Journal articles: '3D Laser vibrometry'

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Breaban, Florin, Roger Debuchy, and Didier Defer. "Laser Scanning Vibrometry and Holographic Interferometry Applied to Vibration Study." Applied Mechanics and Materials 801 (October 2015): 303–11. http://dx.doi.org/10.4028/www.scientific.net/amm.801.303.

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The applications of high performance materials in the aerospace and in the automotive technology in the next years need to develop new vibration study, nondestructive testing, predictive maintenance and industrial control methods.The Laser Scanning Vibrometry and Holographic Interferometry methods of vibration study and nondestructive testing by modal analysis are described. The Laser Scanning Vibrometer PSV 400 is made by Polytec GmbH and the PSV software reconstructs the 3D model of the measured micro-deformation of the object. The holographic laser system HLS-3 from Lumonics Inc. has 100 MW ruby laser peak power and 30 ns pulse width.Using mechanical excitation to induce a measurable vibration, the Laser Scanning Vibrometry and Holographic Interferometry modal analysis measurements show up the vibrational signatures and the damaged areas of the objects made by high performance materials - polymers, composites.

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Orta, Adil Han, Mathias Kersemans, and Koen Van Den Abeele. "On the Identification of Orthotropic Elastic Stiffness Using 3D Guided Wavefield Data." Sensors 22, no. 14 (July 15, 2022): 5314. http://dx.doi.org/10.3390/s22145314.

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Scanning laser Doppler vibrometry is a widely adopted method to measure the full-field out-of-plane vibrational response of materials in view of detecting defects or estimating stiffness parameters. Recent technological developments have led to performant 3D scanning laser Doppler vibrometers, which give access to both out-of-plane and in-plane vibrational velocity components. In the present study, the effect of using (i) the in-plane component; (ii) the out-of-plane component; and (iii) both the in-plane and out-of-plane components of the recorded vibration velocity on the inverse determination of the stiffness parameters is studied. Input data were gathered from a series of numerical simulations using a finite element model (COMSOL), as well as from broadband experimental measurements by means of a 3D infrared scanning laser Doppler vibrometer. Various materials were studied, including carbon epoxy composite and wood materials. The full-field vibrational velocity response is converted to the frequency-wavenumber domain by means of Fourier transform, from which complex wavenumbers are extracted using the matrix pencil decomposition method. To infer the orthotropic elastic stiffness tensor, an inversion procedure is developed by coupling the semi-analytical finite element (SAFE) as a forward method to the particle swarm optimizer. It is shown that accounting for the in-plane velocity component leads to a more accurate and robust determination of the orthotropic elastic stiffness parameters.

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Weekes, Ben, and David Ewins. "Multi-frequency, 3D ODS measurement by continuous scan laser Doppler vibrometry." Mechanical Systems and Signal Processing 58-59 (June 2015): 325–39. http://dx.doi.org/10.1016/j.ymssp.2014.12.022.

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Marks, Ryan, Clare Gillam, Alastair Clarke, Joe Armstrong, and Rhys Pullin. "Damage detection in a composite wind turbine blade using 3D scanning laser vibrometry." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 16 (December 6, 2016): 3024–41. http://dx.doi.org/10.1177/0954406216679612.

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As worldwide wind energy generation capacity grows, there is an increasing demand to ensure structural integrity of the turbine blades to maintain efficient and safe energy generation. Currently, traditional non-destructive testing methods and visual inspections are employed which require the turbine to be out-of-operation during the inspection periods, resulting in costly and lengthy downtime. This study experimentally investigates the potential for using Lamb waves to monitor the structural integrity of a composite wind turbine blade that has been subject to an impact representative of damage which occurs in service. 3D scanning laser vibrometry was used to measure Lamb waves excited at three different frequencies both prior to, and after, impact to identify settings for an optimal system. Signal processing techniques were applied to the datasets to successfully locate the damage and highlight regions on the structure where the Lamb wave was significantly influenced by the presence of the impact damage. Damage size resulting from the impact was found to correlate well with the laser vibrometry results. The study concluded that acousto-ultrasonic-based structural health monitoring systems have great potential for monitoring the structural integrity of wind turbine blades.

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Derusova, Daria A., Vladimir P. Vavilov, Nikolay V. Druzhinin, Victor Y. Shpil’noi, and Alexey N. Pestryakov. "Detecting Defects in Composite Polymers by Using 3D Scanning Laser Doppler Vibrometry." Materials 15, no. 20 (October 14, 2022): 7176. http://dx.doi.org/10.3390/ma15207176.

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The technique of 3D scanning laser Doppler vibrometry has recently appeared as a promising tool of nondestructive evaluation of discontinuity-like defects in composite polymers. The use of the phenomenon of local defect resonance (LDR) allows intensifying vibrations in defect zones, which can reliably be detected by means of laser vibrometry. The resonance acoustic stimulation of structural defects in materials causes compression/tension deformations, which are essentially lower than the material tensile strength, thus proving a nondestructive character of the LDR technique. In this study, the propagation of elastic waves in composites and their interaction with structural inhomogeneities were analyzed by performing 3D scanning of vibrations in Fast Fourier Transform mode. At each scanning point, the in-plane (x, y) and out of plane (z) vibration components were analyzed. The acoustic stimulation was fulfilled by generating a frequency-modulated harmonic signal in the range from 50 Hz to 100 kHz. In the case of a reference plate with a flat bottom hole, the resonance frequencies for all (x, y, and z) components were identical. In the case of impact damage in a carbon fiber reinforced plastic sample, the predominant contribution into total vibrations was provided by compression/tension deformations (x, y vibration component) to compare with vibrations by the z coordinate. In general, inspection results were enhanced by analyzing total vibration patterns obtained by averaging results at some resonance frequencies.

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Crua, Cyril, and Morgan R. Heikal. "Time-resolved fuel injector flow characterisation based on 3D laser Doppler vibrometry." Measurement Science and Technology 25, no. 12 (October 29, 2014): 125301. http://dx.doi.org/10.1088/0957-0233/25/12/125301.

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Scislo, Lukasz. "Single-Point and Surface Quality Assessment Algorithm in Continuous Production with the Use of 3D Laser Doppler Scanning Vibrometry System." Sensors 23, no. 3 (January 22, 2023): 1263. http://dx.doi.org/10.3390/s23031263.

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In the current economic situation of many companies, the need to reduce production time is a critical element. However, this cannot usually be carried out with a decrease in the quality of the final product. This article presents a possible solution for reducing the time needed for quality management. With the use of modern solutions such as optical measurement systems, quality control can be performed without additional stoppage time. In the case of single-point measurement with the Laser Doppler Vibrometer, the measurement can be performed quickly in a matter of milliseconds for each product. This article presents an example of such quality assurance measurements, with the use of fully non-contact methods, together with a proposed evaluation criterion for quality assessment. The proposed quality assurance algorithm allows the comparison of each of the products’ modal responses with the ideal template and stores this information in the cloud, e.g., in the company’s supervisory system. This makes the presented 3D Laser Vibrometry System an advanced instrumentation and data acquisition system which is the perfect application in the case of a factory quality management system based on the Industry 4.0 concept.

