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IDENTIFICATION OF CHATTER VIBRATIONS AND ACTIVE VIBRATION CONTROL BY USING THE SLIDING MODE CONTROLLER ON DRY TURNING OF TITANIUM ALLOY (TI6AL4V) 钛合金(ti6al4v)干车削颤振辨识及滑模主动控制
IF 7.9 2区 工程技术 Q1 Engineering Pub Date : 2023-08-10 DOI: 10.22190/fume210728067g
M. Guvenc, H. H. Bilgic, S. Mistikoglu
In recent years, with the development of sensor technologies, communication platforms, cyber-physical systems, storage technologies, internet applications and controller infrastructures, the way has been opened to produce competitive products with high quality and low cost. In turning, which is one of the important processes of machining, chatter vibrations are among the biggest problems affecting product quality, productivity and cost. There are many techniques proposed to reduce chatter vibrations for which the exact cause cannot be determined. In this study, an active vibration control based on the Sliding Mode Control (SMC) has been implemented in order to reduce and eliminate chatter vibration, which is undesirable for the turning process. In this context, three-axis acceleration data were collected from the cutting tool during the turning of Ti6Al4V. Finite Impulse Response (FIR) filtering, Fast Fourier Transform (FFT) analysis and integral process were carried out in order to use the raw acceleration data collected over the system in control. The system is modeled mathematically and an active control block diagram is created. It is observed that chattering decreased significantly after the application of active vibration control. The surface quality formed by the amplitude of the graph obtained after active control has been compared and verified with the data obtained from the actual manufacturing result.
近年来,随着传感器技术、通信平台、网络物理系统、存储技术、互联网应用和控制器基础设施的发展,为生产高质量、低成本的有竞争力的产品开辟了道路。车削是机械加工的重要工序之一,颤振振动是影响产品质量、生产率和成本的主要问题之一。提出了许多技术来减少颤振振动,但其确切原因无法确定。针对车削加工中存在的颤振问题,提出了一种基于滑模控制(SMC)的主动振动控制方法。在这种情况下,从Ti6Al4V车削过程中收集刀具的三轴加速度数据。为了利用采集到的原始加速度数据进行控制,对系统进行了有限脉冲响应(FIR)滤波、快速傅立叶变换(FFT)分析和积分处理。对系统进行了数学建模,建立了主动控制框图。采用主动振动控制后,系统的抖振明显减小。将主动控制后得到的图形幅值所形成的表面质量与实际制造结果所得到的数据进行了对比验证。
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引用次数: 1
FRACTURE PARAMETERS EVALUATION FOR THE CRACKED NONHOMOGENEOUS ENAMEL BASED ON THE FINITE ELEMENT METHOD AND VIRTUAL CRACK CLOSURE TECHNIQUE 基于有限元法和虚拟裂纹闭合技术的非均匀牙釉质裂纹断裂参数评估
IF 7.9 2区 工程技术 Q1 Engineering Pub Date : 2023-08-10 DOI: 10.22190/fume210619072c
Y. Cai, Liming Zhou, Ming Li
To accurately solve the fracture parameters of enamel, we have established computational nonhomogeneous enamel models and constructed the fracture element of enamel dumb nodes, based on the enamel mineral concentration, nonhomogeneous mechanical properties, and virtual crack closure technique. Through the commercial finite element software ABAQUS and the fracture element of the enamel dumb nodes, we have established the user subroutines UMAT and UEL, which enabled solving of the energy release rates of the nonhomogeneous enamel structure with cracks. The stress intensity factors of central cracks, three-point bend and compact stretched enamels, and double-edge notched stretched enamels are determined. By comparing them with analytical solutions, we have proved that the fracture element of the enamel dumb nodes is highly accurate, simple, and convenient. In addition, the cracks can be other elements rather than singular or special elements; they show versatility and other advantages. The stress intensity factor of the dental enamel can be solved more realistically. Thus, a new numerical method for prevention and treatment of dental diseases is provided.
