Balamati Choudhury¹, Pavani Vijay Reddy¹, Sanjana Bisoyi¹, R. M. Jha¹

CMC-Computers, Materials & Continua, Vol.37, No.3, pp. 135-146, 2013, DOI:10.3970/cmc.2013.037.135

Abstract The terahertz region of the electromagnetic spectrum plays a vital role in biomedical imaging because of its sensitivity to vibrational modes of biomolecules. Advances in broadband terahertz imaging have been emerging in the field of biomedical spectroscopy. Biomedical imaging is used to distinguish between the infected (cancer) and the non-infected tissue, which requires broad band and highly efficient radar absorbing material (RAM) designs (to obtain high resolution image of the tissue). In this paper, a metamaterial broadband RAM design is proposed towards biomedical spectroscopy applications in the THz region. The particle swarm optimization (PSO) algorithm is used for the design… More >

J. Joseph¹, Y. C. Lu¹

CMC-Computers, Materials & Continua, Vol.37, No.1, pp. 59-75, 2013, DOI:10.3970/cmc.2013.037.059

Abstract The aligned carbon nanotube (A-CNT) structure is composed of arrays of individual CNTs grown vertically on a flat substrate. The overall structure and properties of an A-CNTs are highly dependent upon the designs of various architectures and geometric parameters. In Part 2, we have presented the detailed designs and modeling of various aligned carbon nanotube structures. It is found the A-CNT structures generally have much lower modulus than an individual CNT. The reason is due to the high porosity and low density of the A-CNT structures, since the interstitial space between nanotubes is mostly occupied by air. Increasing the nanotube… More >

J. Joseph¹, Y. C. Lu¹

CMC-Computers, Materials & Continua, Vol.37, No.1, pp. 39-57, 2013, DOI:10.3970/cmc.2013.037.039

Abstract Aligned carbon nanotubes structures are emerging new materials that have demonstrated superior mechanical, thermal, and electrical properties and have the huge potential for a wide range of applications. In contrast with traditional materials whose microstructures are relatively "fixed", the aligned carbon nanotube materials have highly "tunable" structures. Therefore, it is crucial to have a rational strategy to design and evaluate the architectures and geometric factors to help process the optimal nanotube materials. Astructural mechanics based computational modeling is used for designing the aligned carbon nanotubes structures. Part 1 of the papers presents the theory of the computational method as well… More >

Yao Hsu¹, Chih-Yen Su², Wen-Fang Wu^3,4

CMC-Computers, Materials & Continua, Vol.36, No.2, pp. 155-176, 2013, DOI:10.3970/cmc.2013.036.155

Abstract To study the fatigue reliability of a flip-chip chip scale package (FCCSP) subject to thermal cyclic loading, a Monte Carlo simulation-based parametric study is carried out in the present study. A refined procedure as compared with the recently released Probabilistic Design System (PDS) of ANSYS is proposed and employed in particular. The thermal-cyclic fatigue life of the package is discussed in detail since it is related directly to the reliability of the package. In consideration of the analytical procedure as well as real manufacturing processes, a few geometric dimensions and material properties of the package are assumed random. The empirical… More >

Cheng-Hung San¹, Che-Wun Hong^1,2

CMC-Computers, Materials & Continua, Vol.23, No.2, pp. 101-118, 2011, DOI:10.3970/cmc.2011.023.101

Abstract Poly(ethylene oxide) (PEO) is a commonly used electrolytic polymer in lithium ion batteries because of its high viscosity which allows fabricating thin layers. However, its inherent low ionic conductivity must be enhanced by the addition of highly conductive salt additives. Also its weak mechanical strength needs a complementary block, such as poly(styrene) (PS), to strengthen the electrolytic membrane during charging/discharging processes. PS is a strong material to complement the PEO and to create a reinforced copolymer electrolyte termed as the poly(styrene-b-ethylene oxide) (PS-PEO). In this work, molecular dynamics simulations are employed to study the effects of doping the PS constituents… More >

