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Auswahl der wissenschaftlichen Literatur zum Thema „Acoustic material characterisatio“
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Zeitschriftenartikel zum Thema "Acoustic material characterisatio"
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Zhao, Tianfei, Baorui Pan, Xiang Song, Dan Sui, Heye Xiao und Jie Zhou. „Heuristic Approaches Based on Modified Three-Parameter Model for Inverse Acoustic Characterisation of Sintered Metal Fibre Materials“. Mathematics 10, Nr. 18 (08.09.2022): 3264. http://dx.doi.org/10.3390/math10183264.
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Modelling of sound propagation in porous media generally requires the knowledge of several transport properties of the materials. In this study, a three-parameter analytical model that links microstructure properties of sintered metal fibre materials and non-acoustical parameters of the JCAL model is used and modified, and two heuristic approaches based on the established model for inverse acoustic characterisation of fibrous metal felts are developed. The geometric microstructure of sintered fibrous metals is simplified to derive the relationship between pores and fibre diameters. The new set of transport parameters in the modified three-parameter model can cover two controllable parameters during the fabrication process of fibrous metals. With two known transport parameters, six sintered specimens are characterised using a deterministic algorithm, and a satisfactory result is achieved in fitting the normalised surface impedance measured by an acoustic measurement system. Moreover, the forward evaluation shows that our modified three-parameter theoretical model is capable of yielding accurate results for the sintered metal fibre materials. A numerical investigation of the complete inverse acoustic characterisation of fibrous metals by a global non-deterministic algorithm indicates that inversion from two porous material properties is preferable to the normalised surface impedance.
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PETTONI POSSENTI, Vincenzo, Emanuele MACCAFERRI, Gioia FUSARO, Luca BARBARESI und Laura MAZZOCCHETTI. „Preliminary investigation of nanofibrous membranes for sound absorption“. INTER-NOISE and NOISE-CON Congress and Conference Proceedings 270, Nr. 4 (04.10.2024): 7051–57. http://dx.doi.org/10.3397/in_2024_3903.
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Nanofibrous membranes show interesting mechanical properties, low thickness and lightness, besides the possibility of using a great variety of polymers. The electrospinning technique makes possible the production of polymeric random nanofibres to form nonwoven membranes, which are currently used in several application fields, such as filtration, biomedicine, biomechanics, electronics, and composite materials. Their application in the automotive and aerospace engineering field could bring significant benefits to the acoustic comfort design. However, their acoustics properties still need to be further assessed. This study investigates the acoustic absorption of electrospinning-made nanofibrous membranes in Nylon 66 with different fibre diameters and mat thicknesses. Morphological and thermal characterisation of the electrospun membranes have been assessed via Scanning Electron Microscope (SEM) and Differential Scanning Calorimetry (DSC), respectively. The acoustic absorption characteristics of various samples changing fibre diameter, membrane thickness and mounting conditions were tested in the impedance tube. The results showed more relevant acoustic absorption properties in the nanofibrous membrane coupled with a polyester fibre. Further studies will clarify if filament direction and constituent material can be improved for a more durable and resistant membrane application.
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Tandon, R. P., und Ramadhar Singh. „Development and Characterisation of Composite Hydrophones“. Engineering Plastics 2, Nr. 5 (Januar 1994): 147823919400200. http://dx.doi.org/10.1177/147823919400200502.
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Piezo components have been fabricated using lead zirconate titanate (PZT) and lead titanate (PT) as filler materials in a passive chloroprene rubber matrix. The temperature dependence of the dielectric parameters of PT composites has been studied. Effect of poling temperature and poling field on piezoelectric charge coefficient (d33) has also been examined in order to achieve optimum polarization. Three types of hydrophones were developed using solid PZT, PZT composite and PT composite. Their acoustic sensitivities have been presented over a frequency range 10–100 KHz. The hydrophone based on lead titanate composite exhibited the highest acoustic sensitivity (-202 dB re IV/mPa) which could find numerous applications in underwater acoustics.
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Tandon, R. P., und Ramadhar Singh. „Development and Characterisation of Composite Hydrophones“. Polymers and Polymer Composites 2, Nr. 5 (Januar 1994): 287–92. http://dx.doi.org/10.1177/096739119400200502.
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Piezo components have been fabricated using lead zirconate titanate (PZT) and lead titanate (PT) as filler materials in a passive chloroprene rubber matrix. The temperature dependence of the dielectric parameters of PT composites has been studied. Effect of poling temperature and poling field on piezoelectric charge coefficient (d33) has also been examined in order to achieve optimum polarization. Three types of hydrophones were developed using solid PZT, PZT composite and PT composite. Their acoustic sensitivities have been presented over a frequency range 10–100 KHz. The hydrophone based on lead titanate composite exhibited the highest acoustic sensitivity (-202 dB re IV/mPa) which could find numerous applications in underwater acoustics.
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Nuawi, Mohd Zaki, Abdul Rahim Bahari, Shahrum Abdullah, Ahmad Kamal Ariffin Mohd Ihsan und Fauziana Lamin. „Material Property Characterisation Method Using Vibro-Acoustic Signals“. Applied Mechanics and Materials 663 (Oktober 2014): 447–52. http://dx.doi.org/10.4028/www.scientific.net/amm.663.447.