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Staszewski, W. J., B. C. Lee, and R. Traynor. "Fatigue crack detection in metallic structures with Lamb waves and 3D laser vibrometry." Measurement Science and Technology 18, no. 3 (January 24, 2007): 727–39. http://dx.doi.org/10.1088/0957-0233/18/3/024.

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Pedrini, G., S. Schedin, and H. J. Tiziani. "Pulsed digital holography combined with laser vibrometry for 3D measurements of vibrating objects." Optics and Lasers in Engineering 38, no. 3-4 (September 2002): 117–29. http://dx.doi.org/10.1016/s0143-8166(02)00005-2.

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Filippov, Andrey V., Vladimir A. Krasnoveikin, Nikolay V. Druzhinin, and Valery E. Rubtsov. "The Use of Laser-Doppler Vibrometry for Modal Analysis of Carbon-Fiber Reinforced Composite." Key Engineering Materials 712 (September 2016): 313–18. http://dx.doi.org/10.4028/www.scientific.net/kem.712.313.

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Both modal analysis procedure and the results obtained on a three-component 3D-printed carbon-fiber reinforced composite (CFRC) are presented. Experimental modal analysis of on the composite has been carried out to obtain the dynamic behavior characteristics. As revealed, the different eigen-oscillations waveforms possess different sensitivity of its amplitude frequency response to structural defects of the composite. For the similar waveforms we observed the differences in eigen-oscuillation frequencies, vibration velocities and damping factors which can be caused by the presence of numerous defects homogeneously distributed in one of the samples.

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Medel, Francisco, Víctor Esteban, and Javier Abad. "On the use of laser-scanning vibrometry for mechanical performance evaluation of 3D printed specimens." Materials & Design 205 (July 2021): 109719. http://dx.doi.org/10.1016/j.matdes.2021.109719.

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Aryan, P., A. Kotousov, C. T. Ng, and B. S. Cazzolato. "A baseline-free and non-contact method for detection and imaging of structural damage using 3D laser vibrometry." Structural Control and Health Monitoring 24, no. 4 (June 10, 2016): e1894. http://dx.doi.org/10.1002/stc.1894.

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Lee, Hee Yoon, Patrick D. Raphael, Jesung Park, Audrey K. Ellerbee, Brian E. Applegate, and John S. Oghalai. "Noninvasive in vivo imaging reveals differences between tectorial membrane and basilar membrane traveling waves in the mouse cochlea." Proceedings of the National Academy of Sciences 112, no. 10 (March 3, 2015): 3128–33. http://dx.doi.org/10.1073/pnas.1500038112.

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Sound is encoded within the auditory portion of the inner ear, the cochlea, after propagating down its length as a traveling wave. For over half a century, vibratory measurements to study cochlear traveling waves have been made using invasive approaches such as laser Doppler vibrometry. Although these studies have provided critical information regarding the nonlinear processes within the living cochlea that increase the amplitude of vibration and sharpen frequency tuning, the data have typically been limited to point measurements of basilar membrane vibration. In addition, opening the cochlea may alter its function and affect the findings. Here we describe volumetric optical coherence tomography vibrometry, a technique that overcomes these limitations by providing depth-resolved displacement measurements at 200 kHz inside a 3D volume of tissue with picometer sensitivity. We studied the mouse cochlea by imaging noninvasively through the surrounding bone to measure sound-induced vibrations of the sensory structures in vivo, and report, to our knowledge, the first measures of tectorial membrane vibration within the unopened cochlea. We found that the tectorial membrane sustains traveling wave propagation. Compared with basilar membrane traveling waves, tectorial membrane traveling waves have larger dynamic ranges, sharper frequency tuning, and apically shifted positions of peak vibration. These findings explain discrepancies between previously published basilar membrane vibration and auditory nerve single unit data. Because the tectorial membrane directly overlies the inner hair cell stereociliary bundles, these data provide the most accurate characterization of the stimulus shaping the afferent auditory response available to date.

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Wang, Chia-Fu, Junghyun Wee, and Kara Peters. "Amplifying Lamb Wave Detection for Fiber Bragg Grating with a Phononic Crystal GRIN Lens Waveguide." Sensors 22, no. 21 (November 2, 2022): 8426. http://dx.doi.org/10.3390/s22218426.

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This paper demonstrates that a graded-index (GRIN) phononic lens, combined with a channel waveguide, can focus anti-symmetric Lamb waves for extraction by a detector with strong directional sensitivity. Guided ultrasonic wave inspection is commonly applied for structural health monitoring applications; however, obtaining sufficient signal amplitude is a challenge. In addition, fiber Bragg grating (FBG) sensors have strong directional sensitivity. We fabricate the GRIN structure, followed by a channel waveguide starting at the focal point, using a commercial 3D printer and mount it on a thin aluminum plate. We characterize the focusing of the A0 mode Lamb wave in the plate, traveling across the GRIN lens using 3D laser Doppler vibrometry. We also measure the extraction of focused energy using an FBG sensor, examining the optimal sensor bond location and bond length in the channel of the waveguide for maximum signal extraction. The measured amplification of the ultrasound signal is compared to theoretical predictions. The results demonstrate that significant amplification of the waveform is achieved and that selecting the location of the FBG sensor in the channel is critical to optimizing the amplification.

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Marks, R., A. Clarke, C. Featherston, L. Kawashita, C. Paget, and R. Pullin. "Using genetic algorithms to optimize an active sensor network on a stiffened aerospace panel with 3D scanning laser vibrometry data." Journal of Physics: Conference Series 628 (July 9, 2015): 012116. http://dx.doi.org/10.1088/1742-6596/628/1/012116.

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Rittmeier, Liv, Thomas Roloff, Natalie Rauter, Andrey Mikhaylenko, Jan Niklas Haus, Rolf Lammering, Andreas Dietzel, and Michael Sinapius. "Influence of a Flat Polyimide Inlay on the Propagation of Guided Ultrasonic Waves in a Narrow GFRP-Specimen." Materials 15, no. 19 (September 29, 2022): 6752. http://dx.doi.org/10.3390/ma15196752.

