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Strength analysis of marine biaxial warp-knitted glass fabrics as composite laminations for ship material 船用双轴经编玻璃织物复合层合材料的强度分析
IF 1.5 Q4 MECHANICS Pub Date : 2023-01-01 DOI: 10.1515/cls-2022-0209
B. Ma’ruf, A. Ismail, Dian Purnama Sari, S. H. Sujiatanti
Abstract Fiberglass-reinforced plastics (FRP) composite materials for ships that are widely used are marine-grade unsaturated polyester resin matrix and combimat fiber, a combination of marine-grade chopped strand mat (CSM) and woven roving (WR) fibers. Although less popular than marine CSM–WR, marine biaxial warp-knitted glass fabrics have the potential to be applied as fiber laminates for ship hull materials. A comparative study of tensile and bending strength between marine CSM–WR composite and marine CSM–biaxial composite had been conducted. All composites met the criteria of the Indonesian Classification Bureau. Specifically, the CSM–biaxial had higher tensile and flexural strength with fewer laminations than the CSM–WR. Laminate type II had the highest average normalized tensile and flexural strength, 186.1 and 319.2 MPa. A layer of biaxial fiberglass had a very significant effect on tensile and flexural strength. Besides its strength, fewer type II laminations can speed up the production process of FRP ship hulls. Furthermore, the CSM–biaxial composite had relatively high normalized flexural strength compared to other references. However, the normalized tensile strength achieved in this study was at an intermediate level compared to other references.
摘要船舶用玻璃纤维增强塑料(FRP)复合材料是海洋级不饱和聚酯树脂基体和组合纤维,由海洋级短切条毡(CSM)纤维和梭织粗纱(WR)纤维组合而成。虽然不像船用CSM-WR那样受欢迎,但船用双轴经编玻璃织物具有作为船体材料纤维层压板的潜力。对船用CSM-WR复合材料与船用csm -双轴复合材料的拉伸和弯曲强度进行了对比研究。所有复合材料均符合印尼船级局的标准。具体来说,csm -双轴具有比CSM-WR更高的拉伸和弯曲强度,层数更少。层压板II型的平均归一化拉伸和弯曲强度最高,分别为186.1和319.2 MPa。一层双轴玻璃纤维对拉伸和弯曲强度有非常显著的影响。除了提高强度外,减少II型层压可以加快玻璃钢船体的生产过程。此外,与其他参考文献相比,csm -双轴复合材料具有相对较高的归一化抗弯强度。然而,与其他文献相比,本研究中获得的归一化抗拉强度处于中等水平。
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引用次数: 0
Experimental measurement and numerical predictions of thickness variation and transverse stresses in a concrete ring 混凝土环中厚度变化和横向应力的实验测量和数值预测
IF 1.5 Q4 MECHANICS Pub Date : 2023-01-01 DOI: 10.1515/cls-2022-0180
Djopkop Kouanang Landry, Bodol Momha Merlin, Amba Jean Chills, Nkongho Anyi Joseph, Fongho Eric, Zoa Ambassa, Nzengwa Robert
Abstract Concrete shells are widespread in civil engineering constructions. Because of the moldability of concrete, special structures such as domes, bridge caissons, buried or raised reservoirs, and arch dams are built with concrete. In this study, we are particularly interested in the variation of the thickness and the resulting strains during a short-term mechanical loading of a concrete ring in its elastic phase. On the one hand, transverse stresses through the thickness are calculated numerically by implementing a particular family of finite elements (four degrees of freedom per summit node) with a two-dimensional shell model, which accounts for thickness variations and transverse distortions. On the other hand, an experimental device was mounted in order to validate numerical predictions.
