PSI - Issue 64

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 64 (2024) 2246–2253

SMAR 2024 – 7th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures 3D Vibration Measurements with Optical Systems: Selected Methods for Measurement Enhancements Lukasz Scislo a, *, Izabela Drygala b a Faculty of Electrical and Computer Engineering, Cracow University of Technology, Warszawska 24, 31-155 Cracow, Poland b Faculty of Civil Engineering, Cracow University of Technology, Warszawska 24, 31-155 Cracow, Poland Abstract This paper presents selected measurement enhancement techniques while using a three-dimensional vibration measurement optical system. In this case, the 3D scanning Laser Doppler Vibrometer (3D LDV) is used to obtain the investigated test objects' frequency response functions (FRF). The 3D LDV system allows for contactless measurements of complicated objects and is ideal for cultural heritage objects where, in most cases, it is not permitted to mount sophisticated sensors or use contact methods for the excitation of vibrations. This approach can incorporate sound pressure to input the energy into the system and a LDV as sensing technology. In this way, the whole measurement procedure is performed entirely non-contact. Additionally, a high number of scan points can be obtained in a very short time. In the case of many objects, especially heritage ones, the additional problem is the lack of visibility of some surfaces from the place where the 3D LDV system is mounted or/and the lack of sufficient signal strength for proper signal acquisition. This paper presents typical problems and solutions to those issues. Some solutions include the advanced use of mirrors, stitching of measurement planes, and the use of enhancement surface techniques to improve signal strength during the measurement of particular surfaces or for particular difficult environmental conditions. This last element is especially worth evaluating in the case of the measurement of cultural objects in dark and dusty locations. The results demonstrate the feasibility of applying selected methods for 3D vibration measurement by the LDV system for specific objects. © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organisers Keywords: 3D LDV; Laser Doppler Vibrometer; optical measuremet system; surface enhancements; speckle pattern. © 2024 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers

* Corresponding author. E-mail address: lscislo@pk.edu.pl

2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers

2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers 10.1016/j.prostr.2024.09.352