Wave Propagation In Composite Materials Research Articles

Validation of a ray-tracing-based guided Lamb wave propagation methodology in aerostructures

Validation of a ray-tracing-based guided Lamb wave propagation methodology in aerostructures

A surrogate model for finite element simulation of elastic wave propagation in composite materials

Deep learning surrogate models can be employed in solid mechanics to forecast the behavior of structures subjected to various loading conditions, substantially decreasing the computational costs associated with simulations. In this letter, we have utilized convolutional neural networks and Fourier transform to predict the elastic wave output from composite bars. The microstructures of the bar are utilized as inputs to the deep learning model, while the output is the elastic wave response. The convolutional neural network learns to identify crucial input composite features and utilizes this information to predict the output elastic waves. Finally, the mean squared error of the predicted output signals is compared to the actual output signals, which was used to evaluate the model. The outcomes of this study demonstrate that the deep learning model can precisely and swiftly predict the output elastic waves of the composites, thus serving as a surrogate model for time-consuming finite element simulations.

Probabilistic modeling and simulation of wave speeds in random composites

Investigations of wave propagation in composite materials have been used both to experimentally measure material properties and to validate material property model characterizations. For continuous fiber reinforced composites, these characterizations often have relied on a bulk description of the effective behavior of a Representative Volume Element (RVE) and assumed ideal conditions of transverse isotropy and a well defined direction of the fibers. Analytic models, based on these composite properties and fiber directions, can then be used to predict the speeds of waves propagating through the material. The goal of this work is to develop a probabilistic simulation to examine how variations in the composite properties and small angles of mis-alignment of the fibers affect wave speed. To achieve this, a joint probability function is constructed where a dominant material property and the angle of fiber orientation are considered independent random variables. Sampling from this joint distribution produces pairs of parameters that can be input into wave speed analysis. The resulting wave speed distributions can be used to characterize the joint effects of randomness in material property and fiber angle.

Calculation of Wave Dispersion Curves in Multilayered Composite-Metal Plates

The major purpose of this paper is the development of wave dispersion curves calculation in multilayered composite-metal plates. At first, equations of motion and characteristic equations for the free waves on a single-layered orthotropic plate are presented. Since direction of wave propagation in composite materials is effective on equations of motion and dispersion curves, two different cases are considered: propagation of wave along an axis of material symmetry and along off-axes of material symmetry. Then, presented equations are extended for a multilayered orthotropic composite-metal plate using the transfer matrix method in which a global transfer matrix may be extracted which relates stresses and displacements on the top layer to those on the bottom one. By satisfying appropriate boundary conditions on the outer boundaries, wave characteristic equations and then dispersion curves are obtained. Moreover, presented equations may be applied to other materials such as monoclinic, transversely isotropic, cubic, and isotropic materials. To verify the solution procedure, a number of numerical illustrations for a single-layered orthotropic and double-layered orthotropic-metal are presented.

Numerical simulation of effective phase velocity and attenuation of shear elastic wave propagation in unidirectional composite materials

In this paper, a simple simulation approach is presented for calculating the effective phase velocity and attenuation coefficient of elastic shear waves propagating in composite materials with randomly distributed unidirectional inclusions. As an application of the developed numerical approach, the phase velocities and attenuation coefficients of the coherent waves in four different types of composite material are simulated for various incident frequencies up to π. Numerical results are compared with theoretical predictions obtained from three representative theoretical models. While all theoretical results agree very well with numerical values at low incident frequencies, the discrepancies increase with the increased incident frequency and volume fraction of inclusions. It has been found that within the frequency and volume fraction ranges considered in this work, the generalized self-consistent model by Kanaun and Levin [18] seems to provide the most accurate estimations.

The ultrasonic wave propagation in composite material and its characteristic evaluation

The use of the ultrasonic wave technology was expected as one of important technologies in health monitoring of composite materials and/or structures. However, the propagation of ultrasonic wave becomes very complicated for polymer based composite materials due to reflection, transmission, dispersion and so on, which may occur on the interface of matrix and reinforcements. Therefore, in this paper, elastic wave motion equation was dispersed using the finite element analysis of the PZFlex code; then the propagation of ultrasonic wave in several model composite materials was simulated. Then, the influence of the fiber/matrix interface shape, fiber size and other fiber conditions on wave propagation behavior was clarified. Moreover, the complicated wave propagation resulting from reflection, transmission and refraction on the fiber/matrix interface was visualized and the influence of the fiber arrangements and fiber volume fraction on the ultrasonic wave behavior was investigated for both conditions with and/or without attenuation in matrix.