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Structural health monitoring systems for composite laminates using guided ultrasonic waves become more versatile with the structural integration of sensors. However, the data generated within these sensors have to be transmitted from the laminate to the outside, where polyimide-based printed circuit boards play a major role. This study investigates, to what extent integrated polyimide inlays with applied sensor bodies influence the guided ultrasonic wave propagation in glass fiber-reinforced polymer specimens. For reasons of resource efficiency, narrow specimens are used. Numerical simulations of a damping-free specimen indicate reflections of the S0-mode at the integrated inlay. This is validated experimentally with an air-coupled ultrasonic technique and a 3D laser Doppler vibrometry measurement. The experimental data are evaluated with a method including temporal and spatial continuous wavelet transformations to clearly identify periodically occurring wave packages as edge reflections and distinguish them from possible inlay reflections. However, even when separating in-plane and out-of-plane movements using the 3D measurement, no reflections at the inlays are detected. This leads to the conclusion that polyimide inlays are well suited as substrates for printed circuit boards integrated into fiber-reinforced polymer structures for structural health monitoring, since they do not significantly influence the wave propagation.

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Sharma, Arun K., and Bishakh Bhattacharya. "Parameter estimation of butyl rubber aided with dynamic mechanical analysis for numerical modelling of an air-inflated torus and experimental validation using 3D-laser Doppler vibrometer." Journal of Low Frequency Noise, Vibration and Active Control 38, no. 2 (January 30, 2019): 296–311. http://dx.doi.org/10.1177/1461348419825685.

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Over the few decades, there has been an exponential growth in the application of inflated torus system in the field of space deployable antenna design, solar propulsion, and aerodynamic deceleration system. However, such a system is inherently susceptible to mechanical vibration and hence requires precise modal analysis to produce stable inflatable structures. This paper summarizes all the necessary steps to be followed for dynamic analysis of inflatable structures. With this objective, a butyl rubber-based inflated torus system with dynamic material properties has been considered in this work. On performing mechanical tests of the rubber sample, properties like Prony series parameters, complex modulus, and damping values were obtained. Using laser Doppler vibrometry, the modal behavior of a butyl rubber-based air-inflated torus with free–free boundary condition was studied. The results achieved from experimental modal analysis and simulation involving fluid–structure interaction were found to be in close proximity. It is envisaged that the test template integrated with numerical validation can lay the foundation for designing complex inflatable torus structures.

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Woodrow, Charlie, Ed Baker, Thorin Jonsson, and Fernando Montealegre-Z. "Reviving the sound of a 150-year-old insect: The bioacoustics of Prophalangopsis obscura (Ensifera: Hagloidea)." PLOS ONE 17, no. 8 (August 10, 2022): e0270498. http://dx.doi.org/10.1371/journal.pone.0270498.

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Determining the acoustic ecology of extinct or rare species is challenging due to the inability to record their acoustic signals or hearing thresholds. Katydids and their relatives (Orthoptera: Ensifera) offer a model for inferring acoustic ecology of extinct and rare species, due to allometric parameters of their sound production organs. Here, the bioacoustics of the orthopteran Prophalangopsis obscura are investigated. This species is one of only eight remaining members of an ancient family with over 90 extinct species that dominated the acoustic landscape of the Jurassic. The species is known from only a single confirmed specimen–the 150-year-old holotype material housed at the London Natural History Museum. Using Laser-Doppler Vibrometry, 3D surface scanning microscopy, and known scaling relationships, it is shown that P. obscura produces a pure-tone song at a frequency of ~4.7 kHz. This frequency range is distinct but comparable to the calls of Jurassic relatives, suggesting a limitation of early acoustic signals in insects to sonic frequencies (<20 kHz). The acoustic ecology and importance of this species in understanding ensiferan evolution, is discussed.

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Hedayatrasa, Saeid, and Mathias Kersemans. "3D intra-cellular wave dynamics in a phononic plate with ultra-wide bandgap: attenuation, resonance and mode conversion." Smart Materials and Structures 31, no. 3 (February 2, 2022): 035010. http://dx.doi.org/10.1088/1361-665x/ac4d65.

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Abstract The intra-cellular wave dynamics of a water jetted phononic plate are experimentally investigated by means of high-resolution three-dimensional (3D) scanning laser Doppler vibrometry. The study is focused on the vibrational behavior around the ultra-wide bandgap of the plate (with a relative bandgap width of 0.89), as the critical frequency range of its phononic functionality. Broadband vibrational excitations are applied using a piezoelectric transducer and both in-plane and out-of-plane operational deflection shapes of the unit-cells are analyzed with respect to mode shapes calculated by finite element (FE) simulation. Attenuation and resonance of both symmetric and antisymmetric wave modes are validated, and it is shown that despite the absence of in-plane wave energy actuation, the symmetric modes are effectively excited in the phononic lattice, due to mode conversion from co-existing antisymmetric modes. Supported by FE modal analysis, this mode conversion observation is explained by the slight through-the-thickness asymmetry introduced during manufacturing of the phononic plate which leads to coupling of modes with different symmetry. The results confirm the potential of such detailed 3D inspection of phononic crystals (and in general acoustic metamaterials) in gaining full insight about their intracellular dynamics, which can also illuminate discrepancies with respect to idealized numerical models that might be due to manufacturing imperfections.

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Heinz, Stefan, Frank Balle, Guntram Wagner, and Dietmar Eifler. "Analysis of fatigue properties and failure mechanisms of Ti6Al4V in the very high cycle fatigue regime using ultrasonic technology and 3D laser scanning vibrometry." Ultrasonics 53, no. 8 (December 2013): 1433–40. http://dx.doi.org/10.1016/j.ultras.2013.03.002.

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Normandin, Benjamin, and Martin Veidt. "Single Transducer Pair Lamb Wave Time Reversal for Damage Detection in Composite Laminates." Key Engineering Materials 558 (June 2013): 205–17. http://dx.doi.org/10.4028/www.scientific.net/kem.558.205.

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This paper investigates the potential of single transducer pair guided waves time reversal to detect damage in composite laminates. According to dynamic reciprocity of Lamb waves propagation in linear media, the time reversal process should reconstruct the original signal. The similarity of original and reconstructed time signals is calculated for different damage types using numerical and experimental studies with the aim to investigate, if the interaction of the wave pulse with inhomogeneities introduces any nonlinearity that time reversibility breaks down and single transducer pair time reversal could be used as damage diagnostics tool. 3D explicit finite element analysis is used for the numerical simulation and laser Doppler vibrometry is used to capture out-of-plane displacement time histories excited by an adhesively bonded piezoceramic transducer disc in the experimental time reversal process. In the case of an undamaged composite laminate the similarity index used to quantify the similarity of the original and reconstructed wave pulses is better than 95%. The similarity index is smaller for laminates with artificial damages including embedded fluoro polymer films to simulate delamination damage, through holes and bonded mass inhomogeneities. Although numerical and experimental similarity indices are smaller at higher frequencies, there is no clear evidence that single transducer pair time reversibility breaks down and represents a reliable damage diagnostics tool.

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Díaz-García, Lara, Andrew Reid, Joseph Jackson-Camargo, and James Windmill. "Directional passive acoustic structures inspired by the ear of Achroia grisella." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A92. http://dx.doi.org/10.1121/10.0015652.

