Visible and infrared deflectometry for contactless and full-field vibration measurements

点击翻译按钮获取中文摘要

Mechanical, acoustical or aerodynamic excitations can induce structural vibrations, and the latter are of interest in noise and vibration monitoring and control, material testing and structural dynamics. Vibrations have been measured for more than a century using accelerometers. Contactless vibration measurements were introduced with the laser Doppler vibrometry that allows 2D and 3D vibration measurement on structures. In parallel, contactless and full-field vibration measurements have burgeoned with the availability of high-speed digital cameras. By imaging an entire surface at once, they can provide time- and space-resolved measurements that are well-suited for the study of non-stationary or transient phenomena. Among well-established techniques like digital image correlation, deflectometry is a measurement method gaining interest. Deflectometry provides reliable measurements with good sensitivity, all with a simple setup and a single camera. A recent progress is the successful application of deflectometry in the infrared spectrum for dynamic vibration measurements. Moving to the infrared domain and longer wavelengths compared to the visible domain relaxes the constraints on the surface roughness of a tested specimen, and allows measurements to be performed on common and unprepared surfaces. The two main objectives of the program are to increase the technology readiness level and to extend the application range of the deflectometry method. The development of an integrated measurement system to be used in laboratory and research contexts will play a centralizing role, being developed and used in projects conducted with several collaborators. Covered topics will range from the characterization of plane and curved isotropic panels and eco-materials, to identification methods concerning loadings or materials properties. Two novel implementations of deflectometry will also be considered at moderate frame rates (< 1000-2000 images per second). The first will be based on the development of a multi-camera setup using industrial grade cameras, and the second will be based on the development of a portable device (cellular phone, tablet) to evaluate the possibility of performing dynamic deflectometry measurements using such devices. The effectiveness of infrared deflectometry for dynamic vibration measurements was only established in 2021, and this work is expected to generate a subsequent stream of scientific developments and publications. The availability of a tool will broaden the range of potential applications for the deflectometry technique, and will provide a strategic advantage for industries and research in Canada. The availability of reliable full-field contactless measurements can pave the way towards a « materials and structures testing 2.0 » paradigm. This work will finally provide a perfect setting for training students by providing practical and modern industry-encouraged research and education topics in a multidisciplinary context.