International Journal of Pressure Vessels and Piping最新文献

Enhanced creep lifetime in P91 steel weldments via stabilizing tempered martensite structure 通过稳定回火马氏体结构提高 P91 钢焊接件的蠕变寿命

IF 3 2区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Pressure Vessels and Piping

Pub Date : 2024-11-14 DOI: 10.1016/j.ijpvp.2024.105361

Zhengman Gu , Ming Zhong , Artem Minkov , Fedor Panteleyenko , Cong Wang

P91 steel weldments are susceptible to Type IV creep cracking during high-temperature service, significantly reducing the creep lifetime of impacted components. For enhancing the creep lifetime of P91 steel weldments, the present work proposes a novel post-weld heat treatment strategy to stabilize the tempered martensite structure and avoid Type IV creep cracking. Compared to conventional post-weld tempered treatment weldments, the creep lifetime of as-welded weldment is improved by 1.7 times, while the creep lifetime of weldment subjected to post-weld normalizing followed by tempering is enhanced by 4.6 times, effectively preventing Type IV cracking. It has been revealed that creep weakness zones, that is, soft zones, occur in as-welded weldment and post-welded tempering treatment weldment, where the microstructure is predominantly recrystallized ferrites. Creep fracture always occurs in the region of the highest fraction of recrystallized grains. Post-weld normalizing and subsequent tempering can enhance prior austenite grain size and stabilize tempered martensite structure. For as-welded weldment and post-welded tempering treatment weldment, creep cavities preferentially grow along ferrite grain boundaries as compared to prior austenite grain boundaries, which could easily lead to intergranular premature cracking. For post-weld normalizing and subsequent tempering weldment, cavities form along prior austenite grain boundaries of base metal and are elongated together with martensitic packets/blocks under stress. Finally, the final fracture is caused by the rupture of elongated grains.

P91 钢焊接件在高温服役期间容易出现 IV 型蠕变裂纹，从而大大降低受影响部件的蠕变寿命。为提高 P91 钢焊接件的蠕变寿命，本研究提出了一种新型焊后热处理策略，以稳定回火马氏体结构，避免 IV 型蠕变裂纹。与传统的焊后回火处理焊件相比，焊接后焊件的蠕变寿命提高了 1.7 倍，而经过焊后正火再回火处理的焊件的蠕变寿命提高了 4.6 倍，有效防止了 IV 型裂纹的产生。研究发现，在焊接后的焊件和焊接后回火处理的焊件中会出现蠕变薄弱区，即软区，其微观结构主要是再结晶铁素体。蠕变断裂总是发生在再结晶晶粒比例最高的区域。焊后正火和随后的回火可提高奥氏体晶粒尺寸并稳定回火马氏体结构。对于焊接后的焊接件和焊接后回火处理的焊接件，蠕变空穴会沿着铁素体晶界生长，而不是之前的奥氏体晶界，这很容易导致晶间过早开裂。在焊后正火和随后的回火焊接中，空穴沿着母材之前的奥氏体晶界形成，并在应力作用下与马氏体包/块一起伸长。最后，拉长的晶粒破裂导致最终断裂。

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引用次数: 0

Study on stress concentration and fatigue life of tubing with slip indentation 滑动压痕管材的应力集中和疲劳寿命研究

IF 3 2区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Pressure Vessels and Piping

