Engineering Failure Analysis最新文献_第3页

Failure mechanism of the roller for roll-forming of single-piece flywheels in automobiles 汽车单件飞轮滚压成形辊筒失效机理研究

IF 5.7 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis

Pub Date : 2026-04-01 Epub Date: 2026-01-26 DOI: 10.1016/j.engfailanal.2026.110619

Yu Huang , Zhian Chen , Musa Sheikh MD Abu , Derek O. Northwood , Cheng Liu

A comprehensive failure analysis is conducted on the first roller, made of 18CrNiMo7-6 steel, in cold roll-forming automotive single-piece flywheels. The results show that the thickness of the carburized layer on the roll groove (the working part of the roller) is about 2 mm, which is below the design requirement of 3 mm. Macro-hardness testing reveals that the surface hardness of the roll groove is below the design requirement. The results from over 1,000 microhardness measurement points within entire carburized layer across the roll groove show that some low-hardness micro-zones with a microhardness below 550 HV are present, indicating an overall inhomogeneous hardness distribution. Fractographic examination reveals the presence of material loss and cracks within the groove. Once initiated, cracks propagate along adjacent regions with high microhardness differences within the carburized layer, and extend into the interior of the roller. The uneven hardness distribution is associated with the non-uniform dispersion of retained austenite and tempered martensite. Electron backscatter diffraction (EBSD) analysis indicates that the microstructure at the groove surface is finer than that in the core region, accompanied by higher Kernel Average Misorientation (KAM) values. Compared to the crack arrest region, the crack propagation area contains fewer high-angle grain boundaries and higher KAM values. Finite element simulation demonstrates that the high stress concentration at the feeding slot of the roller groove is the main driving force for crack propagation. The roller failure is linked to a combination of its specific geometry, heat treatment process, and operating conditions. This research forms the basis for developing new roller types in the future.

对18CrNiMo7-6钢冷滚成形汽车单件飞轮第一辊进行了全面的失效分析。结果表明：轧辊槽（轧辊工作部位）渗碳层厚度约为2mm，低于设计要求的3mm；宏观硬度测试表明，轧辊槽表面硬度低于设计要求。对轧辊槽整层渗碳层内1000多个显微硬度测点的测量结果表明，存在显微硬度低于550 HV的低硬度微区，表明整体硬度分布不均匀。断口学检查显示槽内存在材料损失和裂纹。一旦开始，裂纹沿着渗碳层内具有高显微硬度差异的相邻区域扩展，并延伸到辊的内部。硬度分布的不均匀与残余奥氏体和回火马氏体的不均匀分布有关。电子背散射衍射（EBSD）分析表明，沟槽表面的微结构比核心区域的微结构更精细，同时具有更高的核平均取向偏差（KAM）值。与裂纹止裂区相比，裂纹扩展区含有较少的高角度晶界和较高的KAM值。有限元模拟结果表明，滚子槽进给槽处的高应力集中是裂纹扩展的主要驱动力。轧辊的失效与其特定的几何形状、热处理工艺和操作条件有关。本研究为今后开发新型轧辊奠定了基础。

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引用次数: 0

Base metal vs. weld metal hydrogen embrittlement sensitivity in L245NS pipeline steel after eight years of pure hydrogen exposure: a slow strain rate tensile test analysis L245NS管线钢8年纯氢暴露后母材与焊缝金属氢脆敏感性：慢应变速率拉伸试验分析

IF 5.7 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis

Pub Date : 2026-04-01 Epub Date: 2026-01-26 DOI: 10.1016/j.engfailanal.2026.110618

Xu Wang , Jingyu He , Guohui Li , Liqian Zhao , Shuo Li , Yan Li , Huawei Zhang , Xiang Chen

This study investigates the hydrogen embrittlement (HE) sensitivity of L245NS steel (a low-strength carbon-manganese steel) after 8 years of service under a pure hydrogen atmosphere. The steel was welded using a combination of Gas Tungsten Arc Welding (GTAW) and Shielded Metal Arc Welding (SMAW). Results show that despite the weld metal having a finer average grain size (10.9 μm) than the base metal (17.6 μm), its hydrogen embrittlement sensitivity index (HEI) (59.2%) is significantly higher than the base metal’s (17.5%). Thermal desorption spectroscopy (TDS) tests identify a characteristic desorption peak at 105 °C (shallow-trapped hydrogen, with the weld metal accumulating more hydrogen (1.81 ppm) than the base metal (1.50 ppm). EBSD analysis reveals the weld metal has a longer grain boundary length (5610 μm) and a higher density of high-Σ grain boundaries, which collectively provide abundant shallow hydrogen trapping sites, promoting long-term hydrogen accumulation and higher HE sensitivity.

