Diffraction interaction of cracklike defects
- PDF / 1,418,013 Bytes
- 7 Pages / 595.276 x 793.701 pts Page_size
- 73 Downloads / 197 Views
DIFFRACTION INTERACTION OF CRACKLIKE DEFECTS Z. T. Nazarchuk and T. M. Stadnik
UDC 537.874
We study the influence of the electric permittivity of the material of two thin inclusions in the field of plane E-polarized electromagnetic waves and some parameters of the corresponding diffraction problem on the scattered field in the far-field zone.
The basic electrodynamic problem in the theory of nondestructive testing of materials is to find the final distribution of the field interacting with macroinhomogeneities of the investigated object [1]. To study the influence of a system of arbitrarily located thin inclusions with diffraction interaction, it is natural to consider the simplest case of two infinitely long (cylindrical) scatterers. This immediately decreases the dimensionality of the problem and substantially simplifies its numerical analysis. However, as a specific feature of description of the electromagnetic interaction of dangerous stress concentrators, i.e., cracklike defects, one can mention the necessity of taking into account the effect of penetration of sounding fields through their lips. This requires to use the electrophysical parameters of the material inside defects of this sort in mathematical models. There are different approaches to the solution of the corresponding diffraction problem [2]. In the two-dimensional case studied in the present work, the application of approximate one-dimensional integral equations, obtained as a result of averaging of their exact analogs defined on the cross-sectional areas of the defects turns out to be especially efficient. The procedure of averaging is based on the concept of electric and magnetic polarization currents, the assumption of small thicknesses of the defects, and some additional assumptions concerning the behavior of electric current inside the scatterers [3]. In [4], the numerical algorithm is constructed for this approach in the where the material contains a finite system of randomly located curvilinear cracklike defects. The aim of the present work is to study the influence of some electrophysical and geometric parameters of two permeable defects on their scattered field. Statement of the Problem Consider two identical cracklike defects, i.e., (cylindrical) inclusions of infinite length placed in a homogeneous isotropic material. The Oz-axis of a Cartesian coordinate system x y z is parallel to the generators of the inclusions. The plane x O y is perpendicular to the inclusions. Thus, the cross sections of the inclusions form certain regions whose median lines describe simple open Lyapunov arcs Lk = ak b k , k = 1, 2. We study the two-dimensional (scalar) problem of diffraction on the outlined structure of plane E-polarized electromagnetic waves of unit amplitude and length λ propagating in the plane xOy at an angle π + β to the abscissa. The materials of the defects and the body are nonmagnetic (i.e., their magnetic permeabilities μk and μ are equal to the magnetic permeability of vacuum μ0 ) and the wave numbers Karpenko Physicomechanical Inst
Data Loading...
