Identification of composite materials elastic moduli from Lamb wave velocities measured with single sided, contactless ultrasonic method

2001 ◽  
Author(s):  
Bernard Hosten
Keyword(s):  
Composite Materials ◽  
Lamb Wave ◽  
Elastic Moduli ◽  
Ultrasonic Method ◽  
Wave Velocities

scholarly journals On the Theory of Elasticity of Microinhomogeneous Media with Account for Stochastic Changes in the Connectivity of Constituent Components

2021 ◽  
pp. 132-143
Author(s):  
L. A Saraev
Keyword(s):  
Differential Equation ◽  
Composite Material ◽  
Composite Materials ◽  
Numerical Solution ◽  
Elastic Moduli ◽  
Production Factor ◽  
Effective Elastic Moduli ◽  
Connectivity Function ◽  
Isotropic Composite ◽  
Random Connectivity

The paper proposes a mathematical model aimed at calculating the effective elastic moduli of a micro-inhomogeneous two-component isotropic composite material, which components are connected randomly depending on the level of their relative volumetric contents. A stochastic equation is formulated for the connectivity parameter of the constituent components, according to which, with an increase in the volumetric content of the filler, individual inclusions build the structures of the matrix mixture in the form of interpenetrating frameworks, and then turn into a new binding matrix with individual inclusions from the material of the rest of the old matrix. The algorithm for the numerical solution of this stochastic differential equation is constructed in accordance with the Euler-Maruyama method. For each implementation of this algorithm, the corresponding stochastic trajectories are constructed for the random connectivity function of the constituent components of the composite material. A variant of the method aimed at calculating the mathematical expectation of a random connectivity function of the constituent components has been developed and the corresponding differential equation has been obtained for it. It is shown that the numerical solution of this equation and the average value of the production factor function calculated for all realizations of stochastic trajectories give close numerical values. New macroscopic constitutive relations are found for microinhomogeneous materials with a variable microstructure and their effective elastic moduli are calculated. It is noted that the formulas for these effective elastic moduli generalize the known results for isotropic composite materials. The values of the effective elastic moduli, constructed according to the expressions obtained in the paper, lie within the Khashin-Shtrikman range for the lower and upper bounds of the effective elastic moduli of the composite materials. The numerical analysis of the developed models showed a good agreement with the known experimental data.

Lamb wave detection in prepreg composite materials with fibre Bragg grating sensors

2011 ◽  
Author(s):  
Nick Miesen ◽  
Yoshihiro Mizutani ◽  
Roger M. Groves ◽  
Jos Sinke ◽  
Rinze Benedictus
Keyword(s):  
Composite Materials ◽  
Lamb Wave ◽  
Bragg Grating ◽  
Fibre Bragg Grating ◽  
Wave Detection

Determination of Vibration Source Locations in Laminated Composite Plates Using Lamb Wave Analysis

2010 ◽  
Vol 123-125 ◽  
pp. 899-902
Author(s):  
Chao Du ◽  
Qing Qing Ni ◽  
Toshiaki Natsuki
Keyword(s):  
Lamb Wave ◽  
Guided Waves ◽  
Lamb Waves ◽  
Laminated Composite ◽  
Composite Plates ◽  
Wave Dispersion ◽  
Laminated Plates ◽  
Vibration Source ◽  
Arrival Times ◽  
Wave Velocities

Signals propagate on plate-like structures as ultrasonic guided waves, and analysis of Lamb waves has been widely used for on-line monitoring. In this study, the wave velocities of symmetric and anti-symmetric modes in various directions of propagation were investigated. Since the wave velocities of these two modes are different, it is possible to compute the difference in their arrival times when these waves propagated the distance from the vibration source to sensor. This paper presents an evaluation formulation of wave velocity and describes a generalized algorithm for locating a vibration source on a thin, laminated plate. With the different velocities of two modes based on Lamb wave dispersion, the method uses two sensors to locate the source on a semi-infinite interval of a plate. The experimental procedure supporting this method employs pencil lead breaks to simulate vibration sources on quasi-isotropic and unidirectional laminated plates. The transient signals generated in this way are transformed using a wavelet transform. The vibration source locations are then detected by utilizing the distinct wave velocities and arrival times of the symmetric and anti-symmetric wave modes. The method is an effective technique for identifying impact locations on plate-like structures.

scholarly journals The permeability and elastic moduli of tuff from Campi Flegrei, Italy: implications for ground deformation modelling

Solid Earth ◽  
2014 ◽  
Vol 5 (1) ◽  
pp. 25-44 ◽  
Author(s):  
M. J. Heap ◽  
P. Baud ◽  
P. G. Meredith ◽  
S. Vinciguerra ◽  
T. Reuschlé
Keyword(s):  
Ultrasonic Wave ◽  
Elastic Moduli ◽  
Ground Deformation ◽  
Laboratory Data ◽  
Campi Flegrei ◽  
Pore Collapse ◽  
Campanian Ignimbrite ◽  
Wave Velocities ◽  
Neapolitan Yellow Tuff ◽  
Dynamic Elastic Moduli

Abstract. The accuracy of ground deformation modelling at active volcanoes is a principal requirement in volcanic hazard mitigation. However, the reliability of such models relies on the accuracy of the rock physical property (permeability and elastic moduli) input parameters. Unfortunately, laboratory-derived values on representative rocks are usually rare. To this end we have performed a systematic laboratory study on the influence of pressure and temperature on the permeability and elastic moduli of samples from the two most widespread lithified pyroclastic deposits at the Campi Flegrei volcanic district, Italy. Our data show that the water permeability of Neapolitan Yellow Tuff and a tuff from the Campanian Ignimbrite differ by about 1.5 orders of magnitude. As pressure (depth) increases beyond the critical point for inelastic pore collapse (at an effective pressure of 10–15 MPa, or a depth of about 750 m), permeability and porosity decrease significantly, and ultrasonic wave velocities and dynamic elastic moduli increase significantly. Increasing the thermal stressing temperature increases the permeability and decreases the ultrasonic wave velocities and dynamic elastic moduli of the Neapolitan Yellow Tuff; whereas the tuff from the Campanian Ignimbrite remains unaffected. This difference is due to the presence of thermally unstable zeolites within the Neapolitan Yellow Tuff. For both rocks we also find, under the same pressure conditions, that the dynamic (calculated from ultrasonic wave velocities) and static (calculated from triaxial stress-strain data) elastic moduli differ significantly. The choice of elastic moduli in ground deformation modelling is therefore an important consideration. While we urge that these new laboratory data should be considered in routine ground deformation modelling, we highlight the challenges for ground deformation modelling based on the heterogeneous nature (vertically and laterally) of the rocks that comprise the caldera at Campi Flegrei.

On quantifying damage severity in composite materials by an ultrasonic method

2019 ◽  
Vol 216 ◽  
pp. 213-221 ◽  
Author(s):  
Lalith Sai Srinivas Pillarisetti ◽  
Ramesh Talreja
Keyword(s):  
Composite Materials ◽  
Ultrasonic Method
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