• Sels, Seppe

Abstract

Scientists and engineers are increasingly using cameras and laser-based optical measurement techniques to understand complex material behaviour or to assess the condition of a component or structure. Infrared thermography, for example, can be used to detect damage (as for instance delaminations) in an aircraft composite panel or composite bicycle frames. Scanning laser vibrometry on the other hand enables full-field vibration measurements, which can be used to detect fatigue crack propagating. One common feature of camera and laser-based techniques is that they provide information in a two-dimensional (2D) array (a camera image or laser scan responses in a set of vertical and horizontal angles). In this PhD thesis, we present a new computer vision methodology to link 2D measurement information with the three-dimensional (3D) coordinates of the real-world measurement locations. We use 2D or 3D cameras in combination with geometrical information of the test object (i.e. a CAD file) to get the location of the measurement instrument relative to the object. This information allows us to automatically determine the 3D location (and orientation) of each of the 2D measurement points. This location is crucial when comparing the measurements with simulation results (for instance from finite element simulations). Moreover, we show that the link between the 2D measurements and the 3D locations can also be used to physically project back the measurement information on the real-life object (for example by using a projector). This 3D location information can assist the user during the interpretation of the measurement results and the diagnosis of faults. In this thesis a framework is developed that is able to combine different measurement techniques, which is applied on real-world components or structures (a composite material bicycle frame, a car body, etc.).

Topics

• impedance spectroscopy
• simulation
• crack
• fatigue
• composite
• two-dimensional
• collision-induced dissociation
• thermography