Pub Date : 2024-11-13 DOI: 10.1016/j.ijpvp.2024.105360

Qiang Zhang , Hao Li , Feng Wang , Liangliang Ding , Xianfu Wang , Zhanghua Lian

The indentation caused by slip on the outer wall of tubing is a significant contributor to stress concentration and, consequently, fatigue failure in the tubing string. Through an analysis of the interaction between slips and tubing, a mathematical model to predict slip-tubing interaction and slip crushing load is formulated, accounting for external pressure, internal pressure, and axial forces. On this basis, the influence factors and influence rules of slip crushing load are studied, and three-dimensional yield surface and tri-axial stress ellipse of tubing are investigated, considering different transverse load factors and design factors. To accurately forecast the fatigue life of tubing subjected to slip indentation, two models are established: one for fatigue life prediction and the other for tubing string vibration. In order to quantitatively assess the stress concentration arising from slip indentation, a finite element model of tubing featuring slip indentation is established. Finite element analysis reveals that stress concentration and non-uniformity are evident in the vicinity of slip indentation, with their severity intensifying as the indentation depth grows. The initial step in assessing fatigue life involves fatigue life tests on tubing material subjected to varying stress levels. Subsequently, a case study is conducted and the variations of wellhead pressure and axial stress are evaluated. Fatigue life analysis reveals that the fatigue life is notably sensitive to variations in stress amplitude and slip indentation depth. An increase in the magnitude of alternating stress and the depth of slip indentation will result in a significant reduction in the fatigue lifespan. The methodologies employed in this research, along with the resulting findings, offer a robust theoretical framework and a solid practical basis for forecasting and managing stress concentration and fatigue durability in tubing affected by slip indentation.

滑移对油管外壁造成的压痕是造成应力集中的重要因素，进而导致油管串疲劳失效。通过分析滑移与油管之间的相互作用，建立了预测滑移-油管相互作用和滑移压溃载荷的数学模型，并考虑了外压、内压和轴向力。在此基础上，研究了滑移压溃载荷的影响因素和影响规律，并在考虑不同横向载荷系数和设计系数的情况下，研究了管材的三维屈服面和三轴应力椭圆。为了准确预测油管在滑移压痕作用下的疲劳寿命，建立了两个模型：一个是疲劳寿命预测模型，另一个是油管串振动模型。为了定量评估滑移压痕产生的应力集中，建立了具有滑移压痕的油管有限元模型。有限元分析表明，滑移压痕附近存在明显的应力集中和不均匀现象，其严重程度随着压痕深度的增加而加剧。评估疲劳寿命的第一步是在不同应力水平下对管材进行疲劳寿命测试。随后进行案例研究，评估井口压力和轴向应力的变化。疲劳寿命分析表明，疲劳寿命对应力振幅和滑移压痕深度的变化非常敏感。交变应力幅值和滑移压痕深度的增加会导致疲劳寿命显著缩短。本研究采用的方法以及由此得出的结论为预测和管理受滑移压痕影响的管道中的应力集中和疲劳耐久性提供了强大的理论框架和坚实的实践基础。

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引用次数: 0

Failure mechanisms of fusion-bonded reinforcement joints in reinforced thermoplastic pipes under uniaxial tensile conditions 单轴拉伸条件下增强热塑性塑料管道中熔融粘接加固接头的破坏机理

IF 3 2区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Pressure Vessels and Piping

Pub Date : 2024-11-13 DOI: 10.1016/j.ijpvp.2024.105359

Jingwen Ren , Hanxiang Wang , Yanxin Liu , Jiaqi Che , Yanwen Zhang

As deep-sea oil and gas extraction technologies advance, the demand for high-performance joints in reinforced thermoplastic pipes (RTPs) has increased. This study introduces a novel fusion-reinforced joint for RTPs and analyzes its tensile failure mechanism. Two user-defined material (VUMAT) subroutines were developed for unidirectional fiber composites and plain fabric composites to analyze the damage of RTPs and joints. The tensile damage mechanisms were evaluated using the 3D Hashin failure criterion, the maximum strain failure criterion, the residual stiffness model, and the cohesive zone model (CZM). To validate the numerical model, fusion-reinforced joints were designed, machined, and subjected to uniaxial tensile tests. Findings suggest that matrix damage in RTPs is the primary factor contributing to stiffness degradation. The shear stress in the adhesive layer at both ends of the joint reaches the shear strength, resulting in the failure of the adhesive. The tensile process can be divided into four distinct stages: the no-damage stage, the bonding damage stage, the matrix damage stage, and the failure stage. Initially, damage in the adhesive layer leads to a minor decrease in tensile stiffness, followed by significant matrix damage in the RTPs. Failure of the adhesive layer at both ends of the joint gradually propagates to the middle, culminating in the failure of the fusion zone. The time required to reach maximum strain in the central joint region is longer than at the ends.

