Mode I+II Fatigue Crack Growth Delay by Stop-Holes

ABSTRACT: The technique of retarding the growth of fatigue cracks by drilling holes on the crack tip is well known. Most of the research works on this subject are limited to fatigue cracks subjected to mode I loading conditions. In the present work the fatigue crack growth retardation by stop-holes of cracks under mode I+II loading is investigated. The proposed approximate solution is based on the implementation of a mixed-mode fatigue crack growth model and a multiaxial high cycle fatigue criterion. Numerical results for mode I+II fatigue crack growth retardation on Al-2024 thin plate are derived and the effect of the crack inclination angle, as well as the diameter of the stop-hole, are discussed and commented.

摘要：通过在裂纹尖端钻孔以延缓疲劳裂纹扩展的技术早已为学界熟知。此前针对该主题的多数研究均仅聚焦于受I型加载（mode I）作用的疲劳裂纹。本研究则针对I+II复合型加载（mode I+II）条件下，通过裂纹止裂孔实现疲劳裂纹扩展延缓的效应展开探究。本文所提出的近似求解方法，基于复合型疲劳裂纹扩展模型（mixed-mode fatigue crack growth model）与多轴高周疲劳准则（multiaxial high cycle fatigue criterion）构建而成。针对2024铝合金（Al-2024）薄板的I+II复合型疲劳裂纹扩展延缓效应，本文推导得到了数值计算结果，并就裂纹倾角与止裂孔直径的影响展开了详细讨论与评述。