S. Hernández^1,2, A. Baldomir¹, J. Díaz¹, F. Pereira¹

CMC-Computers, Materials & Continua, Vol.32, No.3, pp. 219-240, 2012, DOI:10.3970/cmc.2012.032.219

Abstract A numerical optimization method was proposed time ago by Templeman based on the maximum entropy principle. That approach combined the Kuhn-Tucker condition and the information theory postulates to create a probabilistic formulation of the optimality criteria techniques. Such approach has been enhanced in this research organizing the mathematical process in a single optimization loop and linearizing the constraints. It turns out that such procedure transforms the optimization process in a sequence of systems of linear equations which is a very efficient way of obtaining the optimum solution of the problem. Some examples of structural optimization, namely, a planar truss, a… More >

B. Kriegesmann¹, R. Rolfes¹, E. L. Jansen¹, I. Elishakoff², C. Hühne³, A. Kling³

CMC-Computers, Materials & Continua, Vol.32, No.3, pp. 177-200, 2012, DOI:10.3970/cmc.2012.032.177

Abstract Four different approaches for the design of axially compressed cylindrical shells are presented, namely (1) the knockdown factor (KDF) concept, (2) the single perturbation load approach, (3) a probabilistic design procedure and (4) the convex anti-optimization approach. The different design approaches take the imperfection sensitivity and the scatter of input parameters into account differently. In this paper, the design of a composite cylinder is optimized considering the ply angles as design variables. The KDF concept provides a very conservative design load and in addition an imperfection sensitive design, whereas the other approaches lead to a significantly less conservative design load… More >

D. Chrupalla¹, J. Kreikemeier¹, S. Berg², L. Kärger³, M. Doreille⁴, T. Ludwig⁴, E. Jansen², R. Rolfes², A.Kling¹

CMC-Computers, Materials & Continua, Vol.32, No.3, pp. 159-176, 2012, DOI:10.3970/cmc.2012.032.159

Abstract In this paper, a loose coupling multiscale modeling technique for the detailed numerical analysis of critical areas in composite structures is presented. It is used to describe the global (macroscopic) behaviour of composite structures taking into account the effects of local phenomena. This is done by indirectly connecting the global and local FE-models. Prescribed displacements are assigned to the local boundaries in the transition from the global to local modeling level. The local-to-global transition is realized by assigning averaged local stresses to the respective global Gauss points and by updating the global tangent stiffness operator. To illustrate the feasibility of… More >

Cheng-Yu Ku^1,2,3, Weichung Yeih^1,2

CMC-Computers, Materials & Continua, Vol.31, No.3, pp. 173-200, 2012, DOI:10.3970/cmc.2012.031.173

Abstract In this paper, a dynamical Newton-like method with the adaptive stepsize based on the construction of a scalar homotopy function to transform a vector function of non-linear algebraic equations (NAEs) into a time-dependent scalar function by introducing a fictitious time-like variable is proposed. With the introduction of the fictitious time-like function, we derived the adaptive stepsize using the dynamics of the residual vector. Based on the proposed dynamical Newton-like method, we can also derive the dynamical Newton method (DNM) and the dynamical Jacobian-inverse free method (DJIFM) with the transformation matrix as the inverse of the Jacobian and the identity matrix,… More >

Linjun Wang^1,2, Xu Han³, Youxiang Xie⁴

CMC-Computers, Materials & Continua, Vol.31, No.2, pp. 113-126, 2012, DOI:10.3970/cmc.2012.031.113

Abstract In this paper, a new iterative regularization method (ITR) is presented to solve the reconstruction of multi-source dynamic loads acting on the structure of simple supported plate. Based on a quadratical convergence method, this method is used to compute the the approximate inverse of square matrix. The theoretical proofs and numerical test show that the proposed method is very effective. Finally, the present method is applied to the identification of the multi-source dynamic loads on a surface of simply supported plate. Numerical simulations of two examples demonstrate the effectiveness and robustness of the present method. More >