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Material play an important role in engineering design and the characterisation of material property has become an essential requirement for their successful application as structural elements. In this paper, the development of material property characterisation method has been presented. Impulsive excitation test has been performed on rectangular bars (medium carbon steel S50C, cast iron FCD 500, stainless steel AISI 304and brass). The transient vibro-acoustic signals generated during the excitation test have been captured using data acquisition system consist of accelerometer-microphone combination. A new method for reducing the noise components from the recorded signals is introduced by an extensive process of a new Z-stem filtering technique. The filtered signals have been analysed using an alternative statistical method known as Integrated Kurtosis-based Algorithm for Z-notch filter (I-kazTM) to determine the pattern of the signal and to estimate the significance differences among those materials. The representation of the experimental curves obtained by the determination of I-kaz coefficient, Z∞ for various impact forces and materials revealed that the results are statistically significant and can be successfully used for determining the correlation between the curves and material property. Implications of this research to material property characterisation will be discussed.
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Włodarska, Dorota, Andrzej Klepka, Wieslaw Jerzy Staszewski und Tadeusz Uhl. „Comparative Study of Instantaneous Frequency Extraction in Nonlinear Acoustics Used for Structural Damage Detection“. Key Engineering Materials 588 (Oktober 2013): 33–42. http://dx.doi.org/10.4028/www.scientific.net/kem.588.33.
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Nonlinear acoustics deals with various nonlinear effects that occur in ultrasonic wave propagation. The method is suitable for material characterisation, as it uses different nonlinear phenomena associated with material imperfections. The method has been used for detecting nonlinearities in cracked solids by: measuring distortions of acoustic signals, estimating resonance frequency shifts or assessing nonlinear vibro-acosutic modulations. The latter is the most widely used non-classical approach to probe material nonlinearities. The method involves vibro-acoustic interactions of ultrasonic wave and modal vibration in damaged specimens. Modulation intensity that strongly relates to damage severity - is usually assessed in the frequency domain and often leads to confusing results when large modulations are involved. The paper investigates the time domain analysis of vibro-acoustic modulated signals. Several methods for instantaneous frequency calculation used to assess the intensity of modulation - are compared. Simulated and experimental data are used in these investigations.
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Wang, Lian, Lian Wang und Victor Humphrey. „The use of a parametric array source and nearfield scanning in the characterisation of panel materials for underwater acoustics“. INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, Nr. 1 (01.02.2023): 6403–12. http://dx.doi.org/10.3397/in_2022_0965.
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The properties of the materials used in underwater acoustics are important for applications such as acoustic windows, reflectors and baffles, acoustic barriers or screens, decoupling materials, and anechoic coatings. To characterise the performance of such materials at frequencies above 1 kHz, measurements are typically undertaken on samples of the material in the form of finite sized panels. Such measurements suffer from uncertainty due to the finite size of the panel (leading to contaminating signals from edge diffraction), and the difficulty in simulating the ideal plane-wave insonification. This paper describes work at the UK National Physical Laboratory to minimise these effects by use of: (i) a parametric array as a sound source that provides a directional beam and short broadband pulses; and (ii) nearfield scanning using a hydrophone to sample the complex sound pressure field interacting with the test sample, decomposing the sound field into its plane-wave components. Results are presented of these techniques applied to measurements in laboratory test tanks at frequencies between a few kilohertz and a few hundred kilohertz to determine the reflection and transmission performance of a range of test samples, including panels consisting of homogeneous polymers and materials with regular periodic structure.
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Mao, Huina, Romain Rumpler und Peter Göransson. „An inverse method for design and characterisation of acoustic materials“. MATEC Web of Conferences 304 (2019): 02002. http://dx.doi.org/10.1051/matecconf/201930402002.
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This paper presents applications of an inverse method for the design and characterisation of anisotropic elastic material properties of acoustic porous materials. Full field 3D displacements under static surface loads are used as targets in the inverse estimation to fit a material model of an equivalent solid to the measurement data. Test cases of artificial open-cell foams are used, and the accuracy of the results are verified. The method is shown to be able to successfully characterise both isotropic and anisotropic elastic material properties. The paper demonstrates a way to reduce costs by characterising material properties based on the design model without a need for manufacturing and additional experimental tests.
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Claes, Leander, Sarah Johannesmann, Henning Zeipert und Bernd Henning. „Broadband acoustic waves in plate-like structures for acoustic material characterisation“. Journal of Physics: Conference Series 2822, Nr. 1 (01.09.2024): 012171. http://dx.doi.org/10.1088/1742-6596/2822/1/012171.
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Abstract Guided acoustic waves can be used for a multitude of different testing and material characterisation purposes. The options for evaluation are especially plentiful if a method for broadband excitation, e.g. thermoelastic excitation using focused, pulsed laser radiation, is used, and if the distance between excitation and detection of the acoustic waves can be varied. In this contribution, methods to infer different quantitative material properties from the recorded spatiotemporal measurement data are presented, ranging from isotropic elastic properties to parameters describing absorption for complex absorption models.
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Ciaburro, Giuseppe, Gino Iannace, Laura Ricciotti, Antonio Apicella, Valeria Perrotta und Raffaella Aversa. „Acoustic Applications of a Foamed Geopolymeric-Architected Metamaterial“. Applied Sciences 14, Nr. 3 (31.01.2024): 1207. http://dx.doi.org/10.3390/app14031207.