研究了L245NS钢（一种低强度碳锰钢）在纯氢气氛下使用8年后的氢脆敏感性。采用钨极气体保护弧焊（GTAW）和保护金属电弧焊（SMAW）相结合的方法焊接钢。结果表明：尽管焊缝金属的平均晶粒尺寸（10.9 μm）比母材（17.6 μm）细，但其氢脆敏感性指数（HEI）（59.2%）显著高于母材（17.5%）；热解吸光谱（TDS）测试在105°C时发现了一个特征解吸峰（浅陷氢），焊缝金属积累的氢（1.81 ppm）比母材（1.50 ppm）多。EBSD分析表明，焊缝金属具有更长的晶界长度（5610 μm）和更高的高-Σ晶界密度，这些共同提供了丰富的浅层氢捕获位点，促进了氢的长期积累和更高的HE灵敏度。

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引用次数: 0

Dynamic split tensile behaviour of different rocks pre-treated with sulphuric acid: Effect of long exposure durations and pH of acid 不同岩石经硫酸预处理后的动态劈裂拉伸行为：暴露时间和酸的pH值的影响

IF 5.7 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis

Pub Date : 2026-04-01 Epub Date: 2026-01-23 DOI: 10.1016/j.engfailanal.2026.110615

Anand A , Kumar S , Tiwari G , Venkitanarayanan Parameswaran

Rocks are often subjected to acidic environments due to both natural (e.g., acid rain) and anthropogenic factors (e.g., nuclear waste repositories), in addition to dynamic loading conditions. To investigate their response under such conditions, an extensive experimental program comprising 160 tests was conducted to study the dynamic tensile behavior of acid-treated rocks. Five representative rock types were selected based on their distinct origins, outcrop locations, mineralogical characteristics, and frequent use in construction projects: Makrana marble, Kota limestone, and three granite varieties, i.e., Colonial White, Rajasthani Black, and Jhansi Red. Circular disc specimens were prepared and exposed to sulphuric acid solutions of varying pH (1–5) for durations ranging from 30 to 120 days, simulating long-term in-situ conditions, an aspect relatively less explored in rock mechanics. The acid-treated specimens were then tested under dynamic loading using the Brazilian Disc (BD) method in a Split Hopkinson Pressure Bar (SHPB) setup. Fracture propagation was continuously monitored through high-speed camera-assisted Digital Image Correlation (DIC). The underlying micro-mechanisms governing the macroscopic response were further examined using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and petrographic thin-section analysis. Results revealed a progressive reduction in dynamic tensile strength with decreasing pH and increasing exposure duration, with limestone showing the greatest strength loss due to its higher susceptibility to chemical disintegration. Acid exposure also significantly influenced fragmentation behavior, with Fragment Size Distributions (FSDs) shifting toward well-graded types and the Average Fragment Size (AFS) reducing, attributed to grain and grain-boundary degradation. These findings highlight the coupled chemical–mechanical degradation processes in rocks subjected to acid environments under dynamic loading.

除了动态加载条件外，由于自然因素（如酸雨）和人为因素（如核废料库），岩石经常受到酸性环境的影响。为了研究它们在这种条件下的反应，进行了包括160次试验在内的广泛实验程序，研究酸处理岩石的动态拉伸行为。根据其独特的起源、露头位置、矿物学特征和在建筑项目中的频繁使用，选择了五种具有代表性的岩石类型：Makrana大理石、Kota石灰石和三种花岗岩品种，即殖民地白色、拉贾斯坦黑色和Jhansi红色。制作圆形圆盘试样，并将其暴露在不同pH值（1-5）的硫酸溶液中，持续时间为30至120天，模拟长期的原位条件，这是岩石力学中相对较少探索的方面。然后，在分离式霍普金森压力杆（SHPB）装置中，使用巴西盘（BD）方法对酸处理后的试样进行动载测试。通过高速摄像机辅助的数字图像相关（DIC）连续监测裂缝扩展。利用x射线衍射（XRD）、扫描电镜（SEM）和岩石薄片分析进一步研究了控制宏观响应的潜在微观机制。结果表明，随着pH值的降低和暴露时间的延长，动态抗拉强度逐渐降低，其中石灰石的强度损失最大，因为它对化学崩解的敏感性更高。酸暴露也显著影响破碎行为，由于颗粒和晶界降解，碎片大小分布（FSDs）向分级良好的类型转移，平均碎片大小（AFS）减少。这些发现强调了岩石在动态加载下受酸性环境影响的化学-力学耦合降解过程。

