JP Journal of Solids and Structures
Volume 1, Issue 3, Pages 237 - 254
(November 2007)
|
|
AN FEM APPROACH INTO NANOINDENTATION ON LINEAR ELASTIC AND VISCOELASTIC CHARACTERIZATION OF POLYMERIC THIN FILMS
Ch. Srinivasa Rao (India) and C. Eswara Reddy (India)
|
Abstract:
Nanoindentation technique is being used extensively to measure the nanomechanical properties of hard thin films. However, the determination of the surface mechanical properties of polymeric materials with such techniques is relatively new. An attempt is made to extract linear elastic and viscoelastic properties of polymeric thin films by using Finite Element Modeling (FEM) technique. The experimental values of elastic moduli available from the literature for bulk Polymethyl Methacrylate (PMMA) and ultra-high molecular weight polyethylene (UHMWPE) are used to simulate the nanoindentation into their thin films. In linear elastic case, load-displacement data obtained by simulation is used to calculate the Young’s modulus. The simulated results obtained are compared with that of the analytical results of Hertz. The model is extended to measure time-dependent behavior of polymeric films. The possibility to extract Relaxed shear modulus and Creep compliance of the polymeric films is evaluated using a Spherical indenter. The elastic and viscoelastic properties are extracted to analyze the thin film behavior as a function of stress, film thickness and indenter size effect. Further, the viscoelastic indentation theories are assessed by comparing with that of the FE results and thus validated. A good correlation is found between the analytical results and numerical simulated results in both the linear elastic and viscoelastic cases. |
| Keywords and phrases: nanoindentation, FEM, polymeric thin films, elastic and viscoelastic properties. |
| |
| Number of Downloads: 157 | Number of Views: 340 |
|
