Shuji Takashima¹, Michihiko Nakagaki², Noriyuki Miyazaki¹

CMES-Computer Modeling in Engineering & Sciences, Vol.20, No.3, pp. 193-202, 2007, DOI:10.3970/cmes.2007.020.193

Abstract Composite materials have complicated microstructures. These microstructures affect the macroscopic deformation of composite materials. In the present study, we focus on the effect of particle size in a particle-dispersed composite material on the mechanical strength of the material. For this purpose, we derived a macroscopic elastic-plastic constitutive equation using a modified version of the Eshelby's equivalent inclusion method combined with the gradient plasticity. We incorporated this macroscopic elastic-plastic constitutive equation into a finite element program and performed a homogenized finite element analysis of a particle-dispersed composite material in which both the macroscopic and microscopic behaviors More >

R.S. Olivito¹, F.A. Zuccarello¹

Structural Durability & Health Monitoring, Vol.2, No.1, pp. 19-28, 2006, DOI:10.3970/sdhm.2006.002.019

Abstract During the last decades FRP materials have been utilized in many civil engineering applications for their good performances in substituting traditional restoration techniques, especially in reinforcing and restoring damaged structures. At present, the use of composite materials is greatly increasing as a consequence of the fact that conservation and restoration of existing historic heritage are becoming key issues for civil engineers and architects. This paper deals with the behavior of brick masonry models subjected to cyclic loads with the aim of studying their performances and durability. Firstly the models were damaged by imposing a strain More >

A. N. Guz, V. A. Dekret¹

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.3, pp. 165-170, 2006, DOI:10.3970/cmes.2006.013.165

Abstract Stability problem of composite material reinforced by two parallel short fibers is solved. The problem is formulated with application of equations of linearized three-dimensional theory of stability. The composite is modeled as piecewise-homogeneous medium. The influence of geometrical and mechanical parameters of the material on critical strain is investigated. More >

R. Han¹, M.S. Ingber¹, H.L. Schreyer¹

CMC-Computers, Materials & Continua, Vol.4, No.3, pp. 163-176, 2006, DOI:10.3970/cmc.2006.004.163

Abstract Decohesion is an important failure mode associated with fiber-reinforced composite materials. Analysis of failure progression at the fiber-matrix interfaces in fiber-reinforced composite materials is considered using a softening decohesion model consistent with thermodynamic concepts. In this model, the initiation of failure is given directly by a failure criterion. Damage is interpreted by the development of a discontinuity of displacement. The formulation describing the potential development of damage is governed by a discrete decohesive constitutive equation. Numerical simulations are performed using the direct boundary element method. Incremental decohesion simulations illustrate the progressive evolution of debonding zones More >

G. Haasemann¹, M. Kästner¹ and V. Ulbricht¹

CMC-Computers, Materials & Continua, Vol.3, No.3, pp. 131-146, 2006, DOI:10.3970/cmc.2006.003.131

Abstract Novel textile reinforced composites provide an extremely high adaptability and allow for the development of materials whose features can be adjusted precisely to certain applications. A successful structural and material design process requires an integrated simulation of the material behavior, the estimation of the effective properties which need to be assigned to the macroscopic model and the resulting features of the component. In this context two efficient modelling strategies - the Binary Model (Carter, Cox, and Fleck (1994)) and the Extended Finite Element Method (X-FEM) (Moës, Cloirec, Cartraud, and Remacle (2003)) - are used to… More >

D.S. Liu^1,2 , C.Y. Chen² , D.Y. Chiou³

CMES-Computer Modeling in Engineering & Sciences, Vol.9, No.2, pp. 179-192, 2005, DOI:10.3970/cmes.2005.009.179

Abstract A three-dimensional heterogeneous infinite element method (HIEM) for modeling inclusions with interphases in composite materials is presented. This special element is formulated based on the conventional finite element method (FEM) using the similarity stiffness property and matrix condensation operations. An HIE-FE coupling scheme is also developed and implemented using the commercial software ABAQUS to conduct the elastostatic analysis. The proposed approach was validated first to study heterogeneous material containing one spherical inclusion. The displacement and stress variations around the inclusion vicinity are verified against conventional FEM. The proposed approach was next applied to analyze the effective More >

C. Tapp¹, W. Hansel, C. Mittelstedt, W. Becker²

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.6, pp. 563-574, 2004, DOI:10.3970/cmes.2004.005.563

Abstract A heuristic algorithm for the weight minimization of sandwich plates is presented. The method is based on a preexisting algorithm for the layerwise topology optimization of symmetric laminates under in-plane loads. The presented algorithm uses structural analyses based on finite elements and explicitly accounts for the special sandwich situation. During the optimization procedure the algorithm adds or subtracts material from the layers of the face sheets and the core of the sandwich plate in regions of high or low stresses respectively. The orientation angles of the layers of the sandwich facings are not varied inorder More >

P. Raghavan¹, S. Ghosh²

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.2, pp. 151-170, 2004, DOI:10.3970/cmes.2004.005.151

Abstract This paper presents an adaptive multi-level computational model that combines a conventional displacement based finite element model with a microstructural Voronoi cell finite element model for multi-scale analysis of composite structures with non-uniform microstructural heterogeneities as obtained from optical or scanning electron micrographs. Three levels of hierarchy, with different resolutions, are introduced in this model to overcome shortcomings posed by modeling and discretization errors. Among the three levels are: (a) level-0 of pure macroscopic analysis; (b) level-1 of macro-micro coupled modeling, used for signaling the switch over from macroscopic analyses to pure microscopic analyses; and More >

Hiroshi Okada¹, Yasuyoshi Fukui¹, Noriyoshi Kumazawa¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.2, pp. 135-150, 2004, DOI:10.3970/cmes.2004.005.135

Abstract A method to obtain the effective mechanical properties of particulate composite materials is presented in this paper. The methodology is based on the boundary element method (BEM) coupled with analytical solutions for ellipsoidal inclusions such as Eshelby's tensor. There is no numerical integration for the surfaces or the domains of distributed particles, and, therefore, proposed technique is very efficient. Homogenization analysis based on representative volume element (RVE) is carried out considering a unit cell containing many particles (up to 1000). By using a conventional BEM approach (i.e., multi-region BEM), it would be extremely difficult to More >

Kunigal Shivakumar¹, Anil Bhargava²

CMC-Computers, Materials & Continua, Vol.1, No.2, pp. 173-190, 2004, DOI:10.3970/cmc.2004.001.173

Abstract The fiber optic sensor (FOS) embedded perpendicular to reinforcing fibers causes an `Eye' shaped defect. The length is about 16 times fiber optic radius (R_Fos) and height is about 2R_Fos. The eye contains fiber optics in the center surrounded by an elongated resin pocket. Embedding FOS causes geometric distortion of the reinforcing fiber over a height equal to 6 to 8 R_Fos. This defect causes severe stress concentration at the root of the resin pocket, the interface (in the composite) between the optical fiber and the composite, and at 90° to load direction in the composite. The… More >