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 >

A.J. de Wit¹, D. Akçay Perdahcıoğlu², T. Ludwig³, W.M. van den Brink¹, A. de Boer²

CMC-Computers, Materials & Continua, Vol.32, No.3, pp. 201-218, 2012, DOI:10.3970/cmc.2012.032.201

Abstract Depending on the type of analysis, Finite Element (FE) models of different fidelity are necessary. Creating these models manually is a labor intensive task. This paper discusses two approaches for generating FE models of different fidelity from a single reference FE model. The models are created with a single modelling and meshing toolkit. These different fidelity models are created for use with global-local non-linear static analysis and for use with dynamic linear sub-structuring reduction method. Efficiency of the developed approaches is demonstrated via non-linear static and modal analysis of a carbon-fiber stiffened panel. 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 >

Luiz F. Kawashita¹, Alexandre Bedos², Stephen R. Hallett³

CMC-Computers, Materials & Continua, Vol.32, No.2, pp. 133-158, 2012, DOI:10.3970/cmc.2012.032.133

Abstract A methodology is proposed for modelling transverse matrix cracks in laminated composites in a three-dimensional explicit finite element analysis framework. The method is based on the introduction of extra degrees of freedom to represent the displacement discontinuity and the use of a cohesive zone model to determine damage evolution and crack propagation. The model is designed for the analysis of matrix cracks in laminates made of uni-directional fibre-reinforced plies, allowing several assumptions to be made which greatly simplify the algorithm. This was implemented in the commercial software Abaqus/Explicit as a user-defined element subroutine (VUEL). The methodology was verified via the… More >

O. Allix¹, P. Gosselet¹, P. Kerfriden², K. Saavedra³

CMC-Computers, Materials & Continua, Vol.32, No.2, pp. 107-132, 2012, DOI:10.3970/cmc.2012.032.107

Abstract This paper deals with the parallel simulation of delamination problems at the meso-scale by means of multi-scale methods, the aim being the Virtual Delamination Testing of Composite parts. In the non-linear context, Domain Decomposition Methods are mainly used as a solver for the tangent problem to be solved at each iteration of a Newton-Raphson algorithm. In case of strongly non linear and heterogeneous problems, this procedure may lead to severe difficulties. The paper focuses on methods to circumvent these problems, which can now be expressed using a relatively general framework, even though the different ingredients of the strategy have emerged… More >

M. Pankow¹, A.M. Waas², C.F. Yen³

CMC-Computers, Materials & Continua, Vol.32, No.2, pp. 81-106, 2012, DOI:10.3970/cmc.2012.032.081

Abstract The compression response of 3D woven textile composites (3DWC) that consist of glass fiber tows and a polymer matrix material is studied using a combination of experiments and finite element based analyses. A previous study reported by the authors consisted of an experimental investigation of 3DWC under high strain rate loading, Pankow, Salvi, Waas, Yen, and Ghiorse (2011). Those experimental results were explained by using the finite element method to analyze the high rate deformation response of representative volume elements (RVEs) of the 3DWC, Pankow, Waas, Yen, and Ghiorse (2012). In this paper, the same modeling strategy is used to… More >

C. Wang¹, J.H. Qiu^1,2, R. Nie¹, H.L. Ji¹, W. Deng¹

CMC-Computers, Materials & Continua, Vol.32, No.1, pp. 61-80, 2012, DOI:10.3970/cmc.2012.032.061

Abstract The morphing skin has been a main obstacle in the real-world implementation of morphing aircrafts. This paper presents a morphing skin made of the elastomer reinforced by the honeycomb structure. A matrix made from elastomer provides possibilities to configure the morphing skin and the honeycomb structure with smaller in-plane modulus and larger out-of-plane modulus is thought to be suitable to reinforce the elastomer. The polyurethane elastomer is selected and synthesized by the casting method with the prepolymer approach, after which a tensile test is conducted to get its stress-strain relationship. To decrease the skin depth and diminish the local deformation… More >

S.D. Akbarov^1,2

CMC-Computers, Materials & Continua, Vol.32, No.1, pp. 29-60, 2012, DOI:10.3970/cmc.2012.032.029

Abstract By the use of the Murnaghan potential the influence of third order elastic constants on axisymmetric longitudinal wave propagation velocity in a pre-stressed two-layered circular hollow cylinder is investigated. This investigation is carried out within the scope of the piecewise homogeneous body model by utilizing the first version of the small initial deformation theory of the Three-dimensional Linearized Theory of Elastic Waves in Initially Stressed Bodies. Numerical results are obtained and analyzed for the cases where the material of the outer hollow cylinder material is aluminum, but the material of the inner cylinder is steel (Case 1) and tungsten (Case… More >

S. K. Panthi¹, Sanjeev Saxena²

CMC-Computers, Materials & Continua, Vol.32, No.1, pp. 15-28, 2012, DOI:10.3970/cmc.2012.032.015

Abstract Sheet metal forming process like deep drawing subjected to large irreversible deformation. It leads to high strain localization zones and then internal or superficial micro defects. The deformation behavior and crack initiation in cylindrical deep drawing of aluminum alloy are simulated by the elasto-plastic finite element simulation. A1100-O and A2024-T4 sheet material are used in the simulation. Material properties based on the tensile and plane strain test is used in the simulation. Six cases are simulated in this study with different blank diameter. The simulated results are compared with the experimental results in terms of the crack location and critical… More >