为了准确求解牙釉质的断裂参数,基于牙釉质矿物浓度、非均质力学性能和虚拟裂纹闭合技术,建立了计算非均质牙釉质模型,构建了牙釉质哑节点断裂单元。通过商用有限元软件ABAQUS和釉质哑节点断裂单元,建立了用户子程序UMAT和UEL,实现了含裂纹的非均质釉质结构能量释放率的求解。确定了中心裂纹、三点弯曲紧致拉伸瓷釉和双面缺口拉伸瓷釉的应力强度因子。通过与解析解的比较,证明了牙釉质哑结的断裂单元具有较高的准确性、简单性和方便性。此外,裂缝可以是其他元素而不是单一或特殊元素;它们表现出多功能性和其他优点。牙釉质的应力强度因子可以更真实地求解。从而为预防和治疗牙病提供了一种新的数值方法。
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引用次数: 1
NONLINEAR VIBRATION RESPONSE OF PIEZOELECTRIC NANOSENSOR: INFLUENCES OF SURFACE/INTERFACE EFFECTS 压电纳米传感器的非线性振动响应:表面/界面效应的影响
IF 7.9 2区 工程技术 Q1 Engineering Pub Date : 2023-08-10 DOI: 10.22190/fume210612064k
Sayyid H. Hashemi Kachapi
In the present work, surface/interface energy effects for pull-in instability analysis on dimensionless natural frequency (DNF) and nonlinear dynamics response (NDR) of piezoelectric nanosensor (PENS) subjected to nonlinear electrostatic excitation and harmonic force are studied using Gurtin–Murdoch (GM) surface/interface energy approach. To achieve this purpose, the Hamilton’s approach, assumed mode and Lagrange–Euler’s theories and also arc-length continuation and complex averaging methods are used to investigate influences of surface/interface parameters of PENS such as Lame’s constants, residual stress, piezoelectric constants and mass density for analysis of pull-in instability voltage.
本文采用Gurtin-Murdoch (GM)表面/界面能方法,研究了压电纳米传感器(PENS)在非线性静电激励和谐波力作用下的无量纲固有频率(DNF)和非线性动力学响应(NDR)的表面/界面能对拉入失稳分析的影响。为此,采用Hamilton方法、假设模态和拉格朗日-欧拉理论以及弧长延延法和复平均法研究了拉梅常数、残余应力、压电常数和质量密度等表面/界面参数对拉入不稳定电压分析的影响。
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引用次数: 3
PULL-DOWN INSTABILITY OF THE QUADRATIC NONLINEAR OSCILLATORS 二次型非线性振子的下拉不稳定性
IF 7.9 2区 工程技术 Q1 Engineering Pub Date : 2023-08-10 DOI: 10.22190/fume230114007h
Ji-Huan He, Qian Yang, Chun-Hui He, Abdulrahman Alsolami
A nonlinear vibration system, over a span of convincing periodic motion, might break out abruptly a catastrophic instability, but the lack of a theoretical tool has obscured the prediction of the outbreak. This paper deploys the amplitude-frequency formulation for nonlinear oscillators to reveal the critically important mechanism of the pseudo-periodic motion, and finds the quadratic nonlinear force contributes to the pull-down phenomenon in each cycle of the periodic motion, when the force reaches a threshold value, the pull-down instability occurs. A criterion for prediction of the pull-down instability is proposed and verified numerically.
一个非线性振动系统,经过一段令人信服的周期运动,可能会突然爆发灾难性的不稳定,但缺乏理论工具使爆发的预测变得模糊。本文利用非线性振子的幅频公式揭示了伪周期运动的重要机理,发现二次非线性力对周期运动的每一个周期的拉下现象都有贡献,当力达到某一阈值时,就会发生拉下失稳。提出了下拉失稳的预测准则,并进行了数值验证。
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引用次数: 7
DESIGN AND OPTIMIZATION OF THE VARIABLE-DENSITY LATTICE STRUCTURE BASED ON LOAD PATHS 基于载荷路径的变密度点阵结构设计与优化
IF 7.9 2区 工程技术 Q1 Engineering Pub Date : 2023-08-10 DOI: 10.22190/fume220108017w
Fenghe Wu, H. Lian, Guobin Pei, Baosu Guo, Zhaohua Wang
Lattice structure is more and more widely used in engineering by replacing solid structure. But its mechanical performances are constrained by the external shape if the unit cells are directly filled in the design domain, and the traditional topology optimization methods are difficult to give the explicitly mechanical guidance for the distribution of internal unit cells. In this paper, a novel design and optimization method of variable-density lattice structure is proposed in order to simultaneously optimize the external shape and the internal unit cells. First of all, the envelope model of any given structure should be established, and the load paths need to be visualized by the theory of load path. Then, the design criteria of external shape are established based on the principle of smoother load paths in the structure. An index of load flow capacity is defined to indicate the load paths density and to control the density distribution of unit cells, and a detailed optimization strategy is given. Finally, three examples of a cantilever plate, an L-shaped bracket and a classical three-point bending beam are used to verify the method. The results show that the models designed by the proposed method have better mechanical performances, lower material usage and less printing time.
