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Dynamic FEM Simulation for the Development of a Sensor Head for a Drone Based Concrete Inspection System

The Uncrewed Aerial Concrete Inspection System (UACIS) research project represents the introduction of modern and highly capable drone technology to non-destructive testing. Drones are hereby identified as the key to efficiency and effectiveness in non-destructive testing (NDT). The objective of the development is to apply the system to infrastructures as well as to supporting structures for example in energy technology. In particular, bridges, containments or cooling towers are the focus of structural inspections due to their aging structure and limited accessibility. In addition to non-contact inspection, the drone system is also able to apply mechanical contact forces to component surfaces in almost any orientation. Areas that are otherwise difficult to access are thus also reachable for contact inspection techniques. The system is based on a developer drone platform, which can realize sufficiently large contact pressures to component surfaces for several seconds. A drone-based impact echo measurement payload was developed for this platform. The impact echo method is a NDT technique where elastic stress waves are excited in the inspected structure with a hammer or a steel ball, and the reflections are measured and analyzed in the frequency domain. This technique can be used to measure wall thicknesses, but also to find defects such as flaws or delaminations. It is very important to understand the dynamic response of the entire measurement system as it is very sensitive to its own stiffness and resonance behavior as well as to external noise. Furthermore, the structural coupling between the hammer and the sensor also influences the dynamics and thus the measurement quality. Detailed simulation studies are crucial for the successful development of such a measurement payload. In particular, the dynamic behavior of the payload structure itself, but also its interaction with the wall is of interest. Therefore, a parametric design study is conducted solving for the steady state dynamic solution due to harmonic excitations with the goal to find the most suitable mechanical design solution for the sensor support structure. This also considers different boundary conditions which distinguish between different contact situations of the drone with the wall. A further addressed challenge is the modeling of the mechanical behavior of the 3D printed support structure in terms of geometrical as well as material properties. To conduct the parametric study an engineering simulation workflow is established using a commercial finite element software package. The most promising design is then realized using 3D printing. Finally, the payload is tested, and the results are compared to the simulation. This payload solution has a high potential to contribute to predictive maintenance and thus to maximize the service life of relevant building structures.

Document Details

ReferenceNWC23-0291-fullpaper
AuthorsThurnherr. C
LanguageEnglish
TypePaper
Date 18th May 2023
OrganisationSVTI Schweizerischer Verein für technische Inspektionen
RegionGlobal

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