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The paper compares and evaluates the influence of the presence of perforations on the sound absorption coefficient (SAC) of a negative stiffness metamaterial based on a foamed ceramic geopolymer. Chemical–physical, microstructural, dynamic–mechanical, and sound characterisations are presented. A rigid, lightweight geopolymeric porous material has been prepared using an inorganic/organic monomeric mixture containing oligomeric sialates and siloxanes foamed with aluminium powder. This process results in an amorphous rigid light foam with an apparent 180 Kg/m3 density and a 78% open-pore. The viscoelastic characterisation by dynamic mechanical analysis (DMA) carried out from 10−3 to 103 Hz indicates the behaviour of a mechanical metamaterial with negative stiffness enabling ultrahigh energy absorption at straining frequencies from 300 to 1000 Hz. The material loss factor (the ratio of dissipative/elastic shear moduli) is about 0.03 (essentially elastic behaviour) for frequencies up to 200 Hz to suddenly increase up to a value of six at 1000 Hz (highly dissipative behaviour). The corresponding storage and loss moduli were 8.2 MPa and 20 MPa, respectively. Impedance tube acoustic absorption measurements on perforated and unperforated specimens highlighted the role of perforation-resonant cavities in enhancing sound absorption efficiency, particularly within the specified frequency band where the mass of the negative stiffness foamed geopolymer matrix magnifies the dissipation effect. In the limits of a still exploratory and comparative study, we aimed to verify the technological transfer potentiality of using architected metamaterials in sustainable building practices.
Dissertationen zum Thema "Acoustic material characterisatio"
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Manoochehrnia, Pooyan. „Characterisatiοn οf viscοelastic films οn substrate by acοustic micrοscοpy. Direct and inverse prοblems“. Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMLH38.
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Dans le cadre de cette thèse de doctorat, la caractérisation des films épais et minces déposés sur un substrat a été réalisée à l'aide de la microscopie acoustique via des algorithmes de résolution de problèmes directs et inverses. La méthode de Strohm est utilisée pour la résolution directe des problèmes, tandis qu'une variété de modèles mathématiques comprenant le modèle de la série de Debye (DSM), le modèle de la ligne de transmission (TLM) et la méthode spectrale utilisant le modèle de la rapport entre les réflexions multiples (MRM) ont été utilisés pour résoudre les problèmes inverses. Une application spécifique de la microscopie acoustique a été utilisée, consistant à monter des transducteurs à ondes planes à haute fréquence (50 MHz et 200 MHz) au lieu d'utiliser les transducteurs à focalisation traditionnels utilisés pour l'imagerie acoustique, ainsi qu'à utiliser le A-Scan à ondes complètes, qui pourrait être étendu à l'analyse en vrac des A-Scan consécutifs. Les modèles ont été validés expérimentalement par un film épais en époxy-résine d'une épaisseur d'environ 100μm et un film mince en vernis d'environ 8μm. Les paramètres caractérisés comprennent des paramètres mécaniques (par exemple la densité et l'épaisseur) ainsi que des paramètres viscoélastiques (par exemple la vitesse longitudinale acoustique et l'atténuation acoustique) et parfois le déphasage du transducteurIn the framework of this PhD thesis, the characterisation of the thick and thin films deposited on asubstrate has been done using acoustic microscopy via direct and inverse problem-solving algorithms.Namely the Strohm’s method is used for direct problem-solving while a variety of mathematical modelsincluding Debye series model (DSM), transmission line model (TLM) and spectral method using ratiobetween multiple reflections model (MRM) have been used to solve inverse-problem. A specificapplication of acoustic microscopy has been used consisting of mounting the plane-wave high frequency(50 MHz and 200MHz) transducers instead of use of the traditional focus transducers used for acousticimaging as well as using full-wave A-scan which could be well extended to bulk analysis of consecutivescans. Models have been validated experimentally by a thick film made of epoxy-resin with thicknessof about 100μm and a thin film made of polish of about 8μm. The characterised parameters includemechanical parameters (e.g. density and thickness) as well as viscoelastic parameters (e.g. acousticlongitudinal velocity and acoustic attenuation) and occasionally transducer phase-shift
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Guastavino, Rémi. „Elastic and acoustic characterisation of anisotropic porous materials“. Doctoral thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4782.
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For an accurate prediction of the low and medium frequency surface vibration and sound radiation behaviour of porous materials, there is a need to improve the means of estimating their elastic and acoustic properties. The underlying reasons for this are many and of varying origin, one prominent being a poor knowledge of the geometric anisotropy of the cell microstructure in the manufactured porous materials. Another one being, the characteristic feature of such materials i.e. that their density, elasticity and dissipative properties are highly dependent upon the manufacturing process techniques and settings used. In the case of free form moulding, the geometry of the cells and the dimensions of the struts are influenced by the rise and injection flow directions and also by the effect of gravity, elongating the cells. In addition the influence of the boundaries of the mould also introduces variations in the properties of the foam block produced. Despite these complications, the need to predict and, in the end, optimise the acoustic performance of these materials, either as isolated components or as part of a multi-layer arrangement, is growing. It is driven by the increasing demands for an acoustic performance in balance with the costs, a focus which serves to increase the need for modelling their behaviour in general and the above mentioned, inherent, anisotropy in particular. The current work is focussing on the experimental part of the characterisation of the material properties which is needed in order to correctly represent the anisotropy in numerical simulation models. Then an hybrid approach based on a combination of experimental deformation, strain field mapping, flow resistivity measurement and physically based porous material acoustic Finite Element (FE) simulation modelling is described. This inverse estimation linked with high quality measurements is crucial for the determination of the anisotropic coefficients of the porous materials is illustrated here for soft foam and fibrous wool materials.QC 20100729
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Guastavino, Rémi. „Elastic and acoustic characterisation of anisotropic porous materials /“. Stockholm : Department of Aeronautical and Vehicle Engineering, Royal Institute of Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4782.
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Van, der Kelen Christophe. „Vibro-acoustic modelling of anisotropic poroelastic materials : characterisation of the anisotropic properties“. Doctoral thesis, KTH, MWL Strukturakustik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-137809.