摘要混凝土壳体广泛应用于土木工程中。由于混凝土的可塑性,圆顶、桥梁沉箱、埋入式或抬高式水库以及拱坝等特殊结构都是用混凝土建造的。在这项研究中,我们对处于弹性阶段的混凝土环在短期机械载荷期间的厚度变化和由此产生的应变特别感兴趣。一方面,通过使用二维壳体模型实现特定的有限元族(每个顶点节点四个自由度),对穿过厚度的横向应力进行数值计算,该模型考虑了厚度变化和横向变形。另一方面,为了验证数值预测,安装了一个实验装置。
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引用次数: 1
Laminar Rayleigh–Benard convection in a closed square field with meshless radial basis function method 用无网格径向基函数法求解封闭正方形场中的层流Rayleigh–Benard对流
IF 1.5 Q4 MECHANICS Pub Date : 2023-01-01 DOI: 10.1515/cls-2022-0204
I. Santosa, E. P. Budiana, Syamsul Hadi, A. Wijayanta
Abstract Research on natural convection is exciting in some experimental and numerical cases, especially in rectangular cavities with relatively low heat dissipation and thermal control systems with low cost, reliability, and ease of use. The present study will use the meshless radial basis function method to solve the velocity formulation of the Navier–Stokes equations by varying some nominal Rayleigh numbers of 104, 105, and 106. The numerical accuracy is compared with the previous research. The advantages of the meshless method are that it does not require a structured mesh and does not require inter-nodal connectivity. The results show that the temperature pattern is identical to the previous research. The calculations have been done for three different Rayleigh numbers of 104, 105, and 106 for 151 × 151 nodes. The variations of the Ra number will affect the isothermal, velocity contours, and Nusselt number.
摘要自然对流的研究在一些实验和数值案例中是令人兴奋的,特别是在具有相对低散热的矩形腔和低成本、可靠和易于使用的热控制系统中。本研究将使用无网格径向基函数方法通过改变一些标称瑞利数104、105和106来求解Navier-Stokes方程的速度公式。并将数值精度与前人的研究结果进行了比较。无网格方法的优点是它不需要结构化的网格,也不需要节点间的连接。结果表明,温度模式与前人的研究结果一致。对于151 × 151节点,已经对三个不同的瑞利数(104、105和106)进行了计算。Ra数的变化会影响等温线、速度线和努塞尔数。
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引用次数: 0
Numerical investigations of two vibrating cylinders in uniform flow using overset mesh 均匀流中两个振动圆柱的超集网格数值研究
IF 1.5 Q4 MECHANICS Pub Date : 2023-01-01 DOI: 10.1515/cls-2022-0208
F. O. Hamdoon, Enass H. Flaieh, Alaa Abdulhady Jaber
Abstract In this research, flow around two vibrating cylinders in a tandem arrangement is simulated at Reynolds number Re = 200 using the dynamic overset mesh technique in finite volume-based commercial software. This investigation aims to study the combined influences of the spacing between the two identical circular cylinders and their excitation frequency in the flow. The cylinders are excited by a transverse forced vibration in a uniform cross-flow by applying a simple harmonic motion. The gap distance between the vibrating cylinders is chosen to be L/D = 1.5 and 4, and the vibration amplitude is kept constant at A/D = 0.25. The study focuses on three frequency ratios of the cylinders’ excitation frequency to Strouhal shedding frequency of the single stationary cylinder f e/f s = 0.8, 1.0, and 1.2. Simulation results showed that the flow characteristics over the two vibrating circular cylinders differ from that of a single vibrating cylinder. Also, it is observed that the lock-in state (resonance) for the two vibrating cylinders and the vortex wake patterns are highly affected by the gap distance between cylinders and the excitation frequency.
摘要在本研究中,使用基于有限体积的商业软件中的动态超集网格技术,模拟了雷诺数Re=200时串联布置的两个振动圆柱体周围的流动。本研究旨在研究两个相同圆柱体之间的间距及其在流动中的激励频率的综合影响。圆柱体通过施加简谐运动,在均匀横流中受到横向强迫振动的激励。振动筒之间的间隙距离选择为L/D=1.5和4,并且振幅保持恒定在A/D=0.25。研究的重点是气缸的激励频率与单个静止气缸的斯特劳哈尔脱落频率的三个频率比f e/f s=0.8、1.0和1.2。模拟结果表明,两个振动圆柱的流动特性不同于单个振动圆柱。此外,还观察到两个振动圆柱体的锁定状态(共振)和涡流尾流模式在很大程度上受到圆柱体之间的间隙距离和激励频率的影响。
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引用次数: 1
In-plane nonlinear postbuckling and buckling analysis of Lee’s frame using absolute nodal coordinate formulation 李氏框架平面内非线性后屈曲及屈曲的绝对节点坐标分析
IF 1.5 Q4 MECHANICS Pub Date : 2023-01-01 DOI: 10.1515/cls-2022-0212
Abdur Rahman Shaukat, Peng Lan, Jia Wang, Tengfei Wang, Nianli Lu
Abstract In this study, four absolute nodal coordinate formulation (ANCF)-based approaches are utilized in order to predict the buckling load of Lee’s frame under concentrated load. The first approach employs the standard two-dimensional shear deformable ANCF beam element based on the general continuum mechanics (GCM). The second approach adopts the standard ANCF beam element modified by the locking alleviation technique known as the strain-split method. The third approach has the standard ANCF beam element with strain energy modified by the enhanced continuum mechanics formulation. The fourth approach utilizes the higher-order ANCF beam element based on the GCM. Two buckling load estimation methods are used, i.e., by tracing the nonlinear equilibrium path of the load–displacement space using the arc-length method and applying the energy criterion, which requires tracking eigenvalues through the dichotomy scheme. Lee’s frame with different boundary conditions including pinned–pinned, fixed-pinned, pinned-fixed, and fixed–fixed are studied. The complex nonlinear responses in the form of snap-through, snap-back, and looping phenomena during nonlinear postbuckling analysis are simulated. The critical buckling loads and buckling mode shapes obtained through the energy criterion-based buckling method are obtained. After the comparison, higher-order beam element is found to be more accurate, stable, and consistent among the studied approaches.