点阵结构逐渐取代实体结构,在工程中得到越来越广泛的应用。但如果在设计域内直接填充单元胞,其力学性能受到外部形状的限制,传统的拓扑优化方法难以对内部单元胞的分布给出明确的力学指导。本文提出了一种变密度点阵结构的设计与优化方法,以同时优化外部形状和内部单元格。首先,建立任意给定结构的包络模型,利用荷载路径理论实现荷载路径的可视化。然后,基于结构内载荷路径更平滑的原则,建立了结构外形状的设计准则。定义了负荷流容量指标来表示负荷路径密度和控制单元格的密度分布,并给出了详细的优化策略。最后,以悬臂板、l型支架和经典三点弯曲梁为例进行了验证。结果表明,采用该方法设计的模型具有较好的力学性能、较低的材料用量和较短的打印时间。
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引用次数: 0
RESEARCH ON THE FLUID-INDUCED EXCITATION CHARACTERISTICS OF THE CENTRIFUGAL PUMP CONSIDERING THE COMPOUND WHIRL EFFECT 考虑复合旋转效应的离心泵流体激振特性研究
IF 7.9 2区 工程技术 Q1 Engineering Pub Date : 2023-08-10 DOI: 10.22190/fume210528065z
Wenhao Zhou, Dongliang Yu, Yifan Wang, Junlin Shi, B. Gan
In order to study the correlation mechanism between the flow characteristics and the fluid-induced force under the compound whirl motion in the centrifugal pump, the RNG k-ε model is selected in this paper to simulate a low specific speed centrifugal pump with impeller eccentricity based on the N-S equation. The changes of fluid-induced force with impeller eccentricity and the unsteady flow characteristics of the internal flow field of centrifugal pump under different flow conditions and rotation speeds are investigated, and the relationship between the fluid-induced force of the impeller and the internal flow field characteristics is discussed. The results show that the trend of fluid-induced force and the pressure coefficient is similar. When the rotation speed changes and when the flow is similar, the pressure coefficient under different rotation speeds almost coincides. With the increase of impeller speed and impeller eccentricity, the dynamic and static interferences between the impeller and the volute tongue are more significant, the uneven distribution of the pressure around the impeller makes the internal flow of centrifugal pump more disordered and increases the fluid-induced force near the volute tongue. The research results can provide important reference value for accurately grasping the internal flow excitation principle of the centrifugal pump.