随着深海油气开采技术的发展，对增强热塑性塑料管（RTP）高性能接头的需求也在增加。本研究介绍了一种用于 RTP 的新型熔融增强接头，并分析了其拉伸失效机理。针对单向纤维复合材料和普通织物复合材料开发了两个用户自定义材料（VUMAT）子程序，用于分析 RTP 和接头的损坏情况。使用三维哈辛破坏准则、最大应变破坏准则、残余刚度模型和内聚区模型（CZM）对拉伸破坏机制进行了评估。为了验证数值模型，对熔融加固接头进行了设计、加工和单轴拉伸试验。研究结果表明，RTP 中的基体损伤是导致刚度下降的主要因素。接头两端粘合剂层中的剪应力达到剪切强度，导致粘合剂失效。拉伸过程可分为四个不同阶段：无损坏阶段、粘接损坏阶段、基体损坏阶段和失效阶段。最初，粘合剂层的损坏导致拉伸刚度轻微下降，随后 RTP 中的基质发生明显损坏。接头两端粘合层的破坏逐渐向中间扩展，最终导致融合区的破坏。在接头中心区域达到最大应变所需的时间比两端长。

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引用次数: 0

A comprehensive finite element framework for modeling of PEX-Al-PEX composite pipes 用于 PEX-Al-PEX 复合管道建模的综合有限元框架

IF 3 2区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Pressure Vessels and Piping

Pub Date : 2024-11-07 DOI: 10.1016/j.ijpvp.2024.105358

Ameer Alaa Oleiwi, Hamed Afrasiab, Abbas Zolfaghari

While PEX-Al-PEX composite pipes are widely used in various applications, suitable tools and models for simulating their performance under different working conditions have not been made available. Therefore, the present study aims to develop a comprehensive finite element model to study the behavior of PEX-AL-PEX pipes at different temperatures and strain-rates. To achieve this, the properties of the pipe layers have been obtained for different temperature and strain-rate values through experimental tests. To assess the accuracy of the developed finite element model, the lateral compression and the split-disc tension tests have been performed under different conditions using both experimental and finite element analysis methods, and their results have been compared. The proposed model can be used to study the behavior of PEX-AL-PEX pipes with different materials and geometries in various conditions and applications, as well as for optimizing the design and manufacturing of these pipes.

虽然 PEX-Al-PEX 复合管道被广泛应用于各种领域，但目前还没有合适的工具和模型来模拟其在不同工作条件下的性能。因此，本研究旨在开发一种全面的有限元模型，以研究 PEX-AL-PEX 管道在不同温度和应变速率下的行为。为此，我们通过实验测试获得了管道层在不同温度和应变率值下的特性。为了评估所建立的有限元模型的准确性，使用实验和有限元分析方法在不同条件下进行了横向压缩和分瓣拉伸试验，并对其结果进行了比较。所提出的模型可用于研究不同材料和几何形状的 PEX-AL-PEX 管道在各种条件和应用下的行为，以及优化这些管道的设计和制造。

引用次数: 0

Effects of different types of corrosion on seismic performance of circular hollow section T-joints subjected to coupling load 不同类型的腐蚀对承受耦合载荷的圆形空心截面 T 型接头抗震性能的影响

IF 3 2区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Pressure Vessels and Piping