Chenxi Xiong^1,2, Xianghe Peng^1,2,3, Chunwei Zhao^1,2,4, Ning Hu^1,5,6

CMC-Computers, Materials & Continua, Vol.31, No.1, pp. 65-86, 2012, DOI:10.3970/cmc.2012.031.065

Abstract A method to reduce the sedimentation of the ferromagnetic particles in magnetorheological fluids (MRFs) is studied with numerical simulation and experiment. It shows that, making use of the magnetic field generated by a permanent magnet put simply above an MRF, the sedimentation of the particles in the MRF can be reduced remarkably. The magnetic force on a ferromagnetic particle and that on a particle chain are computed with the finite element (FE) code ANSYS. It reveals that the magnetic force on a particle-chain is much larger than the sum of the magnetic force on each individual particle in the chain… More >

Chien-Ching Ma^1,2, Yi-Hsien Lin², Shih-Hao Lin²

CMC-Computers, Materials & Continua, Vol.31, No.1, pp. 37-64, 2012, DOI:10.3970/cmc.2012.031.037

Abstract In this article, the transient response in a functionally graded material (FGM) slab is analyzed by Laplace transform technique. The numerical Laplace inversion (Durbin's formula) is used to calculate the dynamic behavior of the FGM slab. The slab is subjected an uniform loading at the upper surface, and the lower surface are assumed to be traction-free or fixed conditions. The analytical solutions are presented in the transform domain and the numerical Laplace inversion is performed to obtain the transient response in time domain. To take the accuracy and computational efficiency in consideration, Durbin's method is suitable for calculating the long-time… More >

Shiv Narayan¹, Shamala Joshi B¹, Raveendranath U. Nair¹, R M Jha¹

CMC-Computers, Materials & Continua, Vol.31, No.1, pp. 1-16, 2012, DOI:10.3970/cmc.2012.031.001

Abstract The electromagnetic design and performance analysis of dual/ multi-band metamaterial frequency selective surface (FSS) structures have been carried out for radome applications in microwave and millimeter wave frequency regimes. The proposed metamaterial FSS structure, consisting of cascaded MNG (mu-nega -tive) and DPS (double positive) layers, exhibits dual-band transmission responses at V-band and W-band. Excellent transmission efficiency (more than 95%) has been obtained over the frequency range 45.8-53.1 GHz at first resonance, and from 93.0-97.1 GHz at second resonance. The incorporation of additional DPS layer to the proposed metamaterial-FSS structure facilitates multiband bandpass characteristics at 30 GHz (in Ka-band), 64 GHz… More >

E. Ferretti

CMC-Computers, Materials & Continua, Vol.30, No.3, pp. 237-284, 2012, DOI:10.3970/cmc.2012.030.237

Abstract The procedure of the effective law outlined in this paper [Ferretti (2001); Ferretti and Di Leo (2003); Ferretti (2004b)] is an experimental procedure for identifying the constitutive law in uniaxial compression of brittle heterogeneous materials, and is based on the physical, analytical and numerical discussions about the existence or otherwise of strain-softening [Ferretti (2004a); Ferretti (2005)]. This procedure allows us to correct several incongruities that characterize the average stress versus average strain diagrams: it produces evidence against strain-softening in uniaxial compression [Ferretti (2004b)], whose existence may be questioned from a physical point of view [Ferretti (2004a); Ferretti (2005)], it provides… More >

Chunwei Zhao^1,2, Xianghe Peng^1,2,3, Jin Huang⁴, Ning Hu^1,5,6

CMC-Computers, Materials & Continua, Vol.30, No.3, pp. 219-236, 2012, DOI:10.3970/cmc.2012.030.219

Abstract The validity of the two conventional micro-macro descriptions for MRFs, based respectively on the exact dipole model and the simplified dipole model, is examined with the results obtained with the commercially available finite element (FE) code ANSYS. It is found that although the simplified dipole model can match better the result by FE computation, there is still a marked difference. An enhanced dipole model is then suggested, which takes into account the contribution of the magnetized particles to magnetic field. Making use of a statistical approach and neglecting the interaction between particle chains, a micro-macro approach is developed for the… More >