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The present-day challenges in the transport industry, steered by the increasing environmental awareness, necessitate manufacturers to take measures to reduce emissions related to the movements of goods and humans. In particular, the measures aiming at a reduced mass or higher load capacity to increase fuel efficiency, generally deteriorate the noise and vibration insulation properties of their products. In order to comply with the regulations and customer demands, modern vehicles increasingly move towards a multifunctional integrated design approach, if possible for all subcomponents involved. Such a multifunctional design approach is an iterative process, evaluating the proposed solutions in every stage, and is therefore best performed in a virtual testing environment. \\Poroelastic materials are interesting to include in a multifunctional design, offering reasonably good vibro-acoustic insulation properties at a low weight penalty. These materials can also be combined in multilayer arrangements to further enhance the overall performance. \\In order to achieve an accurate modelling of the vibro-acoustic behaviour of poroelastic materials, the input data describing the material properties should be of a high quality. Two characteristics inherent to these materials encumber a precise characterisation with traditional techniques. Poro-elastic aggregates are anelastic due to the constituent material used, and anisotropic as a consequence of the production process. Characterisation techniques allowing for an accurate determination of the material properties need to take these intrinsic characteristics into account.\\The objective in this thesis is to enable the characterisation of a constitutive material model for poroelastic materials which is as general as possible, and includes the inherent material anelasticity and anisotropy. For this purpose, a set of advanced characterisation techniques has been developed to characterise the anisotropic flow resistivity tensor and the anisotropic dynamic Hooke's tensor. \\These advanced characterisation techniques are based on an inverse estimation procedure, used consistently throughout the work, and includes both experiments and numerical predictions. The property to characterise is isolated in a specially designed set-up such that it can be modelled by physics solely involving this property. The obtained experimental and numerical data then serve as the input to an optimisation, which returns the material properties for which the difference between both is as small as possible. These methods have been successfully applied to melamine foam, which is found to be both anisotropic and anelastic, confirming the need for such advanced characterisation techniques.QC 20131219
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Sun, Chao. „Acoustic characterisation of ultrasound contrast agents at high frequency“. Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8093.
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This thesis aims to investigate the acoustic properties of ultrasound contrast agents (UCAs) at high ultrasound frequencies. In recent years, there has been increasing development in the use of high frequency ultrasound in the fields of preclinical, intravascular, ophthalmology and superficial tissue imaging. Although research studying the acoustic response of UCAs at low diagnostic ultrasonic frequencies has been well documented, quantitative information on the acoustical properties of UCAs at high ultrasonic frequencies is limited. In this thesis, acoustical characterisation of three UCAs was performed using a preclinical ultrasound scanner (Vevo 770, VisualSonics Inc., Canada). Initially the acoustical characterisation of five high frequency transducers was measured using a membrane hydrophone with an active element of 0.2 mm in diameter to quantify the transmitting frequencies, pressures and spatial beam profiles of each of the transducers. Using these transducers and development of appropriate software, high frequency acoustical characterisation (speed and attenuation) of an agar-based tissue mimicking material (TMM) was performed using a broadband substitution technique. The results from this study showed that the acoustical attenuation of TMM varied nonlinearly with frequency and the speed of sound was approximately constant 1548m·s-1 in the frequency range 12-47MHz. The acoustical properties of three commercially available lipid encapsulated UCAs including two clinical UCAs Definity (Lantheus Medical Imaging, USA) and SonoVue (Bracco, Italy) and one preclinical UCAs MicroMarker (untargeted) (VisualSonics, Canada) were studied using the software and techniques developed for TMM characterisation. Attenuation, contrast-to-tissue ratio (CTR) and subharmonic to fundamental ratio were measured at low acoustic pressures. The results showed that large off-resonance and resonant MBs predominantly contributed to the fundamental response and MBs which resonated at half of the driven frequency predominantly contributed to subharmonic response. The effect of needle gauge, temperature and injection rate on the size distribution and acoustic properties of Definity and SonoVue was measured and was found to have significant impacts. Acoustic characterisations of both TMM and UCAs in this thesis extend our understanding from low frequency to high frequency ultrasound and will enable the further development of ultrasound imaging techniques and UCAs design specifically for high frequency ultrasound applications.
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Ukpai, Jonathan I. „Erosion-corrosion characterisation for pipeline materials using combined acoustic emission and electrochemical monitoring“. Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7328/.
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The prediction and monitoring of erosion and erosion-corrosion attack on oil and gas pipeline materials in service is useful for facilities design, material selection and maintenance planning so as to predict material performance accurately, operate safely, and prevent unplanned production outages. Conventional methods such as failure records, visual inspection, weight-loss coupon analysis, can be time-consuming and can only determine erosion or erosion-corrosion rates when the damage has already occurred. To improve on this, the acoustic emission (AE) technique combined with electrochemical monitoring was chosen and implemented in this study to investigate and characterise erosion and erosion-corrosion degradation rates of oil and gas pipeline materials (X65) under Submerged Impinging Jet (SIJ) systems in a saturated CO2 environment. Measured acoustic emission energy was correlated with the mass loss from gravimetric measurement for different flow velocities and sand loadings. Sand particle impacts were quantified and compared with theoretical predictions, and the associated impact energies predicted from Computational Fluid Dynamics (CFD) were correlated with measured acoustic emission energy and mass loss. The combined acoustic emission and electrochemical monitoring (involving Linear Polarisation Resistance (LPR) and Electrochemical Impedance spectroscopy (EIS)) helped to simultaneously investigate the surface reactivity of the corroding materials as well as capture the sand impacts contribution during the erosion-corrosion degradation processes. Results reveal that the effect of the mechanical damage which is not sensed by in-situ electrochemical measurement is adequately captured by the AE method, thus making the combined technique a novel approach for in-situ monitoring of both the electrochemical and mechanical damage contributions of erosion-corrosion degradation processes.
