Souli, M.¹, Gabrys, J.²

CMES-Computer Modeling in Engineering & Sciences, Vol.85, No.2, pp. 177-192, 2012, DOI:10.3970/cmes.2012.085.177

Abstract Bird impacts on aircraft are very common and cause significant safety threats to commercial and military aircraft. According to FAA ( Federal American Aviation) regulations, aircraft should be able to land safely following specified types of bird impact on components such as radomes, windshields, engines leading edge structures and other exposed components. Thus exposed components are required to be certified for bird impact. In order to evaluate whether the aircraft is compliant to FAA requirements, several experimental tests and numerical simulations of bird impact on components need to be preformed. This paper presents an experimental More >

N. Thai-Quang¹, K. Le-Cao¹, N. Mai-Duy¹, T. Tran-Cong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.6, pp. 528-558, 2012, DOI:10.3970/cmes.2012.084.528

Abstract This study is concerned with the development of integrated radial-basis-function (IRBF) method for the simulation of two-dimensional steady-state incompressible viscous flows governed by the pressure-velocity formulation on Cartesian grids. Instead of using low-order polynomial interpolants, a high-order compact local IRBF scheme is employed to represent the convection and diffusion terms. Furthermore, an effective boundary treatment for the pressure variable, where Neumann boundary conditions are transformed into Dirichlet ones, is proposed. This transformation is based on global 1D-IRBF approximators using values of the pressure at interior nodes along a grid line and first-order derivative values of… More >

T.-T. Hoang-Trieu¹, N. Mai-Duy¹, T. Tran-Cong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.2, pp. 171-204, 2012, DOI:10.3970/cmes.2012.084.171

Abstract In this paper, new compact local stencils based on integrated radial basis functions (IRBFs) for solving fourth-order ordinary differential equations (ODEs) and partial differential equations (PDEs) are presented. Five types of compact stencils - 3-node and 5-node for 1D problems and 5×5-node, 13-node and 3×3 -node for 2D problems - are implemented. In the case of 3-node stencil and 3×3-node stencil, nodal values of the first derivative(s) of the field variable are treated as additional unknowns (i.e. 2 unknowns per node for 3-node stencil and 3 unknowns per node for 3×3-node stencil). The integration constants… More >

Weiwei Gong, Yan Liu, Xiong Zhang, Honglei Ma

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.5, pp. 527-546, 2012, DOI:10.3970/cmes.2012.083.527

Abstract Owing to its low density and good energy absorption capability, aluminum foam is an excellent protective material for spacecraft against debris impact. However, because of its complicated microstructure, it is very difficult to generate a FEM mesh accounting for the real microstructure of the alluminum foam. On the contrary, it is very easy to model three-dimensional problems with very complicated geometry with meshfree/meshless methods. Furthermore, the material point method has obvious advantages in modeling problems involving extreme large deformation problems like hypervelocity impact problem. In this paper, a three-dimensional material point model accounting for the More >

Li Shan, Ning Cui, Ming Cheng, Kaixin Liu

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.4, pp. 353-384, 2012, DOI:10.3970/cmes.2012.083.353

Abstract In the present paper, a combined scheme of discrete element method (DEM) and meshless method for numerical simulation of impact problems is proposed. Based on the basic principle of continuum mechanics, an axisymmetric DEM framework is established for modeling the elastoplastic behavior of solid materials. Failure criteria are introduced to model the transformation from a continuum to a discontinuum. The friction force between contact elements is also considered after the failure appears. So our scheme can calculate not only the behavior of continuum and discontinuum, but also the transformation process from a continuum to a More >

K.I. Tserpes¹, A.S. Koumpias¹

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.2, pp. 169-182, 2012, DOI:10.32604/cmes.2012.083.169

Abstract In this work, a comparison between a cohesive zone model and a continuum damage model in predicting the mode-I fracture behavior of adhesively bonded joints is performed on the basis of reliability and applicability. The cohesive zone model (CZM) is based on an exponential traction law characterizing the behavior of the interface elements. The continuum damage model (CDM) is based on the stiffness degradation of adhesive elements imposed by a damage parameter. Both models have been implemented by means of a 3D finite element model. Mode-I fracture behavior of the bonded joints was characterized using… More >

Zhen Luo^1,2, Nong Zhang^1,3, Yu Wang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.1, pp. 73-96, 2012, DOI:10.3970/cmes.2012.083.073

Abstract This paper aims to present a physically meaningful level set method for shape and topology optimization of structures. Compared to the conventional level set method which represents the design boundary as the zero level set, in this study the boundary is embedded into non-zero constant level sets of the level set function, to implicitly implement shape fidelity and topology changes in time via the propagation of the discrete level set function. A point-wise nodal density field, non-negative and value-bounded, is used to parameterize the level set function via the compactly supported radial basis functions (CSRBFs)… More >

S. Oukach^1,2,3, H. Hamdi², M. El Ganaoui⁴, B. Pateyron¹

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.2, pp. 173-196, 2012, DOI:10.3970/fdmp.2012.008.173

Abstract The splat formation is one of the basic processes in thermal spray coatings. The performance of these coatings is strongly related to the process of spreading and solidification of molten droplets. The aim of the present paper is to simulate the fluid flow, heat transfer and phase-change that occur when a micrometric molten droplet impacts onto a rigid substrate and to examine the effect of the substrate conditions, such as initial temperature and material on the solidification time and spreading process. The effect of thermal contact resistance is also investigated. The simulation model used is More >

Channarong Wantha^a, Kriengkrai Assawamartbunlue^a,*

Frontiers in Heat and Mass Transfer, Vol.2, No.4, pp. 1-8, 2011, DOI:10.5098/hmt.v2.4.3006

Abstract This paper presents a study of the impact of the resonance tube on performance of a thermoacoustic stack. The resonance tube is a key component of a standing-wave thermoacoustic refrigerator. The appropriated resonance tube’s length leads to an increase of performance of the stack in terms of the temperature difference. The results also indicate that the optimal operating frequency differs from the design based on the equation of a half-wavelength. The resonance tube length is elongated to compensate for some effects that occur in the resonance tube, especially when the stack is placed in the More >

Sina Alavi, Mohammad Passandideh-Fard^*

Frontiers in Heat and Mass Transfer, Vol.2, No.2, pp. 1-9, 2011, DOI:10.5098/hmt.v2.2.3007

Abstract In this paper, a numerical study is performed to investigate the effects of thermal shrinkage on the deposition of molten particles on a substrate in a thermal spray process using the Volume-of-Fluid (VOF) method. Thermal shrinkage is a phenomenon caused by the variation of density during cooling and solidification of a molten metal. The Navier-Stokes equations along with the energy equation including phase change are solved using a 2D/axisymmetric mesh. The VOF method is used to track the free surface of molten particles, and an enthalpy-porosity formulation is used to model solidification. For the normal More >