Sinuo Zhang¹, Daicong Da², Yingjun Wang^1,3,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.26, No.2, pp. 1-2, 2023, DOI:10.32604/icces.2023.09085

Abstract Topology optimization (TO) designs involving multiple materials suffer either difficult interface modeling or finding physically meaningful transition domains with an accurate structural representation. Simple interpolation approaches are usually used in multi-material designs to represent the overlapped regions of different materials, which cannot solve either of these problems. In this paper, a moving morphable component (MMC)-based TO is developed to overcome this issue by leveraging the triply periodic minimal surfaces (TPMS). The TMPS-based architecture will serve as the infilling microstructure to accurately represent the overlapped domains of different materials. A TPMS function interpolation scheme is used to generate new microstructures for… More >

Hui Fang¹, Jingsen Zhou¹, Haozheng Wang^2,*, Yanxu Wang², Hongji Xiang¹, Yechun Xin²

Energy Engineering, Vol.120, No.4, pp. 831-850, 2023, DOI:10.32604/ee.2023.025171

Abstract Recently, high-frequency oscillation of the modular multilevel converter (MMC) based high-voltage direct current (HVDC) projects has attracted great attentions. In order to analyze the small-signal stability, this paper uses the harmonic state-space (HSS) method to establish a detailed frequency domain impedance model of the AC-side of the HVDC transmission system, which considers the internal dynamic characteristics. In addition, the suggested model is also used to assess the system's high-frequency oscillation mechanism, and the effects of the MMC current inner loop control, feedforward voltage links, and control delay on the high-frequency impedance characteristics and the effect of higher harmonic components. Finally,… More >

Xudong Jiang¹, Chang Liu^1,2,*, Shaohui Zhang³, Weisheng Zhang^1,2, Zongliang Du^1,2, Xiaoyu Zhang³, Huizhong Zeng³, Xu Guo^1,2,*

CMES-Computer Modeling in Engineering & Sciences, Vol.135, No.2, pp. 809-838, 2023, DOI:10.32604/cmes.2023.023561

Abstract This paper proposes an explicit method for topology optimization of stiffened plate structures. The present work is devoted to simultaneously optimizing stiffeners’ shape, size and layout by seeking the optimal geometry parameters of a series of moving morphable components (MMC). The stiffeners with straight skeletons and the stiffeners with curved skeletons are considered to enhance the modeling and optimization capability of the current approach. All the stiffeners are represented under the Lagrangian-description framework in a fully explicit way, and the adaptive ground structure method, as well as dynamically updated plate/shell elements, is used to obtain optimized designs with more accurate… More > Graphic Abstract

C. Gnana Thilaka^*, M. Mary Linda

Intelligent Automation & Soft Computing, Vol.35, No.3, pp. 3429-3445, 2023, DOI:10.32604/iasc.2023.024028

Abstract The application of non-linear loads in the power electronic device causes serious harmonic issues in the power system since it has the intrinsic property of retrieving harmonic current and reactive power from Alternating Current (AC) supply that leads to voltage instability. To maintain a reliable power flow in the power system, an innovative Unified Power Flow Converter (UPFC) is utilized in this proposed approach. The conventional series converter is replaced with the Modular Multilevel Converter (MMC) that improves the power handling capability and achieves higher modular level with minimized distortions. The shunt compensator assists in minimizing the voltage fluctuations and… More >

Mingwan Mei¹, Ping Wang¹, Yanbo Che^1,*, Zihan Lv¹, Zmarrak Wali Khanand¹, Chao Xing^1,2

Energy Engineering, Vol.119, No.2, pp. 591-607, 2022, DOI:10.32604/ee.2022.016585

Abstract

In the medium voltage direct current (MVDC) transmission system, a small number of MMC sub modules will reduce the power quality. In this paper, based on the research background of Photovoltaic Medium Voltage Direct Current (PV-MVDC) system, a Hybrid Modulation Strategy based on the Decoupled Double Synchronous Reference Frame (DDSRF) control strategy is proposed. The dual arm complementary hybrid modulation combining nearest-level-SPWM (NL-SPWM) can keep the number of SMs in the ON state constant. Then, the corresponding voltage sharing control algorithm of sub module (SM) is introduced. Through theoretical calculation, the modulation strategy can be found to stabilize the DC… More >

S. Yotte¹, J. Riss, D. Breysse, S. Ghosh

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.2, pp. 171-188, 2004, DOI:10.3970/cmes.2004.005.171

Abstract Particle distribution influences the particulate reinforced metal matrix composites (PMMC). The knowledge of particle distribution is essential for material design. The study of particle distribution relies on analysis of material images. In this paper three methods are used on an image of an Al/SiC composite. The first method consists in applying successive dilations to the image. At each step the number of objects and the total object area are determined. The decrease of the number of objects as a function of the area is an indicator of characteristic distances. The second method is based on dilations of one particle among… More >

H.J. Bohm¨ ¹, W. Han^1,2, A. Eckschlager^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.1, pp. 5-20, 2004, DOI:10.3970/cmes.2004.005.005

Abstract Three-dimensional periodic micromechanical models are used for studying the mechanical behavior of discontinuously reinforced ductile matrix composites. The models are based on unit cells that contain a number of randomly positioned and, where applicable, randomly oriented spherical, spheroidal or cylindrical reinforcements. The Finite Element method is used to resolve the microscale stress and strain fields and to predict the homogenized responses under overall uniaxial tensile loading in the elastic and elastoplastic regimes. Periodicity boundary conditions are employed in the analyses.\\ The main emphasis of the contribution is put on studying the microscale stresses in the reinforcements, which are evaluated in… More >

V. Tvergaard¹, T. Ørts Pedersen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 89-94, 2000, DOI:10.3970/cmes.2000.001.249

Abstract The development of fatigue damage in a tool-steel metal matrix discontinuously reinforced with TiC particulates is analysed using a numerical cell model. The material is subjected to cyclic loading, and the matrix material is represented by a cyclic plasticity model, which uses a superposition of kinematic and isotropic hardening, with continuum damage mechanics incorporated to model fatigue damage evolution. The cell model represents a material with transversely staggered particulates. With focus on low cycle fatigue, the effect of balanced as well as unbalanced cyclic loading is studied. More >

Metin Kök^1,2, Erdogan Kanca³

CMC-Computers, Materials & Continua, Vol.18, No.3, pp. 213-236, 2010, DOI:10.3970/cmc.2010.018.213

Abstract In this investigation, a new model was developed to predict the wear rate of Al2O3 particle-reinforced aluminum alloy composites by Genetic Expression Programming (GEP). The training and testing data sets were obtained from the well established abrasive wear test results. The volume fraction of particle, particle size of reinforcement, abrasive grain size and sliding distance were used as independent input variables, while wear rate (WR) as dependent output variable. Different models for wear rate were predicted on the basis of training data set using genetic programming and accuracy of the best model was proved with testing data set. The two-body… More >