摘要本研究采用四种基于绝对节点坐标公式(ANCF)的方法来预测集中荷载作用下李氏框架的屈曲载荷。第一种方法采用基于通用连续介质力学(GCM)的标准二维剪切变形ANCF梁单元。第二种方法采用了标准的ANCF梁单元,该单元采用了锁紧缓解技术,即应变分裂法。第三种方法是采用增强连续介质力学公式修正应变能的标准ANCF梁单元。第四种方法利用基于GCM的高阶ANCF光束单元。屈曲载荷估计采用两种方法,即采用弧长法跟踪载荷-位移空间的非线性平衡路径和采用能量准则,这两种方法需要通过二分法跟踪特征值。研究了不同边界条件下的Lee框架,包括钉-钉、固定-钉、钉-固定、固定-固定。在非线性后屈曲分析过程中,对复杂的非线性响应进行了仿真分析,分析结果表明,非线性后屈曲分析过程中存在着突进、突进和回环现象。通过基于能量准则的屈曲方法得到了临界屈曲载荷和屈曲模态振型。通过比较,发现高阶梁单元的计算精度更高、稳定性更好、一致性更好。
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引用次数: 0
Nonlocal state-space strain gradient wave propagation of magneto thermo piezoelectric functionally graded nanobeam 磁热压电功能梯度纳米梁的非局域状态空间应变梯度波传播
IF 1.5 Q4 MECHANICS Pub Date : 2023-01-01 DOI: 10.1515/cls-2022-0192
R. Selvamani, Rubine Loganathan, R. Dimitri, Francesco Tornabene
Abstract In this work, the state -space nonlocal strain gradient theory is used for the vibration analysis of magneto thermo piezoelectric functionally graded material (FGM) nanobeam. An analysis of FGM constituent properties is stated by using the power law relations. The refined higher order beam theory and Hamilton’s principle have been used to obtain the motion equations. Besides, the governing equations of the magneto thermo piezoelectric nanobeam are extracted by developed nonlocal state-space theory. And to solve the wave propagation problems, the analytical wave dispersion method is used. The effect of magnetic potential, temperature gradient, and electric voltage in variant parameters are presented in graph.
摘要本文将状态空间非局部应变梯度理论应用于磁热压电功能梯度材料纳米梁的振动分析。利用幂律关系对FGM的组成性质进行了分析。利用改进的高阶光束理论和哈密顿原理得到了运动方程。此外,利用发展的非局部状态空间理论提取了磁热压电纳米梁的控制方程。为了解决波的传播问题,采用了解析波色散法。用图形表示了磁势、温度梯度和电压在不同参数下的影响。
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引用次数: 2
A methodological approach for detecting multiple faults in wind turbine blades based on vibration signals and machine learning 一种基于振动信号和机器学习的风电叶片多故障检测方法
Q4 MECHANICS Pub Date : 2023-01-01 DOI: 10.1515/cls-2022-0214
Ahmed Ali Farhan Ogaili, Alaa Abdulhady Jaber, Mohsin Noori Hamzah
Abstract Wind turbines generate clean and renewable energy for the international market. The most ‎‎important aspect of wind turbine maintenance is reducing failures, downtime, and operating and maintenance expenses. ‎This study aims to detect multiple faults exhibited by wind turbine blades; failures such as cracks (tip crack, mid-span crack, and crack ‎near the root) were observed in the blades at different locations. The research suggests a new approach, incorporating vibration signals and machine learning techniques to identify various failures in wind turbine blades. The technology of ranking features such as ReliefF algorithms, chi-squares, and information gains was adopted to discuss a method framework to diagnose several problems in wind turbine blades, such as cracks in different locations. The k-nearest neighbors (KNNs), support vector machines, and random forests are used to classify data based on measured vibration signals. The eight main time-domain features are calculated from the vibration signals. The proposed methodology was validated using four databases. The results showed good classification accuracy in four databases, with at least three non-conventional features in each database’s top nine features of the three classification techniques. The results also showed that when the ReliefF selection algorithm is applied with the KNN classification algorithm, it generates the highest classification accuracy under all failure conditions, and the value is 97%. Finally, the performance of the proposed classification model is compared with other machine learning classification models, and a promising result is obtained. ‎
