On the Crack Closure Effect in Metallic Nanomaterials

On the Crack Closure Effect in Metallic Nanomaterials

Paper in proceedings (conference paper)

Asymmetric arrangements of stored crack-wake dislocations and low values of the size ratio SR, the plastic zone size divided by the characteristic microstructural distance, were found to be of basic importance for the misfit of crack flanks causing the roughness-induced crack closure. According to newly derived formulae including these effects, an estimation of a maximum level of roughness-induced crack closure can be made for metallic materials in the near threshold crack growth regime. On the basis of statistical considerations, the assessments can be extended for the whole fatigue crack propagation regime. A negligible level of roughness-induced crack closure in nanomaterials is predicted as a partial result of the statistical analysis.

Asymmetric arrangements of stored crack-wake dislocations and low values of the size ratio SR, the plastic zone size divided by the characteristic microstructural distance, were found to be of basic importance for the misfit of crack flanks causing the roughness-induced crack closure. According to newly derived formulae including these effects, an estimation of a maximum level of roughness-induced crack closure can be made for metallic materials in the near threshold crack growth regime. On the basis of statistical considerations, the assessments can be extended for the whole fatigue crack propagation regime. A negligible level of roughness-induced crack closure in nanomaterials is predicted as a partial result of the statistical analysis.

crack closure, nanomaterials, fatigue threshold, crack wake plasticity

crack closure, nanomaterials, fatigue threshold, crack wake plasticity

POKLUDA, J.; ŠANDERA, P.

01.01.2005

Vutium

Brno

80-214-3085-0

Nano 05

1

213

218

6