Cryoultrasonic NDE: Ultrasonic inspections with ice cold waves
The inspection of complex shaped parts, which may contain multiple internal vanes and present highly curved surfaces, poses a major challenge to conventional NDE techniques. In current industrial practice, these parts are inspected using x-ray CT (XCT) for internal volumetric defects and liquid penetrant inspections (LPI) for surface breaking cracks. However, the sensitivity of XCT rapidly decreases with part size and material mass density, while LPI is ineffective on internal surfaces or in the presence of high surface roughness. Cryoultrasonic NDE is a new technique that uses the remarkable properties of ice to transform a complex object into a simple-shaped solid, which can then be inspected by combining ultrasonic array measurements with advanced imaging methods.
Download the 2018 QNDE Poster
F. Simonetti & M. Fox, NDT & E Inter., 103, 1-11, (2019);
F. Simonetti et al., IEEE Trans. Ultrason. Ferroelectr. Freq. Contr., 65 , 638-647, (2018).
NDE of Ceramic Matrix Composite (CMC) Engine Components
GE Aviation has pioneered a new breed of ceramic materials formed with Silicon Carbide fibers in a Silicon Carbide matrix (SiC/SiC) which allow jet engine turbines to operate at significantly higher temperatures than those possible with conventional superalloys, thus leading to higher efficiency and lower emissions. At USIL we work closely with GE to develop the next generation NDE technology specifically tailored to the unique microstructural characteristics of CMCs and aimed at managing the life cycle of CMC components. At a fundamental level we are developing non-contact methods, such as laser ultrasonics, to study damage formation and progression in CMC specimens tested at very high temperatures. At the applied end we design and test inspection solutions for quality control at manufacture and routine maintenance during service.
Additive Manufacturing
Also known as 3-D printing, this technology offers unparalleled flexibility in the manufacture of complex-geometry engineering components. USIL is engaged with a number of industrial partners and federal agencies to develop ultrasonic NDE methods for the inspection of metallic components produced by selective laser melting (SLM) and electron beam melting (EBM). The focus is on developing sensitive methods for the detection of damage such as porosity in complex-shaped parts.
Guided Wave Tomography
Accurate thickness mapping of large engineering structures is critical to assess the integrity and residual life of mechanical components subject to erosion or corrosion damage. However, in many industrial settings, it is not possible to access the region of interest directly, e.g. because of remote location or due to the presence of physical obstacles. Guided ultrasonic waves offer a promising approach to remote wall thickness loss estimation thanks to their ability to propagate over a long distance along a structure. Using the principles of tomography in conjunction with guided wave technology, a point-by-point spatial map of the wall thickness loss can be obtained over the entire volume of a structure section delimited by two ring arrays of ultrasonic transducers. Our research focuses on the development of a highly sensitive guided wave tomography system based on an innovative array technology and advanced inversion schemes. This technology is now being commercialized through Cincinnati NDE, Ltd. a start-up company from UC.
C. L. Willey et al., NDE & E International, 2014
Ultrasound Tomography
Tomography attempts to reconstruct the spatial distribution of one or more
physical parameters of an object by studying the perturbation induced by the object's structure on the free propagation of either mechanical or electromagnetic waves. The wave-matter interaction can be modeled according to classical ray theory or under the more general framework of diffraction theory, which includes the former in the short wavelength limit. Thus, while a ray is, in general, sufficient to describe the propagation of high-energy photons in X-ray tomography of biological materials, diffraction, refraction and multiple scattering can become dominant when imaging the same material with ultrasound or microwave. The presence of these effects poses a number of fundamental challenges to the development of tomography technology. We have shown that ultrasound tomography can be engineered to achieve the same resolution as X-ray CT but without the risks associated with ionizing radiation.