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The need for small directional microphones is patent in the current market. From smartphones to hearing aids, a small microphone capable of rejecting ambient noise is highly desirable. Most MEMS microphones are omnidirectional and have to resort to arrays to achieve directionality, effectively counteracting the reduced size that they offer in the first place. For this reason, we use bio-inspiration and turn to nature to find examples of solutions to this problem. The female specimens of the moth Achroia grisella are capable of monoaural directional hearing, which they use to track the males’ mating calls. It is believed that they achieve directionality solely due to the morphology of their tympana. To test it, we first produce a multiphysics simulation of the structure that serves as a starting point. For experimental measurements, additive manufacturing is chosen for its ease and cost-efficiency. 3D-printed samples of the same model are examined through micro-CT scanning and then measured using laser-Doppler vibrometry to determine their frequency and directivity responses. The results of both approaches are compared, and it is found that the structure does indeed show directionality with the second eigenfrequency showing a hypercardioid-like pattern towards the front of the moth.

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Reid, Andrew, Thibaut Marin-Cudraz, James F. C. Windmill, and Michael D. Greenfield. "Evolution of directional hearing in moths via conversion of bat detection devices to asymmetric pressure gradient receivers." Proceedings of the National Academy of Sciences 113, no. 48 (November 14, 2016): E7740—E7748. http://dx.doi.org/10.1073/pnas.1615691113.

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Small animals typically localize sound sources by means of complex internal connections and baffles that effectively increase time or intensity differences between the two ears. However, some miniature acoustic species achieve directional hearing without such devices, indicating that other mechanisms have evolved. Using 3D laser vibrometry to measure tympanum deflection, we show that female lesser waxmoths (Achroia grisella) can orient toward the 100-kHz male song, because each ear functions independently as an asymmetric pressure gradient receiver that responds sharply to high-frequency sound arriving from an azimuth angle 30° contralateral to the animal's midline. We found that females presented with a song stimulus while running on a locomotion compensation sphere follow a trajectory 20°–40° to the left or right of the stimulus heading but not directly toward it, movement consistent with the tympanum deflections and suggestive of a monaural mechanism of auditory tracking. Moreover, females losing their track typically regain it by auditory scanning—sudden, wide deviations in their heading—and females initially facing away from the stimulus quickly change their general heading toward it, orientation indicating superior ability to resolve the front–rear ambiguity in source location. X-ray computer-aided tomography (CT) scans of the moths did not reveal any internal coupling between the two ears, confirming that an acoustic insect can localize a sound source based solely on the distinct features of each ear.

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Shen, Zhiyuan, Thomas R. Neil, Daniel Robert, Bruce W. Drinkwater, and Marc W. Holderied. "Biomechanics of a moth scale at ultrasonic frequencies." Proceedings of the National Academy of Sciences 115, no. 48 (November 12, 2018): 12200–12205. http://dx.doi.org/10.1073/pnas.1810025115.

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The wings of moths and butterflies are densely covered in scales that exhibit intricate shapes and sculptured nanostructures. While certain butterfly scales create nanoscale photonic effects, moth scales show different nanostructures suggesting different functionality. Here we investigate moth-scale vibrodynamics to understand their role in creating acoustic camouflage against bat echolocation, where scales on wings provide ultrasound absorber functionality. For this, individual scales can be considered as building blocks with adapted biomechanical properties at ultrasonic frequencies. The 3D nanostructure of a full Bunaea alcinoe moth forewing scale was characterized using confocal microscopy. Structurally, this scale is double layered and endowed with different perforation rates on the upper and lower laminae, which are interconnected by trabeculae pillars. From these observations a parameterized model of the scale’s nanostructure was formed and its effective elastic stiffness matrix extracted. Macroscale numerical modeling of scale vibrodynamics showed close qualitative and quantitative agreement with scanning laser Doppler vibrometry measurement of this scale’s oscillations, suggesting that the governing biomechanics have been captured accurately. Importantly, this scale of B. alcinoe exhibits its first three resonances in the typical echolocation frequency range of bats, suggesting it has evolved as a resonant absorber. Damping coefficients of the moth-scale resonator and ultrasonic absorption of a scaled wing were estimated using numerical modeling. The calculated absorption coefficient of 0.50 agrees with the published maximum acoustic effect of wing scaling. Understanding scale vibroacoustic behavior helps create macroscopic structures with the capacity for broadband acoustic camouflage.

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Ruiz-Díez, Víctor, Jorge Hernando-García, Javier Toledo, Abdallah Ababneh, Helmut Seidel, and José Luis Sánchez-Rojas. "Bidirectional Linear Motion by Travelling Waves on Legged Piezoelectric Microfabricated Plates." Micromachines 11, no. 5 (May 20, 2020): 517. http://dx.doi.org/10.3390/mi11050517.

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This paper reports the design, fabrication and performance of MEMS-based piezoelectric bidirectional conveyors featuring 3D printed legs, driven by linear travelling waves (TW). The structures consisted of an aluminium–nitride (AlN) piezoelectric film on top of millimetre-sized rectangular thin silicon bridges and two electrode patches. The position and size of the patches were analytically optimised for TW generation in three frequency ranges: 19, 112 and 420 kHz, by the proper combination of two contiguous flexural modes. After fabrication, the generated TW were characterized by means of Laser–Doppler vibrometry to obtain the relevant tables of merit, such as the standing wave ratio and the average amplitude. The experimental results agreed with the simulation, showing the generation of a TW with an amplitude as high as 6 nm/V and a standing wave ratio as low as 1.46 for a device working at 19.3 kHz. The applicability of the fabricated linear actuator device as a conveyor was investigated. Its kinetic performance was studied with sliders of different mass, being able to carry a 35 mg silicon slider, 18 times its weight, with 6 V of continuous sinusoidal excitation and a speed of 0.65 mm/s. A lighter slider, weighting only 3 mg, reached a mean speed of 1.7 mm/s at 6 V. In addition, by applying a burst sinusoidal excitation comprising 10 cycles, the TW generated in the bridge surface was able to move a 23 mg slider in discrete steps of 70 nm, in both directions, which is a promising result for a TW piezoelectric actuator of this size.

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Ding, Chengqiao, Dachen Wang, Zhe Feng, and Di Cui. "Extracting and Modifying the Vibration Characteristic Parameters of Watermelon Based on Experimental Modal Measurement and Finite Element Analysis for Hollow Heart Defect Detection." Journal of the ASABE 65, no. 1 (2022): 151–67. http://dx.doi.org/10.13031/ja.14871.

