Fatigue life prediction for Q420qFNH weathering steel welded joints considering the effect of multiple cracks

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue Pub Date : 2024-10-21 DOI:10.1016/j.ijfatigue.2024.108665

Yan Ma , Chuang Cui , Qing-hua Zhang , Kun Tang , Zhen-yu Cheng

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引用次数: 0

Abstract

Multiple semi-elliptical cracks frequently develop at the weld toes of welded joints. These interfering multiple cracks significantly accelerate crack growth rates and reduce the fatigue life of a welded joint compared to a single crack. This study proposes a method for predicting the fatigue life of a welded joint with multiple cracks, considering weld toe amplification effect, multiple crack interference amplification effect, and crack closure effect. The method is validated through fatigue tests on Q420qFNH weathering steel welded joints. The main factors influencing the interference amplification effect are investigated, and theoretical formulas for the interference amplification factor of the stress intensity factor are derived using the finite element method and the superposition principle. The initiation, aggregation, and morphological evolution during the propagation process of multiple cracks is accurately simulated, and the fatigue life of both cruciform-welded and butt-welded joints is predicted. Additionally, a quantitative analysis is conducted to assess the impact of the number of fatigue cracks on fatigue strength. The results indicate that the interference amplification effect of cracks depends on their distance and mainly affects the surface point where the crack front is closest. The proposed fatigue life prediction method can accurately estimate the fatigue life of Q420qFNH steel welded joints considering the effect of multi-cracks. The interference and coalescence of multiple cracks significantly reduce the fatigue life of welded joints. An increase in the number of fatigue cracks notably decreases the fatigue strength.

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考虑多裂纹影响的 Q420qFNH 耐候钢焊接接头疲劳寿命预测

在焊接接头的焊点处经常会出现多条半椭圆形裂纹。与单条裂纹相比，这些相互影响的多条裂纹大大加快了裂纹的生长速度，降低了焊点的疲劳寿命。本研究提出了一种预测多裂纹焊接接头疲劳寿命的方法，其中考虑了焊趾放大效应、多裂纹干涉放大效应和裂纹闭合效应。该方法通过 Q420qFNH 耐候钢焊接接头的疲劳试验进行了验证。研究了影响干涉放大效应的主要因素，并利用有限元法和叠加原理推导出了应力强度因子干涉放大系数的理论公式。精确模拟了多条裂纹在扩展过程中的萌发、聚集和形态演变，并预测了十字形焊接接头和对接焊接接头的疲劳寿命。此外，还进行了定量分析，以评估疲劳裂纹数量对疲劳强度的影响。结果表明，裂纹的干涉放大效应取决于裂纹的距离，主要影响裂纹前沿最近的表面点。考虑到多裂纹的影响，所提出的疲劳寿命预测方法可以准确估计 Q420qFNH 钢焊接接头的疲劳寿命。多裂纹的干涉和凝聚会显著降低焊接接头的疲劳寿命。疲劳裂纹数量的增加会明显降低疲劳强度。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

International Journal of Fatigue 工程技术-材料科学：综合

CiteScore

10.70

自引率

21.70%

发文量

619

审稿时长

58 days

期刊介绍： Typical subjects discussed in International Journal of Fatigue address: Novel fatigue testing and characterization methods (new kinds of fatigue tests, critical evaluation of existing methods, in situ measurement of fatigue degradation, non-contact field measurements) Multiaxial fatigue and complex loading effects of materials and structures, exploring state-of-the-art concepts in degradation under cyclic loading Fatigue in the very high cycle regime, including failure mode transitions from surface to subsurface, effects of surface treatment, processing, and loading conditions Modeling (including degradation processes and related driving forces, multiscale/multi-resolution methods, computational hierarchical and concurrent methods for coupled component and material responses, novel methods for notch root analysis, fracture mechanics, damage mechanics, crack growth kinetics, life prediction and durability, and prediction of stochastic fatigue behavior reflecting microstructure and service conditions) Models for early stages of fatigue crack formation and growth that explicitly consider microstructure and relevant materials science aspects Understanding the influence or manufacturing and processing route on fatigue degradation, and embedding this understanding in more predictive schemes for mitigation and design against fatigue Prognosis and damage state awareness (including sensors, monitoring, methodology, interactive control, accelerated methods, data interpretation) Applications of technologies associated with fatigue and their implications for structural integrity and reliability. This includes issues related to design, operation and maintenance, i.e., life cycle engineering Smart materials and structures that can sense and mitigate fatigue degradation Fatigue of devices and structures at small scales, including effects of process route and surfaces/interfaces.