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Van, der Kelen Christophe. „Characterisation of anisotropic acoustic properties of porous materials - inverse estimation of static flow resistivity“. Licentiate thesis, KTH, MWL Strukturakustik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31183.
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The production processes of porous materials introduce an inherent geometric anisotropy in the material at micro scale, which influences the material properties at macro scale. In this thesis, the focus is turned to one of these macroscopic properties, the flow resistivity, which is a measure of the resistance felt by the sound pressure waves as they propagate through a porous space. In the current work, two different porous materials have been studied, a fibrous glass wool and a Melamine foam. The two materials are expected to show different degrees of anisotropy with respect to flow resistivity. Glass wool is assumed to be transversely isotropic, as a result of the stacking of layers of fibres. The level of anisotropy in Melamine foam is not as obvious, and might be related to production specific aspects, such as the rise-direction, and the position of the injection nozzles. The thesis begins by giving an introduction to porous materials in general, and to glass wool and Melamine foam in particular, followed by an introduction to flow resistivity, together with two methods to measure the flow resistivity. The full anisotropic flow resistivity of glass wool and Melamine foam samples is determined by means of measurements and inverse estimation. An eigenvalue and eigenvector decomposition of the flow resistivity tensor provides an insight into the connection between the directionality of the flow resistivity in each material, and its production process. A study of the homogeneity in density and flow resistivity for the two materials shows that these properties vary within the block of material. However, for each material, there seems to be no connection between the variation in the two properties, investigated at the macroscopic scale.QC 20110311
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Zlatev, Zahari. „Ultrasonic guided wave propagation in pipes coated with viscoelastic materials“. Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/12753.
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This work studies guided wave propagation in pipes coated with thick highly viscoelastic coating materials. The main motivation for this study is the problems associated with Long Range Ultrasonic Testing (LRUT) of coated pipelines. The results reported in the literature show that the proper determination of the optimum LRUT parameters depends strongly on the bulk acoustic properties of the coating materials. The bulk acoustic properties of coating materials reported in the literature show that they could vary significantly depending on the coating material age, temperature and bonding level. The methods for acoustic characterisation of coating materials reported by other researchers, have been studied and it was found that they do not take into account the temperature changes and bonding level variation. In this work, the bulk acoustic properties of two highly viscoelastic bitumen based coating materials are investigated. The conventional methods for acoustic characterisation are studied and a new method for independent measurement of bulk shear properties of bitumen is developed. The bulk acoustic properties of bitumen based coating materials are also studied by two new characterisation methods. The first method derives the bulk coating material properties from experimental data on guided wave reflection coefficients. The second method derives the coating material bulk properties from experimentally measured guided wave attenuation data. It is demonstrated that these new methods deliver much more accurate values for the bulk acoustic properties when compared to the data measured by conventional methods. The second method is used to study the temperature effect on the bulk acoustic properties and it is demonstrated that temperature has a significant effect. The validity of the acoustic properties for the two bitumen materials is investigated through comparison between numerical predictions and experimental data measured for guided wave reflection coefficients and attenuation of the torsional T(0,1) and longitudinal L(0,2) guided wave modes. Good agreement is achieved in the frequency range between 20 kHz and 100 kHz, which is typical for LRUT of pipes.
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Windisch, Thomas. „Laser-akustische Messtechnik in der Materialcharakterisierung“. Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-209721.
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Testing equipment based on the propagation of elastic waves are commonly used for measuring specific material properties. As a prerequisite for accurate measurements a reliable acoustic coupling of probe and specimen is highly important. Therefore, high-resolution testing equipment is using fluids as couplant. In certain conditions, only non-contacting methods can be considered. This is the case for example, if particular high or low temperatures are present, if topographic features impede the use of ultrasonic probes, diffusion or solubility processes exist, measurements at vacuum are addressed and if high purity requirements need to be fulfilled. Hence, subject of this work is a method which offers to handle these constraints. With the emergence of modern laser systems the scientific basics for a non-contacting, laser-acoustic excitation of ultrasound were discovered. The tremendous development of commercially available laser systems during the last decade was taken as reason to investigate, to which extent former scientifically designed laboratory setups can now be merged into one single application oriented measuring system. All considerations are based on the thermoelastic excitation of ultrasound in combination with a likewise laser-based detection. By this, a self-contained measuring chain is built which combines the attributes non-destructive, non-contacting and application oriented within one ultrasonic measurement system for the first time. Thermal calculations lead to more precise equations which predict a