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HighlightsAn impulse vibration method is proposed to excite watermelon for hollow heart defect detection.Experimental models of watermelon were acquired with 3D scanning laser vibrometry.The relationship between hollow heart defect and vibration characteristic parameters was investigated with finite element analysis.Better prediction of hollow heart defect in watermelon was achieved with the wavelet transform method.Abstract. Hollow heart defect seriously influences the taste and storability of watermelon. In this study, a non-destructive detection system based on an impulse vibration method was developed to detect hollow watermelon. First, acceptable agreement between the theoretical and experimental models of watermelon proved the suitability of investigating the relationship between hollow heart defect and vibration characteristic parameters by finite element analysis (FEA). Through modal analysis, the optimum location for the detection sensor was determined at the opposite location or 90° from the excitation point. The normalized second to fourth resonance frequencies (f2n, f3n, and f4n) and the peak value at the second frequency (A2) were extracted as latent variables for prediction of hollow watermelon. The technical parameters of the pressurized-air excitation device were then modified in orthogonal tests, and the best combination of technical parameters was as follows: air pressure of 275 kPa, excitation distance of 9 cm, and pulse width of 200 ms. In the qualitative discrimination of hollow watermelon, the results showed that a back-propagation neural network (BPNN) using 13 vibration characteristic parameters had the best classification performance, with accuracies of 91.7% and 88.9% for the calibration and prediction sets. In the quantitative analysis of hollow rate, the best prediction result was achieved with the BPNN (rp = 0.829, RMSEP = 0.016), which selected ten vibration characteristic parameters as input variables. Therefore, it is feasible to detect hollow watermelon by impulse vibration, and this method has potential to be applied in on-line defect detection. Keywords: Doppler vibrometry, Finite element analysis, Hollow heart defect, Laser modal analysis, Watermelon.

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Li, Jia, Liujie Ren, Tongge Wu, Dongming Yin, Peidong Dai, Lifen Chen, and Tianyu Zhang. "Experimental and Numerical Studies on Vibration Modes and Transcranial Attenuation Characteristics in Unilateral Bone Conduction Hearing." Shock and Vibration 2020 (June 1, 2020): 1–17. http://dx.doi.org/10.1155/2020/4962098.

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Bone conduction (BC) hearing devices have been used to improve hearing in patients with unilateral conductive hearing loss; however, the clinical results of improvement in the sound localization ability are still controversial. Transcranial transmission in BC may be an important factor affecting sound localization abilities. Transcranial or interaural attenuation, derived from energy attenuation during the BC process, is determined by the different transfer functions of multiple pathways and affected by the whole-head vibration modes. The purpose of this study is to analyze the frequency dependence of BC vibration modes of the whole head, the contribution of middle and inner ear pathways to BC hearing, and the relationship between transcranial attenuation results by dynamics measurement and hearing thresholds. Experimental studies of vibration modes and transcranial attenuation characteristics in BC are performed using scanning laser Doppler vibrometry (LDV) measurements on human cadaver heads. Differences in vibration modes between the excitation and contralateral sides are observed. Additionally, a multiscale human whole-head FE model, including the skull, bony outer ear, ossicular chains, and bony inner ear structures, is proposed to study the mechanism of BC in the human hearing system. After verifying the rationality of the FE model using mechanical impedance and frequency response data, the transcranial attenuation on the temporal bone surfaces and the middle ear structure is calculated in the FE model. Moreover, the vibration characteristics of bilateral ossicular chains and the cochlear bony wall are observed in the whole-head FM model to study their contributions to BC hearing. By analyzing the experimental and numerical results of the vibration modes and the frequency response of the whole head incorporating the ossicular chain and cochlear bony wall, the intrinsic relationship between the results of transcranial attenuation by 1D LDV, 3D LDV, and hearing threshold measurements is further investigated.

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Matczak, Joanna, and Kamil Matczak. "Research position for testing the natural frequency of rotor blades using a PSV-500-3D vibrometer." AUTOBUSY – Technika, Eksploatacja, Systemy Transportowe 19, no. 12 (December 31, 2018): 566–69. http://dx.doi.org/10.24136/atest.2018.453.

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The article presents the possibilities of using a laser vibrometer to perform non-contact vibration measurements, allowing it to be used as a tool for many measuring applications. The authors pointed to the possibilities of effective use of a laser vibrometer in the aviation industry for the purpose of designing the optimal geometry of the rotor blades, studying the impact of vibrations on the work of the blades and, as a consequence, increasing the efficiency and reliability of their work.

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Weisbecker, H., B. Cazzolato, S. Wildy, S. Marburg, J. Codrington, and A. Kotousov. "Surface Strain Measurements Using a 3D Scanning Laser Vibrometer." Experimental Mechanics 52, no. 7 (October 6, 2011): 805–15. http://dx.doi.org/10.1007/s11340-011-9545-5.

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Sels, Seppe, Bart Ribbens, Boris Bogaerts, Jeroen Peeters, and Steve Vanlanduit. "3D model assisted fully automated scanning laser Doppler vibrometer measurements." Optics and Lasers in Engineering 99 (December 2017): 23–30. http://dx.doi.org/10.1016/j.optlaseng.2016.09.007.

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Píštěk, Václav, Pavel Kučera, Oleksij Fomin, Alyona Lovska, and Aleš Prokop. "Acoustic Identification of Turbocharger Impeller Mistuning—A New Tool for Low Emission Engine Development." Applied Sciences 10, no. 18 (September 14, 2020): 6394. http://dx.doi.org/10.3390/app10186394.

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At present, exhaust gas turbochargers not only form the basis for the economical operation of petrol, diesel or gas engines of all power categories, but also have an irreplaceable role on reducing their emissions. In order to reduce emissions from internal combustion engines, various systems are being developed, all of which have a turbocharger as an important component. Demands on turbocharger system durability and reliability keep growing, which requires the application of increasingly advanced computational and experimental methods at the development beginning of these systems. The design of turbochargers starts with a mathematical description of their rotationally cyclic impellers. However, mistuning, i.e., a slight individual blade property deviation from the intended design parameters, leads to a disturbance of the rotational cyclic symmetry. This article deals with the effects of manufacturing-related deviations on the structural dynamic behaviour of real turbine rotors. As opposed to methods exploiting expensive scanning vibrometers for experimental modal analysis or time-consuming accurate measurement of the geometry of individual blades using 3D optical scanners. A suitable microphone and a finite element rotor wheel model are the basis of this new method. After comparing the described acoustic approach with the laser vibrometer procedure, the results seemed to be practically identical. In comparison with the laser technique the unquestionable added value of this new method is the fact that it brings a significant reduction in the financial requirements for laboratory equipment. Another important benefit is that the measuring process of bladed wheel mistuning is significantly less time-consuming.

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Ohara, Yoshikazu, Marcel C. Remillieux, T. J. Ulrich, Serina Ozawa, Kosuke Tsunoda, Toshihiro Tsuji, and Tsuyoshi Mihara. "High-resolution 3D phased-array imaging of fatigue cracks using piezoelectric and laser ultrasonic system (PLUS)." Japanese Journal of Applied Physics 61, SG (May 19, 2022): SG1043. http://dx.doi.org/10.35848/1347-4065/ac48cd.

