Session: 18: Student poster competition

Paper Number: 117624

117624 - Wideband Nondestructive Characterization With Noncontact Guided Ultrasonic Waves 

There is a growing demand for new engineered materials and structures that meet today’s challenging operation needs such as composite materials for commercial aviation fleets or the new fuel rod cladding materials that can tolerate extreme accidental conditions. Coming with such a need is the equally important demand for the nondestructive evaluation (NDE) of the new materials for quality control. Manufacturing of engineered material structures is a multivariable task often involving several procedures where deviations from the design and even defects may occur, resulting in the need for assessment and quality control. Material properties such as Young’s modulus and structural thickness are key parameters for quality assurance and are often assessed by destructive tests on a very limited number of samples. On the other side, manufacturing defects such as void and delamination may appear in coated structures and laminated composites. If not detected these defects can cause significant degradation of the material strength and thus weaken the structural performance. Rapidly evaluating material parameters or detecting any anomalies that may occur from manufacturing is hence essential to the structural components to avoid ultimate failure.

Guided ultrasonic waves (GUW) nondestructive evaluation (NDE) represents a promising approach to assessing the structural integrity of components. The GUW method relies on elastic waves to achieve broad coverage across a range of material types and various failure modes. It usually includes two ultrasonic heads for transmitting and receiving ultrasonic signals. Laser technologies have been reported in the use of laser-based techniques to actuate ultrasonic waves to overcome the limitations of standard ultrasonic testing (UT). Using a nanosecond short pulse laser (PL) a correspondingly short ultrasonic signal will be produced and it can be used to measure the thickness of the structure as well as characterize its material properties such as Young’s modulus. The principal underneath is that the GUW characteristic parameters are significantly modified when thickness or Young’s modulus changes.

In this presentation, we will show the generation of ultra-wideband Lamb and Rayleigh surface waves on metallic or composite surfaces. A novel high-fidelity nondestructive fully remote ultrasonic inspection methodology using non-contact laser technology is developed for such a purpose. It uses a pulsed laser to excite high-frequency, wide-band ultrasonic waves through thermos-elastic transduction and a scanning laser Doppler vibrometer to measure the resulting waves in the time-space domain. By analyzing measurements, structural properties or integrity can be assessed. Work on effective actuation and sensing of such wideband, very high-frequency waves is also presented. Multidimensional Fourier transform is applied to the acquired wave propagation data to generate quantitative evaluations of structural conditions. Finally, inspection capabilities with the laser-based GUW NDE are demonstrated in samples made of various materials and of different thicknesses. The results shown in this work demonstrate a unique characterization and inspection methodology that provides an evaluation of engineered structural components.

Presenting Author: Andrew Campbell University of South Carolina - College of Engineering and Computing

Presenting Author Biography: I received my bachelor's and Master's in Mechanical Engineering from the University of South Carolina, I am currently working on a Ph.D. under the guidance of Dr. Lingyu Yu as a part of the Visualized Structural Health Monitoring Laboratory where I am working on the development of a fully noncontact Nondestructive Evaluation (NDE) method using Guided Ultrasonic Waves (GUW). This method aims to have applications in isotropic metallic structures, composites, and complex structures.