laser-induced, local temperature rise of about 100 K. The examination of sound field simulations, as a prerequisite for the design of ultrasonic systems, identified an additional complex of problems. Although existing calculation approaches presuppose laser intensity profiles what can be described in analytical terms, real-world laser sources exhibit a complex shaped spatial distribution of laser energy. Based on a preceding CEFIT simulation, the developed CPSS method enables the calculation of the time resolved, 3D wave propagation of arbitrary shaped sources. A comparison to measured data successfully validated the results of simulation. By presenting selected scenario of measurements, the practical suitability of this non-contacting method is demonstrated. Using a transmission setup enables the characterization of open-pore ceramic coatings as well as the deduction of longitudinal and transversal speeds of sound. Equally, the imaging and estimation of the depth position of artificial defects with 0.7 mm in diameter is shown. Measurements based on a reflection setup provided evidence of a resolution limit of at least FBH = 1 mm in 4.5 mm depth. Additional examples demonstrate the ability to detect close-surface defects, the analysis of the challenging lamb waves zero-group-velocity S1 mode as well as the utilization of buried laser-acoustic sourcesPrüfsysteme, welche die Ausbreitungseigenschaften elastischer Wellen zur Ableitung spezifischer Messgrößen nutzen, sind etablierte Messverfahren. Voraussetzung für zuverlässige Ergebnisse ist stets die sichere akustische Kopplung zwischen Sensor und Material. Daher arbeiten hochauflösende Prüfsysteme mit Fluiden als Koppelmedium. Unter bestimmten Bedingungen scheiden kontaktierende Ultraschallsysteme allerdings ersatzlos aus. Dies ist beispielsweise der Fall, wenn die Probe eine besonders niedrige oder hohe Temperatur besitzt, topografische Eigenschaften ein sicheres Ankoppeln der Kontaktprüfköpfe erschweren, Diffusionsvorgänge oder Löslichkeiten zu beachten sind, in Vakuum zu arbeiten ist oder erhöhte Reinheitsanforderungen vorliegen. Gegenstand der vorliegenden Arbeit ist eine Technik welche hilft, diese Einschränkungen zu umgehen. Mit dem Aufkommen der ersten Laserquellen entstanden die wissenschaftlichen Grundlagen zur kontaktlosen Anregung und Detektion von Ultraschall. Die rasante Entwicklung kommerziell verfügbarer Lasersysteme der vergangenen Dekade wurde zum Anlass genommen zu untersuchen, in wie weit sich die einst wissenschaftlich orientierte Laboraufbauten zu einem anwendungsnahen Messsystem zusammenführen lassen. Basis der Arbeiten ist die thermoelastische Anregung von Ultraschall in Kombination mit einer ebenfalls kontaktlosen Detektion. Damit entsteht eine geschlossene Messkette welche erstmals die Eigenschaften zerstörungsfrei, kontaktlos und anwendungsorientiert in einem Ultraschallmesssystem vereint. Ausgangspunkt stellt die thermische Simulation der Anregung dar. Mit Hilfe präzisierter Gleichungen wird eine lokale Erwärmung von lediglich 100 K vorausgesagt. Für die zur Auslegung eines akustischen Messsystems notwendige Schallfeldsimulation wurde eine weitere Problematik identifiziert. Während bekannte Rechenansätze stets analytisch beschreibbare Strahlprofile des Lasers voraussetzen, zeigen reale Laserquellen kompliziert gestaltete räumliche Intensitätsverteilungen. Auf Basis einer vorangestellten CEFIT-Simulation ist mit der entwickelten CPSS-Methode eine zeitdiskrete Berechnung der 3D-Wellenausbreitung beliebiger Quellgeometrien möglich. Vergleiche mit realen Messdaten bestätigen die Simulationsrechnungen. Anhand ausgewählter Messszenarien wird die Praxistauglichkeit der kontaktlosen Arbeitsweise demonstriert. Neben der Charakterisierung einer offenporigen keramischen Beschichtung erlauben Transmissionsmessungen die Berechnung der longitudinalen und transversalen Schallgeschwindigkeiten. Ebenso ist die Abbildung wie auch die Beurteilung der Tiefenlage von Referenzfehlern mit lediglich 0,7 mm Durchmesser möglich. In Reflexionsmessungen wurde eine Auflösungsgrenze von mindestens KSR = 1 mm in 4,5 mm Tiefe nachgewiesen. Weitere Beispiele zeigen die Sensitivität hinsichtlich oberflächennaher Fehler, die Auswertung der anspruchsvollen „Zero Group Velocity“ S1-Mode der Lambwelle wie auch die Nutzung eingebetteter Quellen
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Bentahar, Mourad. „Acoustique non-linéaire : application à la caractérisation ultrasonore de l'endommagement des matériaux hétérogènes et à la prédiction de la durée de vieNonlinear acoustics : application to ultrasonic characterisation of damage in heterogeneous materials and remaining life determination“. Lyon, INSA, 2005. http://theses.insa-lyon.fr/publication/2005ISAL0038/these.pdf.
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Dans ce travail, nous avons étudié les potentialités des méthodes d'évaluation non destructive (END) par ondes acoustiques non-linéaires en résonance pour la caractérisation et le suivi de l'endommagement des matériaux hétérogènes (bétons et composites base polymère). Pour cela, un dispositif expérimental permettant une réception avec et sans contact et pouvant s'adapter à différentes géométries a été développé. Pour les deux matériaux, les variations de la fréquence de résonance observées en fonction du niveau d'excitation (dynamique rapide) sont directement corrélées aux niveaux d'endommagement. Après une forte excitation (conditionnement) des éprouvettes endommagées, un décalage vers les plus basses fréquences est observé pour les deux matériaux. Ce décalage ne disparaît pas immédiatement après l'arrêt de la forte excitation, mais se résorbe en fonction du logarithme du temps, fortement lié au degré d'endommagement. A travers ce phénomène appelé " dynamique lente " nous avons pu définir de nouveaux indicateurs d'endommagement ayant une grande sensibilité aux premiers états de dégradation du matériau. Pour le béton, ces observations, traduisant le comportement hystérétique non-linéaire des matériaux endommagés, sont étayées qualitativement et quantitativement par un modèle unidirectionnel, basé sur l'approche d'interaction locale dans le cadre de la description phénoménologique de Preisach-Mayergoitz. Enfin, nous avons trouvé d'intéressantes corrélations entre les indicateurs non-linéaires d'endommagement (dynamiques rapide et lente) et l'énergie élastique libérée sous forme d'émission acoustique par le matériau lors du processus d'endommagement. Ce résultat liant pour la première fois le comportement acoustique hystérétique non-linéaire et l'émission acoustique ouvre d'intéressantes perspectives pour la caractérisation de l'état de santé des matériaux hétérogènes et l'évaluation de leur potentiel restantIn this work, we have studied the potentials of nondestructive evaluation methods using resonant nonlinear acoustics phenomena to characterize and follow damage induced in heterogeneous materials (concrete and polymer composites). For this, we have conceived an experimental device adapted to different geometries, which allows contact and contactless reception. For both materials, changes of the resonance frequency with increasing excitation level “fast dynamics” were correlated to the damage level. As a response to the application a strong excitation, resonance frequency of damage samples shifts to low frequencies. This shift does not disappear instantaneously when the strong excitation is removed but changes as a logarithm of time. The duration of the frequency recovery is strongly dependent on the damage state. Through this phenomenon, called “slow dynamics”, we have defined new damage indicators very sensitive to primary damage states. For concrete, these observations, which manifest hysteretic nonlinear behavior of damaged materials, are supported qualitatively and quantitatively by a one-dimensional model based on the phenomenological description of Preisach-Mayergoitz. We have found interesting correlations between the different nonlinear damage indicators (slow and fast dynamics) and the elastic energy, freed by the material during the damage process, calculated through acoustic emission signals. This result, linking for the first time hysteretic nonlinear acoustics emission, offers a good opportunity and future prospects for structural health monitoring of heterogeneous materials and their remaining life determination
Buchteile zum Thema "Acoustic material characterisatio"
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Andersen, Kristian Gjerrestad, Gbanaibolou Jombo, Sikiru Oluwarotimi Ismail, Yong Kang Chen, Hom Nath Dhakal und Yu Zhang. „Damage Characterisation in Composite Laminates Using Vibro-Acoustic Technique“. In Springer Proceedings in Energy, 275–82. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63916-7_34.
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AbstractThe need to characterise in-service damage in composite structures is increasingly becoming important as composites find higher utilisation in wind turbines, aerospace, automotive, marine, among others. This paper investigates the feasibility of simplifying the conventional acousto-ultrasonic technique set-up for quick and economic one-sided in-service inspection of composite structures. Acousto-ultrasonic technique refers to the approach of using ultrasonic transducer for local excitation while sensing the material response with an acoustic emission sensor. However, this involves transducers with several auxiliaries. The approach proposed herewith, referred to as vibro-acoustic testing, involves a low level of vibration impact excitation and acoustic emission sensing for damage characterisation. To test the robustness of this approach, first, a quasi-static test was carried out to impute low-velocity impact damage on three groups of test samples with different ply stacking sequences. Next, the vibro-acoustic testing was performed on all test samples with the acoustic emission response for the samples acquired. Using the acoustic emission test sample response for all groups, the stress wave factor was determined using the peak voltage stress wave factor method. The stress wave factor results showed an inverse correlation between the level of impact damage and stress wave factor across all the test sample groups. This corresponds with what has been reported in literature for acousto-ultrasonic technique; thus demonstrating the robustness of the proposed vibro-acoustic set-up. Structural health monitoring, impact damage, acousto-ultrasonic testing, non-destructive testing.
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Pfleiderer, K., R. Stoessel, I. Solodov und G. Busse. „Acoustic Imaging with Surace and Lamb Waves for NDE and Material Characterisation“. In Acoustical Imaging, 157–64. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-1-4020-2402-3_20.
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Pullin, Rhys, Karen M. Holford, Sam L. Evans und Matthew Baxter. „Advanced Location and Characterisation of Damage in Complex Metallic Structures Using Acoustic Emission“. In Experimental Analysis of Nano and Engineering Materials and Structures, 925–26. Dordrecht: Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-6239-1_460.
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Schoone, Sunny, Tobias Vraetz, Ralph Baltes und Elisabeth Clausen. „Blue Nodules: Use of Acoustic Emission Technology for an Inline Characterisation of Hydraulic Material Streams“. In Yearbook of Sustainable Smart Mining and Energy 2021, 213–27. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-84315-1_12.
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Fey, P., D. Döring, G. Busse, J. Frick, F. Grüner und M. Kersemans. „Preliminary results on non-contact characterisation of weathered mineral materials by surface acoustic waves“. In Emerging Technologies in Non-Destructive Testing V, 271–74. CRC Press, 2012. http://dx.doi.org/10.1201/b11837-48.
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Acoustic material characterisatio"
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RODRÍGUEZ, CARLOS, ISIDRO SÁNCHEZ, SALVADOR MARTÍNEZ, JESÚS CARBAJO, JAIME RAMIS und IGNACIO GARCÍA-LEGAZ. „USE OF RECYCLED AGGREGATES FROM DEMOLITION WASTES IN CONCRETE: ACOUSTIC PROPERTIES“. In MATERIALS CHARACTERISATION 2019. Southampton UK: WIT Press, 2019. http://dx.doi.org/10.2495/mc190041.
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ASTRAUSKAS, Tomas, Mantas PRANSKEVIČIUS und Tomas JANUŠEVIČIUS. „Primary study of plastic micro fibre waste for sound absorption applications“. In 12th International Conference “Environmental Engineering”. VILNIUS TECH, 2023. http://dx.doi.org/10.3846/enviro.2023.867.
