Elastic stress field model and micro-crack evolution for isotropic brittle materials during single grit scratching

Wei Wang, Peng Yao, Jun Wang, Chuanzhen Huang, Tsunemoto Kuriyagawa, Hongtao Zhu, Bin Zou, Hanlian Liu

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)

Abstract

An analytical model for the elastic stress field in isotropic hard and brittle materials during scratching is presented. The model considers the entire elastic stress field and the effect of material densification that was ignored in past studies, and is developed under a cylindrical coordinate system to make the modeling process simpler. Based on the model's predictions, the location and sequence of crack nucleation are estimated and the associated mechanisms are discussed. A single grit scratching experiment with an increasing scratch depth up to 2 µm is conducted for two types of optical glasses representing isotropic brittle materials: fused silica and BK7 glasses. It is found that the model's predictions correlate well with experimental data. Median cracks are found to be formed first during scratching, and the corresponding depth of the scratch sets the basis for determining the critical depth for brittle to ductile machining. Lateral cracks are initiated in the plastic yielding region and deflect to the work surface to cause material removal, while Hertzian cracks interact with lateral cracks to help remove lateral-cracked material. Furthermore, it is found that, owing to its open network molecular structure, fused silica has a much worse ductile machinability than the BK7 glass.

Original languageEnglish
Pages (from-to)10726-10736
Number of pages11
JournalCeramics International
Volume43
Issue number14
DOIs
Publication statusPublished - 2017 Oct 1

Keywords

  • Ductile to brittle transition
  • Elastic stress field
  • Isotropic brittle materials
  • Micro-crack evolution
  • Optical glass
  • Single grit scratching

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Process Chemistry and Technology
  • Surfaces, Coatings and Films
  • Materials Chemistry

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