The severity of local undercut on fatigue life of welded joints

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue Pub Date : 2025-03-24 DOI:10.1016/j.ijfatigue.2025.108949

Abinab Niraula , Heikki Remes

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Abstract

Fatigue cracks most commonly initiate from local weld imperfections, such as undercuts, that have a significant impact on the fatigue life of the structure. The influence of local undercut on fatigue has been traditionally classified on the level of workmanship for quality control purposes, and a systematic quantified approach to determine the influence of local undercut on fatigue strength is needed. In this paper, the influence of the 3D undercut geometry on the fatigue strength of welded joints is investigated to quantify the severity of different undercut sizes and shapes in butt welded joints. Systematic elastic and elasto-plastic analyses are performed on butt-welded joints with different steel grades and local undercut geometries under multiple stress ranges. As a result, a semi-analytical formulation is proposed to estimate the elastic stress concentration factor for butt welds with an undercut, considering the 3D undercut geometry as well as the global weld geometry. Furthermore, a novel undercut severity index for fatigue analysis is introduced and validated, considering the variation of the local undercut 3D shape, weld bead geometry, stress ranges, and materials.

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局部咬边的严重程度对焊接接头疲劳寿命的影响

疲劳裂纹通常是由局部焊接缺陷引起的，如凹口，这对结构的疲劳寿命有重大影响。局部下切对疲劳的影响传统上被归类为工艺水平的质量控制，需要一种系统的量化方法来确定局部下切对疲劳强度的影响。本文研究了三维凹边几何形状对焊接接头疲劳强度的影响，量化了不同凹边尺寸和形状对对接焊接接头疲劳强度的影响程度。对不同钢种和局部凹边几何形状的对接焊接接头在多种应力范围下进行了系统的弹性和弹塑性分析。在此基础上，提出了一种考虑三维凹边几何形状和整体焊缝几何形状的半解析公式，用于估计具有凹边的对接焊缝的弹性应力集中系数。此外，引入并验证了一种用于疲劳分析的新型咬边严重程度指标，该指标考虑了局部咬边三维形状、焊缝几何形状、应力范围和材料的变化。

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.