Study of Rebar Localization in Concrete Based on Magnetic Reluctance Technique Using COMSOL Multiphysics®

D. Tamhane[1], S. Tallur[1]
[1]Department of Electrical Engineering, Indian Institute of Technology Bombay, India
Published in 2019

Rebar detectors are used extensively by construction contractors to locate rebars while drilling, coring or cutting in RCC to avoid causing damage to the reinforcement steel. These detectors are also used by inspection engineers for spot checking of civil infrastructure. Most cost-efficient and portable rebar detectors conventionally employ eddy current based sensing, and come with limited utility i.e. they cannot detect intersecting rebars and are unable to provide area scans.

In this work we propose a modified magnetic reluctance technique to overcome this challenge. We use COMSOL Multiphysics®  to investigate the feasibility of our design modification by simulating the 2D cross sections of a permanent magnet with orthogonal soft iron arms and reinforcing steel bars. By implementing the Magnetic Fields interface and Stationary study in the AC/DC module, the profile of magnetic flux density is studied in this configuration. With the use of Domain Point Probe under the soft iron arm, we visualize the change in magnetic field density, which enables us to determine the location for optimal sensor placement. Generating a magnetic field profile in different Cut-Planes of the geometry allows us to calibrate our method for localizing the rebars in the area under test.