Mingzhe Jiang¹, S. Nicole DeMass¹, D. Ross Economy², Thomas Shackleton¹, Christopher L. Kitchens^1*

Journal of Renewable Materials, Vol.4, No.5, pp. 377-387, 2016, DOI:10.7569/JRM.2016.634131

Abstract Spin coating was used to cast a uniform film of cellulose nanocrystals with low surface roughness and variable thickness as a function of operational parameters that include rotational speed and dispense suspension concentration. The film thickness was controllable from 40 nm up to 1 μm with surface roughness an order of magnitude less than blade-coating methods. The degree of radial orientation was qualitatively assessed and shown to be variable with processing parameters. Under specific processing conditions, the formation of striation patterns was observed and associated with film drying instability. The striation patterns are periodic in nature where the wavelength and… More >

Monique de Alvarenga Pinto Cotrim^1*, Jessyca Aparecida Paes Dutra², Suzana Gonçalves Carvalho², Janaina Cecília Oliveira Villanova², Eliane Ayres¹

Journal of Renewable Materials, Vol.4, No.1, pp. 9-17, 2016, DOI:10.7569/JRM.2015.634122

Abstract In recent years there has been an increasing demand for the application of natural products to address problems in the environment. The use of products derived from renewable resources can provide a sustainable strategy to replace totally or partially synthetic products. Cymbopogon, commonly known as lemongrass, is a tropical grass cultivated mostly for its essential oil, which has demonstrated several bioactivities, including antibacterial and antifungal properties. In the present work the formation of inclusion complex between β-cyclodextrin (β-CD) and lemongrass essential oil (LGEO) as well as its fi xation onto cotton fabric were investigated. Inclusion complex was prepared through solution… More >

Hui Zheng¹, Wen Chen^1,2,3, Chuanzeng Zhang⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.3, pp. 179-195, 2013, DOI:10.3970/cmes.2013.090.179

Abstract This paper develops a multi-domain boundary knot method (BKM) formulation to solve the heat conduction problems of ultra-thin coatings. This approach overcomes the troublesome singular integration difficulty in the boundary element method in the simulation of such ultra-thin coating problems. Our numerical results show that the present BKM is very promising with sufficient accuracy in predicting the temperature distributions and the other physical quantities in thin coated layers even when the thickness ranges from 10-1m to 10-9m. The present method can also easily be extended to the three-dimensional problems. More >

C. Y. Chen¹, C. Atkinson²

CMES-Computer Modeling in Engineering & Sciences, Vol.48, No.3, pp. 219-240, 2009, DOI:10.3970/cmes.2009.048.219

Abstract In this paper, we extend our previous analysis of a contact problem with a circular indenter pressed normally against a semi-infinite elastic composite to that of a semi-infinite viscoelastic composite which consists of a contact layer with uniform thickness welded together with another dissimilar medium. Using the correspondence principle between the Laplace transformed elastic equations and the viscoelastic ones, the asymptotic results derived previously for the pure elastic case are readily adopted for the viscoelastic one with the elastic constants replaced by appropriate functions of Laplace transformed variables for the linear viscoelastic solid. We focus our analysis on the force… More >

L.K. Keppas¹, G.I. Giannopoulos¹, N.K. Anifantis¹

CMES-Computer Modeling in Engineering & Sciences, Vol.25, No.3, pp. 181-196, 2008, DOI:10.3970/cmes.2008.025.181

Abstract In the present paper a boundary element procedure is formulated to treat two-dimensional time dependent thermo-elastic contact problems incorporating thermal resistance along the contacting surfaces. The existence of pressure-dependent thermal contact leads to coupling of temperature and stress fields. Therefore, the inherent non-linearity of the problem demands simultaneous treating of both thermal and mechanical boundary integral equations while iterative procedures are introduced to ensure equilibrium of mechanical and thermal contact conditions at each step of the process. The transient behavior of interfacial cracks in bimaterial solids when undergo thermal shock in the presence of partial crack closure and thermal contact… More >

Xiaolin Chen, Yijun Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.2, No.3, pp. 337-350, 2001, DOI:10.3970/cmes.2001.002.337

Abstract An advanced boundary element method (BEM) is developed in this paper for analyzing thin layered structures, such as thin films and coatings, under the thermal loading. The boundary integral equation (BIE) formulation for steady-state thermoelasticity is reviewed and a special case, that is, the BIE for a uniform distribution of the temperature change, is presented. The new nearly-singular integrals arising from the applications of the BIE/BEM to thin layered structures under thermal loading are treated in the same way as developed earlier for thin structures under the mechanical loading. Three 2-D test problems involving layered thin films and coatings on… More >

Adeline Tchikango Siagam¹, Gunther Brenner¹, Peter Giese², Volker Wesling²

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.2, pp. 77-84, 2008, DOI:10.3970/fdmp.2008.004.077

Abstract The PTA (''Plasma-Transferred-Arc'') is a widespread variant of plasma powder processes to manufacture coatings against corrosion or abrasion. For the optimization of this technique, an explanation of the processes which lead to a maximal deposition performance (i.e. maximal quantity of powder converted per time) is required. Especially the gas and particle flow in the region between the burner nozzle and the work piece is of interest. In the present study, flow simulations (Computational Fluid Dynamics, CFD) have been done in order to investigate the determining factors for the dimensioning of the processes. Additionally, velocity measurements have been obtained with PIV… More >

Joseph G. Lawrence, John P. Dismukes, Arunan Nadarajah¹

FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.3, pp. 255-264, 2007, DOI:10.3970/fdmp.2007.003.255

Abstract The atmospheric chemical vapor deposition process on continuous glass sheets is a well developed one and the parameters that affect it are relatively well understood. When this process is converted to coat discrete glass plates it introduces a new variable, the gap between the glass plates, which can significantly impact the quality of the coatings. In this study a 2D pseudo steady state model of the process was developed to study the effect of the gap, and the ratio of outlet to inlet gas flow rates (called the bias), on the coating quality. The model was solved with the commercially… More >

Joseph G. Lawrence, Arunan Nadarajah¹

FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.3, pp. 247-254, 2007, DOI:10.3970/fdmp.2007.003.247

Abstract A simplified 2D pseudo steady state model was developed for an atmospheric chemical vapor deposition (CVD) process on glass. This is used to study the feasibility of converting a continuous coating process to one with discrete glass plates with a gap between them. A preliminary estimate employing mass transfer correlations suggested that there would be significant concentration variations due to the gap between the plates. More detailed studies were done by solving the model numerically employing a finite difference scheme with a vorticity-stream function formulation, and employing the commercial computational fluid dynamics program FIDAP which employs a finite element scheme.… More >

Taotao Hu¹, gping Shen^1,2

CMC-Computers, Materials & Continua, Vol.17, No.1, pp. 41-58, 2010, DOI:10.3970/cmc.2010.017.041

Abstract In this paper, an axisymmetric indentation model is set up to calculate the effects of the roughness of the thermally grown oxide (TGO) layer, which was modeled as a sinusoidal wave, on the indentation response of the thermal barrier coatings. It is found that the amplitude, wavelength, and thickness of the thermally grown oxide layer have obvious influences on the indentation response, while the effect of the indenter position can be neglected. In the top coating layer, residual stress mainly occurs below the indenter and around the nearest two peaks of the thermally grown oxide layer to the indenter. Only… More >