Ki-Yeol Eom¹, Byungseok Min^2,*

CMC-Computers, Materials & Continua, Vol.75, No.3, pp. 6337-6350, 2023, DOI:10.32604/cmc.2023.035336 - 29 April 2023

Abstract Automated X-ray defect inspection of occluded objects has been an essential topic in semiconductors, autonomous vehicles, and artificial intelligence devices. However, there are few solutions to segment occluded objects in the X-ray inspection efficiently. In particular, in the Ball Grid Array inspection of X-ray images, it is difficult to accurately segment the regions of occluded solder balls and detect defects inside solder balls. In this paper, we present a novel automatic inspection algorithm that segments solder balls, and detects defects fast and efficiently when solder balls are occluded. The proposed algorithm consists of two stages.… More >

Bingxiao Du¹, Yong Zhao^{1, *}, Wen Yao², Xuan Wang³, Senlin Huo¹

CMES-Computer Modeling in Engineering & Sciences, Vol.122, No.3, pp. 1119-1140, 2020, DOI:10.32604/cmes.2020.08859 - 01 March 2020

Abstract A general and new explicit isogeometric topology optimisation approach with moving morphable voids (MMV) is proposed. In this approach, a novel multiresolution scheme with two distinct discretisation levels is developed to obtain high-resolution designs with a relatively low computational cost. Ersatz material model based on Greville abscissae collocation scheme is utilised to represent both the Young’s modulus of the material and the density field. Two benchmark examples are tested to illustrate the effectiveness of the proposed method. Numerical results show that high-resolution designs can be obtained with relatively low computational cost, and the optimisation can More >

Yunfa Zhang¹, Xiaozhou Xia^{1, *}, Zhenjie Wu¹, Qing Zhang¹

CMC-Computers, Materials & Continua, Vol.62, No.1, pp. 413-442, 2020, DOI:10.32604/cmc.2020.04660

Abstract Considering the fact that the initial defects, like the imperfect interfacial transition zones (ITZ) and the micro voids in mortar matrix, weaken the mechanical properties of concrete, this study develops corresponding constitutive models for ITZ and matrix, and simulates the concrete failure with finite element methods. Specifically, an elastic-damage traction-separation model for ITZ is constructed, and an anisotropic plastic-damage model distinguishing the strength-difference under tension and compression for mortar matrix is proposed as well. In this anisotropic plastic-damage model, the weakening effect of micro voids is reflected by introducing initial isotropic damage, the distinct characteristic More >

Jichang Wang, Xiaoming Guo^*, Xiaoxiao Sun

The International Conference on Computational & Experimental Engineering and Sciences, Vol.21, No.4, pp. 79-79, 2019, DOI:10.32604/icces.2019.05248

Abstract Cement mortar is an important component of many composite materials and one of the most widely used materials in engineering construction. At microscopic level, cement mortar can be regarded as a multiphase material composed of fine aggregates, cement paste, and a great many of initial defects, the form of which are micro-cracks and micro-voids. The macroscopic properties of cement mortar will be influenced by mechanical properties of different constituents and complex internal structures. The microscopic model containing micro-voids is established by the method of secondary development. The process of cement mortar damage fracture is studied.… More >

Jan Sladek¹, Vladimir Sladek¹, Peter Stanak¹

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.4, pp. 229-262, 2015, DOI:10.3970/cmes.2015.106.229

Abstract The scaled boundary finite element method (SBFEM) is presented to study thermoelastic problems in materials with voids. The SBFEM combines the main advantages of the finite element method (FEM) and the boundary element method (BEM). In this method, only the boundary is discretized with elements leading to a reduction of spatial dimension by one. It reduces computational efforts in mesh generation and CPU. In contrast to the BEM, no fundamental solution is required, which permits to analyze general boundary value problems, where the conventional BEM cannot be applied due to missing fundamental solution. The computational More >

M. Marin^1,2, A.M. Abd-Alla^3,4, D. Raducanu¹, S.M. Abo-Dahab^3,5

CMC-Computers, Materials & Continua, Vol.45, No.2, pp. 107-126, 2015, DOI:10.3970/cmc.2015.045.107

Abstract Our study is dedicated to mixed initial boundary value problem for porous micropolar bodies. We prove that the solution of this problem depends continuously on coefficients which couple the micropolar deformation equations with the equations that model the evolution of voids. The evaluation of this dependence is made by using an appropriate measure. More >

Mohamed I. A. Othman¹, Magda E. M. Zidan¹, Mohamed I. M. Hilal¹

CMC-Computers, Materials & Continua, Vol.40, No.3, pp. 179-201, 2014, DOI:10.3970/cmc.2014.040.179

Abstract This investigation is aimed to study the two dimensional problem of thermoelastic medium with voids under the effect of the gravity. The modulus of elasticity is taken as a linear function of the reference temperature and employing the two-temperature generalized thermoelasticity. The problem is studied in the context of Green-Naghdi (G-N) theory of types II and III. The normal mode analysis method is used to obtain the exact expressions for the physical quantities which have been shown graphically by comparison between two types of the (G-N) theory in the presence and the absence of the More >

Marin Marin¹, Ravi P. Agarwal², Mohamed Othman³

CMC-Computers, Materials & Continua, Vol.40, No.1, pp. 35-48, 2014, DOI:10.3970/cmc.2014.040.035

Abstract In this study we want to decide whether the decay of the solutions of the mixed initial boundary value problem in the context of thermoelasticiy of micropolar bodies with voids is sufficiently fast to guarantee that they vanish after a finite time. In fact, we prove that the effect of the micropolar structure in combination with the thermal and porous dissipation can not determine the thermomechanical deformations vanish after a finite time. 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 >

R. R. Valisetty¹, A.M. Dongare², A.M. Rajendran³, R. R. Namburu¹

CMC-Computers, Materials & Continua, Vol.36, No.3, pp. 231-255, 2013, DOI:10.3970/cmc.2013.036.231

Abstract Materials used in soldier protective structures, such as armor, vehicles and civil infrastructures, are being improved for performance in extreme dynamic environments. Nanocrystalline metals show significant promise in the design of these structures with superior strengths attributed to the dislocation-based and grain-boundary-based processes as compared to their polycrystalline counterparts. An optimization of these materials, however, requires a fundamental understanding of damage evolution at the atomic level. Accordingly, atomistic molecular dynamics simulations are performed using an embedded-atom method (EAM) potential on three nano-crystalline aluminum atom systems, one a Voronoi-based nano-crystalline system with an average grain size More >