Study on the Impedance Change of Rectangular Coil Perpendicular to Conductive Cylinder
- PDF / 976,768 Bytes
- 11 Pages / 612 x 792 pts (letter) Page_size
- 25 Downloads / 159 Views
LECTROMAGNETIC METHODS
Study on the Impedance Change of Rectangular Coil Perpendicular to Conductive Cylinder Ligang Liu* School of Automation Science and Electrical Engineering, Beihang University, Haidian District, Beijing, 100191 China *e-mail: [email protected] Received March 16, 2019; revised March 25, 2020; accepted April 29, 2020
Abstract—Cover meter is widely used to monitor the reinforced structures, and the response of the cover meter probe coil is used to locate the rebar, evaluate the diameter and cover depth of the rebar embedded in concrete. In order to analyze and optimize the performance of the cover meter, the analytical solution to the response of the probe is of great importance. Based on the theory of the second order vector potential (SOVP), the integral solutions to the coil coefficient and the impedance change of the rectangular coil are achieved when the normal direction of the coil is perpendicular to the axis of the conductive cylinder. The theoretical and experimental results are in excellent agreement induced not only by nonmagnetic materials but also by magnetic materials. The impedance changes of the rectangular coil and the circular coil with same sectional area are compared theoretically, as a consequence, the rectangular coil can help to find the direction of the rebar embedded in concrete. The allowed frequency of the coil is also discussed. These integral solutions to the impedance change of the rectangular coil can help the cover meter designers to optimize the coil parameters and the exciting frequency conveniently. Keywords: impedance, nondestructive test, cover meter, cover depth, rebar diameter DOI: 10.1134/S1061830920070062
1. INTRODUCTION The strength of concrete structures, such as load bearing beams and platforms, is critically dependent upon the integrity of the reinforcing components embedded within concrete. The most widely used reinforcing components are the steel reinforcing bars, such as round steel bars and ribbed bars. The position, diameter and the cover depth of the reinforcing components are essential parameters of the structural health. Evaluating these parameters without damage to the buildings is an essential part of constructing reinforced concrete structures. Electromagnetic detection has become the most common non-destructive method of locating the reinforcement embedded in reinforced concrete. Early in 1985, Behnam Motazed built a magnetic image system to analyze the bar size and the cover depth [1]. The workgroup of Junji Koido developed a mutual induction test coils with two tangential excitation coils and eight pairs of detection coil to test rebar diameter and cover depth [2]. The workgroup of Patrick Gaydecki made great efforts to image and analyse the parameters of the reinforcing steel bars embedded in concrete since 1994. They constructed an inductive scanning system, the original sensor was a tuned oscillator with a search coil installed at its head. It worked on the beat-frequency principle [3]. They also developed a magnetic field imaging sy
Data Loading...