W.H. Chen¹, C.W. Hong^1,2

CMC-Computers, Materials & Continua, Vol.21, No.2, pp. 147-170, 2011, DOI:10.3970/cmc.2011.021.147

Abstract Nanorod/nanowell/nanotube arrays are effective nanotechnologies that can increase the performance of a photo-electrochemical solar cell by increasing the reaction area of the working electrode. However, the confined space due to the nano-arrays also tends to decrease the redox ion diffusivity. This paper describes computer modeling on the ionic diffusion of the active species (I-/I3-) among the nano-arrays of the working electrode material (TiO2). A three dimensional periodic boundary molecular dynamics simulation technique is employed to simulate the nano-scale transport phenomenon. Performance improvement tendency can be evaluated from the Butler-Volmer equation. Simulation results reveal that the increasing reaction area times the… More >

X.P. Shen, A. Diaz¹, T. Sheehy²

CMC-Computers, Materials & Continua, Vol.20, No.3, pp. 205-224, 2010, DOI:10.3970/cmc.2010.020.205

Abstract This paper presents a case study for the design of a mud-weight window (MWW) with three-dimensional (3-D), finite-element (FE) tools for subsalt wells. The trajectory of the target well penetrates a 7 km thick salt body. A numerical scheme has been proposed for calculating the shear failure gradient (SFG) and fracture gradient (FG) with 3-D FE software. User subroutines have been developed to address non-uniform pore-pressure distribution. A series of FE calculations were performed to obtain the MWW of the target wellbore, which consists of the SFG and FG for the subsalt sections. Although no reverse faulting structure exists in… More >

Haofeng Chen¹

CMC-Computers, Materials & Continua, Vol.20, No.2, pp. 159-184, 2010, DOI:10.3970/cmc.2010.020.159

Abstract In this paper a state-of-the-art numerical method is discussed for the evaluation of the shakedown and ratchet limits for an elastic-perfectly plastic body subjected to cyclic thermal and mechanical load history. The limit load or collapse load, i.e. the load carrying capacity, is also determined as a special case of shakedown analysis. These design limits in plasticity have been solved by characterizing the steady cyclic state using a general cyclic minimum theorem. For a prescribed class of kinematically admissible inelastic strain rate histories, the minimum of the functional for these design limits are found by a programming method, the Linear… More >

Richard K. F. Lee¹, James M. Hill²

CMC-Computers, Materials & Continua, Vol.20, No.1, pp. 85-100, 2010, DOI:10.3970/cmc.2010.020.085

Abstract In this study, we investigate the mechanics of a metallofullerene shuttle memory device, comprising a metallofullerene which is located inside a closed carbon nanotube. The interaction energy for the system is obtained from the 6-12 Lennard-Jones potential using the continuum approximation, which assumes that a discrete atomic structure can be replaced by an average atomic surface density. This approach shows that the system has two equal minimum energy positions, which are symmetrically located close to the tube extremities, and therefore it gives rise to the possibility of being used as a two-state memory device. On one side the encapsulated metallofullerene… More >

Fangyi Li¹, Guangyao Li^2,3, Guangyong Sun², Zhen Luo⁴, Zheng Zhang²

CMC-Computers, Materials & Continua, Vol.19, No.1, pp. 37-56, 2010, DOI:10.3970/cmc.2010.019.037

Abstract The focus of this paper is concentrated on multi-disciplinary and multi-objective optimization for thin walled beam systems considering safety, normal mode, static loading-bearing and weight, in which the uncertainties of the parameters are described via intervals. The size and shape of the cross-section are treated as design parameters during optimization. Considering the lightweight and safety, the design problem is formulated with two individual objectives to measure structural weight and maximum energy absorption, respectively, constrained by the average force, normal mode and maximum stress. The optimization problem with uncertainties is further transformed into a deterministic optimization based on interval number programming.… More >