Features of ultrasonic shadow testing of foam plastics based on time-amplitude parameters Part II

摘要

Features of ultrasonic shadow testing of hard foam plastics are discussed. Foam plastics are very difficult objects of testing because of their highly inhomogeneous structure depending on the processes of foaming and solidification of polymers. The main conclusion of the reported study is that shadow techniques based on the amplitude and temporal characteristics present a particular case of the more complex time-amplitude ultrasonic shadow testing technique. At low frequencies, flaws can he treated as entities transparent to acoustic waves. With due account of this fact, both the flaw extension and its thickness can be estimated. In addition, variations in the ultrasound velocity due to anisotropy and dominant orientations of cells in foam plastics should be taken into consideration.