共查询到19条相似文献,搜索用时 125 毫秒
1.
单向纤维复合材料粘弹性性能预测 总被引:2,自引:0,他引:2
建立了基于均匀化理论的单向纤维复合材料粘弹性性能预测方法。对单向纤维增强复合材料粘弹性问题的控制方程进行Laplace变换,在像空间中利用均匀化理论建立宏观松弛模量的Laplace变换与微结构描述参数以及变换参数间的关系。用Prony级数模拟松弛模量随变换参数的变化形式,并根据像空间中一系列变换参数对应的松弛模量的数值,采用函数拟合技术确定Prony级数的形式,从而确定用显示形式表示的松弛模量的Laplace变换随变换参数的变化规律。对显式表达式的逆变换获得时间域内的松弛模量。该方法利用拟合函数的逆变换避开了复杂的数值Laplace逆变换,使单向纤维增强复合材料的粘弹性性能的确定变得容易。文中给出了单向纤维复合材料松弛模量的数值预测结果并同有限元法模拟试验的结果对比,验证了预测结果的准确性以及本文方法的有效性。 相似文献
2.
3.
4.
用振动梁方法测量粘弹性材料的复模量和粘弹性参数 总被引:2,自引:0,他引:2
本文利用共振梁方法,通过对一点响应、相位滞后和共振频率的测量,可以获得粘弹性材料的复模量以及标准线性固体模型的三个参数,即松弛模量、松弛系数和蠕变系数.实验结果表明,实验原理正确,测试系统可靠而且简单实用. 相似文献
5.
将幂函数引入Eringen非局部线粘弹性本构,导出Riesz势形式的应力-应变关系。利用该关系,构造非局部弹簧和非局部阻尼器两类元件;利用元件的串联和并联,建立非局部Kelvin和非局部Maxwell粘弹性模型,推导模型的松弛模量和蠕变柔量。进一步,给出非局部粘弹性模型在生物组织超声波耗散建模中的应用。 相似文献
6.
一维流体饱和粘弹性多孔介质层的动力响应 总被引:2,自引:1,他引:2
本文研究了不可压流体饱和粘弹性多孔介质层的一维动力响应问题。基于粘弹性理论和多孔介质理论,在流相和固相微观不可压、固相骨架服从粘弹性积分型本构关系和小变形的假定下,建立了不可压流体饱和粘弹性多孔介质层一维动力响应的数学模型,利用Laplace变换,求得了原初边值问题在变换空间中的解析解,并利用Laplace逆变换的Crump数值反演方法,得到原动力响应问题的数值解。数值研究了饱和标准线性粘弹性多孔介质层的动力响应,分析了固相位移、渗流速度、孔隙压力及固相有效应力等的响应特征。结果表明,与不可压流体饱和弹性多孔介质相同,不可压流体饱和粘弹性多孔介质中亦只存在一个纵波,并且固相骨架的粘性对动力行为有显著的影响。 相似文献
7.
8.
区域分层介质模型下, 可以将地震波场描述为矩张量各分量作为权重的基本格林函数的线性组合,利用该理论地震波场可以反演实际天然地震或地下核爆炸的震源机制,反演结果中不同震源机制成分的比重,可以用来识别地下核爆炸,该系统方法越来越受到关注。给出了基于广义反射-透射系数方法的水平分层介质模型的地震波场正演公式,并对基于该公式的单台反演结果的准确性、稳定性、可靠性进行了理论分析,为利用该公式对实际地下核爆炸进行反演提供了理论基础,该方法对利用区域少量甚至是单站记录数据检测、识别地下核爆炸具有重要参考意义。 相似文献
9.
10.
讨论了弹性水平层状介质中SH波的反演问题,在平面脉动SH波激励和反射模式下利用的传递算子方法逐层反演了介质的速度,密度和厚度,反演过程转化为线性回归,并且进行了数值模拟这种逐层反演方法简化了方程的阶数和计算量。 相似文献
11.
Inversionofthematerialfunctionswiththemeasurementdataobtainedfromthescatteringexperimentisofcentralimportanceinsomeengineeringproblems.Forexample,scatteredelectromagneticwavescanbeusedtoreconstructthepermittivity,conductivityandsusceptibilitykernelof… 相似文献
12.
The complex effective moduli of viscoelastic materials can be experimentally measured by a number of techniques giving relaxation
data for materials at discrete frequencies. In this paper we present a method which allows one to find bounds on the moduli
of the material at the unmeasured frequencies. Our bounds can be very tight, and are, therefore, good approximations to the
data. Using our bounds, experimentalists can concentrate their efforts on gathering highly accurate data at only a few frequencies
and numerically generate data at other frequencies that may be of interest.
Received: 10 August 1999 Accepted: 21 December 2000 相似文献
13.
Lev Khazanovich 《International Journal of Solids and Structures》2008,45(17):4739-4747
This paper revisits the elastic–viscoelastic correspondence principle for non-homogeneous materials. Several recent publications discussed this principle for functionally graded materials (FGMs) with time translation invariant viscoelastic properties. It was demonstrated that the correspondence principle is valid only for the FGMs with separable relaxation moduli (moduli in separable form in space and time). This paper reconsiders this issue. It shows that the correspondence principle is valid even for non-homogeneous materials with separable relaxation moduli even if the time-dependences of the relaxation moduli in shear and dilatation are not necessarily time translation invariant. The property of similarity of Volterra operators is used to obtain the corresponding elastic solution. The correspondence is established between the elastic solution and the operator-transformed viscoelastic solution. The transformation operators are combinations of the Laplace transform operator and additional integral operators. 相似文献
14.