Pub Date : 2024-11-05 DOI: 10.1016/j.ijpvp.2024.105355

Hao Wang , Sida Li , Shangxian Hu , Youde Wang , Haijiang Zhang , Xiaogang Liu

The purpose of this paper is to investigate the effects of different types of corrosion on seismic performances of circular hollow section (CHS) T-joints subjected to in-plane cyclic load. Firstly, the validity of a numerical modeling method introducing the actual corrosion morphological characteristics was verified by comparing with experimental results. Subsequently, the influences of different corrosion characteristic parameters (corrosion types, corrosion position and corrosion level) on the hysteresis behaviors of CHS T-joints under the cyclic bending load were discussed in detail, and the analysis results indicated: 1) compared with the pitting damage, the degradation behavior of CHS T-joints with the equivalent uniform corrosion was closer to that of the CHS T-joints with the actual corrosion morphology; 2) the degradation level of cyclic bearing capacities of CHS T-joints with the general corrosion was higher than that of CHS T-joints with brace or chord corrosion under the same condition; 3) the increase in dimension of the single pit had little influence on affecting the hysteresis behavior of CHS T-joints, the bearing capacities and energy dissipation of CHS T-joints significantly decreased with the increasing distribution density of pits, even leading to the change of failure mode of CHS T-joint under cyclic bending load; 4) when the volume loss of different types of corrosion was similar, the higher the local corrosion damage, the more serious the seismic performance degradation of CHS T-joints. When the volume loss caused by different types of corrosion was transferred to the thickness loss, the ultimate capacities of corroded CHS T-joints could be calculated by applying the existing formulas. However, the calculation value was lower than the numerical results due to overestimating the adverse effects of corrosion on the axial bearing capacity of CHS T-joints.

本文旨在研究不同类型的腐蚀对承受面内循环载荷的圆形空心截面（CHS）T 型接头抗震性能的影响。首先，通过与实验结果比较，验证了引入实际腐蚀形态特征的数值建模方法的有效性。随后，详细讨论了不同腐蚀特征参数（腐蚀类型、腐蚀位置和腐蚀程度）对循环弯曲载荷下 CHS T 型接头滞后行为的影响，分析结果表明1）与点蚀破坏相比，等效均匀腐蚀的 CHS T 型接头的退化行为更接近于实际腐蚀形态的 CHS T 型接头；2）在相同条件下，一般腐蚀的 CHS T 型接头的循环承载力退化程度高于支撑或弦腐蚀的 CHS T 型接头；3）单个凹坑尺寸的增大对 CHS T 型接头的滞回行为影响不大，随着凹坑分布密度的增大，CHS T 型接头的承载力和耗能明显降低，甚至导致循环弯曲荷载作用下 CHS T 型接头破坏模式的改变；4）当不同类型腐蚀造成的体积损失相近时，局部腐蚀破坏程度越高，CHS T 型接头的抗震性能退化越严重。当不同类型腐蚀造成的体积损失转移到厚度损失时，可以通过应用现有公式计算出腐蚀 CHS T 型接头的极限承载力。然而，由于高估了腐蚀对 CHS T 型接头轴向承载能力的不利影响，计算值低于数值结果。

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引用次数: 0

An experimental investigation on fracture toughness predictions for carbon segregation metals using spherical indentation tests 利用球形压痕试验预测碳偏析金属断裂韧性的实验研究

IF 3 2区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Pressure Vessels and Piping

Pub Date : 2024-11-05 DOI: 10.1016/j.ijpvp.2024.105357

Weiwei Yu , Lu Zhang , Weipeng Li , Mingya Chen , Qunjia Peng , Yaolei Han , Han Liu , Tairui Zhang

The occurrence of carbon segregation in steam generator (SG) often leads to a decrease in fracture toughness and an increase in failure risk. To ensure the service safety of SG, a non-destructive testing method for quantitative evaluation of fracture toughness reduction with carbon segregation is necessary. To this end, this study provides an experimental investigation on whether the spherical indentation tests (SITs) are capable of revealing the fracture toughness reduction with the increasing carbon content. Solidarity of the existing fracture toughness prediction models has been extensively investigated through experiments on four carbon segregation samples with carbon content 0.21 %, 0.31 %, 0.35 %, and 0.39 %, respectively. It is found that both the critical strain and critical damage criteria, depending on phenomenologically summarized fixed critical values, failed in reproducing the decreasing trend of fracture toughness with increasing carbon content. For the critical stress criterion, the updated critical value, achieved by comparing the results of conventional fracture toughness and indentation tests on the steel with 0.21 % carbon content, can improve the prediction accuracy and successfully reproduce of variation of fracture toughness with carbon contents. However, consistency of three repeated predictions from the critical stress criteria is poor, which may hinder its engineering application. By contrast, the energy release rate model independent of phenomenologically summarized critical values can yield roughly well predictions, from viewpoints of both decreasing trend of fracture toughness with increasing carbon content and the repeatability of three tests. This experimental investigation can provide methodological guidance for nondestructive fracture toughness evaluation on SG facing carbon segregation.

