Applied Mathematics and Mechanics (English Edition) ›› 2025, Vol. 46 ›› Issue (6): 1143-1166.doi: https://doi.org/10.1007/s10483-025-3256-7

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Surface effects on double-ended dislocation sources in single-crystal micropillars: implications for size-dependent and stochastic yield strength

Xu ZHANG1, Dayang DENG1, M. YE2, T. SUMIGAWA2, H. R. MA2, Xuewei HUANG1,()   

  1. 1.School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou 450001, China
    2.Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan
  • Received:2025-02-24 Revised:2025-04-07 Published:2025-06-06
  • Contact: Xuewei HUANG, E-mail: huangxw@zzu.edu.cn
  • Supported by:
    Project supported by the Henan International Science and Technology Cooperation Program (No. 242102521055), the Japan Science and Technology Agency (No. JPMJCR2092), and the Japan Society for the Promotion of Science (Nos. JP24H00283, JP24K21575, and JP22K18754)

Abstract:

This study investigates the surface effects on the operation of double-ended dislocation sources in single-crystal micropillars under compression. A comprehensive theoretical framework is formulated to derive the stress field of the source segment and the corresponding Peach-Koehler (PK) forces acting on this segment near the free surfaces. An analytical formulation is then developed to compare the source strength with and without the influence of the surface stress. The results reveal that the surface effects on the dislocation source strength are highly sensitive to the interplay between the source length and its distance from the free surface. These surface effects can either enhance or reduce the critical stress required for the source operation by up to 50%, leading to significant fluctuations in yield strength, as commonly observed in discrete dislocation dynamics simulations and experimental studies. These findings provide different interpretations for the size-dependent and stochastic yield stress behavior in face-centered cubic (FCC) micropillars.

Key words: surface effect, double-ended dislocation source, stress field, micropillar, yield strength

2010 MSC Number: 

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