风力涡轮机为国际市场提供清洁和可再生能源。风力涡轮机维护最重要的方面是减少故障、停机时间以及运行和维护费用。该研究旨在检测风力涡轮机叶片所表现出的多种故障;在叶片的不同位置观察到裂纹等失效(尖端裂纹、跨中裂纹和近根部裂纹)。这项研究提出了一种新的方法,结合振动信号和机器学习技术来识别风力涡轮机叶片的各种故障。排名的技术特性,比如ReliefF算法,卡方检验,并采用信息增益方法框架,讨论诊断风力涡轮叶片中的几个问题,如裂缝在不同的位置。再邻居(资讯),使用支持向量机,和随机森林分类基于振动信号测量的数据。从振动信号中计算出八个主要时域特征。该方法使用四个数据库进行验证。结果表明,4个数据库的分类准确率较高,在3种分类技术的前9个特征中,每个数据库至少有3个非常规特征。结果还表明,当ReliefF选择算法与KNN分类算法结合使用时,在所有失效条件下产生的分类准确率最高,达到97%。最后,将该分类模型的性能与其他机器学习分类模型进行了比较,得到了令人满意的结果。‎
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引用次数: 1
Temperature-dependent mechanical properties of Al/Cu nanocomposites under tensile loading via molecular dynamics method 分子动力学方法研究拉伸载荷下Al/Cu纳米复合材料的温度相关力学性能
IF 1.5 Q4 MECHANICS Pub Date : 2022-01-01 DOI: 10.1515/cls-2022-0009
M. Abdulrehman, M. Hussein, I. Marhoon
Abstract Al-Cu Nanocomposites (NCs) are widely used in industrial applications for their high ductility, light weight, excellent thermal conductivity, and low-cost production. The mechanical properties and deformation mechanisms of Metal Matrix NCs (MMNCs) strongly depend on the matrix microstructure and the interface between the matrix and the second phase. The present study relies on Molecular Dynamics (MD) to investigate the effects of temperature on the mechanical properties and elastic and plastic behavior of the Al-Cu NC with single-crystal and polycrystalline matrices. The effects of heating on microstructural defects in the aluminum matrix and the Al/Cu interface were also addressed in the following. It was found that the density of defects such as dislocations and stacking fault areas are much higher in samples with polycrystalline matrices than those with single-crystal ones. Further, by triggering thermally activated mechanisms, increasing the temperature reduces the density of crystal defects. Heating also facilitates atomic migration and compromises the yield strength and the elastic modulus as a result of the increased energy of atoms in the grain boundaries and in the Al-Cu interface. The results showed that the flow stress decreased in all samples by increasing the temperature, making them less resistant to the plastic deformation.
摘要Al-Cu纳米复合材料以其高延展性、轻量化、优异的导热性和低成本生产而在工业应用中得到广泛应用。金属基纳米晶体的力学性能和变形机制在很大程度上取决于基体微观结构以及基体与第二相之间的界面。本研究依靠分子动力学(MD)研究了温度对具有单晶和多晶基体的Al-Cu NC的力学性能和弹塑性行为的影响。加热对铝基体和Al/Cu界面中微观结构缺陷的影响也在下文中讨论。研究发现,多晶基体样品中位错和层错区等缺陷的密度远高于单晶基体样品。此外,通过触发热激活机制,提高温度降低了晶体缺陷的密度。加热还促进了原子迁移,并且由于晶界和Al-Cu界面中原子的能量增加而损害了屈服强度和弹性模量。结果表明,随着温度的升高,所有样品的流动应力都有所降低,使其对塑性变形的抵抗力降低。
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引用次数: 2
Numerical and experimental investigation of two phase flow geometrical characteristics 两相流几何特性的数值与实验研究
IF 1.5 Q4 MECHANICS Pub Date : 2022-01-01 DOI: 10.1515/cls-2022-0018
Hyder M. Abdul Hussein, Sabah T Ahmed, L. Habeeb
Abstract This paper presents an experimental and numerical analysis of the effect of the geometric parameter on the two-phase flow (white kerosene-water) flow pattern system. The investigation was carried out using three lengths (1, 2 and 3) m of rectangular horizontal smooth channel and three channel heights of (5, 7.5 and 10) cm respectively. The flow conditions for the input water velocity (0.2 m/s) and the input kerosene velocity (0.1 m/s) for both measurements have been investigated. Two-inlet techniques have been employed. Firstly, at the inlet, the kerosene was on top of the bath. Then, second, from the center, the kerosene inlets (water is above and below the kerosene). A numerical verification analysis was introduced using the ANSYS software using the method of volume of fluid (VOF) and mixture multiphase flow modeling coupled with the normal k-ε turbulence schemes. A collection of seven methods of CFD types is explored by running 224 instances. Comparisons were made between numerical and experimental works.