蒸汽发生器（SG）中碳偏析的发生通常会导致断裂韧性下降，增加失效风险。为确保蒸汽发生器的使用安全，有必要采用无损检测方法对碳偏析导致的断裂韧性降低进行定量评估。为此，本研究对球形压痕测试（SIT）是否能够揭示断裂韧性随碳含量增加而降低的情况进行了实验研究。通过对碳含量分别为 0.21 %、0.31 %、0.35 % 和 0.39 % 的四种碳偏析样品进行实验，广泛研究了现有断裂韧性预测模型的稳固性。结果发现，临界应变准则和临界损伤准则（取决于现象学总结的固定临界值）都无法再现断裂韧性随碳含量增加而降低的趋势。就临界应力准则而言，通过比较含碳量为 0.21 % 的钢材的常规断裂韧性和压痕测试结果而得出的更新临界值可以提高预测精度，并成功再现断裂韧性随含碳量的变化。然而，根据临界应力准则进行的三次重复预测的一致性较差，这可能会妨碍其工程应用。相比之下，独立于现象学总结的临界值的能量释放率模型，无论从断裂韧性随碳含量增加而降低的趋势，还是从三次试验的重复性来看，都能得出大致良好的预测结果。这项实验研究可为面临碳偏析的 SG 的无损断裂韧性评估提供方法指导。

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引用次数: 0

Microstructure, mechanical properties, and corrosion resistance of dissimilar weld joints between SS304 and Inconel 600 welded using gas tungsten arc welding 使用气体钨极氩弧焊焊接 SS304 和 Inconel 600 异种焊点的显微结构、机械性能和耐腐蚀性能

IF 3 2区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Pressure Vessels and Piping

Pub Date : 2024-11-04 DOI: 10.1016/j.ijpvp.2024.105356

V. Salarvand , F. Ahmadian , M. Torabpour , M. EsmaeilZadeh , M.H. Abidi , O. Mehrabi , H. Sohrabpoor , A. Mostafaei , D. Brabazon

The microstructure, mechanical characteristics, and corrosion resistance of dissimilar gas tungsten arc welding (GTAW) joints of 304 stainless steel (SS304) to Inconel 600 (IN600) with Inconel 600, using ERNiCr-3 and ERSS308 filler metals were investigated. The welding process was executed at a current of 110 Amps under argon shielding gas, and all fabricated welds successfully joined SS304 to Inconel 600 without visible cracks or porosity at the weld metal interface. Microstructural analysis with optical and scanning electron microscopy revealed a mix of columnar and equiaxed dendritic structures in the weld zone for all samples. An unmixed zone was noted at the interface on the SS304 side when welded with Inconel 600 and ERNiCr-3, attributed to the differing melting points and chemical compositions of these fillers compared to SS304. The presence of Nb and Ti in the ERNiCr-3 filler facilitated the formation of TiC and NbC carbides in the welded metal structure, resulting in higher hardness compared to other specimens. Mechanically, the ERNiCr-3 welded sample exhibited superior hardness, with the highest microhardness values recorded in the ERNiCr-3 weld metal (197–207 HV) and higher values on the SS304 side (176–194 HV) compared to the IN600 side (164–176 HV). Corrosion tests, including Tafel and Electrochemical Impedance Spectroscopy, indicated that the ERNiCr-3 weld metal had better corrosion resistance than the IN600 weld metal. Due to the differences in chemical compositions of the base metals SS304 and IN600, it is necessary to consider an appropriate filler for welding these materials. ERNiCr-3 demonstrated increased hardness due to the formation of TiC and NbC carbides, along with enhanced corrosion resistance. These properties make it a promising material for industrial applications that require durability, strength, and resistance to corrosion, particularly in high-temperature or corrosive environments.

