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论文类型：期刊论文

发表时间：2004-07-09

发表刊物：COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING

收录刊物：Scopus、SCIE、EI

卷号：193

期号：27-29

页面范围：2867-2884

ISSN号：0045-7825

关键字：multiphase materials; porous medium; stability analysis; strain softening; strain localization; internal length scale

摘要：Following the work by Zhang et al. [Mech. Cohes.-Frict. Mater. Struct. 4 (1999) 443] we discuss some special features of the internal length scale found in multiphase materials such as saturated and partially saturated porous media, where viscous terms are introduced in the fluid mass balance equations naturally by Darcy's law. Particular attention is focused on the two cases of wave number K = 0 and K --> infinity of the perturbation waves. The internal length scale properties corresponding to the two cases called "lower and upper critical hardening modulus phi" mentioned in Zhang and Schrefler [lnt. J. Numer. Anal. Methods Geomech. 25 (2001) 29], are discussed in detail. It is shown that for the case of the upper value of the critical hardening modulus there will be also a wave number domain for which the material model is dispersive when strain softening behavior occurs for solid skeleton. However, this kind of dispersive waves may not supply enough energy to activate the internal length scale in strain localization analysis. This is true also for the quasi-static case, where it has been found that for both zero and infinite wave numbers the internal length scale associated with permeability disappears. However, it will be pointed out in this paper that the consideration of fluid interaction is necessary for the prediction of the internal length when regularization through a constitutive model is introduced in the numerical model to overcome mesh dependence in a finite element solution. This problem is discussed by considering a gradient dependent model. (C) 2004 Elsevier B.V. All rights reserved.