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引用次数: 0

Experimental study on the influence of water saturation state on the progressive failure characteristics in mudstone subjected stress loading 含水饱和状态对泥岩应力加载下渐进破坏特征影响的试验研究

IF 5.7 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis

Pub Date : 2026-04-01 Epub Date: 2026-01-23 DOI: 10.1016/j.engfailanal.2026.110607

Jinghua Li , Guichen Li , Haoyu Rong , Yaoqi Liu , Zeyu Shao , Bo Zhang

Most studies on progressive failure in rocks have mainly focused on brittle materials, with limited attention given to mudstone, particularly regarding the effects of water. To address this gap, this study conducted mechanical tests on mudstone with varying water saturation, together with AE monitoring and SEM characterisation. The influence of water on physical state in mudstone was analyzed. The mechanisms by which water affects failure was revealed. The influence of water on progressive failure was discussed. Results indicate that, after water intruding mudstone develops tensile microcracks. Elastic modulus decreases linearly with saturation increasing. In mechanical tests, the proportion of AE tensile events and tensile cracking energy decrease linearly with water saturation, while plastic energy is the opposite. Macroscopic failure shifts from compressive shear to tensile rupture occurs with water saturation increasing. During the progressive failure process, crack initiation stress, crack damage stress, and peak stress all decreases exponentially with saturation increasing. While the uniformity of water distribution within the mudstone exerts a limited influence on both elastic modulus and P-wave velocity, it does effect on both stress threshold and progressive failure behaviour. After water intruding, the proportion of microcracking in elasto-plastic deformation stage (stage Ⅱ&Ⅲ) increases 20% average. Failure to account for the increased cracking behaviour into the elasto-plastic stage, may lead to overestimation of the long-term bearing capacity of mudstone in engineering application where potential leakage is a concern. This study provided a new insight into the long-term stability of mudstone under water intruding and stress loading.

大多数关于岩石渐进破坏的研究主要集中在脆性材料上，对泥岩的关注有限，特别是对水的影响。为了解决这一问题，本研究对不同含水饱和度的泥岩进行了力学测试，并进行了声发射监测和扫描电镜表征。分析了水对泥岩物理状态的影响。揭示了水影响破坏的机制。讨论了水对进行性破坏的影响。结果表明，泥岩受水后发育张性微裂缝。弹性模量随饱和度的增加而线性减小。力学试验中，声发射拉伸事件和拉伸开裂能所占比例随含水饱和度的增加而线性减小，塑性能则相反。随着含水饱和度的增加，宏观破坏由压缩剪切向拉伸破坏转变。在逐渐破坏过程中，裂纹起裂应力、裂纹损伤应力和峰值应力均随饱和度的增加呈指数递减。虽然泥岩内部水分分布的均匀性对弹性模量和纵波速度的影响有限，但对应力阈值和渐进破坏行为都有影响。水侵后，弹塑性变形阶段（Ⅱ&；Ⅲ阶段）微开裂比例平均增加20%。如果不考虑进入弹塑性阶段的裂缝行为，可能会导致在工程应用中高估泥岩的长期承载能力，因为潜在的泄漏是一个问题。该研究为泥岩在水侵和应力作用下的长期稳定性提供了新的认识。

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引用次数: 0

Dynamic response and safety assessment of high-speed railway simply-supported beam bridge under rockfall impact 落石冲击下高速铁路简支梁桥动力响应与安全评价

IF 5.7 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis

Pub Date : 2026-04-01 Epub Date: 2026-01-27 DOI: 10.1016/j.engfailanal.2026.110623

