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The Metallurgical hydrogen as an indicator and cause of damage to rolled steel: Hydrogen diagnostics of fracture 冶金氢作为轧钢损伤的指示物和原因:断裂的氢诊断
Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-12-21 DOI: 10.3221/igf-esis.63.23
V. Polyanskiy, V. Loginov, Y. Yakovlev, A. Polyanskiy, Vecheclav Olekov, Gregory Rostovykh
Fatigue tests and measurements of the volumetric distribution of metallurgical hydrogen in specimens cut from rolled I-beam 60Sh3 made of steel 10KhSND were carried out. Fatigue tests show a 20% reduction in fatigue limits compared to similar sheet material. On the fractures of the samples, there are flock-like defects in the areas of interface of the flanges of the I-beam, or the so-called zones of difficult deformation. The concentration of metallurgical hydrogen is unevenly distributed and varies from 0.17 ppm to 1.8 ppm. Large concentrations of hydrogen are observed in the zones of difficult deformation, which indicates the hydrogen nature of the metal defects observed at the fracture. The result of mechanical tests and hydrogen diagnostics is a manufacturing defect of rolled products that cannot be corrected. Hydrogen diagnostics using metallurgical hydrogen (without hydrogen charging samples) takes tens of times less time than mechanical tests, and gives an adequate result.
对10KhSND钢60Sh3工字钢轧制试样进行了疲劳试验和冶金氢的体积分布测量。疲劳试验表明,与同类板材相比,其疲劳极限降低了20%。在试样的断口处,工字钢法兰的界面区域,即所谓的难变形区,存在着一团状的缺陷。冶金氢的浓度分布不均匀,在0.17 ppm ~ 1.8 ppm之间。在难变形区观察到高浓度的氢,这表明在断口观察到金属缺陷的氢性质。机械测试和氢诊断的结果是轧制产品的制造缺陷,无法纠正。使用冶金氢(没有充氢样品)进行氢诊断所需的时间比机械测试少几十倍,并且给出了足够的结果。
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引用次数: 0
A method and apparatus for inspecting large flat composite parts by using the Infrared LST technique 一种利用红外LST技术检测大型扁平复合材料零件的方法和装置
Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-12-21 DOI: 10.3221/igf-esis.63.11
V. Vavilov, A. Chulkov, D. Nesteruk, D. Burleigh, A. Moskovchenko
The principle of Line Scan Thermography (LST) was used to develop a self-propelled infrared thermographic nondestructive testing device for the inspection of large, relatively flat composite aerospace parts, such as aircraft wings. The design of the unit allowed the suppression of noise from reflected radiation. The new equipment, using the LST method, provided defect detectability similar to that achieved with a classic, static, flash heating procedure, but with a higher rate of testing. Also, the line heating principle ensured more uniform thermal patterns, and the proper choice of scan speed and field of view allows the selection of optimal time delays and the creation of maps of defects at different depths. Defect characterization efficiency was improved by using a trained neural network.
利用线扫描热成像(LST)原理开发了一种自行式红外热成像无损检测装置,用于检测大型、相对平坦的复合航空航天零件,如机翼。该装置的设计允许抑制反射辐射产生的噪声。使用LST方法的新设备提供了类似于经典静态闪光加热程序的缺陷检测能力,但测试率更高。此外,线加热原理确保了更均匀的热图案,扫描速度和视场的正确选择允许选择最佳时间延迟并创建不同深度的缺陷图。使用经过训练的神经网络提高了缺陷表征的效率。
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引用次数: 0
The earth-fill dam state express investigation using mechanical vibrations produced by HPP 利用高压电机产生的机械振动对土坝状态进行研究
Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-12-21 DOI: 10.3221/igf-esis.63.05
G. Antonovskaya, N. Kapustyan
The usage of mechanical vibrations produced by the hydropower plant (HPP) turbine may be used for seismic sounding of large-scale constructions as the earth-fill dam and its abutment contacts. Such vibrations are monochromatic oscillations on main frequencies and their harmonics produced by turbine. Seismic sensors installed on the dam's crest and inside it, if it possible, and in the area of abutment contacts register microseisms include HPP turbine operation vibrations which may be extracted by seismic data processing, i.e., filtering. We discuss two data processing possibilities: symphonious filter as the hardware one and power spectrum calculation as digital one. We consider the two case of earth-fill dams state investigations. There are the Chiryurt HPP dam (Republic of Dagestan, Russia, 9.5 m high) and the Nurek HPP dam (Tajikistan, 300 m high). We show the possibilities of seismic express investigations using signals of main frequencies produced by HPP turbine for dam sounding. For Chiryurt dam the extra fluid filtering in the central part of the dam was revealed. Nurek dam abutment contact monitoring showed the temporal variation of its stress-strain state associated with deformation variation 10-5-10-6 presumably due to regional seismicity.
