Piezoelectric Polymer Transducers for Detection of Structural Defects in Aircraft.

摘要

A new, versatile thin flim material, PVF2 (poly-vinylidene fluoride), has been fabricated into sensors for ultrasonic transducers because of its outstanding piezoelectric properties as well as its mechanical strength and chemical stability. PVF2 has a compliance ten times higher than that found in ceramics, and its g-constant (voltage per unit stress) is very high. Since the material can be made into very thin films, very wide-band electro-acoustic transducers can be incorporated into sensors that are flexible, variable in shape and a wide range of sizes. This fabrication versatility along with its relatively low cost, and its attractive piezoelectric, mechanical strength, and chemical stability makes this material a prime candidate for a large range of applications to monitor or inspect aircraft structures. A number of inspection techniques have been explored and are discussed. These include acoustic impact testing for ball bearing wear and crack formation in metal structures; pulse-echo and transmission ultrasonics to inspect composites. (Author)