Gao Zhang, Chang He, LiZhong Jiang, Wei Guo

This study systematically investigates the dynamic response and traffic safety performance of simply supported beam bridges on mountainous high-speed railways under rockfall hazards. By coupling rockfall trajectory simulation with refined finite element analysis, the study elucidates the damage evolution mechanism of bridge structures under rockfall impacts and the correlations among key parameters. The findings indicate that the dynamic response of superstructure components (including the track system, mortar layer, and sliding layer) is a strong correlation with pier displacement and exhibits higher damage sensitivity. Furthermore, an innovative bridge fragility model accounting for rockfall mass ranges is established, enabling quantitative assessment of the damage probabilities for piers, mortar layers, and sliding layers. Building upon this foundation, a method for evaluating train safety based on track geometric deformation after rockfall impact is proposed, identifying critical impact conditions at different operational speeds. This research provides theoretical support and technical references for the anti-impact design, safety protection, and operational decision-making of high-speed railway bridges in rockfall hazard environments.

本文系统地研究了山地高速铁路简支梁桥在落石灾害作用下的动力响应和交通安全性能。通过岩崩轨迹模拟与精细化有限元分析相结合的方法，阐明了桥梁结构在岩崩冲击作用下的损伤演化机制以及关键参数之间的相关性。研究结果表明：上部结构构件（包括轨道系统、砂浆层和滑动层）的动力响应与桥墩位移有较强的相关性，且具有较高的损伤敏感性。此外，还建立了考虑岩崩质量范围的创新性桥梁易损性模型，可以定量评估桥墩、砂浆层和滑动层的损伤概率。在此基础上，提出了一种基于岩崩冲击后轨道几何变形的列车安全评价方法，确定了不同运行速度下的临界冲击条件。本研究为落石灾害环境下高速铁路桥梁的抗冲击设计、安全防护及运营决策提供理论支持和技术参考。

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引用次数: 0

Failure analysis of a centrifugal pump impeller in erosive flow conditions 某离心泵叶轮在侵蚀工况下的失效分析

IF 5.7 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis

Pub Date : 2026-04-01 Epub Date: 2026-01-16 DOI: 10.1016/j.engfailanal.2026.110584

Rehan Khan , Moiz Ahmad , Shahbaz Ali , Faez Qahtani , Tariq Talha , Saeed Alqaed , Jawed Mustafa , Syed Osama Safdar

Erosion is a critical factor that significantly reduces the service life of rotor blades in centrifugal pumps operating under sand particle-laden flows. In this study, a carbon steel blade from a submerged centrifugal pump experienced severe damage after only a few days of continuous operation at the Centre for Erosion-Corrosion Research. The most prominent damage was observed along the outer edges and raised guide vanes of the impeller blade, with localized wall thinning. To investigate the underlying failure mechanisms, a comprehensive analysis was conducted combining visual inspection, scanning electron microscopy (SEM), 3D surface scanning, energy-dispersive spectroscopy (EDS), and laser profilometry measurements. Numerical simulations were performed using computational fluid dynamics (CFD) coupled with the discrete phase model (DPM) to model particle-laden flow behavior and identify critical erosion zones. Unlike prior studies focused solely on simulation or idealized models, this work integrates real-world failure evidence with validated CFD-DPM modeling to establish a direct correlation between physical degradation and predicted erosion. The results revealed that erosion in high-impact regions was nearly twice as severe as in low-impact areas, primarily driven by high turbulence intensity and repeated impingement of 300 µm sand particles at flow velocities exceeding 5 m/s. A maximum erosion rate of 3.8 × 10⁻⁵ kg/m²·s was observed. This study provides new insights into the spatial relationship between flow-induced turbulence and material loss, contributing valuable data for improving pump blade durability and predictive wear modeling in abrasive fluid environments.