利用水电站水轮机产生的机械振动,可用于土石坝及其坝肩接触等大型建筑的地震测深。这种振动是在主频率上的单色振荡,其谐波由涡轮机产生。安装在坝顶和坝内的地震传感器,如果可能的话,以及在坝肩接触区域,记录的微地震包括高压汽轮机的运行振动,这些振动可以通过地震数据处理,即滤波来提取。我们讨论了两种数据处理的可能性:硬件的谐波滤波和数字的功率谱计算。我们考虑了两种情况下的土坝状态调查。有Chiryurt水电站大坝(俄罗斯达吉斯坦共和国,9.5米高)和Nurek水电站大坝(塔吉克斯坦,300米高)。我们展示了利用高压汽轮机产生的主频率信号进行大坝测深的可能性。对于Chiryurt大坝,揭示了大坝中心部分的额外流体过滤。Nurek坝肩接触监测显示其应力-应变状态随变形变化的时间变化(10-5-10-6),可能是由区域地震活动引起的。
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引用次数: 0
Numerical nonlinear analysis of RC beans with un-strengthened and CFRP-strengthened opening drilled under service loads within shear zones 剪切区内使用荷载作用下未加固和加固开孔RC豆的非线性数值分析
Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-12-21 DOI: 10.3221/igf-esis.63.17
Magdy A. Khalaf, Louay Aboul-Nour, M. Khater, Marwa Ibrahim
Current research paper deals with reinforced concrete (R.C.) beams numerical modeling and suggested strengthening procedure if it is required to create an opening within their shear zones. Strengthening is assumed to be achieved during different service load application conditions. Reinforced Concrete beams with rectangular or circular opening in shear zone; as critical regions; sustain two concentrated system of loads are tested till failure before and after performing suggested opening assessing technique by means of Carbon Fibers Reinforced Polymer sheets (CFRP). The main aim of this research is simulating real practice situation where the beam is subjected to service loads, supported temporary by means of hydraulic jacks, opening is created and strengthening is performed then jacking supports are released. Results of achieved numerical nonlinear modeling are introduced and influence of strengthening achieving on improving assessed beams almost structural behavior such as initial cracking loads, load deflection curves, cracking patterns, failure loads & modes for reference (without opening), main un-strengthened control beams, and CFRP strengthened opening beams are introduced and analyzed in details. Some important conclusions & recommendations for designer and executive engineers are stated.