为了研究离心泵内复合旋转运动下流动特性与流体诱导力之间的关系机理,本文选取RNG k-ε模型,基于N-S方程对具有叶轮偏心的低比转速离心泵进行了数值模拟。研究了流体诱导力随叶轮偏心距的变化规律,以及不同工况和转速下离心泵内部流场的非定常流动特性,讨论了叶轮流体诱导力与内部流场特性的关系。结果表明,流体诱导力与压力系数的变化趋势相似。当转速变化和流量相同时,不同转速下的压力系数几乎一致。随着叶轮转速和叶轮偏心距的增大,叶轮与蜗壳隔舌之间的动、静干扰更加显著,叶轮周围压力分布的不均匀使得离心泵内部流动更加无序,增大了蜗壳隔舌附近的流体诱导力。研究结果可为准确掌握离心泵内部激励原理提供重要的参考价值。
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引用次数: 2
AN INVESTIGATION ON MEAN ROUGHNESS DEPTH AND MATERIAL EROSION SPEED DURING MANUFACTURING OF STAINLESS-STEEL MINIATURE RATCHET GEARS BY WIRE-EDM 不锈钢微型棘轮电火花加工过程中平均粗糙度深度和材料侵蚀速度的研究
IF 7.9 2区 工程技术 Q1 Engineering Pub Date : 2023-08-10 DOI: 10.22190/fume221220012c
S. K. Chaubey, K. Gupta, M. Madić
This paper presents the results of an investigation conducted on wire electric discharge machining (wire-EDM) of miniature ratchet gears. Effects of three important process parameters spark duration, ‘Ton’, spark-off-duration ‘Toff’, and wire tension ‘WT’ on surface quality, i.e., mean roughness depth ‘Rz’ and productivity, i.e., material erosion speed ‘MES’, have been investigated by conducting seventeen experimental trials. Both Ton and Toff have been identified as the significant parameters. Further, an optimization of wire-EDM parameters resulted in simultaneously best compromise values of Rz 5.30 µm and MES 6.75 mm/min and is achieved the following cutting regime: Ton 1.5 µs, Toff 42.5 µs, and WT 1500 g. At the end, surface quality study has been conducted to evaluate the tribological fitness of the miniature ratchet gear machined at optimum combination of wire-EDM parameter values. It was investigated that the generation of uniform and shallow craters on the flank surfaces of ratchet gear machined at optimum values of parameters, imparted smoother bearing area curve and lower coefficient of friction. The profile and flank surface of the ratchet gear also found free from cracks, burrs, and dirt.
本文介绍了小型棘轮齿轮的电火花加工研究结果。通过17次试验,研究了三个重要工艺参数火花持续时间“Ton”、火花关闭时间“Toff”和线材张力“WT”对表面质量(即平均粗糙度深度“Rz”)和生产率(即材料侵蚀速度“MES”)的影响。Ton和Toff都被确定为重要参数。此外,线切割参数的优化同时产生了Rz 5.30µm和MES 6.75 mm/min的最佳折衷值,并实现了以下切割模式:Ton 1.5µs, Toff 42.5µs, WT 1500 g。最后,进行了表面质量研究,以评价在电火花加工参数值的最佳组合下加工的微型棘轮齿轮的摩擦学适应性。研究了在最佳参数值下加工棘轮齿轮后侧面形成均匀的浅凹坑,使齿轮的承载面积曲线更光滑,摩擦系数更低。棘轮齿轮的轮廓和侧面也没有发现裂纹,毛刺和污垢。
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引用次数: 0
THE INFLUENCE OF DANCE CONTENTS ON THE PRESCHOOLERS MOTOR FITNESS AND THEIR POSSIBLE APPLICATION IN PRESCHOOL INSTITUTIONS CURRICULUM 舞蹈内容对学龄前儿童运动健身的影响及其在学前机构课程中的应用
2区 工程技术 Q1 Engineering Pub Date : 2023-08-07 DOI: 10.22190/futlte230531031d
Nenad Đorđević, Predrag Stojković, Romina Herodek, Xhelal Mustafa, Slavoljub Uzunović
This paper presents a research focused on dance contents, specific dance programs and preschool children motor fitness. The main goal of this paper was to collect and analyze studies that as an experimental treatment had the contents of dance activities and their impact on the preschool children motor fitness. The necessary literature and papers were collected through the following databases: Google Scholar, PubMed, SCI index and the available professional literature at the Faculty of Sport and Physical Education in Niš, as well as other available literature. The following keywords were used: influence, effects, preschool age, preschoolers, exercise, dance, dance activities, motor skills, motor skills and their adequate translation into English. Twelve papers that met the set criteria were selected for the final analysis. The following conclusion was drawn: there is a positive impact of dance contents on the preschool children motor fitness, therefore, they can be recommended for use as the adequate contents of the PE curricula in preschool institutions.
