Kang-Hyun Lee¹, Gun Jin Yun^1,2,*

CMC-Computers, Materials & Continua, Vol.66, No.1, pp. 87-112, 2021, DOI:10.32604/cmc.2020.012688

Abstract Re-melting process has been utilized to mitigate the residual stress level in the selective laser melting (SLM) process in recent years. However, the complex consolidation mechanism of powder and the different material behavior after the first laser melting hinder the direct implementation of the re-melting process. In this work, the effects of re-melting on the temperature and residual stress evolution in the SLM process are investigated using a thermo-mechanically coupled finite element model. The degree of consolidation is incorporated in the energy balance equation based on the thermodynamically-consistent phase-field approach. The drastic change of material properties due to the variation… More >

Ting Zang¹, Dongbin Zhu^2,*, Guowang Mu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.125, No.2, pp. 597-610, 2020, DOI:10.32604/cmes.2020.09965

Abstract According to the requirement of heterogeneous object modeling in additive manufacturing (AM), the Non-Uniform Rational B-Spline (NURBS) method has been applied to the digital representation of heterogeneous object in this paper. By putting forward the NURBS material data structure and establishing heterogeneous NURBS object model, the accurate mathematical unified representation of analytical and free heterogeneous objects have been realized. With the inverse modeling of heterogeneous NURBS objects, the geometry and material distribution can be better designed to meet the actual needs. Radical Basis Function (RBF) method based on global surface reconstruction and the tensor product surface interpolation method are combined… More >

Jingfa Li¹, Bo Yu^1,*, Qianqian Shao², Dongliang Sun¹

CMES-Computer Modeling in Engineering & Sciences, Vol.125, No.2, pp. 541-563, 2020, DOI:10.32604/cmes.2020.011835

Abstract In this work, the drag-reducing mechanism of high-Reynoldsnumber turbulent channel flow with surfactant additives is investigated by using large eddy simulation (LES) method. An N-parallel finitely extensible nonlinear elastic model with Peterlin’s approximation (FENE-P) is used to describe the rheological behaviors of non-Newtonian fluid with surfactant. To close the filtered LES equations, a hybrid subgrid scale (SGS) model coupling the spatial filter and temporal filter is applied to compute the subgrid stress and other subfilter terms. The finite difference method and projection algorithm are adopted to solve the LES governing equations. To validate the correctness of our LES method and… More >

Donghua Dai^1,2, Dongdong Gu^1,2,*, Qing Ge^1,2, Chenglong Ma^1,2, Xinyu Shi^1,2, Han Zhang^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.124, No.3, pp. 1085-1098, 2020, DOI:10.32604/cmes.2020.010927

Abstract The three-dimensional physical model of the randomly packed powder material irradiated by the laser beam was established, taking into account the transformation of the material phase, the melt spreading and the interaction of the free surface of the molten pool and the recoiling pressure caused by the material evaporation during the selective laser melting. Influence of the processing parameters on the thermal behavior, the material evaporation, the surface morphology and the densification behavior in the connection region of the molten pool and the substrate was studied. It was shown that the powder material underwent the transformation from the partial melting… More >

Zhaohui Xia^1,2, Zhihao He², Qifu Wang¹, Yingjun Wang^2,*

CMES-Computer Modeling in Engineering & Sciences, Vol.124, No.2, pp. 703-720, 2020, DOI:10.32604/cmes.2020.010368

Abstract Additive manufacturing (AM), adding materials layer by layer, can be used to produce objects of almost any shape or geometry. However, AM techniques cannot accurately build parts with large overhangs, especially for the large features close to horizontal, hanging over the void. The overhangs will make the manufactured model deviate from the design model, which will result in the performance of the manufactured model that cannot satisfy the design requirements. In this paper, we will propose a new finite element (FE) analysis model that includes the manufacturing errors by mimicking the AM layer by layer construction process. In such FE… More >

Xiangyu Gao, Weidong Yang^*, Hongxuan Xian, Xiyuan Tu, Yuanyuang Wang^*

CMES-Computer Modeling in Engineering & Sciences, Vol.124, No.1, pp. 227-241, 2020, DOI:10.32604/cmes.2020.09923

