ELASTIC-WAVE INTERACTIONS AS A PRINCIPLE OF VIBRATION MEASUREMENT

It is known that ultrasound can be used to measure the constant in tim e deformations and residual stresses, through the acoustoelasticity ef fect. The method presented here is different from this principle. It i s based on the non-resonant parametric interaction of elastic waves an d enables measurement of the dynamic deformation in elastic media. The aim of this work is to investigate the interaction of waves in non-li near elastic media with the deformation fields in parametric approxima tion and to create a method that permits observation (in three-dimensi ons) of the dynamic stress-state of the opaque elements of a structure . In particular, interest in the solution of this problem arises for h igh-frequency non-stationary loading on the structure, when it is impo ssible to determine the internal stress-state of the elastic body by m easurement of the vibration of its surface. The solution to this is fo und by using ultrasonic waves as a type of transducer that can freely penetrate the elastic body in the necessary direction.