本文从舞蹈内容、具体舞蹈节目和学龄前儿童运动健身三个方面进行了研究。本文的主要目的是收集和分析作为实验治疗的舞蹈活动的内容及其对学龄前儿童运动健身的影响的研究。通过以下数据库收集必要的文献和论文:Google Scholar、PubMed、SCI索引和niis体育与体育学院的现有专业文献,以及其他可用文献。使用以下关键词:影响,效果,学龄前,学龄前儿童,锻炼,舞蹈,舞蹈活动,运动技能,运动技能及其适当的英语翻译。符合既定标准的12篇论文被选中进行最终分析。得出以下结论:舞蹈内容对学龄前儿童运动体能有积极的影响,因此可以推荐作为学前机构体育课程的适当内容使用。
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引用次数: 0
DESIGN OF FIRST ORDER DIFFERENTIATOR WITH PARALLEL ALL-PASS STRUCTURE 一阶并联全通结构微分器的设计
2区 工程技术 Q1 Engineering Pub Date : 2023-07-29 DOI: 10.22190/fuacr230324004s
Goran Stančić, Ivan Krstić, Saša S. Nikolić, Ivana Kostić
In this paper a new method for design of the first order differentiator is presented. The proposed differentiator consists of two parallel branches, i.e. direct path and IIR all-pass filter. The described design method allows one to obtain solution with minimum mean relative error at the desired region by controlling the ratio of phase response extremes. A small relative magnitude error, as well as a low phase error, at low frequencies is condition for good time domain behaviour. The obtained differentiator can be realized by means of only two multipliers, hence being a good choice for real time applications. The proposed solution provides a lower magnitude error than several known differentiators with similar phase error.
本文提出了一种设计一阶微分器的新方法。该微分器由两个平行分支组成,即直接路径和IIR全通滤波器。所描述的设计方法允许人们通过控制相响应极值的比率来获得在期望区域具有最小平均相对误差的解。小的相对幅度误差,以及低相位误差,在低频率是良好的时域行为的条件。所得到的微分器只需两个乘法器即可实现,因此是实时应用的良好选择。该方案提供了一个较小的幅度误差比几个已知的微分器具有相似的相位误差。
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引用次数: 0
TWO-PARTITION DISCRETE GLOBAL GRID SYSTEMS - A COMPARISON OF APPROACHES BASED ON ADJUSTED SPHERICAL CUBE AND CYLINDRICAL EQUIDISTANT PROJECTION 两分区离散全局网格系统——基于调整球立方和圆柱等距投影的方法比较
2区 工程技术 Q1 Engineering Pub Date : 2023-07-29 DOI: 10.22190/fuacr230322002d
Aleksandar Dimitrijević
The enormous volumes of geospatial data and the need to process and distribute them cry out for a unified framework that enables their efficient storage, analysis, and a high degree of interoperability. Discrete global grid systems provide such a framework by hierarchically tessellating cells to seamlessly partition and address the globe. Since they are usually based on a regular polyhedron, they partition the entire world into as many discrete data sets as the given polyhedron has sides. In this paper, we try to reduce the number of partitions to two, which is a minimum if we want to obtain spatially convex partitions without interruptions. Two approaches are presented, based on an adjusted spherical cube and an equidistant cylindrical projection. The distortions resulting from the application of these projections are compared and guidelines are presented to improve the quality of their implementation by reducing the distortion of the continental plates and making a better mapping to the WGS84 ellipsoid.
海量的地理空间数据以及处理和分发这些数据的需求迫切需要一个统一的框架,以实现有效的存储、分析和高度的互操作性。离散的全球网格系统提供了这样一个框架,通过分层镶嵌单元来无缝划分和处理全球。由于它们通常基于正多面体,因此它们将整个世界划分为给定多面体有多少边的离散数据集。在本文中,我们试图将分区的数量减少到两个,如果我们想要获得没有中断的空间凸分区,这是最小的。提出了两种方法:基于调整球面立方体和等距圆柱投影。比较了这些投影在应用中产生的畸变,并提出了通过减少大陆板块畸变和更好地映射到WGS84椭球来提高其实施质量的指导方针。
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引用次数: 0
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Facta Universitatis-Series Mechanical Engineering
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