“…A popular model is denoted as the spring-layer model, which has been proposed in the work by Goland and Reisner [23]. Examples of works that apply the spring-layer model are the articles by Geymonat et al [21], Krasucki and Lenci [34], Nazarenko et al [39], and Golub and Doroshenko [24]. The works by Danishevskyy et al [13] and Andrianov et al [6] consider a nonlinear spring-layer modeled in their modeling of imperfect bonding.…”
We present a study on the local stress distribution in a composite for a single-fiber pulled-out model. We consider an interphase between a fiber of finite length and the matrix, and we take into account varying bonding conditions in the axial direction between the fiber and the interphase and between the interphase and the matrix. Bonding is modeled by a modification of the classical spring-layer model, in which the quality of bonding between two constituents is quantified by a proportionality constant that describes the ratio of the displacements to the acting shear stresses in an interface. The problem is studied for linear elastic and for viscoelastic problems by the means of the elastic-viscoelastic correspondence principle. In numerical examples, we illustrate the development of the normal stresses in the constituents and of the interfacial shear stresses for different bonding conditions as well as for viscoelastic creep in the matrix.
“…A popular model is denoted as the spring-layer model, which has been proposed in the work by Goland and Reisner [23]. Examples of works that apply the spring-layer model are the articles by Geymonat et al [21], Krasucki and Lenci [34], Nazarenko et al [39], and Golub and Doroshenko [24]. The works by Danishevskyy et al [13] and Andrianov et al [6] consider a nonlinear spring-layer modeled in their modeling of imperfect bonding.…”
We present a study on the local stress distribution in a composite for a single-fiber pulled-out model. We consider an interphase between a fiber of finite length and the matrix, and we take into account varying bonding conditions in the axial direction between the fiber and the interphase and between the interphase and the matrix. Bonding is modeled by a modification of the classical spring-layer model, in which the quality of bonding between two constituents is quantified by a proportionality constant that describes the ratio of the displacements to the acting shear stresses in an interface. The problem is studied for linear elastic and for viscoelastic problems by the means of the elastic-viscoelastic correspondence principle. In numerical examples, we illustrate the development of the normal stresses in the constituents and of the interfacial shear stresses for different bonding conditions as well as for viscoelastic creep in the matrix.
“…Существуют различные подходы к построению решения задачи рассеяния упругих волн на трещинах, среди которых одним из наиболее широко применимых является метод граничных интегральных уравнений (МГИУ) [12][13][14][15][16][17][18][19][20][21][22]. Эффективность этого метода заключается в уменьшении размерности задачи, в возможности получения полуаналитического решения, а в некоторых случаях и асимптотического решения [11,[20][21][22][23][24][25][26][27], а также в его высокой точности.…”
Section: Introductionunclassified
“…При прохождении через волновод упругих волн свойства зондирующего сигнала различны для сплошной и трещиноватой среды [29][30][31], кроме того, упругие волны рассеиваются на границе раздела сред, представляющей собой, как правило, клеевые соединения [32,33], что дополнительно усложняет идентификацию дефектов. При наличии зон концентрации микродефектов на границе раздела двух разнородных сред применяются граничные условия пружинного типа, которые моделируют поврежденный интерфейс [18][19][20][21][22][23][32][33][34][35][36][37]. Другой подход рассматривает поврежденный интерфейс как стохастически распределенный набор микродефектов, при использовании которого необходимо на первом этапе построить решение на одиночной трещине [10,20,21,23].…”
Section: Introductionunclassified
“…Например, полиномы Чебышева и Лежандра учитывают поведение решения в окрестности краев прямоугольной и круговой трещин соответственно. В том случае, если для ядра интегрального уравнения можно построить асимптотику, в результате чего интегральные уравнения решаются аналитически, то можно найти асимптотическое представление для скачка перемещений на трещине в частотном диапазоне, при котором характерный размер дефекта соизмерим с длиной падающей волны [20][21][22][23].…”
Section: Introductionunclassified
“…При нормальном угле падения задача распадается на антиплоскую [20] и плоскую [21], и при условии малых размеров трещины по сравнению с длиной падающих волн строится асимптотика функций раскрытия берегов одиночной полосовой трещины. Аналогичное квазистатическое, а также частотно-зависимое решение для круговой трещины, при построении которого также используется асимптотики ядра ГИУ, можно найти в работе [23]. В работах [21,36] рассматриваются периодические массивы полосовых трещин, в работах [20,21] -стохастически распределенные массивы полосовых трещин, с последующим определением коэффициентов пружинной жесткости, а в работе [42] -резонансные эффекты в слоистом периодическом композите с полосовой трещиной.…”
The ultrasonic non-destructive testing is widely used in different civil and engineering applications as one of the most effective and convenient method of structural health monitoring. It is necessary to have a reliable mathematical model simulating scattering caused by defects and inhomogeneities in order to apply effective ultrasonic methods. Modern composite materials used in manufacturing have a laminated structure; therefore it is important to detect damages occurrence located between two materials. Scattering caused by interface cracks can be investigated using the boundary integral equation (BIE), the method which is analytically oriented. The unknown function of the crack opening displacement in the BIE is expanded in terms of orthogonal polynomials. Then the integral equation is projected onto a set of polynomials. Regularization of the hypersingular BIE using the Bubnov-Galerkin scheme is obtained through a repeated integration on the crack faces. This paper uses the BIE method to derive an asymptotic solution describing the elastic wave diffraction by the strip-like crack located at the interface between two dissimilar elastic half-spaces. The Fourier transformation of Green's matrix is applied to obtain a scattered field. Asymptotic representations of the equation kernel around zero and at infinity are derived with the assumption that the crack size is much less than a wavelength of an incident wave. The Bubnov-Galerkin scheme is used to obtain the frequency dependent asymptotic solution of BIE which has a wider accuracy frequency range than the existing quasi-static solution. A good agreement of the derived asymptotic solution with the numerical solution is shown for different materials of the considered structure. The asymptotic solution allows increasing the BIE method potency by reducing the computational cost of integrals. It can also be used to describe dynamic damaged interfaces in the Bostrom-Wickham model's term.
Composite laminate structures remain an important family of materials used in cutting-edge industrial areas. Building efficient numerical modeling tools for high-frequency wave propagation in order to represent ultrasonic testing experiments of these materials remains a major challenge. In particular, incorporating attenuation phenomena within anisotropic plies, and thin intermediate isotropic layers between the plies often represent significant obstacles for standard numerical approaches. In our work, we address both issues by proposing a systematic study of the fully discrete propagators associated to the Kelvin-Voigt, Maxwell and Zener models, and by incorporating effective transmission conditions between plies using the mortar element method. We illustrate the soundness of our approach by proposing intermediate 1D and 2D numerical evidence, and we apply it to a more realistic configuration of a curved laminate composite structure in a 3D setting.
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