Loc Vu-Quoc^1,*, Yuhu Zhai² and Khai D. T. Ngo³

CMES-Computer Modeling in Engineering & Sciences, Vol.129, No.3, pp. 1441-1486, 2021, DOI:10.32604/cmes.2021.016784

Abstract The Generalized Falk Method (GFM) for coordinate transformation, together with two model-reduction strategies based on this method, are presented for efficient coupled field-circuit simulations. Each model-reduction strategy is based on a decision to retain specific linearly-independent vectors, called trial vectors, to construct a vector basis for coordinate transformation. The reduced-order models are guaranteed to be stable and passive since the GFM is a congruence transformation of originally symmetric positive definite systems. We also show that, unlike the Pad´e-via-Lanczos (PVL) method, the GFM does not generate unstable positive poles while reducing the order of circuit problems. Further, the proposed GFM is… More >

Ye Lu¹, Hengyang Li¹, Sourav Saha², Satyajit Mojumder², Abdullah Al Amin¹, Derick Suarez¹, Yingjian Liu³, Dong Qian³, Wing Kam Liu^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.129, No.3, pp. 1351-1371, 2021, DOI:10.32604/cmes.2021.017719

Abstract This paper presents the concept of reduced order machine learning finite element (FE) method. In particular, we propose an example of such method, the proper generalized decomposition (PGD) reduced hierarchical deeplearning neural networks (HiDeNN), called HiDeNN-PGD. We described first the HiDeNN interface seamlessly with the current commercial and open source FE codes. The proposed reduced order method can reduce significantly the degrees of freedom for machine learning and physics based modeling and is able to deal with high dimensional problems. This method is found more accurate than conventional finite element methods with a small portion of degrees of freedom. Different… More >

Yuan Zhu^{1, 2}, Xin Ning^{1, 2}, Yao Zhang^{1, 2}, Yuwan Yin^{1, 2}

The International Conference on Computational & Experimental Engineering and Sciences, Vol.23, No.1, pp. 11-12, 2021, DOI:10.32604/icces.2021.08311

Abstract High performance of the spacecraft structure is required in the special environment, it includes mechanical performance and operational performance, etc. When performing tasks, the spaceborne equipment requires high precision. Therefore, the design of lightweight, high stability and high reliability structure is essential for spacecraft. Topology optimization is widely used in structural design. However, there are some problems in the structure after macro topology optimization, such as checkerboard, local optimal solution and other phenomena. Despite a long calculation period, the obtained structure is often not smooth enough and hard to manufacture. Aiming to this issue, this paper proposes a combined method… More >

Siyang Piao¹, Huajiang Ouyang^{1, 2}, Yahui Zhang^{1, *}

CMES-Computer Modeling in Engineering & Sciences, Vol.122, No.2, pp. 571-591, 2020, DOI: 10.32604/cmes.2020.08789

Abstract A beam approximation method for dynamic analysis of launch vehicles modelled as stiffened cylindrical shells is proposed. Firstly, an initial beam model of the stiffened cylindrical shell is established based on the cross-sectional area equivalence principle that represents the shell skin and its longitudinal ribs as a beam with annular cross-section, and the circumferential ribs as lumped masses at the nodes of the beam elements. Then, a fine finite element model (FE model) of the stiffened cylindrical shell is constructed and a modal analysis is carried out. Finally, the initial beam model is improved through model updating against the natural… More >

R. Sampaio¹, C. Soize²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.4, pp. 93-100, 2007, DOI:10.3970/icces.2007.002.093

Abstract An analysis of the efficiency of the reduced models constructed using the POD-basis and the LIN-basis is presented in nonlinear dynamics for continuous elastic systems discretized by the finite element method. The POD-basis is the basis constructed with the POD method while the LIN-basis is the basis derived from the generalized eigenvalue problem associated with the underlying linear conservative part of the system and usually called the eigenmodes of vibration. The efficiency of the POD-basis or the LIN-basis is related to the speed of convergence in the frequency domain of the solution constructed with the reduced model with respect to… More >

X.Sheldon Wang^1,∗, Ye Yang², Tao Wu²

CMES-Computer Modeling in Engineering & Sciences, Vol.119, No.1, pp. 5-34, 2019, DOI:10.32604/cmes.2019.04204

Abstract In this work, we employ fluid-structure interaction (FSI) systems with immersed flexible structures with or without free surfaces to explore both Singular Value Decomposition (SVD)-based model reduction methods and mode superposition methods. For acoustoelastic FSI systems, we adopt a three-field mixed finite element formulation with displacement, pressure, and vorticity moment unknowns to effectively enforce the irrotationality constraint. We also propose in this paper a new Inf-Sup test based on the lowest non-zero singular value of the coupling matrix for the selection of reliable sets of finite element discretizations for displacement and pressure as well as vorticity moment. Our numerical examples… More >

J. Herrmann¹, M. Junge¹, L. Gaul¹

CMES-Computer Modeling in Engineering & Sciences, Vol.86, No.6, pp. 487-504, 2012, DOI:10.3970/cmes.2012.086.487

Abstract The influence of an acoustic field on the dynamic behavior of a flexible structure is a common issue in automotive applications. An example is the pressure-induced structure-borne sound of piping and exhaust systems. Efficient model order reduction and substructuring techniques accelerate the finite element analysis and enable the vibroacoustic optimization of such complex systems with acoustic fluid-structure interaction. This research reviews the application of the Craig-Bampton and the Rubin method to fluid-structure coupled systems and presents two automotive applications. First, a fluid-filled piping system is assembled by substructures or superelements according to the Craig-Bampton method. Fluid and structural partitions are… More >