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Abstract This paper reports the effectiveness of a novel imaging system, piezoelectric and laser ultrasonic system (PLUS), for the three-dimensional (3D) imaging of fatigue cracks with a high-resolution. The PLUS combines a piezoelectric transmitter and the two-dimensional (2D) mechanical scanning of a laser Doppler vibrometer, enabling the 2D matrix array with an ultra-multiple number of receiving points for 3D phased array imaging. After describing the principle and 3D imaging algorithm of PLUS, we show the fundamental 3D imaging capability of the PLUS in a flat-bottom-hole specimen with varying the number of receiving points under a fixed large receiving aperture. We then demonstrate that the PLUS with 4275 receiving points (i.e. 75 × 57) achieves high-resolution 3D imaging of a fatigue crack with a high signal-to-noise ratio, providing the outline of the fatigue crack geometry. We also discuss the effectiveness of the ultra-multiple receiving points for suppressing grating lobes and random noise.

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He, Xiao Yuan, Fei Peng Zhu, Cheng Fei Wang, and Ying Jun Xu. "Stroboscopic Fringe Projection Method for 3D Dynamic Displacement Measurement." Applied Mechanics and Materials 70 (August 2011): 255–60. http://dx.doi.org/10.4028/www.scientific.net/amm.70.255.

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The determination of dynamic characteristics of microelectromechanical system (MEMS) devices is of great importance. Currently, vibrometer techniques using a Laser-Doppler Vibrometer (LDV) are used for dynamic measurement of MEMS, utilizing an interferometer based on a stroboscope and high-speed cine photomicrography are used for MEMS. But, these methods can’t be used for 3D dynamic displacement measurement simultaneously because of their limitations. In this paper, an optical system for 3D dynamic displacement measurement of micro-components is presented using stroboscopic fringe projection and digital image correlation (DIC), which can measure both in-plane and out-of-plane motions simultaneously. In the system, stroboscopic fringe patterns are projected onto the surface of a vibrating specimen by a phase-shifting projector and stroboscopic illumination supplied with a pulsed laser diode. Synchronization between the stroboscopic laser and the driving signal for the specimen vibrating is achieved by the stroboscopic controller. For a certain vibration state, four deformed phase-shifting fringe patterns are captured by a high-resolution CMOS camera with a long working distance microscope. The images are processed by a phase-shifting technique to obtain the phase distribution. The surface pattern of the specimen without fringes could be obtained by certain phase-shifting algorithms. When stroboscopic pulses are delayed, the stroboscopic phase is changed and another vibrating status could be captured in the same way. Comparing the phase distributions of these two states, the out-of-plane displacement is achieved, which is the displacement of the specimen between these two states. The in-plane displacement could be obtained from the surface pattern without fringes by DIC. Adjusting the phase delay of illumination by stroboscopic controller, the motions of the specimen in the whole vibration period can be obtained.

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Oyman, Hilmi Artun, Baris Can Efe, Mustafa Akin Icel, Yigit Daghan Gokdel, Onur Ferhanoglu, and Arda Deniz Yalcinkaya. "Towards 3D Confocal Imaging with Laser-Machined Micro-Scanner." Proceedings 2, no. 13 (November 23, 2018): 1067. http://dx.doi.org/10.3390/proceedings2131067.

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A micro-scanner made of stainless-steel is fabricated via laser cutting technology for 3D Lissajous confocal imaging. The multi-gimbaled structure of the device provides two orthogonal torsional modes and three different out-of-plane modes. Torsional modes can be used to achieve 2D scan and all of the out-of-plane modes can be used in changing the focus of the micro-scanner to achieve a 3D scanning pattern. One of the out-of-plane modes along with two orthogonal torsional modes can be employed for scanning a large depth-stack in sparse fashion while another out-of-plane mode can satisfy a much higher scan fill-rate with less field of view (FOV). Simulations of the micro-scanner are obtained using finite element method (FEM) software and compared with the characterization data gathered from Laser Doppler Vibrometer (LDV). Using various out-of-plane modes, the constructed fill patterns are simulated on MATLAB and fill rates compared.

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Khalil, Hossam, Dongkyu Kim, Joonsik Nam, and Kyihwan Park. "Accuracy and noise analyses of 3D vibration measurements using laser Doppler vibrometer." Measurement 94 (December 2016): 883–92. http://dx.doi.org/10.1016/j.measurement.2016.09.003.

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Vehovszky, Balázs, István Horváth, Karl Slenczka, Martin Schuster, and Tamás Jakubík. "Vibration Damping Measurement on Car Windshields." Periodica Polytechnica Mechanical Engineering 63, no. 1 (November 13, 2018): 1–6. http://dx.doi.org/10.3311/ppme.11559.

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Knowledge of the damping properties of a windshield is a fundamental element of the acoustical characterization of a car. The measuring method of damping for a windshield is presented in the paper. The damping loss factor – as a basic measure of mechanical damping – was determined experimentally by two means: the reverberation time from impact hammer testing as well as the modal behavior from 3D laser scanning vibrometer measurements. The results proved that the modal shapes have a fundamental effect on the measured damping values.

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Rau, Mark, Julius O. Smith, and Doug L. James. "Augmenting a single-point laser Doppler vibrometer to perform scanning measurements." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A157. http://dx.doi.org/10.1121/10.0010962.

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Laser Doppler vibrometers (LDV) are used for non-contact vibration measurements of various structures and are frequently used for stringed instrument measurements. Single-point LDVs can be used with the roving hammer or LDV method for mode shape measurements, but this is time-consuming and requires constant attention. Scanning LDVs exist but are expensive and often out of reach of musical acoustics researchers. An inexpensive apparatus to modify a common single-point LDV such that it can perform automated scanning measurements is presented. The augmentation consists of a mirror galvanometer, impact hammer controller, and 3D printed mounting hardware. The scanning system is controlled by a microprocessor and can be easily automated. The total cost of the system, excluding the LDV and impact hammer, is under two hundred dollars. Measurements of guitars are presented to validate the scanning system and discuss any shortcomings.

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38

Bodet, Ludovic, Amine Dhemaied, Roland Martin, Régis Mourgues, Fayçal Rejiba, and Vincent Tournat. "Small-scale physical modeling of seismic-wave propagation using unconsolidated granular media." GEOPHYSICS 79, no. 6 (November 1, 2014): T323—T339. http://dx.doi.org/10.1190/geo2014-0129.1.

