Crack Detection in Metallic Structures Using Planar Monopole Antenna

Abstract

Highlights: What are the main findings? A monopole antenna is established as a crack sensor for Structural Health Monitoring (SHM) applications. Distinguishable sensitivities of −41.2 MHz/mm and −30.2 MHz/mm are observed along the crack propagation directions (X and Y) on the ground plane. What are the implications of the main findings? The proposed sensor can be attached to planar metallic surfaces to monitor the health condition of the structure. Among the other Radio Frequency (RF) sensors, the proposed monopole antenna sensor is unique due to its higher sensitivity, compactness and ease of fabrication. In this paper, a monopole antenna is devised to detect the presence of a crack for Structural Health Monitoring (SHM) application. The performance parameters of the antenna sensor are numerically evaluated using Finite Element Analysis (FEA) and experimentally validated. A crack is introduced as a perturbation in the ground plane of the monopole antenna, resembling the metallic part of the structure that is monitored. The linear resonance frequency shifts in the monopole antenna validate the presence and propagation of a crack in the structure under observation. Different orientations and dimensions of the crack are analyzed to study the sensitivity of the monopole antenna as a sensor for crack detection with a higher sensitivity of −41.2 MHz/mm. The influence of the crack on the gain and radiation patterns is also addressed to evaluate the performance degradation. The simulation and experiment results ensure the ability of the proposed antenna sensor to detect minute structural defects in metallic structures.