applied to components in the hot-gas path of advanced high-efficiency and low-emission gas turbines, including syn-gas fired turbines. As TBCs become “prime reliant,” it becomes important to know their conditions nondestructively to assure the reliability of these compo...

Existing nondestructive evaluation (NDE) technologies are inherently limited by the physical response of the structural material being inspected and are therefore not generally effective at the identification of small discontinuities, making the detection of incipient damage extremely difficult. One innovative solution to this problem is to enhance or complement the NDE signature of structural ...

Magneto-Optic Imaging (MOI) is a relatively new nondestructive evaluation modality that provides real time images of surface and subsurface features. In this technique, flux leakage maps associated with applied currents are recorded and monitored to locate material defects. Various factors affect the sensitivity of nondestructive evaluation using MOI including structure geometry, instrumentatio...