2020 Volume 76 Issue 2 Pages I_15-I_24
This paper presents a 2-D elastodynamic time-reversal method using the topological sensitivity for the defect detection indicator in order to determine the number and position of defects in an elastic solid. The time-reversal method is the method to estimate the defect position and elsewhere from the convergence positions of the time-reversal waves when the received scattered waves by defects are time-reversed, and sent back again into an elastic solid. In general, it is difficult to quantitatively evaluate the convergence positions of the time-reversal waves. To overcome this problem, several researches have been done by us to determine the convergence positions of the time-reversal waves for scalar wave problems. However, these achievements for scalar wave problems cannot be applicable to elastodynamic problems because the waves in a solid show the property of the elastic wave. Therefore, in this research, we extend the previous researches for scalar waves to 2-D elastodynamics, and try to determine the number and positions of defects in a solid by using an elastodynamic time-reversal waves and the topological sensitivity. The ultrasonic non-destructive testing (UT) using a linear array transducer is considered, and the convolution quadrature time-domain boundary element method (CQBEM) for 2-D elastodynamics is utilized to obtain scattered wave ?elds by defects in a solid. As numerical examples, some defect detection results are demonstrated to investigate the performance of the present method.
