1. Combining Effective Plastic Strain and Surface Roughness Change for Identifying Damage Accumulation Sites in a Tensile Sample.
- Author
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Valiollahi, A., Sola, J. F., and Huang, H.
- Subjects
SURFACE strains ,SURFACE roughness ,DIGITAL image correlation ,GRAIN ,FINITE element method ,SURFACE topography - Abstract
Background: Damage index parameters that have been formulated to identify damage localization in plastically deformed materials typically require all six stress or strain components. Recently, simulations through Crystal Plasticity Finite Element Method (CPFEM) have been widely used to extract damage initiation parameters. However, these models are rarely verified due to the challenges in measuring the out of plane deformation/strains experimentally. Objective: A damage index combining the effective plastic strain and surface roughness change is investigated for identifying damage accumulation sites in a tensile sample. Method: A point-wise Digital Image Correlation (DIC) technique is developed to measure large deformations from surface topography images, based on which the effective plastic strains and the surface roughness changes are determined at different load levels. A simple technique that creates random, micro size reflective speckles for sub-grain strain calculation is demonstrated. Results: Damage accumulation sites detected by the effective strain, surface roughness change, and the combined damage index are assessed in terms of damage localization and localization consistency. The combined damage index identified the localized damage accumulation sites consistently after the yielding load. In contrast, the effective strain damage index showed a low degree of localization and consistency while the surface roughness damage index detected only half of the damage accumulation sites identified by the combined damage index. The detected damage accumulation sites were found to be associated with grain orientations that favor "sunken" out-of-plane deformations and large misorientations among neighboring grains. Conclusions: Considering both effective plastic strain and out of plane surface deformation, the combined damage index provides an enhanced damage localization and localization consistency. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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