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Laboratory physical modeling and laser-based experiments are frequently proposed to tackle theoretical and methodological issues related to seismic prospecting, e.g., when experimental validations of processing or inversion techniques are required. Lasers are mainly used to simulate typical field acquisition setups on homogeneous and consolidated materials assembled into laboratory-scale physical models (PMs) of various earth structures. We suggested the use of granular materials to study seismic-wave propagation in unconsolidated and porous media and target near-surface exploration and hydrogeologic applications. We designed and tested the reproducibility of an experimental procedure to build and probe PMs consisting of micrometric glass beads (GBs). A mechanical source and a laser-Doppler vibrometer were used to record small-scale seismic lines at the surface of three GBs models. When guided surface acoustic mode theory should prevail in such unconsolidated granular packed structure under gravity, we only considered elastic-wave propagation in stratified media to interpret recorded data. Thanks to basic seismic processing and inversion methods (first arrivals and dispersion analyses), we were able to correctly retrieve the gradients of pressure- and shear-wave velocities in our models. A 3D elastic finite difference simulation of the experiment offered, despite significant differences in terms of amplitudes, a supplementary validation of our approximation, as far as elastic properties of the medium were concerned.

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Hashimoto, Katsufumi, Tomoki Shiotani, and Masayasu Ohtsu. "Application of Impact-Echo Method to 3D SIBIE Procedure for Damage Detection in Concrete." Applied Sciences 10, no. 8 (April 15, 2020): 2729. http://dx.doi.org/10.3390/app10082729.

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In this study, to visualize damage and defects, such as cracks and voids in concrete, the SIBIE (stack imaging of spectral amplitudes based on impact echo) procedure is applied and numerically improved to construct a three-dimensional (3D) model of elastic wave propagation behavior. A unit of arrayed accelerometers is installed to detect multi-channel signal waveforms in the frequency domain. The resonant frequencies due to reflections at each node in 3D lattice nodes are computed by using the distances from elastic wave input to multiple output locations. The amplitudes corresponding to the resonant frequencies in the spectrum are summed up as the reflection intensity of elastic wave at each node. The reflection intensity distribution is visualized finally in the targeted area three-dimensionally. Case studies are carried out on the proposal of the improved 3D-SIBIE procedure, applied to a concrete specimen with simulated-damage as well as in-situ highway RC (Reinforced Concrete) slabs in service. As for the signal detection, a non-contact elastic wave detecting system using a laser doppler vibrometer is also introduced to consider and validate the promising remote sensing and inspection technique for damage evaluation in concrete with the 3D SIBIE procedure.

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Ambroziński, Łukasz, and Tadeusz Stepinski. "Robust polarization filter for separation of Lamb wave modes acquired using a 3D laser vibrometer." Mechanical Systems and Signal Processing 93 (September 2017): 368–78. http://dx.doi.org/10.1016/j.ymssp.2017.02.002.

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41

Marwitz, S., and V. Zabel. "An Experimental Evaluation of Two Potential Improvements for 3D Laser Vibrometer Based Operational Modal Analysis." Experimental Mechanics 57, no. 8 (July 6, 2017): 1311–25. http://dx.doi.org/10.1007/s11340-017-0307-x.

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42

Liu, Wenjuan, Leming He, Xubo Wang, Jia Zhou, Weijiang Xu, Nikolay Smagin, Malika Toubal, et al. "3D FEM Analysis of High-Frequency AlN-Based PMUT Arrays on Cavity SOI." Sensors 19, no. 20 (October 14, 2019): 4450. http://dx.doi.org/10.3390/s19204450.

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This paper presents three-dimensional (3D) models of high-frequency piezoelectric micromachined ultrasonic transducers (PMUTs) based on the finite element method (FEM). These models are verified with fabricated aluminum nitride (AlN)-based PMUT arrays. The 3D numerical model consists of a sandwiched piezoelectric structure, a silicon passive layer, and a silicon substrate with a cavity. Two types of parameters are simulated with periodic boundary conditions: (1) the resonant frequencies and mode shapes of PMUT, and (2) the electrical impedance and acoustic field of PMUT loaded with air and water. The resonant frequencies and mode shapes of an electrically connected PMUT array are obtained with a laser Doppler vibrometer (LDV). The first resonant frequency difference between 3D FEM simulation and the measurement for a 16-MHz PMUT is reasonably within 6%, which is just one-third of that between the analytical method and the measurement. The electrical impedance of the PMUT array measured in air and water is consistent with the simulation results. The 3D model is suitable for predicting electrical and acoustic performance and, thus, optimizing the structure of high-frequency PMUTs. It also has good potential to analyze the transmission and reception performances of a PMUT array for future compact ultrasonic systems.

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Pieczonka, Łukasz, Łukasz Ambroziński, Wiesław J. Staszewski, David Barnoncel, and Patrick Pérès. "Damage detection in composite panels based on mode-converted Lamb waves sensed using 3D laser scanning vibrometer." Optics and Lasers in Engineering 99 (December 2017): 80–87. http://dx.doi.org/10.1016/j.optlaseng.2016.12.017.

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44

Khalatkar, Abhay, V. K. Gupta, and Ankit Agrawal. "Analytical, FEA, and Experimental Comparisons of Piezoelectric Energy Harvesting Using Engine Vibrations." Smart Materials Research 2014 (April 6, 2014): 1–8. http://dx.doi.org/10.1155/2014/741280.

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Piezoelectric elements can be used as sensors and actuators in flexible structures. In this paper, using the most basic concepts of piezoelectric micropower generators, all useful mathematical equations for getting analytical output are discussed and derived for different piezo positions on cantilever beam and then 3D finite element modeling and simulation of generalized piezoelectric laminated beam problem with proper specifications and properties are done in ANSYS12.0. Experimental analysis is also done on the very practical problem to harvest energy (to get electric energy) by applying some deflection (mechanical energy) on piezo-bonded aluminum beam, that is, to harvest energy (at microlevel at least) by using vibrations of 4-stroke car diesel engine with mounting of piezo cantilever beam. Here piezoelectric beam is used to measure the charge generated from the engine vibrations. The vibration amplitudes are measured with a Laser Vibrometer with considerations of maximum number of power cycles is to be covered for analysis. The vibration response data of displacement of the cantilever at free end measured from Vibrometer are considered for harmonic and analytical analyses as mean displacement amplitude of 3.98 mm at free end. The study further carried out for effect of different piezo positions and various engine speeds also. Then comparison is also done among obtained results from these three analyses to get validation of all derived mathematical equations.

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Galeazzi, S., P. Chiariotti, M. Martarelli, and E. P. Tomasini. "3D Digital Image Correlation for vibration measurement on rolling tire: procedure development and comparison with Laser Doppler Vibrometer." Journal of Physics: Conference Series 1149 (December 2018): 012010. http://dx.doi.org/10.1088/1742-6596/1149/1/012010.

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Wildy, Stuart, Benjamin Cazzolato, and Andrei G. Kotousov. "Detection of Delamination Damage in a Composite Laminate Beam Utilising the Principle of Strain Compatibility." Key Engineering Materials 417-418 (October 2009): 269–72. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.269.