在含砂流中，腐蚀是显著降低离心泵转子叶片使用寿命的关键因素。在这项研究中，浸没式离心泵的碳钢叶片在连续运行几天后就在侵蚀腐蚀研究中心遭受了严重的损坏。叶轮叶片外缘和导叶凸起处损伤最明显，局部壁变薄。为了研究潜在的失效机制，研究人员结合目视检查、扫描电子显微镜（SEM）、3D表面扫描、能量色散光谱（EDS）和激光轮廓测量进行了综合分析。利用计算流体力学（CFD）和离散相模型（DPM）进行了数值模拟，模拟了颗粒载荷下的流动行为，并确定了临界侵蚀区域。与之前的研究只关注模拟或理想化模型不同，这项工作将现实世界的失效证据与经过验证的CFD-DPM模型结合起来，建立了物理退化与预测侵蚀之间的直接关联。结果表明，高冲击区域的侵蚀程度几乎是低冲击区域的两倍，这主要是由高湍流强度和300µm沙粒以超过5 m/s的流速反复撞击造成的。最大侵蚀速率为3.8 × 10−5 kg/m2·s。该研究为流动诱导湍流与材料损失之间的空间关系提供了新的见解，为提高泵叶片耐久性和预测磨料流体环境下的磨损建模提供了有价值的数据。

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引用次数: 0

An interpretable random forest surrogate for rapid SIF prediction and fatigue life assessment of double-sided U-rib welds in orthotropic steel decks 正交各向异性钢甲板双面u肋焊缝的快速SIF预测和疲劳寿命评估的可解释随机森林代理

IF 5.7 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis

Pub Date : 2026-04-01 Epub Date: 2026-01-14 DOI: 10.1016/j.engfailanal.2026.110582

Fanghuai Chen , Benkun Tan , Haitao Tang , Haiping Zhang , Yuan Luo , Xinhui Xiao , Yang Liu , Naiwei Lu

This paper presents an efficient predictive framework based on a random forest (RF) surrogate model for estimating fatigue crack propagation life in double-sided rib-to-deck (RD) welded joints in orthotropic steel decks (OSDs). A comprehensive training dataset for the RF surrogate model of stress intensity factor (SIF) was generated through extensive fatigue crack propagation simulations. The predictive accuracy of the RF surrogate model was rigorously validated, and SHAP-based feature analysis was employed to interpret the influence of input variables. The RF surrogate model was then used to estimate the fatigue life of the welded toe in double-sided RD welded joints, and the effects of initial crack geometry on fatigue life were investigated. The results indicate that the initial surface crack at the weld toe is a mode I-dominated mixed-mode crack and exhibits crack flattening during propagation. The RF surrogate model demonstrates high predictive accuracy for SIF, achieving high R² values and low prediction errors across both training and validation datasets. SHAP analysis identifies applied stress as the primary influencer of SIF, with crack depth and half-length as secondary factors. Increases in initial crack depth and half-length significantly reduce fatigue crack propagation life. This study confirms the robustness of the RF model as a computationally efficient alternative to finite element methods (FEM), providing valuable insights for fatigue assessment and maintenance planning of OSDs.

提出了一种基于随机森林（RF）替代模型的预测框架，用于估算正交各向异性钢甲板（OSDs）双面肋-甲板（RD）焊接接头的疲劳裂纹扩展寿命。通过广泛的疲劳裂纹扩展模拟，生成了应力强度因子（SIF）射频替代模型的综合训练数据集。严格验证了RF代理模型的预测准确性，并采用基于shap的特征分析来解释输入变量的影响。采用射频替代模型估算了双面RD焊接接头焊接趾的疲劳寿命，并研究了初始裂纹几何形状对疲劳寿命的影响。结果表明：焊缝趾部初始表面裂纹为i型为主的混合裂纹，裂纹扩展过程中表现为裂纹扁化；RF代理模型对SIF的预测精度很高，在训练和验证数据集上都实现了高R2值和低预测误差。SHAP分析认为，施加应力是影响SIF的主要因素，裂缝深度和半长是次要因素。初始裂纹深度和半长的增加显著降低了疲劳裂纹扩展寿命。该研究证实了RF模型作为有限元方法（FEM）的计算效率替代方案的鲁棒性，为osd的疲劳评估和维护计划提供了有价值的见解。

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引用次数: 0

Analysis of mechanical behavior and propagation mechanisms of rail cracks considering the influence of three-dimensional weld geometry 考虑焊缝三维几何形状影响的钢轨裂纹力学行为及扩展机制分析

IF 5.7 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis

Pub Date : 2026-04-01 Epub Date: 2026-01-14 DOI: 10.1016/j.engfailanal.2026.110579

