F.C. Araújo¹, L.J. Gray²

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 103-122, 2008, DOI:10.3970/cmes.2008.024.103

Abstract In recent years, carbon nanotubes (CNTs) have been widely employed to build advanced composites. In this work, a Boundary Element Method (BEM) is applied to 3D representative volume elements (RVEs) to estimate mechanical properties of CNT-based composites. To model the thin-walled nanotubes, special integration procedures for calculating nearly-strongly-singular integrals have been developed. The generic BE substructuring algorithm allows modeling complex CNT-reinforced polymers, containing any number of nanotubes of any shape (straight or curved). The subregion-by-subregion strategy, based on Krylov solvers, makes the independent generation, assembly, and storage of the many parts of the complete BE model possible. Thus, significant memory… More >

Daiki Shiozawa¹, Shiro Kubo², Takahide Sakagami², Masaaki Takagi²

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.1, pp. 27-36, 2006, DOI:10.3970/cmes.2006.011.027

Abstract The passive electric potential CT (computed tomography) method using piezoelectric film was applied to the identification of plural through cracks. The use of piezoelectric material made it possible to obtain electric potential field without applying electric current. For identification of cracks an inverse analysis scheme based on the least residual method was applied, in which square sum of residuals is evaluated between the measured electric potential distributions and those computed by using the finite element method. Akaike information criterion (AIC) was used to estimate the number of cracks. Numerical simulations were carried out on the identification of plural cracks and… More >

Y. Tomita ¹, M. Uchida ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.3, pp. 239-248, 2005, DOI:10.3970/cmes.2005.010.239

Abstract In this study, we clarified the micro- to mesoscopic deformation behavior of a semicrystalline polymer by employing a large-deformation finite element homogenization method. The crystalline plasticity theory with a penalty method for the inextensibility of the chain direction and the nonaffine molecular chain network theory were applied for the representation of the deformation behavior of the crystalline and amorphous phases, respectively, in the composite microstructure of the semicrystalline polymer. The 3D structure of lamellae in the spherulite of high-density polyethylene was modeled, and the tensile and compressive deformation behaviors were investigated. A series of computational simulations clarified the difference in… More >

Toru Ikeda¹, Isao Arase, Yuya Ueno, Noriyuki Miyazaki

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 91-98, 2000, DOI:10.3970/cmes.2000.001.091

Abstract In electronic devices, the corners of joined dissimilar materials exist between plastic resin and a die pad or a chip. Failure of the plastic resin is often caused from these corners during the assembly process or the operation of products. The strength evaluation of the corner is important to protect the failure of plastic packages. To evaluate the singular stress field around a corner, we utilize the stress intensity factors of the asymptotic solution for a corner of joined dissimilar materials. We show that the accurate stress intensity factor can be analyzed by the displacement extrapolation method using the displacement… More >

Davood Kalantari¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.2, pp. 169-182, 2013, DOI:10.3970/fdmp.2013.009.169

Abstract In this study, a critical summary of existing spray/wall interaction models is given in synergy with a review of available experimental data. In particular, special attention is devoted to the limitations, difficulties and complexities of the most used approaches in the literatures. An attempt is also made to indicate the bottlenecks and criticalities which typically arise when investigators try to extend results obtained for isolated droplets to the more complex dynamics produced by spray impacts. More >

Chein-Shan Liu¹

CMC-Computers, Materials & Continua, Vol.8, No.1, pp. 1-16, 2008, DOI:10.3970/cmc.2008.008.001

Abstract In the present work we study numerical computations of inverse thermal stress problems. The unknown boundary conditions of an elastically deformable heat conducting rod are not given a priori and are not allowed to measure directly, because the boundary may be not accessible to measure. However, an internal measurement of temperature is available. We treat this inverse problem by using a semi-discretization technique, of which the time domain is divided into many sub-intervals and the physical quantities are discretized at these node points of discrete times. Then the resulting ordinary differential equations in the discretized space are numerically integrated towards… More >

Heng Cheng Lin^1,2, Chieh Kung³, Rong Sheng Chen²

CMC-Computers, Materials & Continua, Vol.6, No.1, pp. 43-50, 2007, DOI:10.3970/cmc.2007.006.043

Abstract Presented herein are the evaluation results of the BGA solder ball shape using energy method, two types of solder, viz. Sn37Pb and Sn80Pb, are selected .The geometry of the solder bump is firstly estimated using free computer software, the Surface Evolver, an interactive program which is an energy-based approach for the study of liquid droplet surfaces shaped by surface tension and other energies. The solder bump is then numerically constructed in a finite element model that simulates a BGA package. The influences of both upper and bottom solder pad radii, the surface tension on the balls, and the external load… More >

Thanh Q. Nguyen^1,2, Thao T. D. Nguyen³, H. Nguyen-Xuan^4,5,*, Nhi K. Ngo^1,2

CMC-Computers, Materials & Continua, Vol.61, No.1, pp. 27-53, 2019, DOI:10.32604/cmc.2019.07756

Abstract This paper presents a new approach using correlation and cross-correlation coefficients to evaluate the stiffness degradation of beams under moving load. The theoretical study of identifying defects by vibration methods showed that the traditional methods derived from the vibration measurement data have not met the needs of the actual issues. We show that the correlation coefficients allow us to evaluate the degree and the effectiveness of the defects on beams. At the same time, the cross-correlation model is the basis for determining the relative position of defects. The results of this study are experimentally conducted to confirm the relationship between… More >

Ruikang Xing^1,*, Chenghai Li¹

CMC-Computers, Materials & Continua, Vol.60, No.2, pp. 767-780, 2019, DOI:10.32604/cmc.2019.04500

Abstract In clustering analysis, the key to deciding clustering quality is to determine the optimal number of clusters. At present, most clustering algorithms need to give the number of clusters in advance for clustering analysis of the samples. How to gain the correct optimal number of clusters has been an important topic of clustering validation study. By studying and analyzing the FCM algorithm in this study, an accurate and efficient algorithm used to confirm the optimal number of clusters is proposed for the defects of traditional FCM algorithm. For time and clustering accuracy problems of FCM algorithm and relevant algorithms automatically… More >

Ma Ning^1,*, Jianhe Guan¹, Pingzeng Liu², Ziqing Zhang³, Gregory M. P. O’Hare⁴

CMC-Computers, Materials & Continua, Vol.58, No.1, pp. 215-227, 2019, DOI:10.32604/cmc.2019.03763

Abstract With the rapid development of China’s economy, the scale of the city has been continuously expanding, industrial enterprises have been increasing, the discharge of multiple pollutants has reached the top of the world, and the environmental problems become more and more serious. The air pollution problem is particularly prominent. Air quality has become a daily concern for people. In order to control air pollution, it is necessary to grasp the air quality situation in an all-round way. It is necessary to evaluate air quality. Accurate results of air quality evaluation can help people know more about air quality. In this… More >