使用 ERNiCr-3 和 ERSS308 填充金属，研究了 304 不锈钢 (SS304) 与 Inconel 600 (IN600) 异种气体钨极氩弧焊 (GTAW) 接头的微观结构、机械特性和耐腐蚀性能。焊接过程在氩气保护下以 110 安培的电流进行，所有制造的焊缝都成功地将 SS304 与 Inconel 600 焊接在一起，在焊接金属界面上没有出现明显的裂缝或气孔。利用光学和扫描电子显微镜进行的微观结构分析表明，所有样品的焊接区都存在柱状和等轴树枝状混合结构。在与铬镍铁合金 600 和 ERNiCr-3 焊接时，SS304 侧的界面上出现了非混合区，这是因为这些填料的熔点和化学成分与 SS304 不同。ERNiCr-3 填料中 Nb 和 Ti 的存在促进了焊接金属结构中 TiC 和 NbC 碳化物的形成，使其硬度高于其他试样。在机械性能方面，ERNiCr-3 焊接试样表现出更高的硬度，ERNiCr-3 焊接金属的显微硬度值最高（197-207 HV），SS304 侧的硬度值（176-194 HV）高于 IN600 侧（164-176 HV）。包括塔菲尔和电化学阻抗谱在内的腐蚀测试表明，ERNiCr-3 焊缝金属的耐腐蚀性优于 IN600 焊缝金属。由于 SS304 和 IN600 母材的化学成分不同，焊接这些材料时必须考虑合适的填充物。ERNiCr-3 由于形成了 TiC 和 NbC 碳化物而提高了硬度，并增强了耐腐蚀性。这些特性使其成为一种很有前途的材料，适用于需要耐久性、强度和抗腐蚀性的工业应用，尤其是在高温或腐蚀性环境中。

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引用次数: 0

Quantitative study on thermal-mechanical failure of overhead steel pipelines under natural gas jet fire 天然气喷射火焰下架空钢质管道热机械故障的定量研究

IF 3 2区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Pressure Vessels and Piping

Pub Date : 2024-10-29 DOI: 10.1016/j.ijpvp.2024.105350

Xidi Lyu , Tengjiao He , Kexi Liao , Yuwei Wang , Huaixin Zhang , Xinhui Jiang , Jiancheng Liao , Yuanjie Huang

Parallel overhead pipelines are particularly adept at traversing intricate terrains. Nonetheless, the emergence of jet flames due to initial pipeline incidents can precipitate failures in adjacent pipelines, thereby intensifying the overall situation. Therefore, it is essential to examine the thermal-mechanical responses of pipelines exposed to natural gas jet fires. Building on combustion mechanisms, a transient thermal-mechanical coupling model has been developed for full-scale steel pipelines in the context of natural gas jet fires. The thermal-mechanical response characteristics of these pipelines are subsequently analyzed, and the impacts of four distinct variables on pipe wall temperature and normalized stress are quantitatively evaluated. Ultimately, a safety evaluation methodology for pipelines subjected to jet flames is proposed, which integrates critical thermal failure criteria with PSO-LSTM algorithm. The results demonstrate that the proposed thermal-mechanical coupling model effectively simulates the thermal effects of jet fires on pipelines, achieving a model error of less than 10 %. Notably, the flow velocity of crude oil has the most pronounced effect on the thermal failure of the pipeline. The established thermal-mechanical failure criterion, in conjunction with the PSO-LSTM hybrid model (average error of 5.57 %), enables the rapid prediction of critical failure conditions across a wide range of operational scenarios.

平行架空管道尤其善于穿越错综复杂的地形。然而，最初的管道事故导致喷射火焰的出现，会引发相邻管道的故障，从而加剧整体状况。因此，研究管道在天然气喷射火焰中的热机械反应至关重要。在燃烧机理的基础上，针对天然气喷射起火情况下的全尺寸钢制管道开发了一个瞬态热机械耦合模型。随后分析了这些管道的热机械响应特性，并定量评估了四个不同变量对管壁温度和归一化应力的影响。最后，提出了一种针对喷射火焰管道的安全评估方法，该方法将临界热失效标准与 PSO-LSTM 算法相结合。结果表明，所提出的热机械耦合模型能有效模拟喷射火焰对管道的热效应，模型误差小于 10%。值得注意的是，原油流速对管道热失效的影响最为明显。已建立的热机械故障标准与 PSO-LSTM 混合模型（平均误差为 5.57%）相结合，能够快速预测各种运行情况下的关键故障条件。