Jiaxin Lei , Yangyong Luoze , Haoyao Xia , Jianing Liu , Caiyou Zhao , Ping Wang

With the continuous increase in train operating speeds, rolling contact fatigue on rail surfaces has become a major concern, especially in welded regions where geometric irregularities and material mismatches intensify stress concentrations and accelerate crack growth. This study integrates ABAQUS and FRANC3D through a fracture-mechanics-based submodeling approach to simulate surface crack propagation in welded rails with realistic 3D weld geometry. The developed model clarifies how crack geometry and weld irregularities jointly affect fatigue behavior under rolling contact loads. The results indicate that surface cracks mainly propagate through a mixed Mode II–III shear mechanism. A 45° inclination angle represents the most critical propagation orientation. Increasing the surface crack length from 2 mm to 6 mm shortens fatigue life by 57.7%, while extending the crack length to 8 mm elevates the peak Mode III stress-intensity factor to 811 MPa, promoting inward growth. In the weld zone, the deeper crack front propagates faster, causing semicircular cracks to evolve into elongated ellipses. A strong interaction is observed between weld wavelength, depth and crack phase position: shorter wavelengths and deeper undulations markedly increase the Mode II stress-intensity factor, with the fastest propagation occurring at 3/8 of the weld wavelength—where fatigue life drops to 44% of that at 7/8 of the wavelength. The findings clarify the shear-dominated crack evolution mechanism and provide theoretical guidance for weld-grinding thresholds and fatigue-life assessment of welded rails in high-speed railway applications.

随着列车运行速度的不断提高，钢轨表面的滚动接触疲劳已成为人们关注的主要问题，特别是在焊接区域，几何不规则和材料不匹配加剧了应力集中，加速了裂纹的扩展。本研究通过基于断裂力学的子建模方法集成ABAQUS和FRANC3D，模拟具有真实三维焊缝几何形状的焊接轨道表面裂纹扩展。建立的模型阐明了裂纹几何形状和焊缝不规则性如何共同影响滚动接触载荷下的疲劳行为。结果表明：表面裂纹主要通过II-III型混合剪切机制扩展；45°的倾角代表最关键的传播方向。当表面裂纹长度从2 mm增加到6 mm时，疲劳寿命缩短57.7%；当表面裂纹长度增加到8 mm时，峰值III型应力强度因子提高到811 MPa，并促进向内扩展。在焊缝区，较深的裂纹前缘扩展速度较快，导致半圆形裂纹演变为细长的椭圆。焊缝波长、深度和裂纹相位置之间存在很强的相互作用：较短的波长和较深的波动显著增加了II型应力强度因子，在焊缝波长的3/8处传播最快，疲劳寿命下降到7/8处的44%。研究结果阐明了以剪切为主的裂纹演化机制，为高速铁路焊接钢轨的焊磨阈值和疲劳寿命评估提供了理论指导。

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引用次数: 0

Fatigue performance of Grade 10.9 M20 high-strength bolts in L-shaped component connections 10.9级M20高强度螺栓在l形构件连接中的疲劳性能

IF 5.7 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis

Pub Date : 2026-04-01 Epub Date: 2026-01-18 DOI: 10.1016/j.engfailanal.2026.110583

Xu-Ze Feng, Xue-Chun Liu, Xuesen Chen, Wei Zhou, Yong-Li Tao, Ai-lin Zhang

Bolted L-shaped component connections, which are typical configurations in bolted flange splicing joints for columns, are subjected to cyclic tension–compression from wind-induced vibration in high-rise buildings, leading to fatigue failure risks. To investigate the fatigue performance of Grade 10.9 M20 bolts, axial cyclic loading fatigue tests were conducted on 20 specimens with different flange thicknesses. Experimental results revealed that all fatigue failures occurred at the root of the first engaged thread or within the thread engagement region, with preload decay exceeding 30% prior to fracture. A refined finite element model incorporating thread was developed to conduct parametric analyses, demonstrating that the fatigue life significantly improves with increasing flange thickness, column wall thickness, bolt edge distance, and preload. Furthermore, a nominal stress calculation method accounting for bending-axial coupling effects was proposed, and an S–N curve describing the relationship between stress range and fatigue life was established with good fitting accuracy. Comparative analysis against fatigue design recommendations in EN 1993-1-9, ANSI/AISC 360-16, and GB 50017-2017 highlighted conservative predictions of the above codes. Macroscopic fracture morphology analysis of the high-strength bolts was carried out to further elucidate the fatigue failure mechanisms.