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Plastic and waste production has increased significantly in recent years. According to the various predictions the plastic production is not slowing down in the near future. Since 1960, plastic production has risen to 322 million tonnes in 2015 and expected to double in the next 20 years (Lusher et al., 2017). According to the 2020 statistical data, the leading sectors in plastic demand are packaging, building and construction, with 40.5% and 20.4% respectively. In 2019, an estimated 41% of plastic packaging waste was recycled in the EU. Despite the advantages of plastic recycling technologies, there are also a number of problems. Mechanical recycling refers to the processing of plastics waste into secondary raw material or products without significantly changing the material’s chemical structure. In this paper, we focused at the problem of plastic micro fibre (PMF) waste, which generated during mechanical recycling. The possibilities of using PMF for sound absorption applications are tested. For primary acoustic characterisation PMF was not treated thermally or bound using other materials. The controlled parameter of the material is density. The density of material changed from 100 to 300 kg/m3. The PMF sound absorption characterisation was performed using standard transfer function method (ISO 10534-2). The acoustic performance of materials predicted with acoustic porous materials Delany-Bazley-Miki model. The aim of this paper is to gain the essential knowledge about the plastic micro fibre sound absorption performance to find the possible recycling application for sound absorption.
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Piana, Edoardo Alessio. „Acoustic characterisation of hosiery factory waste materials“. In 2023 Immersive and 3D Audio: from Architecture to Automotive (I3DA). IEEE, 2023. http://dx.doi.org/10.1109/i3da57090.2023.10414191.
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CARROLL, NL, RJ PAMLEY und JD SMITH. „MATERIALS CHARACTERISATION USING IMPEDANCE TUBE TECHNIQUES“. In Underwater Acoustic Calibration and Measurements 1998. Institute of Acoustics, 2024. http://dx.doi.org/10.25144/18903.
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HOPPER, C., S. ASSOUS, DA GUNN, PD JACKSON, JG REES, MA LOVELL und LM LINNETT. „BIOLOGICALLY-INSPIRED ULTRASONIC SIGNALS FOR PHYSICAL CHARACTERISATION OF GEOLOGICAL MATERIALS“. In Spring Conference Acoustics 2008. Institute of Acoustics, 2023. http://dx.doi.org/10.25144/17543.
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GIANGRECO, CJ. „CHARACTERISATION OF MATERIALS FOR UNDERWATER ACOUSTICS APPLICATIONS USING TEST PANEL MEASUREMENTS“. In Underwater Acoustic Calibration and Measurements 1998. Institute of Acoustics, 2024. http://dx.doi.org/10.25144/18899.
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Zou, H., Y. Li, S. Smith, A. S. Bunting, A. J. Walton und J. G. Terry. „Modification and characterisation of material hydrophobicity for surface acoustic wave driven microfluidics“. In 2012 IEEE International Conference on Microelectronic Test Structures (ICMTS). IEEE, 2012. http://dx.doi.org/10.1109/icmts.2012.6190614.
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Gardiner, Alicia, Roger Domingo-Roca, Mahshid Hafezi, James Windmill und Andrew Feeney. „Characterisation of 3D printable material for an acoustic metamaterial cell with tuneable resonance“. In 2024 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS). IEEE, 2024. http://dx.doi.org/10.1109/fleps61194.2024.10603566.
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Low, S. K. „Quantitative characterisation of acoustic emission source for composite failure mechanism under quasi-static three-point bending“. In Structural Health Monitoring. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902455-25.
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Abstract. Fibre reinforced composites have been discovered to have superior material properties compared to traditional materials. However, composite structures do have weaknesses which is highly susceptible to damage from accidental impacts. Passive approaches have gained popularity in recent years as these can be implemented using less structurally and electrically obtrusive sensor installations. The fundamental hypothesis is that every distinct impact event has a unique modal signature that can be exploited to distinguish between damaging and nondamaging impacts, and to characterize the severity of damage. Preliminary research showed that the possibility to determine the progressive failure mechanism in composite specimens subjected to three-point bending. Each failure mechanisms have its corresponding frequency bandwidth, and it can be seen by plotting the spectrogram of time-frequency analysis. However, the limitation of time-frequency analysis for identifying failure modes arises from the fact that there can be a confluence of modes having more-or-less the same group velocity hence, having the same arrival time in a time-frequency plot for a given frequency. This overlap makes it problematic to identify modes unambiguously from a time-frequency analysis. The modes can be more clearly separated on the basis of dispersion curves obtained in the frequency-wavenumber space. This information paves way to the idea of developing a modal sensor that is capable of providing experimentally determined dispersion curves that can be expected to lead to a quantum advance in capability for modal identification, and hence for determining a far more accurate modal signature for various acoustic emission events.
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Ketoja, J. A., S. Paunonen, E. Pääkkönen, T. Pöhler, T. Turpeinen, A. Miettinen, T. Mäkinen, J. Koivisto und M. J. Alava. „Mean-field Approach to Compression of Thick Porous Fibre Networks“. In Advances in Pulp and Paper Research. Pulp & Paper Fundamental Research Committee (FRC), Manchester, 2022. http://dx.doi.org/10.15376/frc.2022.1.371.
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We discuss a new mean-field theory to describe the compression behaviour of thick low-density fibre networks. The theory is based on the idea that in very large systems, the statistics of free segment lengths causes the stress-deformation behaviour to be quantitatively predictable. The theoretical ideas are supported by several different experimental characterisations. Firstly, we have carried out single-fibre buckling tests using hemp fibres, which indicate a maximum level of axial stress before deformation localization, after which the load carrying ability of a fibre decays. Secondly, the stress-compression behaviour of over 130 different foam-formed lightweight fibre materials were measured. For kraft pulps with low fines content, the average stress compression behaviour closely follows the theoretical prediction as described in terms of a universal s-function. Moreover, the acoustic emission can be described by the same function until collective phenomena cause deviations from the predicted behaviour. Similar deviations at smaller compressive strains are seen with furnishes with high fines content or added nanocelluloses together with samples with large voids. The localized buckling deformations lead to rapid stress re-distributions and subsequent fibre displacements in a fibre network as shown with in-situ CCD imaging.