目前的研究论文涉及钢筋混凝土梁的数值模拟和建议的加固程序,如果需要在其剪切区内创建一个开口。假定在不同的业务负载应用条件下实现强化。具有矩形或圆形剪切区开口的钢筋混凝土梁;作为关键区域;采用碳纤维增强聚合物片材(CFRP)进行建议开孔评估技术前后的连续两组集中荷载试验直至失效。本研究的主要目的是模拟梁承受工作载荷的实际情况,通过液压千斤顶进行临时支撑,打开并进行加固,然后释放千斤顶支撑。介绍了所取得的数值非线性模拟结果,并详细介绍和分析了加固对改善评估梁的基本结构性能的影响,如初始开裂荷载、荷载挠度曲线、开裂形态、参考破坏荷载和模式(无开口)、主要未加固控制梁和CFRP加固开口梁。对设计人员和施工人员提出了一些重要的结论和建议。
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引用次数: 0
Improvement of crack tip position estimation in DIC images by image processing methods 图像处理方法对DIC图像裂纹尖端位置估计的改进
Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-12-21 DOI: 10.3221/igf-esis.63.06
Najat Zekriti, F. Majid, Hachimi Taoufik, Y. Tounsi, R. Rhanim, I. Mrani, H. Rhanim
The study presents and compares an application of two procedures to identify the crack tip location in PVC Sent samples under a uniaxial tensile test based on the image processing method. An IDS camera captures several photos of the PVC surface as part of the image analysis procedure. All relevant data on crack initiation and propagation is collected and assessed using ImageJ software using image processing methods for detecting cracks. However, the second procedure involves a developed algorithm detecting the discontinuity using digital image correlation (DIC) measurement. Although, because of the experimental conditions, the acquisition of images by the digital camera is never perfect. This noise comes from several sources, including the digital camera, image distortion due to lens magnification or lens angle, the shape and size of the pattern, and electronic noise; ... This article discusses image enhancement methods to overcome these objectionable characteristics using and comparing several filters:  Gaussian, median, and Unsharp Mask filters. The performance of the Gaussian filter is better than the Median and Unsharp mask filters. This research demonstrates that DIC is an effective technique for monitoring deformation and understanding the failure mechanism with the best-suited filter.
本研究提出并比较了两种方法在基于图像处理方法的单轴拉伸试验下识别PVC Sent样品裂纹尖端位置的应用。作为图像分析程序的一部分,IDS相机捕捉了PVC表面的几张照片。使用ImageJ软件收集并评估裂纹萌生和扩展的所有相关数据,该软件使用用于检测裂纹的图像处理方法。然而,第二个过程涉及使用数字图像相关(DIC)测量来检测不连续性的开发算法。尽管,由于实验条件的原因,数码相机对图像的采集从来都不是完美的。这种噪声来自几个来源,包括数码相机、由于镜头放大率或镜头角度导致的图像失真、图案的形状和大小以及电子噪声。。。本文讨论了使用并比较几种滤波器(高斯滤波器、中值滤波器和Unsharp Mask滤波器)来克服这些令人反感的特性的图像增强方法。高斯滤波器的性能优于中值和非锐化掩模滤波器。这项研究表明,DIC是一种有效的技术,可以通过最合适的过滤器监测变形并了解失效机制。
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引用次数: 0
Method for weak zones location at the coal-bed – host rock joint relative to the problem of sudden outbursts: theory and laboratory experiment 针对突突问题的煤层-围岩节理薄弱带定位方法:理论与室内试验
Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-12-21 DOI: 10.3221/igf-esis.63.02
L. Nazarova, L. Nazarov
Within the framework of a geomechanical model that describes the deformation of a rock mass during the subhorizontal coal-bed extraction, the mechanism for the formation and implementation of a sudden outburst is substantiated: as working face gets close to the weak zone of coal-bed – host rock joint, areas of tensile stresses arise, which creates the prerequisites for face space spalling and coal loss with methane. The inverse problem of determining the conditions at the horizontal boundaries of a coal-bed is formulated and solved using tomography data (longitudinal wave velocity V distribution) and the empirical dependence of V on the mean normal stress σ. Lab tests results on stepwise compression of parallelepipeds made of artificial geomaterials are presented. Tomography of the specimens was performed by acoustic sounding data, and the distribution of velocities V* was found. Using the pre-established empirical dependence V(σ) for geomaterial, the distribution σ*=V-1(V*) in the specimen was calculated, which served as input data for inverse problem of determining the shear stresses σxy at the “specimen faces – press platens” joints. Lab data inversion confirmed the possibility of identifying weak zones of the boundaries where σxy=0. These zones are associated with probable nucleus of failure and sudden outbursts.
