Solidified/solidifying polymeric coatings are used in many engineering applications because they can provide resistance to corrosion, reduce friction, and provide enhanced magnetic, optical, and mechanical properties. Micro- and nanoindentation and microscratch tests are commonly used techniques for measuring the mechanical properties of thin film/substrate systems. Although these tests can provide indentation hardness, adhesive strength, and driving force, some quantities cannot be measured and must be determined numerically.
Liangsheng Cheng, Research Associate
Donald Kramer, Graduate Student Researcher
Alex Volinsky, Graduate Student Researcher
Xinyun Xia, Graduate Student Researcher
Karl Yoder, Research Associate
99/19 |
"The Effect of Substrate Temperature on the Properties of Nanostructured Silicon Carbide Films Deposited by Hypersonic Plasma Particle Deposition," J. Blum, N. Tymiak, A. Neuman, Z. Wong, N.P. Rao, S.L. Girshick, W.W. Gerberich, P.H. McMurry, and J. Heberlein, University of Minnesota Supercomputing Institute Research Report UMSI 99/19, February 1999. Publication in press. |
99/23 |
"Thermal Plasma Deposition of Nanostructured Films," A. Neuman, J. Blum, N. Tymiak, Z. Wong, N.P. Rao, W.W. Gerberich, P.H. McMurry, J. Heberlein, and S.L. Girshick, IEEE Transactions on Plasma Science, 27, p. 46 (1999). |
99/246 |
"Hypersonic Plasma Particle Deposition of Nanostructured Silicon Carbide Films," N. Tymiak, D.I. Iordanoglou, D. Neumann, A. Gidwani, F. Di Fonzo, M.H. Fan, N.P. Rao, W.W. Gerberich, P.H. McMurry, J. Heberlein, and S.L. Girshick, Proceedings of the 14th International Syumposium on Plasma Chemistry, 4, p. 1989 (1999). |
This research is developing a numerical model and viscoelastic indentation theory in support of the experimental work on micro- and nanoindentation currently being carried out in this research group. The numerical model is expected to provide a better understanding of the mechanical properties of coating/substrate systems. The theory is providing an essential way to interpret the indentation data. At the same time, results from numerical modeling are being used to optimize the experimental process and to provide an alternative tool for designing thin film/substrate materials in industry.
Micro- and nanoindentation process for thin film/substrate systems is classified as normal contact problems while microscratch process falls in the sliding contact category. The contact area, contact pressure, and scratch distance vary with the external load and are unknown prior to analysis. However, the compatibility condition of the contacting surfaces and a friction law must always be satisfied. These factors make contact problems complicated issues even when the simplest constitutive relation is applied to the thin film/substrate materials.
Application of the finite element method in these two kinds of problems is cumbersome because the mathematical treatment becomes complicated for large deformations. Application is further complicated because an implicit computational scheme requires the use of very large matrices, particularly for the three-dimensional problems of principal interest in this research. To overcome these limitations, a numerical model based on the explicit finite difference method has been developed. This numerical procedure allows large displacement, large deformation, large sliding, and elasto-plastic contact problems to be treated in an efficient manner in both two and three dimensions.
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