F. Simonetti et al., Appl. Phys. Lett., 2009; F. Simonetti et al., Med. Phys, 2009; P. Huthwaite and F. Simonetti, J. Acoust. Soc. Am., 2011; P. Huthwaite, et al., J. Acoust. Soc. Am., 2012
Long-range Microwave Inspection
Corrosion under insulation (CUI) is a widespread problem in the oil and gas industry. Often pipes are fitted with a layer of insulation material protected by an external metallic cladding to maintain the fluid that they carry at constant temperature. Water infiltration through the cladding can cause corrosion of the inner pipe, therefore it is necessary to inspect pipeline for CUI. The inspection can be prohibitively expensive due to the need for removing the cladding and insulation to access the pipe with conventional NDE methods. We have developed a new approach that is based on the rationale that water is a necessary precursor to CUI and therefore it is desirable to detect it in order to prevent CUI formation in the first instance. Thanks to the conductivity of the pipe and cladding, the insulated pipeline naturally forms a large coaxial waveguide which supports the propagation of microwave signals along the insulation layer; the latter being typically transparent to microwave radiation. The microwave signal, which is excited by an array of antennas inserted in the insulation, travels along the pipeline and is reflected back towards the array upon impinging on an area of wet insulation. By timing the journey of the reflected signal, the location of the water volume can be determined according to the conventional radar principle.
S.M. Vejjavarapu and F. Simonetti, J. Nondestructive Evaluation, (2014)
Topology of Wave Propagation in Complex Tubular Waveguides
The study of wave propagation in complex 3-D structures is challenging due to the computational burden associated with the 3-D numerical models needed to solve Lamés equations of elasticity. We are developing equivalent acoustic models which use artificially inhomogeneous and anisotropic acoustic properties to capture the key phenomena involved in 3-D propagation. We therefore generalized the concept of unwrapping that is well known for simple cylindrical circular waveguides to any tubular structure. Besides reducing computation time by several orders of magnitude, the 2-D equivalent models facilitate the interpretation of wave phenomena since they are easier to display in 2-D.
Download the #1 2013 QNDE Student Poster
A. J. Brath et al., IEEE Trans. Ultrason. Ferroelectr. Freq. Contr., (2014).
Super Resolution Imaging
The possibility of imaging the structure of a medium with mechanical or electromagnetic waves has been limited by the tradeoff between resolution and imaging depth due to the diffraction limit. While long wavelengths can penetrate deep into a medium, diffraction effects preclude the possibility of observing subwavelength structures. On the other hand, short wavelengths, which would lead to high resolution, are rapidly attenuated with penetration depth so becoming insensitive to deep features. Our aim is to overcome the diffraction limit to obtain super resolved images by combining recent advances in array technology for ultrasonic sensing with novel inversion algorithms that better describe the interaction of waves with matter.
F. Simonetti et al. Phys. Rev. E, (2007);
F. Simonetti. Appl. Phys. Lett., (2006);
F. Simonetti. Phys. Rev. E, (2006).
Ultrasonics of Sessile Droplets
Surface acoustic wave (SAW) devices have attracted renewed attention in the context of microfluidic devices, where there is a need for actuating and manipulating liquids in the micro and nanometer scale to miniaturize biological and chemical processes. The interaction between a SAW and a droplet is highly complex and is presently the subject of extensive research. At USIL we investigate the wave phenomena that take place within the thin fluid layer of the droplet in contact with the substrate. In particular we study the existence of waves that circle around the droplet contact line and we develop methods to probe their characteristics using ultrasonic Rayleigh waves scattered from the droplet. An immediate application of this work is the ultrasonic estimation of the droplet contact angle and hence the surface tension of the liquid. Rayleigh waves can travel a large distance along the surface of the substrate and can be used to track the characteristics of droplet as it slides along an incline in real time, thus opening the possibility for accurate estimation of the dynamic contact angle.
Download the 2013 QNDE Poster
R. Quintero and F. Simonetti, Phys. Rev. E, 88, (2013)
Ultrasonic Imaging Laboratory
