W. Pietraszkiewicz¹

CMES-Computer Modeling in Engineering & Sciences, Vol.70, No.2, pp. 153-190, 2010, DOI:10.3970/cmes.2010.070.153

Abstract Chien Wei-Zhang (1944) derived three equilibrium equations and three compatibility conditions of the nonlinear theory of thin, isotropic elastic shells entirely in terms of the surface stress and strain measures associated with the shell base surface. This allowed Him to divide the complex boundary value problem (BVP) of nonlinear shell analysis into two disjoint and supposedly simpler steps: I) finding the surface stress and strain measures from the intrinsic BVP, and II) establishing position in space of the deformed base surface from already known surface strain measures. In the present paper some achievements of this formulation obtained during the last… More >

Cheng-Hung Huang¹, Chi-An Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.36, No.1, pp. 1-22, 2008, DOI:10.3970/cmes.2008.036.001

Abstract A three-dimensional shape identification problem (or inverse geometry problem) in estimating the unknown irregular shape of internal cavity by using the steepest descent method (SDM) and a general purpose commercial code CFD-RC is examined in this study based on the simulated measured temperature distributions on the outer surface by infrared thermography. The advantage of calling CFD-RC as a subroutine in the present shape identification problem lies in its characteristics of easily-handling the problem considered here since the auto mesh function of CFD-RC enables the handling of this moving boundary problem. \newline Three test cases are performed to test the validity… More >

K. Lee¹ and S.W. Lee ²

CMES-Computer Modeling in Engineering & Sciences, Vol.34, No.3, pp. 253-272, 2008, DOI:10.3970/cmes.2008.034.253

Abstract A geometrically nonlinear assumed strain formulation is used to develop a nine-node solid shell element with quadratic displacement through the thickness. The transversely quadratic element allows direct use of the constitutive equations developed for three-dimensional solids, which is convenient when material nonlinearity is involved. The nodal degrees of freedom associated with the quadratic terms in the assumed displacement through the thickness are statically condensed out at the element level. The results of numerical tests conducted on selected example problems demonstrate the validity and effectiveness of the present approach. For the cases involving linear elastic material, the differences between the present… More >

K. Lee¹, C.T. Wu², G.V. Clarke³, S.W. Lee⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.33, No.1, pp. 109-130, 2008, DOI:10.3970/cmes.2008.033.109

Abstract A geometrically nonlinear finite element analysis of a low areal density composite space reflector is conducted under static conditions and the results are compared with independently carried out experimental data. The finite element analysis is based on an assumed strain formulation of a geometrically nonlinear nine-node solid shell element. Numerical results are in good agreement with experimental data. This demonstrates the effectiveness of the present solid shell element approach when applied to the analysis of highly flexible space structures. The results of numerical analysis and the experimental data reported in the present paper provide a benchmark for future investigations on… More >

Maenghyo Cho¹, Jinbok Choi², Hee Yuel Roh³

CMES-Computer Modeling in Engineering & Sciences, Vol.33, No.1, pp. 17-48, 2008, DOI:10.3970/cmes.2008.033.017

Abstract The framework for the linkage between geometric modeling and an analysis based on the NURBS technology is developed in this study. In the present study, The NURBS surfaces were generated by interpolating a given set of data points or by extracting the necessary information to construct the NURBS surface from the IGES format file which was generated by the commercial CAD systems. Numerical examples showed the rate of displacement convergence for the various parameter-izations of the NURBS surface. Quadric surface, which is generated exactly by NURBS representation, was considered. One of the important advantages of the NURBS equation is its… More >

John L. Volakis¹, Kubilay Sertel¹, Erik Jørgensen², Rick W. Kindt¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 463-476, 2004, DOI:10.3970/cmes.2004.005.463

Abstract In this paper we address several topics relating to the development and implementation of volume integral and hybrid finite element methods for electromagnetic modeling. Comparisons of volume integral equation formulations with the finite element-boundary integral method are given in terms of accuracy and computing resources. We also discuss preconditioning and parallelization of the multilevel fast multipole method, and propose higher-order basis functions for curvilinear quadrilaterals and volumetric basis functions for curvilinear hexahedra. The latter have the desirable property of vanishing divergence within the element but non-zero curl. In addition, a new domain decomposition is introduced for solving array problems involving… More >

Li-Tien Cheng²³, Myungjoo Kang⁴, Stanley Osher⁴, Hyeseon Shim⁴, Yen-Hsi Tsai⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.4, pp. 347-360, 2004, DOI:10.3970/cmes.2004.005.347

Abstract Geometric optics makes its impact both in mathematics and real world applications related to ray tracing, migration, and tomography. Of special importance in these problems are the wavefronts, or points of constant traveltime away from sources, in the medium. Previously in [Osher, Cheng, Kang, Shim, and Tsai(2002)], we initiated a level set approach for the construction of wavefronts in isotropic media that handled the two major algorithmic issues involved with this problem: resolution and multivalued solutions. This approach was quite general and we were able to construct wavefronts in the presence of refraction, reflection, higher dimensions, and, in [Qian, Cheng,… More >

Keejoo Lee¹, Chahngmin Cho², Sung W. Lee¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.3, pp. 339-350, 2002, DOI:10.3970/cmes.2002.003.339

Abstract A geometrically nonlinear assumed strain formulation is introduced in conjunction with bubble function displacements to improve the performance of a nine-node solid shell element. The assumed strain field has been carefully selected to avoid both element locking and undesirable spurious kinematic modes. The results of numerical tests demonstrate that the present approach leads to an element that is significantly less sensitive to mesh distortion than the existing element. More >

Kun Luan¹, Baozhong Sun¹, Bohong Gu^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.1, pp. 31-62, 2011, DOI:10.3970/cmes.2011.079.031

Abstract This paper reports finite element multi-scale simulations of ballistic impact damage of three-dimensional angle-interlock woven composite (3DAWC) penetrated under a hemispherical rigid projectile. A multi-scale geometrical model of the 3DAWC was established for the numerical simulation. The multi-scale geometrical model of the 3DAWC consists two parts: one is the microstructure model and another is the continuum model. The microstructure model has the same microstructure with that of the 3DAWC composite panel, including the fiber tows' diameter, fiber tow configuration and fiber volume fraction. The continuum model has the same mechanical properties with the 3DAWC. The commercial-available finite element software package… More >

A. Gakwaya¹, H. Sharifi², M. Guillot¹, M. Souli³, F. Erchiqui⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.3, pp. 209-266, 2011, DOI:10.3970/cmes.2011.073.209

Abstract A mechanical computer aided design and engineering system can be used to reduce the design-to-manufacture cycle time in metal forming process. Such a system could be built upon a solid modeling geometry engine and an efficient finite element (FE) solver. The maintenance of a high-quality mesh throughout the analysis is an essential feature of an efficient finite element simulation of large strain metal forming problems. In this paper, a mesh adaptation technique employing the Arbitrary Lagrangian-Eulerian formulation (ALE) is applied to some industrial metal forming problems. An ACIS boundary representation of the solid model is employed. This type of representation… More >