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引用次数: 0

Analytical evaluation of the elastic stresses in a multilayer spherical pressure vessel 多层球形压力容器弹性应力的分析评估

IF 3 2区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Pressure Vessels and Piping

Pub Date : 2024-10-29 DOI: 10.1016/j.ijpvp.2024.105354

Yuriy Tokovyy, Yurii Kulchytskyi-Zhyhailo

An explicit-form solution is constructed for a problem on elastic deformation of a multilayer spherical vessel due to uniform internal pressure. The vessel is assembled of perfectly connected elastic layers whose material properties may arbitrarily vary across their thickness. The solution is constructed through the use of the single solid approach along with the modified scheme of the direct integration method which allow for the consideration of the multilayer vessel as a composite sphere with piecewise-variable profiles of the material properties. As a result, the original problem is reduced to solving a governing integral equation of the second kind whose solution is constructed in the form of the explicit dependence on the internal pressure. The solution is verified by the comparison with exact solutions derived by making use the method of tailored solutions for specific benchmark problems. By comparing our with the one for a functionally-graded sphere, whose material properties are evaluated through the use of the micromodular homogenization technique, the specific features of the circumferential stress are analyzed.

本文构建了多层球形容器在均匀内压作用下弹性变形问题的显式解法。该容器由完全连接的弹性层组成，各层的材料特性可在厚度上任意变化。通过使用单实体方法和直接积分法的修正方案，可以将多层容器视为具有材料属性片断可变轮廓的复合球体，从而构建解决方案。因此，原始问题被简化为求解一个第二类控制积分方程，该方程的解是以明确依赖于内部压力的形式构建的。通过与利用特定基准问题的定制解法得出的精确解进行比较，我们验证了该解法。通过与功能分级球体的求解进行比较，分析了圆周应力的具体特征。

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引用次数: 0

Guidance for structural integrity assessment of smooth pipe elbows containing defects using R6 使用 R6 对含有缺陷的光滑管道弯头进行结构完整性评估的指南

IF 3 2区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Pressure Vessels and Piping

Pub Date : 2024-10-29 DOI: 10.1016/j.ijpvp.2024.105353

Yuebao Lei

Recently, guidance for fracture assessment of defective elbows using the R6 failure assessment diagram (FAD) method has been included in R6 Revision 4 Amendment 13 (2023). This paper provides an overview of the new guidance and supporting validation. The guidance is validated using 75 cases of 3-D finite element (FE) elastic-plastic J results of smooth pipe elbows of various geometries with axial/circumferential internal/external semi-elliptical/extended/fully-circumferential surface cracks under internal pressure, in-plane/out-of-plane bending moment, torsion and various load combinations, by comparing the FE-based Option 3 failure assessment curves (FAC) with the R6 Option 2 FAC. The results show that, for 74 out of 75 cases, the FE-based Option 3 data points are above the R6 Option 2 FAC with reasonable conservatism when the guidance for evaluating the elbow stress intensity factor and limit load is followed. In other words, following the new guidance can lead to reasonably conservative assessment results.

最近，使用 R6 失效评估图 (FAD) 方法对有缺陷的弯头进行断裂评估的指南已纳入 R6 修订版 4 第 13 修正案（2023 年）。本文概述了新指南和支持性验证。通过比较基于有限元的方案 3 失效评估曲线 (FAC) 和 R6 方案 2 失效评估曲线 (FAC)，使用 75 个三维有限元 (FE) 弹性-塑性 J 结果验证了该指南，这些三维有限元 (FE) 结果是各种几何形状的光滑管道弯头在内部压力、平面内/平面外弯矩、扭转和各种载荷组合作用下出现轴向/环向内部/外部半椭圆形/延伸/全环形表面裂纹的结果。结果表明，在 75 个案例中，有 74 个案例的基于 FE 的方案 3 数据点高于 R6 方案 2 的 FAC，并且在评估肘部应力强度因子和极限载荷时遵循了合理的保守原则。换句话说，遵循新指南可以得到合理保守的评估结果。

引用次数: 0