On the generalized self-consistent model for elastic wave propagation in composite materials

The generalized self-consistent model (GSCM) for the analysis of elastic wave propagation in composite materials is recast. Following the idea of the GSCM in the static problem, elastic wave energy in the model is evaluated by applying the energy theorem for the elastic wave scattering in an absorbing medium. The conditions for dynamic effective medium are then obtained in a self-consistent way as those under which the extinguished wave energy in the model vanishes, thus without relying on the multiple scattering formalism. It is shown that the present dynamic GSCM is equivalent to the models of Yang and Mal [J. Mech. Phys. Solids 42 (1994) 1945] and Yang [J. Appl. Mech. 70 (2003) 575] that have been obtained through the use of the multiple scattering formalism of Waterman and Truell. Numerical results for both fiber-reinforced and particulate composites are presented. Physical realizability of the dynamic GSCM in the low frequency limit is discussed briefly.

Meshless Method Used in Wave Propagation in Anisotropic Material

The compactly supported radial basis functions (RBFs) is modified and used to the wave propagation in the anisotropic materials. An example to simulate the wave propagation in composite material is used in the paper to verify this method. In this example, stress wave propagation histories are obtained. The comparison between results by this method and by finite element method is also made. And the agreement with two results shows that this method can be used to simulate the wave propagation history in anisotropic material efficiently.

Advanced numerical models and material characterisation techniques for composite materials subject to impact and shock wave loading

The development and validation of an advanced material model for orthotropic materials, such as fibre reinforced composites, is described. The model is specifically designed to facilitate the numerical simulation of impact and shock wave propagation through orthotropic materials and the prediction of subsequent material damage. Initial development of the model concentrated on correctly representing shock wave propagation in composite materials under high and hypervelocity impact conditions [1]. This work has now been extended to further concentrate on the development of improved numerical models and material characterisation techniques for the prediction of damage, including residual strength, in fibre reinforced composite materials. The work is focussed on Kevlar-epoxy however materials such as CFRP are also being considered. The paper describes our most recent activities in relation to the implementation of advanced material modelling options in this area. These enable refined non-linear directional characteristics of composite materials to be modelled, in addition to the correct thermodynamic response under shock wave loading. The numerical work is backed by an extensive experimental programme covering a wide range of static and dynamic tests to facilitate derivation of model input data and to validate the predicted material response. Finally, the capability of the developing composite material model is discussed in relation to a hypervelocity impact problem.

Stress wave propagation in composite materials

The linear constitutive relations and the failure criteria of composite materials made of thermoviscoelastic solids are presented. The post-failure material behavior is proposed and the dynamic finite element equations are formulated. However, a nonlinear term is kept in the energy equation because it represents the effect of the second law of thermodynamics. A general purpose nonlinear three-dimensional dynamic finite element program COMPASS is upgraded and employed in this work to investigate the interdependence among stress wave propagation, stress concentration, failure progression and temperature elevation in composite materials. The consequence of truthfully incorporating the second law of thermodynamics is clearly observed: it will always cause temperature rise if there exists a dynamic mechanical process.

118 複合材料の分散性を考慮した波動伝播の非局所型モデル(OS12-2 非弾性解析)(OS12 材料の塑性挙動の構成式のモデル化とシミュレーション)

118 複合材料の分散性を考慮した波動伝播の非局所型モデル(OS12-2 非弾性解析)(OS12 材料の塑性挙動の構成式のモデル化とシミュレーション)

416 複合材料中の超音波伝播の有限要素法解析

416 複合材料中の超音波伝播の有限要素法解析

Analytical simulation of stress wave propagation in composite materials

This paper discusses the development and the results of an analytical model that simulates the propagation of stress waves caused by slamming impact on composite materials. An introduction to stress wave theory is given, recapitulating and illustrating the most important formulas. The implementation of the analytical model into a Fortran computer program is discussed, focusing respectively on the input, calculation and output routines. The results are evaluated, and it is concluded that the program can be a useful tool when studying impact and fatigue phenomena in composite materials, because substantial stress components were obtained and stress concentrations can be predicted at the locations where delaminations are expected.

