| Title |
Effects of Surface Residual Stress on the Local Indent Strain |
| Authors |
이윤희(Yun Hee Lee); 박종서(Jong Seo Park); 김용일(Yong Il Kim); 허용학(Yong Hak Huh) |
| DOI |
https://doi.org/10.3365/KJMM.2015.53.2.90 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
amorphous materials; deformation; residual stress; indentation; indent strain |
| Abstract |
Berkovich pyramidal indents formed on stressed metallic glass samples were observed with an atomic force microscope. Three-dimensional morphologies of the remnant impressions with pile-up lobes were approximated as six-sided pyramids and their indent strains were estimated according to Milman’s strain definition. Under a residual stress state, it was possible to formulate the indent strain using the sum of the elastic indentation stresses and the residual stress parallel to the sample surface. Finally, the residual stress can be expressed by the multiple of the stress-dependent change in the indent strain and the Young``s modulus of the indented sample. The predicted stresses estimated from the pyramidal indent morphologies were comparable to the applied stresses except in a high stress regime. This deviating phenomenon under high tensile stress is discussed and found to be due to exaggerated plastic deformation and image scatter due to mild pile-ups. |