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This paper presents an experimental investigation of a new method for damage detection based on the most fundamental concept in continuum mechanics: strain compatibility. Compliance with this principle implies a deformed material is free from discontinuities, which are indicative of many types of structural damage. Therefore the principle of strain compatibility, in its ability to identify discontinuities, is very promising as a new foundation for future research into non-destructive evaluation and structural health monitoring technologies. The proposed method has many advantages compared to existing damage detection techniques, such as its invariance to material properties, type and intensity of loading, and the geometry of the structure. In this paper, a proposed formulation of the strain compatibility equation for beam structures, which is invariant to loading intensity, is presented. An experimental investigation of the proposed algorithm was conducted on a delaminated cantilever beam, utilising a PSV-3D scanning laser vibrometer. The experiment demonstrated that the strain compatibility technique can accurately locate delamination damage in composite beam structures.

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47

Huang, Yu-Hsi, and Chun-Yi Lin. "Measurement of Orthotropic Material Constants and Discussion on 3D Printing Parameters in Additive Manufacturing." Applied Sciences 12, no. 13 (July 5, 2022): 6812. http://dx.doi.org/10.3390/app12136812.

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In this study, the orthogonal mechanical properties of additive manufacturing technology were explored. Firstly, six test pieces of different stacking methods were printed with a 3D printer, based on fused deposition modeling. The resonance frequency was measured by a laser Doppler vibrometer as the test piece was struck by a steel ball, which was used to calculate the orthotropic material constants. The accuracy of these orthotropic material constants was then verified using finite element software through a comparison of the experimental results from multiple natural modes. Thus, a set of methods for the measurement and simulation verification of orthotropic material constants were established. Only three specific test specimens are needed to determine the orthotropic material constants using the vibrating sensor technique, instead of a universal testing machine. We also analyzed the influence of different printing parameters, including raster angle and layer height, on the material constants of the test pieces. The results indicate that a raster angle of 0° leads to the highest Young’s modulus, a raster angle of 45° leads to the highest shear modulus G, and a layer height of 0.15 mm leads to the highest material strength. In various stack conditions, the mechanical properties of fuse deposition additive manufacturing can be measured by inversely calculating frequency domain transformation.

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Pang, Toh Yen, and Mohammad Fard. "Reverse Engineering and Topology Optimization for Weight-Reduction of a Bell-Crank." Applied Sciences 10, no. 23 (November 30, 2020): 8568. http://dx.doi.org/10.3390/app10238568.

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This paper describes a new design method that was developed to achieve an optimal design method for weight reduction of a bell crank, sourced from a Louis Christen Road Racing F1 Sidecar. The method involved reverse engineering to produce a 3D model of the mechanical part. The 3D bell crank model was converted to a finite element (FE) model to characterize the eigenvalues of vibration and responses to excitation using the Lanczos iteration method in Abaqus software. The bell crank part was also tested using a laser vibrometer to capture its natural frequencies and corresponding vibration mode shapes. The test results were used to validate the FE model, which was then analysed through a topology optimization process. The objective function was the weight and the optimization constraints were the stiffness and the strain energy of the structure. The optimized design was converted back to a 3D model and then fabricated to produce a physical prototype for design verification and validation by means of FE analysis and laboratory experiments and then compared with the original part. Results indicated that weight reduction was achieved while also increasing the natural frequency by 2%, reducing the maximum principal strain and maximum von Mises stress by 4% and 16.5%, respectively, for the optimized design when compared with the original design. The results showed that the proposed method is applicable and effective in topology optimization to obtain a lightweight (~3% weight saving) and structurally strong design.

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Neupetsch, Constanze, Eric Hensel, Michael Werner, Sven Meißner, Jan Troge, Welf-Guntram Drossel, and Christian Rotsch. "Development and Validation of Bone Models using Structural Dynamic Measurement Methods." Current Directions in Biomedical Engineering 5, no. 1 (September 1, 2019): 343–45. http://dx.doi.org/10.1515/cdbme-2019-0086.

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AbstractVibration measurement and signal analysis methods are common to evaluate the functionality and characteristics of technical components in different industrial and scientific areas. Modal analysis for example is a standard method to characterize the dynamic behavior of a structure and enables the development of validated bone models. The state of the art of analyzing bone structures does not include the modal damping, although it has a significant influence on the dynamic characteristics. Within the presented investigations, the modal analyses have been performed contactless with respect to excitation and response acquisition, which implies that there are no influences of shakers or sensor couplings. Therefore, an automatic impulse hammer and a 3D Scanning Laser Doppler Vibrometer were used for excitation and response detection. Various supports of the test specimens, surface pretreatments, excitation points and excitation impulses were examined to optimize the measurement setup and process. Experimental modal analysis data were analyzed by curve fitting methods to determine the modal parameters. To evaluate different structures and effects of damping, 3D printed artificial bones and animal in vitro bones were used to perform the measurements. To produce the cortical layer of the artificial bone models, volume models were generated based on medical image data and printed by polyamide-based selective laser sintering. The cancellous bone was represented by different foam fillings for the artificial bones. Thereby, the variation of the porosity was achieved by using different mixing ratios of polyurethane foam and hardener. Furthermore, the modal damping parameters were determined from the measurement of animal bones. The measurement time was optimized during the practical implementation of the parameter determination to minimize the influence of drying and decomposition processes on the measurement results.

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Ferhat, Ipar, Rodrigo Sarlo, and Pablo A. Tarazaga. "3D Modal Analysis of a Loaded Tire with Binary Random Noise Excitation." Tire Science and Technology 48, no. 3 (June 4, 2019): 207–23. http://dx.doi.org/10.2346/tire.19.170166.

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ABSTRACT Modal analysis of tires has been a fundamental part of tire research aimed at capturing the dynamic behavior of a tire. An accurate expression of tire dynamics leads to an improved tire model and a more accurate prediction of tire behavior in real-life operations. Therefore, the main goal of this work is to improve the tire-testing techniques and data range to obtain the best experimental data possible using the current technology. With this goal in mind, we propose novel testing techniques such as piezoelectric excitation, high-frequency bandwidth data, and noncontact vibration measurement. High-frequency data enable us to capture the coupling between the wheel and tire as well as the coupling between airborne and structure-borne noise. Piezoelectric excitation eliminates the dynamic coupling of shakers and the inconsistency of force magnitude and direction of impact hammers as well as added mass effect. Noncontact vibration measurements using three-dimensional (3D) scanning laser Doppler vibrometer (SLDV) are superior to accelerometers because of no mass loading, a high number of measurement points in three dimensions, and high sensitivity. In this work, a modal analysis is carried out for a loaded tire in a static condition. Because of the highly damped nature of tires, multiple input excitation with binary random noise signal is used to increase the signal strength. Mode shapes of the tire are obtained and compared using both accelerometers and SLDV measurements.

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Journal articles on the topic '3D Laser vibrometry'

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