在亚水平煤层回采过程中岩体变形的地质力学模型框架内,证实了突突形成和实现的机理:工作面靠近煤层-主岩节理薄弱带时,产生拉应力区域,为工作面空间剥落和煤层甲烷失煤创造了先决条件。利用层析成像数据(纵波速度V分布)和V对平均法向应力σ的经验依赖关系,提出并求解了确定煤层水平边界条件的反问题。介绍了人工岩土材料平行六面体逐步压缩的室内试验结果。利用声波测深数据对试样进行层析成像,得到了速度V*的分布。利用预先建立的岩土材料的经验依赖关系V(σ),计算试件中的分布σ*=V-1(V*),作为确定“试件面-压台”节点剪应力σxy反问题的输入数据。实验数据反演证实了在σxy=0处存在边界弱带的可能性。这些区域与可能的故障核和突然爆发有关。
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引用次数: 0
Delamination effect on the mechanical behavior of 3D printed polymers 分层对3D打印聚合物力学行为的影响
Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-12-21 DOI: 10.3221/igf-esis.63.03
F. Majid, T. Hachimi, H. Rhanim, R. Rhanim
 This study aims to assess the delamination effect and predict the evolution of damage in 3D printed specimens to investigate the mechanical behavior occurring due to the delamination of the layers of 3D printed thermoplastic polymers. Thus, additively manufactured ABS samples are subjected to tensile tests Made for different thicknesses of specimens by subtracting layer by layer. The mechanical behavior of the layers and the adherence between the layers are studied in this paper. The deposition of the layers is modeled as a laminated material. The delamination effect on the resistance of printed material is evaluated experimentally by comparing the mechanical characteristics of homogenously printed specimens, and laminated layers gathered together. Thus, the global resistance is reduced significantly due to the lack of adherence. Besides, crack growth, and critical intensity factor investigation are based on damage and rupture mechanics theories. Furthermore, the results allowed us to evaluate the energy behavior of the 3D printed material subjected to static loads and subsequently predict the evolution of the damage and find out the impact of layers' delamination. Indeed, we determined three stages of damage along with the critical life fraction leading to the failure of the specimen.
本研究旨在评估3D打印样品的分层效应并预测损伤的演变,以研究由于3D打印热塑性聚合物层的分层而发生的力学行为。因此,增材制造的ABS试样通过逐层减法对不同厚度的试样进行拉伸试验。本文研究了各层的力学行为和层间的黏附性。层的沉积被模拟为层压材料。通过比较均匀打印样品和叠层材料聚集在一起的力学特性,实验评估了分层对打印材料阻力的影响。因此,由于缺乏依从性,全球耐药性大大降低。此外,裂纹扩展和临界强度因子的研究基于损伤和破裂力学理论。此外,该结果使我们能够评估3D打印材料在静载荷下的能量行为,从而预测损伤的演变,并找出层分层的影响。事实上,我们确定了三个阶段的损伤以及导致试样失效的临界寿命分数。
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引用次数: 0
The Stress Intensity Factor of convex embedded polygonal cracks 凸嵌埋多边形裂纹的应力强度因子
Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-12-21 DOI: 10.3221/igf-esis.63.07
P. Livieri, F. Segala
In the present work, a simple formula for the evaluation of the stress intensity factor (SIF) of convex embedded polygonal cracks has been proposed. This formula is structured as a correction factor of the Oore-Burns’ equation and is based on accurate three-dimensional FE analysis. Furthermore, a precise formula for a regular polygonal crack has been given.
在本工作中,提出了一个简单的公式来评估凸嵌入多边形裂纹的应力强度因子(SIF)。该公式被构造为Oore Burns方程的校正因子,并基于精确的三维有限元分析。此外,还给出了规则多边形裂纹的精确计算公式。
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引用次数: 0
Study of the slant fracture in solid and hollow cylinders: Experimental analysis and numerical prediction 实心和空心圆柱体的斜断裂研究:实验分析和数值预测
Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-12-21 DOI: 10.3221/igf-esis.63.15
Nassima Ben chabane, Nassim Aguechari, M. Ould Ouali
This paper is devoted to the numerical and experimental study of ductile fracture in bulk metal forming of the 2017A-T4 aluminum alloy. From an experimental standpoint, the ductile fracture of the 2017A-T4 aluminum alloy is investigated under compressive load. Two cross-sections of solid and hollow specimens are considered. The mechanical behavior and the microstructure of the 2017A-T4 aluminum alloy were characterized. It is found that the well-known barrel shape is obtained when a compressive load is applied. Analyses of fracture topographies show a ductile fracture with dimples under tension and coexistence of ductile fracture with dimples and slant under compression. The classical physically-based Gurson-Tvergaard-Needleman (GTN) model and its extension to incorporate shear mechanisms to predict failure at low-stress triaxiality are considered. These two models have been extended to take into account the thermal heating effect induced by the mechanical dissipation within the material during the metal forming process. The two models have been implemented into the finite element code Abaqus/Explicit using a Vectorized User MATerial (VUMAT) subroutine. Numerical simulations of the forging process made for hollow and solid cylindrical specimens show good agreement with experimental results. In contrast with the GTN model, the modified GTN model incorporating shear mechanisms can capture the final material failure.