X. -Q. Feng 《Archive of Applied Mechanics (Ingenieur Archiv)》2001,71(8):537-548
Summary Most of the conventional methods for estimating the overall elastic moduli of microcracked solids are defined based on the
concept of effective medium or effective field. The formal similarity of these methods is examined in this paper. A one-to-one
correspondence relation exists between the effective medium methods and the effective field methods in the sense that they
yield identical results. In addition to the conventional estimation techniques, any other number of such approaches may be
constructed by appropriately specifying the effective matrix compliance (or stiffness) tensor and the effective stress (or
strain) field which a microcrack is assumed to be subjected to. To generate continuous spectra of new methods for estimating
the effective elastic moduli, two simple and straightforward approaches are proposed, which contain one or two adjustable
parameters in order to yield results of good accuracy. The discussion in this paper can be extended to other kinds of heterogeneous
materials.
Received 4 October 2000; accepted for publication 30 January 2001 相似文献
15.
《Comptes Rendus de l'Académie des Sciences》2000,328(12):855-862
The rheological behavior of setting heterogeneous materials is studied from a theoretical approach by means of the homogenization technique of periodic medium. These materials considered as suspensions of gas bubbles at finite concentration in a viscoelastic matrix with low compressibility, present the macroscopic behavior of a compressible viscoelastic medium. The shear and volume macroscopic moduli are of the same order of magnitude and directly proportional to that of the fluid. The effective compressibility of the gas (out of thermal equilibrium) is added to these fluid contributions. 相似文献
16.
流体饱和标准线性粘弹性多孔介质中的平面波 总被引:4,自引:1,他引:3
研究了流体饱和不可压标准线性粘弹性多孔介质中平面波的传播和反射问题.在固相骨架小变形的假定下,得到了粘弹性多孔介质中波动方程的一般解,讨论了弥散关系和波的衰减特性.结果表明:在流体饱和不可压粘弹性多孔介质中,仅存在一个耦合纵波和一个耦合横波,纵波和横波的波速、衰减率等取决于孔隙流体与固相骨架间的相互作用以及固相骨架本身的粘性.同时,研究了半空间自由边界上入射波(纵波、横波)的反射问题。得到了非均匀反射波的波速、反射系数、衰减率等的表达式及其相关的数值结果. 相似文献
17.
Dr. Lucas Duffrène René Gy Hélène Burlet Roland Piques Annelise Faivre Anas Sekkat Joseph Perez 《Rheologica Acta》1997,36(2):173-186
The linear viscoelastic behavior of a soda-lime-silica glass under low frequency shear loading is investigated in the glass transition range. Using the time-temperature superposition technique, the master curves of the shear dynamic relaxation moduli are obtained at a reference temperature of 566°C. A method to determine the viscoelastic constants from dynamic relaxation moduli is proposed. However, some viscoelastic constants cannot be directly measured from the experimental curves and others cannot be precisely obtained due to non-linearity effects at very low frequencies. The generalized Maxwell model is investigated from the experimental dynamic moduli without fixing the viscoelastic constants. A set of parameters is shown to be in good agreement with the experimental dynamic relaxation moduli, but does not give the correct values of the viscoelastic constants of the investigated glass. The soda-lime-silica glass exhibits a non-linear viscoelastic behavior at very low stress level which is usually observed for organic glasses. This non-linear behavior is questioned. 相似文献
18.
Non-linear viscoelastic behavior of fumed silica suspensions 总被引:2,自引:0,他引:2
Suspensions of fumed silica exhibit a wide range of rheological properties depending on the nature and magnitude of the interparticle
forces. In a non-polar fluid, the particles interact through hydrogen bonding and can form a three-dimensional network. The
microstructure formation is responsible for the non-linear viscoelastic behavior of fumed silica suspensions, even at very
small strain. These non-linear rheological properties have been studied in small amplitude oscillatory experiments as a function
of particle size, surface treatment of particles, suspending medium polarity and solids concentration. The non-linear viscoelastic
behavior is characterized by a non-sinusoidal waveform of the signal response. For suspensions in a non-polar fluid, both
the elastic and the loss moduli are shown to be sensitive to the strain amplitude: the elastic modulus is decreasing with
increasing strain whereas the loss moduli is initially increasing with strain. We have chosen to examine the dissipated energy
which is clearly related to the breakup of the suspension structure. A comparison of model predictions and the experimental
data shows the limitations of these models, recently proposed in the literature to describe the behavior of colloidal suspensions.
Received: 9 March 1998 Accepted: 17 November 1998 相似文献
19.
The aim of this paper is to apply the asymptotic homogenization method to deter- mining analytically and numerically the transversely isotropic viscoelastic relaxation moduli of the equivalent particle for the intercalated multi-layer stack of intercalated type nanoplastics.A two-phase multilayered material containing n layers is considered.The matrix is assumed to be an isotropic viscoelastic standard linear body and the reinforcement is assumed to be an isotropic elastic body.Final explicit analytical formulae for the effective elastic moduli of the multilay- ered material are derived first;and then the correspondence principle is employed to obtain the homogenized relaxation moduli of the equivalent intercalated particle.A numerical example is given.Final explicit analytical formulae in the time domain derived here make it convenient to estimate the influence of all the particle parameters of micro-structural details on the effective properties of the equivalent intercalated particle.The results of this paper can also be applied to multi-layer composites. 相似文献