Computational Analysis of Fracture and Surface Deformation Mechanisms in Pre-Cracked Materials under Various Indentation Conditions
Thi-Xuyen Bui1,2, Yu-Sheng Lu1, Yu-Sheng Liao1, Te-Hua Fang1,3,*
1 Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, Kaohsiung, 807, Taiwan
2 Department of Mechanical Engineering, University of Technology and Education-The University of Danang, Danang, 50000, Vietnam
3 Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung, 807, Taiwan
* Corresponding Author: Te-Hua Fang. Email: 
(This article belongs to the Special Issue: Computational Approaches for Tribological Materials and Surface Engineering)
Computers, Materials & Continua https://doi.org/10.32604/cmc.2025.074862
Received 20 October 2025; Accepted 12 December 2025; Published online 30 December 2025
Abstract
Context: The mechanical performance of exceedingly soft materials such as Ag is significantly influenced by various working conditions. Therefore, this study systematically investigates the effects of crack geometry, substrate crystal orientation, and indenter shape on crack propagation. The mechanical response of Ag is analyzed using the quasi-continuum (QC) method. A pre-crack with a predefined depth and angle was introduced to initiate fracture behavior. The results show that when the pre-crack height is 50 Å, the crack propagates rapidly as the imprint depth increases from 0 to 7 Å, grows steadily up to 15 Å, and then accelerates sharply between 15 and 20 Å. For other pre-crack heights, crack propagation occurs at a relatively faster rate. Substrates with [100], [010], and [001] crystal orientations promote crack extension, while the onset of plastic deformation (referred to as the yield point in this study) and the fracture strength both increase with increasing pre-crack height. The yield point, fracture strength, and stress intensity factors are highly sensitive to the pre-crack height. When the pre-crack angle is 90°, the fracture strength reaches its maximum of 0.2% higher than that of the uncracked sample-whereas at 0°, it reaches its minimum, still 53.8% higher than that of the uncracked sample.
Methods: The sample model is conducted using AutoCAD software. The optimized quasi-continuum (QC) method is used to investigate the effects of different crack geometries, substrate crystal orientations, and indenter shapes on the crack extension of Ag material. Baskes and Dow (FBD) potential is borrowed to describe the interaction forces between Ag-Ag, Ni-Ag, and Ni-Ni.
Keywords
QC method; soft material; crack extension; indenter shape; crystal orientation
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