本文对2017A-T4铝合金体成形韧性断裂进行了数值和实验研究。从实验角度研究了压缩载荷作用下2017A-T4铝合金的韧性断裂。考虑了实心和空心试件的两个截面。对2017A-T4铝合金的力学行为和显微组织进行了表征。结果表明,当施加压缩载荷时,得到了众所周知的桶形。断口形貌分析表明,拉伸作用下为韧窝断裂,压缩作用下为韧窝与斜面并存的韧性断裂。考虑了经典的基于物理的Gurson-Tvergaard-Needleman (GTN)模型及其扩展,以纳入剪切机制来预测低应力三轴破坏。将这两种模型进行了扩展,考虑了金属成形过程中材料内部机械耗散引起的热加热效应。这两个模型已经实现到有限元代码Abaqus/Explicit使用矢量用户材料(VUMAT)子程序。对空心和实心圆柱试样的锻造过程进行了数值模拟,结果与实验结果吻合较好。与GTN模型相比,考虑剪切机制的修正GTN模型更能捕捉材料的最终破坏。
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引用次数: 2
Numerical analysis of repaired wall loss defect pipelines for optimum composite wrap thickness 修复壁损缺陷管道复合材料最佳包层厚度的数值分析
Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-12-21 DOI: 10.3221/igf-esis.63.14
Muhammed Khaise, S. De Barros, N. Rohem, M. Banea, S. Budhe
The paper presents the numerical analysis of failure pressure of wall loss defect metallic pipelines and validate it with experimental results. An optimization of composite thickness for repair of wall loss defect pipeline is also carried out using numerical analysis. A nonlinear explicit FE code with constitutive models for metallic steel and composite material to failure modelling was used. Three different cases: non-defective pipe, wall loss defective pipe and composite repaired of defective pipe are considered. It was found that the numerical results are in good agreement with the analytical results in all the three cases. The theoretical failure pressure determined by ISO/TS 24817 standard for wall loss defect pipe is highly conservative compared to the numerical failure pressure for the given composite repair thickness. Additionally, the numerical study on optimization of repair thickness revealed that lower composite repair thickness can also sustain the designed failure pressure (composite repair thickness of 8.4 mm can sustain the same designed pressure instead of 16.1 mm thickness), which implies there is scope to further reduce the composite thickness, which ultimately reduce the repair cost.
本文对壁损缺陷金属管道的失效压力进行了数值分析,并与实验结果进行了验证。利用数值分析方法,对修复壁损缺陷管道的复合材料厚度进行了优化。采用具有本构模型的非线性显式有限元程序对金属钢和复合材料进行了失效模拟。考虑了三种不同的情况:无缺陷管、壁损缺陷管和缺陷管的复合修复。结果表明,三种情况下的数值计算结果与解析计算结果吻合较好。根据ISO/TS 24817标准确定的壁损缺陷管道的理论破坏压力与给定复合修复厚度下的数值破坏压力相比是高度保守的。此外,对修复厚度优化的数值研究表明,较低的复合材料修复厚度也可以承受设计的失效压力(复合材料修复厚度8.4 mm可以承受相同的设计压力,而复合材料修复厚度16.1 mm可以承受相同的设计压力),这意味着复合材料厚度还有进一步减小的空间,从而最终降低修复成本。
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引用次数: 1
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Frattura ed Integrita Strutturale
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