Mingjian Li, Ping Yang^*, Pengyang Zhao

CMES-Computer Modeling in Engineering & Sciences, Vol.140, No.2, pp. 2019-2034, 2024, DOI:10.32604/cmes.2024.048334

Abstract The experimental results in previous studies have indicated that during the ductile fracture of pure metals, vacancies aggregate and form voids at grain boundaries. However, the physical mechanism underlying this phenomenon remains not fully understood. This study derives the equilibrium distribution of vacancies analytically by following thermodynamics and the micromechanics of crystal defects. This derivation suggests that vacancies cluster in regions under hydrostatic compression to minimize the elastic strain energy. Subsequently, a finite element model is developed for examining more general scenarios of interaction between vacancies and grain boundaries. This model is first verified and More >

Haiming Zhang^1,2,*, Shilin Zhao^1,2, Zhenshan Cui^1,2

The International Conference on Computational & Experimental Engineering and Sciences, Vol.25, No.4, pp. 1-1, 2023, DOI:10.32604/icces.2023.08884

Abstract Particle-reinforced aluminum matrix composites (PRAMCs) have great potential for application in aerospace, automobile, defense, and electronics due to their high specific strength and stiffness and good resistance to wear and corrosion. Achieving a superior trade-off between the strength and ductility of PRAMCs necessitates an elaborative control of the microstructures, like the size and distribution of particles, as well as grain size, morphology, and texture of the matrix. The multiscale interaction between the particles and the matrix’s microstructure is insufficiently understood due to the lagging of high-resolved in-situ characterization. This work proposes a nonlocal physically based… More >

Lifeng Gan¹, Baoyin Zhu², Chao Ling^1,*, Esteban P. Busso¹, Dongfeng Li¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.25, No.3, pp. 1-1, 2023, DOI:10.32604/icces.2023.010397

Abstract Heat-resistant austenitic stainless steels are widely used in the final stages of superheater and reheater in in the new generation of fossil fuel power stations, due to their high creep strength. Similar weld joints, fabricated using gas tungsten arc welding, for connecting different components made of the heat resistant austenitic stainless steels usually suffer from premature failures at elevated temperature [1]. Experimental studies showed that cracks may nucleate in the heat affected zone or weld metal of the similar welded joints under service conditions. In order to reveal the physical origin of unexpected failures of… More >

Nassibeh Hosseini¹, Samad Javid¹, Ali Amiri¹, Chad Ulven^1,*, Dean C. Webster², Ghodrat Karami¹

Journal of Renewable Materials, Vol.3, No.3, pp. 205-215, 2015, DOI:10.7569/JRM.2015.634112

Abstract In this study, a novel, bio-based polyol was used in the formulation of a polyurethane (PU) matrix for a composite material where fl ax fi ber was used as the reinforcement. The viscoelastic properties of the matrix and fl ax fi ber were determined by a linear viscoelastic model through experimentation and the results were used as input for the material properties in the computational model. A fi nite element micromechanical model of a representative volume element (RVE) in terms of repeating unit cells (RUC) was developed to predict the mechanical properties of composites. Six… More >

Nian Li^*

Structural Durability & Health Monitoring, Vol.13, No.4, pp. 331-346, 2019, DOI:10.32604/sdhm.2019.07521

Abstract The investigation focusing on the mechanical behaviors at the microstructural level in composite materials can provide valuable insight into the failure mechanisms at larger scales. A micromechanics damage model which comprises the coupling of the matrix constitutive model and the cohesive zone (CZM) model at fiber-matrix interfaces is presented to evaluate the transverse tensile damage behaviors of unidirectional (UD) fiber-reinforced polymer (FRP) composites. For the polymeric matrix that exhibits highly non-linear mechanical responses, special focus is paid on the formulation of the constitutive model, which characterizes a mixture of elasticity, plasticity as well as damage.… More >

Leiting Dong^1,2, Satya N. Atluri^1,3

CMC-Computers, Materials & Continua, Vol.33, No.2, pp. 111-154, 2013, DOI:10.3970/cmc.2013.033.111

Abstract In this study, SGBEM Voronoi Cells (SVCs), with each cell representing a grain of the material at the micro-level, are developed for direct micromechanical numerical modeling of heterogeneous composites. Each SVC can consist of either a (each with a different) homogenous isotropic matrix, and can include micro-inhomogeneities such as inclusions, voids of a different material, and cracks. These inclusions and voids in each SVC can be arbitrarily-shaped, such as circular, elliptical, polygonal, etc., for 2D problems. Further, the cracks in each SVC can be fully-embedded, edge, branching, or intersecting types, with arbitrary curved shapes. By… More >

Shuguang Li

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.1, pp. 23-24, 2011, DOI:10.3970/icces.2011.020.023

Abstract Unit cells have been found as an empowering tool for the characterisations of modern composites. The author is honoured to have contributed to the establishment of a systematic methodology for the formulation of unit cells in the past decade through over a dozen of publications on this specific topic.
The formulation of a unit cell could start as if it was a trivial exercise, at least as sometimes perceived by some users, where casual treatments have been found as a result. However, it could soon become overwhelming in order to stand scrutiny and to deal with… More >

H.K. Lee¹, J.W. Ju²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.4, No.2, pp. 123-128, 2007, DOI:10.3970/icces.2007.004.123

Abstract This paper summarizes the results of an analytical study (Lee and Ju, 2006) conducted to develop an approximate micromechanical analytical formulation to accommodate all the possible second-order, ensemble-volume averaged perturbations due to the interactions of randomly located microcracks and inclusions in brittle composites. To account for the three-dimensional effects of interactions among constituents, an approximate solution of a micromechanical framework considering the pairwise microcrack interactions, the pairwise inclusion interactions and the interactions between microcracks and inclusions have been systematically presented. The proposed pairwise interacting micromechanical damage models are compared to illustrate the influence of constituent More >

Yunfa Zhang¹, Zihui Xia^1,2

CMC-Computers, Materials & Continua, Vol.2, No.3, pp. 213-226, 2005, DOI:10.3970/cmc.2005.002.213

Abstract In the present study, the initiation and evolution of the interphase damage and their influences on the global stress-strain relation of composite laminates are predicted by finite element analysis on a micromechanical unit cell model. A thin layer of interphase elements is introduced and its stress-strain relation is derived based on a cohesive law which describes both normal and tangential separations at the interface between the fiber and matrix. In addition, a viscous term is added to the cohesive law to overcome the convergence difficulty induced by the so-called snap-back instability in the numerical analysis. More >

Leiting Dong¹, Satya N. Atluri1¹

CMC-Computers, Materials & Continua, Vol.30, No.1, pp. 39-82, 2012, DOI:10.3970/cmc.2012.030.039

Abstract In this paper, as an extension to the authors's work in [Dong and Atluri (2011a,b, 2012a,b,c)], three-dimensional Trefftz Voronoi Cells (TVCs) with ellipsoidal voids/inclusions are developed for micromechanical modeling of heterogeneous materials. Several types of TVCs are developed, depending on the types of heterogeneity in each Voronoi Cell(VC). Each TVC can include alternatively an ellipsoidal void, an ellipsoidal elastic inclusion, or an ellipsoidal rigid inclusion. In all of these cases, an inter-VC compatible displacement field is assumed at each surface of the polyhedral VC, with Barycentric coordinates as nodal shape functions. The Trefftz trial displacement… More >