“Smart Sounding System” for Autonomous Evaluation of Concrete and Metallic Structures

Impact sounding is recognized as an effective technique to detect delamination in concrete structures, such as steel reinforced concrete decks. Recent research by the proposers has shown that sound can be generated from an electronic speaker whose magnitude (volume) and frequency can be controlled in the form of electronic sound such as a chirp signal. Different from the mechanical vibration due to traditional hammer impacting, the electronic sounding is consistent and can be designed with certain frequency characteristics as exemplified in a chirp signal, which can excite concrete decks more than sound signals in other frequency bands. The developed electronic sounding tool is very simple and easy to install on multi-sensory robotic platforms such as crawlers and unmanned aerial vehicles (UAVs) without adding significant complexity to their operation and payload. The current sounding tool used a chirp sounding with a broad band of frequency covering 0 kHz to 14 kHz to excite the concrete surface. However, the common defects in concrete structures, such as shallow delamination, generally have a resonant response at a relatively low and narrow frequency band of 1 – 3 kHz and solid areas would show much higher frequency features. In this study, the sounding energy will thus be designed and targeted at the “delamination frequency band” to increase the response of the delamination signal while suppressing the response of the solid areas. Approach and Methodology: To improve the efficiency of delamination detection, the design of the current sounding tool will be refined to make it a “smart-sounding system” so that the emitted sound, speaker, and microphone all have a similar resonant frequency close to the dominant frequency of a defect area. In doing so, the defect will have the “ringing” effect when excited by the “smart-sounding system”. The “smart-sounding system” will also be equipped with an advanced tracking camera and global positioning system (GPS) device to provide detection mapping with accurate local position data for each collected sounding data point. By using the mapping device, no time-consuming and labor-intensive gridding process will be required of the current practice of impact sounding. In this project, the whole detection process of sounding collection, data analysis, and mapping will be integrated into a simple software tool for a fast evaluation of the structure condition. The sounding and mapping devices will also be integrated on a long-range pole for manual inspection, which would increase the accessibility of the detected areas and provide inspectors with greater flexibility for detecting a variety of structures. Both the software and hardware in the “smart sounding system” will be tested and validated at concrete bridge decks, concrete girders, and steel girders at a bridge site. If successful, the integrated sounding devices would be of great utility for damage detection for both concrete and metallic structures with high reliability and can be easily installed in crawlers or UAVs for autonomous detection. Overall Objectives: This project aims to develop a versatile electronic sounding tool that can be used to detect damage and delamination in the surface of concrete, metallic and composite structures. The tool will be incorporated into autonomous systems, such as a structural crawler. Scope of Work in Year 1: (1) Optimize the components of an electronic sounding tool for damage detection in both concrete and metallic structures, such as shallow delamination in concrete decks and cracks in steel beams, (2) Integrate the new “smart-sounding system” with the VSLAM technology for mapping and data collection, and (3) Test the developed “smart-sounding system” on concrete decks and concrete/steel girders at a bridge site.