Abstract This paper studies the binder droplet injection process in the 3DP technique. The mathematical model of the binder penetration process for multi-nozzle and multi-layer in 3DP technique is established, by using the conservation Level set method. According to the two-dimensional plane model of three-dimensional spatial structure of sand bed, the construction method of an equivalent cylindrical mapping infiltration model is proposed to represent the porosity of the model in the two-dimensional plane, which is exactly the same as that in the three-dimensional space, as well as closer to the arrangement of the three-dimensional space, and to realize the differentiation between… More >

Di Wang¹, Guangzhao Ye¹, Jingming Mai², Xiaomin Chen¹, Yongqiang Yang^1,*, Yang Li^1,*, Xiaojun Chen¹, Jie Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.3, pp. 1061-1077, 2020, DOI:10.32604/cmes.2020.09842

Abstract In this paper, a novel micromixer with complex 3D-shape inner units was put forward and fabricated by metal Additive Manufacturing (AM). The design of the micromixer combined the constraints of selective laser melting technology and the factors to improve mixing efficiency. Villermaux-Dushman reaction system and Compute Fluid Design (CFD) simulation were conducted to investigate the performance and the mechanism of this novel micromixer to improve mixing efficiency. The research found that the best mixing efficiency of this novel micromixer could be gained when the inner units divided fluid into five pieces with a uniform volume. Compared with a conventional micromixer… More >

Xinglong Wang^1,2, Cheng Wang^1,2, Xin Zhou^1,*, Mingkang Zhang³, Peiyu Zhang¹, Lei Wang²

CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 495-508, 2020, DOI:10.32604/cmes.2020.09778

Abstract The new regenerative cooling thermal protection system exhibits the multifunctional characteristics of load-carrying and heat exchange cooling, which are fundamental for the lightweight design and thermal protection of hypersonic vehicles. Triply periodic minimal surface (TPMS) is especially suitable for the structural design of the internal cavity of regenerative cooling structures owing to its excellent structural characteristics. In this study, test pieces were manufactured using Ti6Al4V lightweight material. We designed three types of porous test pieces, and the interior was filled with a TPMS lattice (Gyroid, Primitive, I-WP) with a porosity of 30%. All porous test pieces were manufactured via selective… More >

Haiyang Ding¹, Xiaohua Yang¹, Lina Xu¹, Mei Li¹, Shouhai Li¹, Jianling Xia^1,*

Journal of Renewable Materials, Vol.7, No.12, pp. 1391-1401, 2019, DOI:10.32604/jrm.2019.07207

Abstract A water-soluble lubricant additive (RSOPE) was prepared by esterification reaction using fatty acid from rubber seed oil. The RSOPE was added into water-ethylene glycol (W-EG) solution as lubricant additive. Dispersion stability and rheological properties were investigated. We used a four-ball tribotester to assess the lubrication performance of W-EG based fluid with the RSOPE additive. The stainless-steel surface was analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Good dispersion stability was observed in the RSOPE/W-EG solutions. Furthermore, nonNewtonian fluid behavior at low shear rates and Newtonian fluid behavior at high shear rates was exhibited. The addition of RSOPE… More >

Gregory Reimonn¹, Taofeng Lu¹, Neeti Gandhi², Wan-Ting Chen^1,*

Journal of Renewable Materials, Vol.7, No.12, pp. 1251-1268, 2019, DOI:10.32604/jrm.2019.08055

Abstract Microplastic pollution represents a side-effect stemming from a global plastic waste mismanagement problem and includes degraded particles or mass produced plastic particles less than 5 mm in largest dimension. The small nature of microplastics gives this area of pollution different environmental concerns than general plastic waste in the environment. The biological toxicity of particles, their internal components, and their surface level changes all present opportunities for these particles to adversely affect the environment around them. Thus, it is necessary to review the current literature surrounding this topic and identify areas where the study of microplastic can be pushed forward. Here… More >