本文对几何参数对两相流(白煤油-水)流型系统的影响进行了实验和数值分析。研究使用三个长度(1、2和3)m的矩形水平光滑通道和三个高度(5、7.5和10)cm的通道进行。研究了两种测量的输入水速度(0.2m/s)和输入煤油速度(0.1m/s)的流动条件。采用了两种进气技术。首先,在入口,煤油在浴槽的顶部。然后,第二,从中心开始,煤油入口(水在煤油的上方和下方)。利用ANSYS软件,采用流体体积法和混合多相流建模方法,结合正常的k-ε湍流方案,进行了数值验证分析。通过运行224个实例,探索了CFD类型的七种方法的集合。对数值计算和实验结果进行了比较。
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引用次数: 1
Optimization of mechanical wear resistance for recycled (Al-Mg-Si) reinforced SiC composite material using PM method PM法优化再生(Al-Mg-Si)增强SiC复合材料的机械耐磨性
IF 1.5 Q4 MECHANICS Pub Date : 2022-01-01 DOI: 10.1515/cls-2022-0023
S. Omran, M. M. Al-Masoudy, O. H. Hassoon, M. Fayad
Abstract Recently, the increasing demand for advanced materials around the world led to search on require and optimal materials characteristics. An alloy (Al-Mg-Si) named hindalium was used in this study which made from aluminum recycling (aluminums sandwich panel plates). In addition, powder technology was applied to investigate the effect of adding silicon carbide (SiC) particles on the composite properties that enter in fabricate of disc brake rotors. The main reason to use this technology is a single material cannot meet the demands of an extreme engineering setting that encourage towards necessitating the use of composites. Metal matrix composites are a type of material that has a lot of potential for components and structural applications that require a lot of unique modulus, strength, and durability as well as in the same time being light in weight. The composites materials of metal base with good properties are becoming now widely used in several industrial sectors due to their high mechanical properties and resistant to wear. Al-Mg-Si alloys are a common material category because of their inherent hardness, and corrosion resistance. The properties of hardness, wear rate, and microstructure are the physical and mechanical tests were performing in this study. It is indicated that the modeling with using a Genetic Algorithm is the best solution to choose the samples that have been prepared. According to the results, it was observed that the hardness increased by 14% at 15%SiC content and the wear rate decreased by 17% as comparing with the base alloy used in this study.
摘要近年来,世界各地对先进材料的需求不断增加,导致人们对材料特性的需求和优化进行了研究。在本研究中,使用了一种名为hindalium的合金(Al-Mg-Si),该合金是由铝回收(铝夹芯板)制成的。此外,应用粉末技术研究了添加碳化硅颗粒对盘式制动器转子制造中复合材料性能的影响。使用这项技术的主要原因是单一材料无法满足极端工程环境的要求,而极端工程环境鼓励使用复合材料。金属基复合材料是一种在部件和结构应用方面具有很大潜力的材料,需要大量独特的模量、强度和耐久性,同时重量轻。具有良好性能的金属基复合材料由于其高机械性能和耐磨性,目前正被广泛应用于几个工业部门。Al-Mg-Si合金由于其固有的硬度和耐腐蚀性而成为一种常见的材料类别。硬度、磨损率和微观结构的性能是本研究中进行的物理和机械测试。结果表明,利用遗传算法进行建模是选择已制备样品的最佳解决方案。结果表明,与本研究中使用的基体合金相比,在SiC含量为15%时,硬度增加了14%,磨损率降低了17%。
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引用次数: 0
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