CMC-Vol. 40, No. 2, 2014

Open Access

ARTICLE

On the Homogenization Analysis of Electromagnetic Properties for Irregular Honeycombs
Lianhua Ma¹, Qingsheng Yang²
CMC-Computers, Materials & Continua, Vol.40, No.2, pp. 79-98, 2014, DOI:10.3970/cmc.2014.040.079
Abstract Honeycombs are widely used in aerospace structures due to their low density and high specific strength. In this paper, effective electromagnetic properties of irregular honeycombs are investigated, by using the three dimensional homogenization theory and corresponding computational procedure. This homogenization method, being the extension of two-scale asymptotic approach, is employed to determine the expressions of the effective dielectric permittivity, magnetic permeability and electrical conductivity. To verify and validate the proposed model and procedure, effective permittivities of a typical irregular honeycomb are studied and compared with those of semi-empirical formulae. Moreover, the effect of geometry of honeycomb's unit cell on effective… More >

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ARTICLE

A Multiscale Progressive Failure Modeling Methodology for Composites That Includes Fiber Strength Stochastics
Trenton M. Ricks¹, Thomas E. Lacy, Jr.^1,2, Brett A. Bednarcyk³, Steven M.Arnold³, John W. Hutchins¹
CMC-Computers, Materials & Continua, Vol.40, No.2, pp. 99-130, 2014, DOI:10.3970/cmc.2014.040.099
Abstract A multiscale modeling methodology was developed for continuous fiber composites that incorporates a statistical distribution of fiber strengths into coupled multiscale micromechanics/ finite element (FE) analyses. A modified twoparameter Weibull cumulative distribution function, which accounts for the effect of fiber length on the probability of failure, was used to characterize the statistical distribution of fiber strengths. A parametric study using the NASA Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC) was performed to assess the effect of variable fiber strengths on local composite failure within a repeating unit cell (RUC) and subsequent global failure. The NASA code FEAMAC… More >

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Graded Dielectric Inhomogeneous Planar Layer Radome for Aerospace Applications
Raveendranath U. Nair, Preethi D.S, R. M. Jha
CMC-Computers, Materials & Continua, Vol.40, No.2, pp. 131-144, 2014, DOI:10.3970/cmc.2014.040.131
Abstract Controllable artificial dielectrics are used in the design of radomes to enhance their electromagnetic (EM) performance. The fabrication of such radome wall structures with controllable dielectric parameters seems to be an arduous task. Further even minor fluctuations of dielectric properties of radome wall due to fabrication uncertainties tend to result in drastic degradation of radome performance parameters. In the present work, a novel inhomogeneous radome with graded variation of dielectric parameters is proposed which limits the constraints on fabrication and facilitates excellent EM performance characteristics. This radome wall consists of five dielectric layers cascaded such that the middle layer has… More >

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Surface/interface Energy Effect on Electromechanical Responses Around a Nanosized Elliptical Inclusion under Far-field Loading at an Arbitrary Angle
Xue-Qian Fang^1,2, Hong-Wei Liu¹, Yong-Mao Zhao¹, Guo-Quan Nie^1,1 and Jin-Xi Liu¹
CMC-Computers, Materials & Continua, Vol.40, No.2, pp. 145-164, 2014, DOI:10.3970/cmc.2014.040.145
Abstract Electro-elastic surface/interface around nano-sized piezoelectric inclusions shows great effect on the response of piezoelectric nano-structures. In this paper, a theoretical model is proposed to examine the surface/interface effect on the electromechanical responses around a nano-sized elliptical piezoelectric inclusion embedded in an infinite piezoelectric matrix under far-field loading with an arbitrary angle, and the effect of loading angle is considered Combining the conformal mapping technique and electro-elastic surface/interface theory, a closed form solution of this problem is obtained and the interactive effect between the surface/interface and the aspect ratio of the elliptical inclusion is examined. More >

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