Indentation processes in poly(methylmethacrylate). II. Cone indentation and deep punching
| Autor: | R J Kent |
|---|---|
| Rok vydání: | 1983 |
| Předmět: |
Materials science
Acoustics and Ultrasonics Deformation (mechanics) business.industry Radius Condensed Matter Physics Surfaces Coatings and Films Electronic Optical and Magnetic Materials body regions Optics Cone (topology) Position (vector) Indentation Ligand cone angle Composite material business Punching Refractive index |
| Zdroj: | Journal of Physics D: Applied Physics. 16:135-149 |
| ISSN: | 1361-6463 0022-3727 |
| DOI: | 10.1088/0022-3727/16/2/011 |
| Popis: | For pt.I see ibid., vol.14, p.601, (1981). The process of indentation in PMMA by cone indenters is shown to be highly dependent on the cone angle. For blunt cones (greater than 30 degrees semi-angle) a dead zone is formed ahead of the indenter and this acts as the indenter. The formation of this zone is examined for various blunt cones and the resultant zone is similar for all cases. The zone formation is ascribed to frictional forces and such a zone is not formed with sharp indenters. Irrespective of cone angle and dead-zone formation the deformation under the indenter resembles the expansion of a cavity in the material. Observations of the growth and position of the region of anomalous refractive index and the crack path allow assignment of a value to the parameter 'plastic zone radius/cavity radius', c/a, as required by the expanding cavity model. The c/a value determined in this manner is approximately 1.6. Frictional effects on the shank and tip of the indenter make large contributions to the measured indentation pressure, and corrections for these are suggested. If the c/a value of 1.65 is used the pressures predicted by the expanding cavity model of Puttick et al. (1977) correlate well with the corrected experimental results. |
| Databáze: | OpenAIRE |
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