Shihao Tian^1,2, Quanzi Yuan^1,2,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.4, pp. 1-1, 2023, DOI:10.32604/icces.2023.09327

Abstract When one soluble fiber is partially merged into liquid, a meniscus forms and the fiber can be dissolved into one pinpoint with curvature. This process has been used in the manufacture of sophisticated pinpoints. However, it is hard to observe the dissolution process in the laboratory and the dissolution mechanisms are still far from being well understood in the nanoscale. Here we utilize molecular dynamics simulations to study the dissolution process of one meniscus-adhered nanofiber. We find that the tip’s curvature radius decreases and then increases, reaching the maximum in the middle state. This state is defined as the “Sh… More >

Zijie Chen^a , Sanat Modak^a, Massoud Kaviany^a,* , Richard Bonner^b

Frontiers in Heat and Mass Transfer, Vol.14, pp. 1-11, 2020, DOI:10.5098/hmt.14.1

Abstract In dropwise condensation on vertical surface, droplets grow at nucleation sites, coalesce and reach the departing diameter. In biphilic surfaces, when the hydrophobic domain is small, the maximum droplet diameter is controlled by the shortest dimension where the droplets merge at the boundary. Through direct numerical simulations this size-effect heat transfer coefficient enhancement is calculated. Then the 1-D biphilic surface is optimized considering the size-dependent hydrophilic domain partial flooding (directly simulated as a liquid rivulet and using the capillary limit), the subcooling (heat flux) and condenser length effects. The predicted performance is in good agreement with the available experiments. More >

Mei Tao¹, Qingwen Ren^1,*, Hanbing Bian², Maosen Cao¹, Yun Jia³

CMES-Computer Modeling in Engineering & Sciences, Vol.132, No.2, pp. 681-705, 2022, DOI:10.32604/cmes.2022.019522

Abstract Soil-rock mixture (SRM) filling in fault zone is an inhomogeneous geomaterial, which is composed of soil and rock block. It controls the deformation and stability of the abutment and dam foundation, and threatens the long-term safety of high arch dams. To study the macroscopic and mesoscopic mechanical properties of SRM, the development of a viable mesoscopic numerical simulation method with a mesoscopic model generation technology, and a reasonable parametric model is crucially desired to overcome the limitations of experimental conditions, specimen dimensions, and experiment fund. To this end, this study presents a mesoscopic numerical method for simulating the mechanical behavior… More >

Yuxi Xie, Shaofan Li^*

CMES-Computer Modeling in Engineering & Sciences, Vol.129, No.3, pp. 1419-1440, 2021, DOI:10.32604/cmes.2021.016756

Abstract The microstructure of crystal defects, e.g., dislocation patterns, are not arbitrary, and it is possible that some of them may be related to the microstructure of crystals itself, i.e., the lattice structure. We call those dislocation patterns or substructures that are related to the corresponding crystal microstructure as the Geometrically Compatible Dislocation Patterns (GCDP). Based on this notion, we have developed a Multiscale Crystal Defect Dynamics (MCDD) to model crystal plasticity without or with minimum empiricism. In this work, we employ the multiscale dislocation pattern dynamics, i.e., MCDD, to simulate crystal plasticity in body-centered cubic (BCC) single crystals, mainly α-phase… More >

W. Wei¹, David C.C. Lam¹

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.2, pp. 213-226, 2010, DOI:10.3970/cmes.2010.064.213

Abstract Molecular rotation is the elastic deformation mechanism underpinning macroscopic deformation in macromolecular solid. In this investigation, molecular mechanic simulations are used to investigate the effect of size on the higher order material properties macromolecular solid. The rotational behavior of molecular coils embedded in beams was examined as a function of the beam size in tension, and in bending where the strain gradients in the bent direction are size-dependent. Analysis showed that the effective elastic modulus is size dependent when strain gradients are significant in bending, but not in tension. Analysis of the molecular rotation behavior indicated that the increase in… More >

Jian Chen¹, Huang Yuan², Folker H. Wittmann³

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.6, pp. 743-754, 2002, DOI:10.3970/cmes.2002.003.743

Abstract Experimental observation confirms that micro-hardness of metallic materials depends significantly on the indentation depth. In the present paper we discuss simulations of micro-indentation tests based on the gradient plasticity model using the finite element method. The role of intrinsic material length parameters in the gradient plasticity model is investigated. The computational results confirm that the gradient plasticity model is suitable to simulate micro-indentation tests and predicts the depth-dependent hardness in micro- and nano-indentations. Variations of micro-hardness is correlated with the intrinsic material length parameters. More >

B.K.Raghu Prasad¹, Rabindra Kumar Saha¹, A.R.Gopalakrishnan¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.14, No.3, pp. 65-84, 2010, DOI:10.3970/icces.2010.014.065

Abstract Several different models have been proposed to characterize mode-I crack propagation in concrete. The fictitious crack model proposed by Hillerborg et al. and the blunt crack band theory developed by Bazant & Oh are particularly well suited for a finite element analysis. The two-parameter fracture model proposed by Jenq & Shah is found to be applicable only for beams with s/w=4, where s=span & w=depth of the beam. The general applicability of the model for other testing configurations is not published. In the present study an experimental verification of a one-parameter model based on fundamental equation of equilibrium developed by… More >

H. Cifuentes¹, F. Medina²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.7, No.4, pp. 197-202, 2008, DOI:10.3970/icces.2008.007.197

Abstract The most popular expression that considers the size effect showed in concrete structures is the size effect law of Bazant. This law depends on two coefficients G_f and c_f. For the experimental determination of these coefficients is necessary obtaining the ultimate loads, in three points bending tests, of notched beams with different sizes. In this work, a method to determine the coefficients about the results on identical beams varying the deep of the notch, is presented. The necessary values of loads are obtained by a numerical analysis with FEM that considers non linear behaviour of the concrete material. Next the… More >

N. Ohno¹, D. Okumura¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.4, No.4, pp. 207-214, 2007, DOI:10.3970/icces.2007.004.207

Abstract The self energy of geometrically necessary dislocations (GNDs) is considered to inevitably introduce the higher-order stress work-conjugate to slip gradient in single crystals. It is pointed out that this higher-order stress stepwise changes in response to in-plane slip gradient and thus directly influences the onset of initial yielding in polycrystals. The self energy of GNDs is then incorporated into the strain gradient theory of Gurtin (2002). The resulting theory is applied to model crystal grains of size D, leading to a D-1-dependent term with a coefficient determined by grain shape and orientation. It is thus shown that the self energy… More >

B.K. Raghu Prasad¹, T.V.R.L. Rao¹, A.R. Gopalakrishnan¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.3, pp. 179-196, 2009, DOI:10.3970/icces.2009.009.179

Abstract A simple numerical method namely Initial Stiffness Method using finite element method has been employed to study the size effect which is prominent in concrete structures. Numerous experimental investigations performed on notched plain concrete beams subjected to three point or four-point bending have revealed the fracture process to be dependent on size of the structural member. It was found that, the nominal stress at maximum load decreases as the size of the structure increases. The nominal stress at failure on the characteristic dimension of structure is termed as size effect. This has also been explained in energy concepts as, the… More >