Mixed mode (I/II) fatigue crack growth in butt-welded joints using actual stress intensity factors

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL Theoretical and Applied Fracture Mechanics Pub Date : 2025-02-19 DOI:10.1016/j.tafmec.2025.104894

Zhe Zhang, Bing Yang, Shuancheng Wang, Mian Huang, Haoyu Zheng, Shoune Xiao

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Abstract

To more accurately study and analyze the fatigue crack growth (FCG) behavior of welded structures under mixed mode I + II loading, this paper proposes a relative displacement (RD) method to calculate the stress intensity factors at the crack tip. This method simplifies complex stress conditions into measurable displacement variations. It is based on changes in the local displacement field at the crack tip, combining surface node displacement principles and relative displacement techniques to derive the corresponding driving parameters. Subsequently, FCG experiments were conducted at loading angles of 0°, 30°, 45°, and 60°, with analysis performed using digital image correlation technology. The M−integral method, Sajith’s method, and the RD method were used to calculate and compare the SIFs at the crack tip of compact-tension-shear specimens. The results show that, due to the influence of residual stress, the ΔK_I and ΔK_eq values obtained from the RD method are larger during crack growth. The da/dN–ΔK_eq curve based on this method exhibits a higher degree of fitting accuracy. The findings offer new insights into the FCG behavior of welded joints under mixed mode loading and provide theoretical support for predicting the remaining useful life of railway vehicle frames.

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基于实际应力强度因子的对接焊接接头混合模式（I/II）疲劳裂纹扩展

为了更准确地研究和分析混合模式 I + II 载荷下焊接结构的疲劳裂纹生长（FCG）行为，本文提出了一种相对位移（RD）方法来计算裂纹尖端的应力强度因子。该方法将复杂的应力条件简化为可测量的位移变化。它基于裂纹尖端局部位移场的变化，结合表面节点位移原理和相对位移技术，得出相应的驱动参数。随后，在 0°、30°、45° 和 60°加载角度下进行了 FCG 实验，并利用数字图像相关技术进行了分析。使用 M 积分法、Sajith 法和 RD 法计算和比较了紧凑拉伸剪切试样裂缝顶端的 SIF。结果表明，由于残余应力的影响，RD 方法得到的 ΔKI 和 ΔKeq 值在裂纹生长过程中较大。基于这种方法的 da/dN-ΔKeq 曲线具有更高的拟合精度。这些发现为研究混合模式加载下焊接接头的 FCG 行为提供了新的视角，并为预测铁路车辆框架的剩余使用寿命提供了理论支持。

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来源期刊

Theoretical and Applied Fracture Mechanics 工程技术-工程：机械

CiteScore

8.40

自引率

18.90%

发文量

435

审稿时长

37 days

期刊介绍： Theoretical and Applied Fracture Mechanics'' aims & scopes have been re-designed to cover both the theoretical, applied, and numerical aspects associated with those cracking related phenomena taking place, at a micro-, meso-, and macroscopic level, in materials/components/structures of any kind. The journal aims to cover the cracking/mechanical behaviour of materials/components/structures in those situations involving both time-independent and time-dependent system of external forces/moments (such as, for instance, quasi-static, impulsive, impact, blasting, creep, contact, and fatigue loading). Since, under the above circumstances, the mechanical behaviour of cracked materials/components/structures is also affected by the environmental conditions, the journal would consider also those theoretical/experimental research works investigating the effect of external variables such as, for instance, the effect of corrosive environments as well as of high/low-temperature.