Wave propagation in composite materials with fibre waviness

A discrete ray tracing model based on elastodynamic ray theory was developed and applied to a composite material with fibre waviness. The varying anisotropy of this composite causes the ultrasonic waves to travel along curved paths. Particular attention was paid to the comparison with experimental measurements in order to check the applicability of the method for non-destructive characterization of fibre waviness, especially in the high frequency regime. A specimen with intentional fibre waviness was fabricated by winding prepreg tape around a specially designed mandrel. The specimen was tested in the through-transmission mode using special ultrasonic techniques for thick composites. The theoretical model and experimental results agree, at least with regard to the period of fibre waviness.

Calculation of Wave Propagation in Composite Materials Using the LAMB Wave Concept

Over recent years the development of the use of composite materials has led to growing activity in the nondestructive testing field. Widely known techniques such as acoustic emission and ultra-sound have found a new field of application here and new techniques such as acousto-ultrasonics which have recently appeared have shown some interesting results in detecting defects in composite structures. However, acoustic emission for defect localisation and acousto-ultrasonics have sometimes shown a lack of reliability; very little is known about theoretical aspects of wave propagation in these materials, nor about the interaction existing in the material between acoustic waves and defects as the wave propagates. On the basis of some assumptions, theoretical calculations have been made on the prop agation of a steady wave in unidirectional composite plates and compared successfully to experimental results found in the literature.

On Wave Propagation in Composite Materials Reinforced by Fibers With Continuously Varying Directions

This paper concerns certain aspects of wave propagation in composite materials reinforced by fibers whose directions vary continuously in space. Special attention is focused on the case of slight variations in fiber directions and on plane waves that propagate parallel to the unperturbed direction, a case that can be detailed entirely in analytic expressions. The paper concludes with a solution to a specific example in which we assume that the fiber directions vary linearly from an initial to a final position. A discussion of the specific solution follows.

Harmonic wave propagation in composite materials

This paper presents a study of the propagation of harmonic waves of plane strain in elastic composite materials. The composite structure is idealized as an assembly of identical subregions, each with the displacement field represented by a finite number of generalized displacements. The resulting model possesses a periodic lattice-type structure and its response to harmonic waves can be investigated as a problem in lattice dynamics. A set of generalized coordinates, applicable for the case of harmonic wave propagation in the discrete periodic structure, is employed to generate an algebraic eigenvalue problem, the solution of which gives the frequency spectrum for the medium. To show the accuracy of this method, examples of harmonic wave propagation in infinite isotropic and orthotropic homogeneous plates are presented, and cases of harmonic wave propagation in infinite isotropic and orthotropic media. The method is used to generate the frequency spectra for both a fiber-reinforced composite plate and an infinite composite medium to clearly indicate the dispersive effects which exist in periodic media when the half wavelength–lattice dimension ratio approaches unity. These results are compared with several well-known theories for composite materials. Subject Classification: 20.15.

Modal Analysis of Floquet Waves in Composite Materials

A numerical method which admits discontinuous variable coefficients in the wave equation is employed for handling the wave propagation in composite materials. The resulting algebraic eigenvalue system is simplified by a rank–one matrix modification that reduces the computing time by at least one order of magnitude. The first five modes are accurately and efficiently computed as a demonstration of the method presented.

The Use of Artificial Viscosity to Compute One-Dimensional Wave Propagation in Composite Materials

A new and simple numerical method is presented for computing large amplitude, one-dimensional wave propagation in composite materials. The method deals with values of stress, particle velocity, and displacement that are averaged over several unit cells of the composite. The principal advantage of the method over previous macroscopic approaches is that it uses the numerical oscillations and the artificial viscosity already present in one-dimensional hydrocodes to model the geometric and dissipative dispersions of the composite material. The hydrocodes (such as PUFF or WONDY) may be used in their present form without additional dispersion relations. The method is shown to correspond to a definite physical constitutive material model. Comparisons of computational results with this method are made with those from previous models and with experimental measurements.

An Effect of Debonding on Stress Wave Propagation in Composite Materials

An Effect of Debonding on Stress Wave Propagation in Composite Materials