Periodic Reporting for period 1 - NOSTRADAMUS (NOn-contact STRucturAl DAMage for fUture Safety and lightweight)
Reporting period: 2021-10-01 to 2023-09-30
The MSCA NOSTRADAMUS action has advanced the current SoA in the field of remote sensing by developing a new scientific method for modal identification from high-speed video recordings. This has made the use of optical methods in the field of vibration fatigue easier and more reliable. The training components enabled the Fellow to expand his expertise and the Fellow’s previous work led to ground-breaking findings in these areas, so there was a real two-way transfer of knowledge. The NOSTRADAMUS project led to three publications in high impact journals and the presentation of the work at eight scientific conferences worldwide (EU, USA, Brazil). The action had a positive impact on the Fellow and strengthened his professional maturity and independence.
Research on Vibration Fatigue based on the training course consisted of replicating two papers from the host on VF using modal decomposition and short-time estimation of VF life non-stationary loading. During the training, experimental tests were conducted on the laboratory test cases. Then, the short-time life estimation procedure was extended to measuring the vibration response of the structure with a high-speed camera instead of using the limited number of classical sensors (accelerometers like in the repeated research). To enable cycle counting in the frequency domain, the strain-mode-shapes identified with the high-speed camera were converted into stress-mode-shapes. In this process, a new method for modal identification was developed, which is suitable for modal identification from high-speed camera measurements. The developed method was based on the Fellow’s previous research, and it is transferred to the host. Developed method was disseminated in the journal publication, and it is developed as the opensource python package (MorletWaveModal) to allow easy exploitation by others. Also, the presentation of the method and the opensource effort was communicated via scientific conferences and YouTube video presentations. To convert the measured strain to stress a linear elasticity theory was used as implemented in the FEM model (developed from the CAD model of the structure). The FEM model was mixed with the experimentally obtained strain-mode shapes using a sub-structuring method. Cycle counting using the multiaxial VF criteria was performed only for the dominant modes leading to damage assessment.
The work carried out extends the limits of identifying structural changes using high-speed cameras. The methods and software developed/upgraded (MorletWaveModal, PyIDI, FLife) are based on the bottom-up approach, i.e. they can be used independently of each other, which allows a broader application. The main contribution is made in the transport sector for the remote sensing of vehicle components from a vibration fatigue perspective. The work of remote sensing can be extended for the fault detection of bridges and in the energy sector for the blades of wind turbines.