l型螺栓构件连接是柱用螺栓翼缘拼接节点的典型结构形式，在高层建筑中受到风振的循环拉压作用，存在疲劳破坏的风险。为研究10.9级M20螺栓的疲劳性能，对20个不同法兰厚度试件进行了轴向循环加载疲劳试验。实验结果表明，所有疲劳失效都发生在第一次啮合螺纹的根部或螺纹啮合区域内，断裂前预紧力衰减超过30%。建立了包含螺纹的精细化有限元模型进行参数分析，结果表明，随着法兰厚度、柱壁厚度、螺栓边距和预紧力的增加，疲劳寿命显著提高。提出了考虑弯轴耦合效应的名义应力计算方法，建立了描述应力范围与疲劳寿命关系的S-N曲线，拟合精度较好。与EN 1993-1-9、ANSI/AISC 360-16和GB 50017-2017的疲劳设计建议进行对比分析，突出了上述规范的保守预测。为进一步阐明高强螺栓的疲劳破坏机理，对高强螺栓进行了宏观断口形貌分析。

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引用次数: 0

Study on deformation and failure laws and differentiated control of surrounding rock in the return air entry of extremely close distance lower seam 极近距离下煤层回风巷道围岩变形破坏规律及差异化控制研究

IF 5.7 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis

Pub Date : 2026-04-01 Epub Date: 2026-01-07 DOI: 10.1016/j.engfailanal.2026.110557

Xiaofei Guo, Wenbo Zhang, Xiongxiong Jin, Kunlin Yang, Yinwei Wang, Yushan Liu

Stability control of the surrounding rock in development roadways of extremely close-distance lower coal seams is a crucial prerequisite for safe mining in underground coal mines. This study aims to reveal the deformation and failure mechanisms of the surrounding rock in such roadways, taking the extremely close-distance No. 9 and No. 11 coal seams in Dianye No. 1 Mine as the research object. It elucidates the response mechanisms and failure patterns of roadways under such complex mining-induced stresses. The results indicate that the return airway of the No. 11 coal seam is primarily influenced by the mining of the No. 9 coal seam working face and its own excavation. In contrast, the mining of the working face within the same coal seam, due to the presence of protective coal pillars along the roadway, exerts a certain pressure-relief and protective effect on the corresponding roadway section. The study further reveals the evolutionary pattern of the plastic zone morphology in the surrounding rock and clarifies the correlation between stress variations and the plastic zone. The lateral pressure coefficient dominates the failure mode of the surrounding rock, while the magnitude of the principal stress and the strength of the rock mass jointly regulate the extent of failure. The deflection angle of the principal stress directs the propagation path of the plastic zone. A differentiated support design based on the stress zones of the surrounding rock is proposed. Under remnant coal pillars, a trapezoidal roadway section with rock bolting, mesh, and cable support is adopted to utilize the self-supporting capacity of the surrounding rock and the structural characteristics of the strata. In high-stress environments under goaf areas, a arched roadway section with combined support of “rock bolting, mesh, cable, beam, and U-shaped steel supports” is implemented.

极近距离下煤层开发巷道围岩稳定性控制是地下煤矿安全开采的重要前提。本研究以电业1矿距离极近的9号、11号煤层为研究对象，旨在揭示此类巷道围岩变形破坏机理。阐明了巷道在复杂采动应力作用下的响应机制和破坏模式。结果表明：11号煤层回采巷道主要受9号煤层工作面回采及自身开挖的影响。而同一煤层内工作面开采，由于沿巷道存在保护煤柱，对相应的巷道段起到一定的卸压保护作用。研究进一步揭示了围岩塑性区形态演化规律，阐明了应力变化与塑性区的相关性。侧压力系数主导围岩破坏模式，主应力大小和岩体强度共同调节破坏程度。主应力的挠度角指导塑性区的传播路径。提出了一种基于围岩应力区的差异化支护设计方法。在残余煤柱下，采用锚杆支护、网眼支护、锚索支护的梯形巷道断面，充分利用围岩的自支护能力和地层的结构特点。在采空区高应力环境下，采用“锚杆、网、索、梁、u型钢支撑”组合支护的拱式巷道断面。

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