PSI - Issue 64

Lukasz Scislo et al. / Procedia Structural Integrity 64 (2024) 2246–2253 Lukasz Scislo et al./ Structural Integrity Procedia 00 (2019) 000 – 000

2253

8

equipment and tooling. The typical problem of low signal strength can be solved by using one or multiple following solutions: • A speckle pattern approach can be used instead of a typical retro-reflective tape. However, in the case of non destructive testing, the typical approach utilising spray paint must be substituted with a powder-type solution. • A mirror can enhance signal strength and allow access to invisible surfaces. The mirror surface is smooth and allows for precise alignment of the vibrometer and the object, obtaining maximal optical signal strength. • While the typical way to input energy to the object requires a contact method (hammer, shaker), in the case of fragile objects, the energy can be supplied by a sound pressure source. However, in this case, the placement of the loudspeaker is essential. Preferable below 5 cm from the object and no more than 10 cm. Additionally, due to the small response amplitudes, it is advisable to use sensing technology that allows high-resolution measurements, such as a 3D LDV system. • While testing with the sound pressure source as an excitation energy source, it is preferable to use the pseudorandom function to avoid adverse sound effects for people working near the test site. • For challenging objects (dark or transparent, lightweight, fragile), e.g. historical or cultural objects and lightweight structures, all three approaches can be used to enhance the measurement quality. • Additionally, there are numerous techniques to improve the quality of mode shape visualisations, with particular attention to the technique called “ stitching ” , where multiple surfaces measured (e.g., using mirrors) can be put together to show unified measurement node movement. Acknowledgements L. Scislo wants to thank the Mechanical Laboratory at CERN for allowing him to become familiar with professional measurement techniques based on 3D LDV during his three years at this scientific establishment. References Al-Baghdadi, M., Jweeg, M.J., Al-Waily, M., 2021. SCIENCE & TECHNOLOGY Analytical and Numerical Investigations of Mechanical Vibration in the Vertical Direction of a Human Body in a Driving Vehicle using Biomechanical Vibration Model. Pertanika J. Sci. Technol 29, 2791 – 2810. https://doi.org/10.47836/pjst.29.4.30 Chen, Y., Escalera Mendoza, A.S., Griffith, D.T., 2023. Experimental Dynamic Characterisation of Both Surfaces of Structures using 3D Scanning Laser Doppler Vibrometer. Exp. Tech. 47, 989 – 1006. https://doi.org/10.1007/s40799-022-00604-2 Dawood, S.D.S., Harithuddin, A.S.M., Harmin, M.Y., 2022. Modal Analysis of Conceptual Microsatellite Design Employing Perforated Structural Components for Mass Reduction. Aerospace 9, 23. https://doi.org/10.3390/aerospace9010023 Fioriti, V., Roselli, I., Cataldo, A., Forliti, S., Colucci, A., Baldini, M., Picca, A., 2022. Motion Magnification Applications for the Protection of Italian Cultural Heritage Assets. Sensors 22, 9988. https://doi.org/10.3390/s22249988 Guinchard, M., Angeletti, M., Boyer, F., Catinaccio, A., Gargiulo, C., Lacny, L., Laudi, E., Scislo, L., 2018. Experimental modal analysis of lightweight structures used in particle detectors: optical non-contact method, in: Koscielniak, S. (Ed.), 9th International Particle Accelerator Conference, IPAC18, April 29 - May 4, 2018, Vancouver, Canada. JACoW, [S.l.], pp. 2565 – 2567. Hase, A., 2020. Early Detection and Identification of Fatigue Damage in Thrust Ball Bearings by an Acoustic Emission Technique. Lubricants 8, 37. https://doi.org/10.3390/lubricants8030037 Hasheminejad, N., Vuye, C., Van den bergh, W., Dirckx, J., Vanlanduit, S., 2018. A Comparative Study of Laser Doppler Vibrometers for Vibration Measurements on Pavement Materials. Infrastructures 3, 47. https://doi.org/10.3390/infrastructures3040047 Schewe, M., Rembe, C., 2021. Signal Diversity for Laser-Doppler Vibrometers with Raw-Signal Combination. Sensors 21, 998. https://doi.org/10.3390/s21030998 Scislo, L., 2023. Verification of Mechanical Properties Identification Based on Impulse Excitation Technique and Mobile Device Measurements. Sensors 23, 5639. https://doi.org/10.3390/s23125639 Scislo, L., 2021. Quality Assurance and Control of Steel Blade Production Using Full Non-Contact Frequency Response Analysis and 3D Laser Doppler Scanning Vibrometry System, in: 2021 11th IEEE International Conference on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications (IDAACS). IEEE, pp. 419 – 423. https://doi.org/10.1109/IDAACS53288.2021.9661060 Scislo, L., Andruszkiewicz, P., 2023. Verification of the Possibility of Using a Smartphone with Matlab Mobile in Transport Monitoring Applications, in: 2023 IEEE 12th International Conference on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications (IDAACS). IEEE, pp. 735 – 740. https://doi.org/10.1109/IDAACS58523.2023.10348938 Scislo, L., Szczepanik-Scislo, N., 2023. Quantification of Construction Materials Quality via Frequency Response Measurements: A Mobile Testing Station. Sensors 23, 8884. https://doi.org/10.3390/s23218884