ON THE GENERATION AND DETECTION OF ULTRASONIC PLATE WAVES IN MICROPOROUS

Membranes are among the most important engineering components in use in many process industries. Examples of uses for membranes include water purification, industrial effluent treatment, recovery of volatile organic compounds, protein recovery, bio-separations and many others. Polymeric membranes are the most commonly used membranes. Membranes act as a barrier through which fluids and solutes are selectively transported. Quality assurance is a critical aspect of membrane module fabrication. In other materials, ultrasound has been widely used for materials characterization as well as flaw detection. Recently ultrasonic techniques have been used to detect the presence of defects in membranes. This thesis describes the use of guided waves in membrane applications to improve the ability to inspect large areas of membranes. Plate waves also have the potential to provide additional information in asymmetric membranes. The present effort focuses on developing techniques that make it possible to test microporous membranes using low frequency ultrasonic guided waves. The sensitivity of the material attenuation in polyvinylidene fluoride (PVDF) membrane material wit