Inspection of Dissimilar Material Joints Using Ultrasonic Phased Arrays

Abstract

Ultrasonic Inspection is widely used nondestructive testing technique. However, there are limited studies in the field of inspection of metal-composite adhesive joints. Since properties of dissimilar materials are different, reflection from the bonding between metal and composite occurs even without defects in the joint, what complicates the detection of defects in the joint. This work presents numerical and experimental study of ultrasonic inspection of metalcomposite adhesive joints. The numerical investigations were carried out using CIVA software. In this work phased array transducers of 3.5 MHz and 5 MHz frequency were studied and compared. It was determined, that there is a bigger possibility to detect delaminations using 3.5 MHz transducer due to stronger signal, but the complexity of defect detection is caused by dissimilar joint itselfultrasonic signal at the interface composite-metal is reflected even without defects in it. In order to improve the probability of defect detection in the interface the analysis of multiple reflections from the bonding zone was proposed.

Ultrasound-Mediated Drug Delivery in Cancer Therapy: A Review

“…US waves are mechanical sound waves with frequencies too high for the human ear to detect [5]. Within a single phase, be it gas, liquid or solid, the sound wave velocity c is dependent upon the medium's elasticity K and density .…”

“…The frequency of a sound wave is defined as the number of oscillations (or vibrations) per second and is measured in Hertz Hz. The wavelength describes the distance traveled in one oscillation and is derived from the frequency and the velocity [1,5].…”

“…The amplitude of a wave, A, can be measured in units of length or pressure. In terms of length, the amplitude is the maximum displacement of a point on a vibrating body or wave measured from its equilibrium position, whereas in terms of pressure, the amplitude describes the maximum local pressure [1,5,6].…”

“…Reflection is the change in the direction of a wave at an interface between two different media, while refraction is the deflection of a wave from its original direction as it passes between tissues with different acoustic properties. The acoustic property defining the difference between tissues is acoustic impedance Z, expressed mathematically as [1,5,7]:…”

“…Scatter occurs when a wave encounters a structure much smaller than its wavelength, while absorption is the conversion of sound energy into heat and is considered the main source of sound wave attenuation [1,5,7]. Attenuation is measured in relative units based on the intensity of the sound energy along the propagation path [1,5,7].…”