Transient Wave Propagation Methods for Determining the Viscoelastic Properties of Solids

1993 ◽  
Vol 60 (3) ◽  
pp. 763-768 ◽  
Author(s):  
R. H. Blanc
Keyword(s):  
Viscoelastic Properties ◽  
Fourier Transforms ◽  
Filter Method ◽  
Mechanical Wave ◽  
Transient Wave ◽  
One Dimensional ◽  
Ultrasonic Methods ◽  
Transient Wave Propagation ◽  
Propagation Methods ◽  
Set Up

The following two solutions are proposed for deducing the viscoelastic properties of a solid from the change in the shape of a one-dimensional transient mechanical wave as it propagates through the medium: (i) The general solution:—the phase velocity and the attenuation coefficient are expressed in terms of the Fourier transforms of the pulse after two distances of travel, and (ii) A filter method. An experimental set-up is described. The results, which are obtained with no heating of the material, come within the audiofrequency range. This method fills a gap between the existing vibratory and ultrasonic methods.

Transient Wave Propagation in a Harmonically Heterogeneous Elastic Solid

1992 ◽  
Vol 59 (2S) ◽  
pp. S145-S151
Author(s):  
Hyun-Sil Kim ◽  
Jerry H. Ginsberg
Keyword(s):  
Floquet Theory ◽  
Elastic Solid ◽  
Harmonic Excitation ◽  
Additional Insight ◽  
Regular Perturbation ◽  
Transient Wave ◽  
One Dimensional ◽  
Dilatational Wave ◽  
Transient Wave Propagation ◽  
Insight Into

Transient propagation of a one-dimensional dilatational wave in a harmonically heterogeneous elastic solid is studied by several techniques. A regular perturbation analysis in terms of the characteristics of the differential equation shows that initiation of a temporally harmonic excitation that generates a signal whose wavelength is twice the periodicity of the heterogeneity leads to secularity in the first approximation. The frequency at which this situation occurs matches the frequency at which Floquet theory predicts that steady-state waves may be unstable. A finite difference algorithm based on integrating along the characteristics is developed and implemented to obtain a numerical solution. In the critical case, backscattering of the wave from the heterogeneity results in a mixture of propagating and standing wave features. However, rather than being unstable, the heterogeneity in this condition is shown to result in maximum interference with forward propagation. A comparable analysis for a step excitation on the boundary provides additional insight into the underlying propagation phenomena.

Numerical Analysis of Transient Wave Propagation in Nonlinear One-Dimensional Waveguides by Using the Spectral Finite Element Method

2015 ◽  
Vol 10 (5) ◽  
Author(s):  
Yu Liu ◽  
Andrew J. Dick
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Wave Propagation ◽  
Geometric Nonlinearity ◽  
Material Nonlinearity ◽  
Transient Wave ◽  
One Dimensional ◽  
Transient Wave Propagation ◽  
1D Model ◽  
Element Method

In this paper, transient wave propagation in nonlinear one-dimensional (1D) waveguides is studied. A complete nonlinear (CN) 1D model accounting for both axial and transverse displacements is developed and geometric and material nonlinearities are separately modeled. The alternating frequency-time finite element method (AFT-FEM) is implemented for this complete 1D model. Numerical simulations are conducted and the response behaviors for axial and transverse motions are analyzed. Comparison of the responses for the geometrically nonlinear (GN) model with a corresponding linear model supports predictions made from the previous analytical studies that the geometric nonlinearity has limited influence on the response of transient transverse waves in the intermediate strain regime. On the contrary, strong nonlinear behavior appears in the response for the materially nonlinear (MN) models. Depending on the local nonlinear property of the material in the intermediate strain regime, the amplitude of the response can be significantly influenced and additional dispersion can be introduced into the response. An exploration of the interaction between the geometric nonlinearity and the material nonlinearity for a rod model in a large strain regime is also conducted and the responses are analyzed by using time-frequency analysis. The competing effect of the geometric nonlinearity and the material nonlinearity can result in a pseudolinear response in a strong nonlinear system for a given range of impact loading.

Transient wave propagation in bubbly liquids

1982 ◽  
Vol 119 ◽  
pp. 347-365 ◽  
Author(s):  
D. S. Drumheller ◽  
M. E. Kipp ◽  
A. Bedford
Keyword(s):  
Variational Formulation ◽  
Momentum Equation ◽  
Thermal Dissipation ◽  
Bubbly Liquid ◽  
Balance Equations ◽  
Transient Wave ◽  
One Dimensional ◽  
Bubbly Liquids ◽  
Transient Wave Propagation ◽  
Good Agreement

A theoretical and numerical investigation of the propagation of one-dimensional waves in a bubbly liquid is presented. A variational formulation of the problem is used that yields both the linear-momentum equation and the equation that describes the oscillations of the bubbles. The compressibility of the liquid is taken into account in the formulation. The thermal dissipation is treated by solving the energy-balance equations simultaneously with the mechanical equations. Solutions are obtained by a finite-difference procedure and are compared to the experimental data of Kuznetsov et al. and Noordzij & van Wijngaarden. In some cases quite good agreement is obtained, but in others substantial errors are found. It is suggested that the observed discrepancies may be due to the breakup of the bubbles in the case of very large amplitude disturbances; the fact that the formulation does not include relative motion between the liquid and the bubbles; and possible non-planarity effects in the experiments.

One-Dimensional Transient Wave Propagation in a Dry Overlying Saturated Ground

2019 ◽  
Vol 23 (10) ◽  
pp. 4297-4310
Author(s):  
Jiang Tao Yi ◽  
Lei Zhang ◽  
Fei Jian Ye ◽  
Siang Huat Goh
Keyword(s):  
Wave Propagation ◽  
Transient Wave ◽  
One Dimensional ◽  
Transient Wave Propagation

scholarly journals Assessment of the Deterioration State of Post-Installed Bonded Anchors Using Ultrasonic

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2077
Author(s):  
Oliver Zeman ◽  
Michael Schwenn ◽  
Martin Granig ◽  
Konrad Bergmeister
Keyword(s):  
Maximum Load ◽  
Assessment Method ◽  
Load Level ◽  
Experimental Investigations ◽  
Load History ◽  
Anchor System ◽  
Ultrasonic Methods ◽  
Building Maintenance ◽  
History Of ◽  
Set Up

The assessment of already installed anchorages for a possible exceeding of the service load level is a question that is gaining more and more importance, especially in building maintenance. Bonded anchors are of particular interest here, as the detection of a capacity reduction or load exceedance can cause damage to the concrete-bonded mortar behavior. This article investigates the extent to which ultrasonic methods can be used to make a prediction about the condition of anchorages in concrete and about their load history. A promising innovative assessment method has been developed. The challenges in carrying out the experimental investigations are the arrangement of the transducers, the design of the test set-up and the applicability of direct, indirect or semidirect ultrasonic transmission. The experimental investigations carried out on a test concrete mix and a bonded anchor system show that damage to the concrete structure can be detected by means of ultrasound. The results indicate the formation of cracks and therefore a weakening of the response determined by means of direct, indirect and semidirect ultrasonic transmission. However, for application under non-laboratory conditions and on anchors with unknown load history, the calibration with a reference anchor and the identification of the maximum load is required. This enables a referencing of the other loaded anchors to the unloaded conditions and allows an estimation of the load history of individual anchors.

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