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Obtaining The Fracture Resistance Curve Using The General Displacement 用一般位移求断裂阻力曲线
IF 0.7 4区 工程技术 Q4 MECHANICS Pub Date : 2023-02-06 DOI: 10.5755/j02.mech.31368
Goksel Saracoglu
In this paper, the energy release energy corresponding to the unit crack propagation obtained from the displacement controlled load-displacement plot is equalized to the elastic energy release rate, and the variation of stiffness based on the crack length is obtained. For this purpose, instead of measuring the amount of crack mouth opening in the single edge-cracked tensile specimen, the extensiometer elongation amount was taken in the middle part of the specimen. Thanks to the equality of the stiffness to the crack length, the transformation of the load-displacement curve into the material resistance curve was realized.
在本文中,从位移控制的载荷-位移图中获得的对应于单位裂纹扩展的能量释放能量与弹性能量释放率相等,并获得了刚度基于裂纹长度的变化。为此,不是测量单边裂纹拉伸试样中的裂纹开口量,而是在试样的中间部分取伸长计伸长量。由于刚度与裂纹长度相等,实现了荷载-位移曲线向材料阻力曲线的转换。
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引用次数: 0
Investigation of the single point heating tool for the robotised incremen-tal polymer sheet forming process 单点加热工具在聚合物片材自动成型中的应用研究
IF 0.7 4区 工程技术 Q4 MECHANICS Pub Date : 2023-02-06 DOI: 10.5755/j02.mech.31366
D. Eidukynas, Baltramiejus Andrijaitis, V. Jūrėnas
Incremental sheet forming (ISF) technology is a suitable and flexible solution to create complex 3D geometries of the sheet. A sheet is gradually formed into the desired shape with a forming tool usually attached to a CNC machine or robot. This process is valid with metal as well as with polymer sheets. However, the inaccuracy of geometry and occurring process errors in previously discussed industries prove the novelty of the technology. In this research a novel single point heated toll with control system for incremental sheet forming process is proposed and investigated. Experimental research results revealed main heating parameters necessary for ISF and mechanical properties dependency from heating.
增量片材成形(ISF)技术是一种合适且灵活的解决方案,可以创建复杂的片材三维几何形状。用通常连接到CNC机器或机器人上的成形工具将片材逐渐成形为所需形状。该工艺适用于金属以及聚合物片材。然而,在先前讨论的行业中,几何形状的不准确和出现的工艺误差证明了该技术的新颖性。在本研究中,提出并研究了一种用于渐进式板材成形过程的新型单点加热带控制系统。实验研究结果揭示了ISF所需的主要加热参数以及加热对力学性能的依赖性。
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引用次数: 0
Research on intelligent formation operation performance of straddle-type rapid transit vehicles in heterogeneous operating environment 跨座式快速交通车辆在异构运行环境下的智能编队运行性能研究
IF 0.7 4区 工程技术 Q4 MECHANICS Pub Date : 2023-02-06 DOI: 10.5755/j02.mech.32110
Zixue Du, Haoxin Wu, Zhen Yang, X. Wen
This paper presents an intelligent formation operation mode (IFOM) based on straddle-type rapid transit vehicles. Taking the straddle-type rapid transit vehicles operating in IFOM as the object, the operation mode of the vehicle is defined in the control system architecture of the straddle-type rapid transit system. In addition, considering the heterogeneous operating environ-ment of formation vehicles, an evaluation index system for formation vehicles is proposed. Then, according to the vehicle longitudinal dynamics model and the artificial potential field formation algorithm, we build the formation vehicle operation controller. After that, referring to the vehicle dynamics model, a multi rigid body dynamics simulation model of formation vehicles in a heterogeneous operating environment is established. Finally, the operating performance of formation vehicles in heterogeneous operating environment is analyzed. The analysis results show that the operation performance of the formation vehicle meets the requirements of the evaluation index system, which proves the feasibility of the formation operation of straddle-type rapid transit vehicles operating in IFOM.
提出了一种基于跨坐式快速交通车辆的智能编队运行模式。以在IFOM中运行的跨座式快速交通车辆为对象,在跨座式高速交通系统的控制系统架构中定义了车辆的运行模式。此外,考虑到编队车辆运行环境的异质性,提出了编队车辆的评价指标体系。然后,根据车辆纵向动力学模型和人工势场形成算法,建立了编队车辆运行控制器。然后,参考车辆动力学模型,建立了编队车辆在非均质运行环境下的多刚体动力学仿真模型。最后,分析了编队车辆在异构作战环境下的作战性能。分析结果表明,编队车辆的运行性能符合评价指标体系的要求,证明了跨座式快速交通车辆在IFOM中运行编队运行的可行性。
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引用次数: 1
Electro-Hydraulic Load-Sensitive Simulation Study of Walking Hy-draulic System of Electric Agricultural Machinery 电动农机行走液压系统的电液负载敏感仿真研究
IF 0.7 4区 工程技术 Q4 MECHANICS Pub Date : 2022-12-05 DOI: 10.5755/j02.mech.31470
Hongyun Mu, Y. Luo, Yu-gong Luo
The conventional load-sensitive hydraulic drive chassis system for agricultural machinery uses a combination of engine and load-sensitive pump, which cannot adjust the control strategy according to the working conditions. It does not meet the current trend of energy-saving and emission reduction. To this end, an electro-hydraulic load-sensitive hydraulic drive chassis system for agricultural machinery, which uses a combination of permanent magnet synchronous motor and quantitative pump, is proposed. A variable LS differential pressure control and a variable differential pressure control of the pressure compensation valve to improve agricultural machinery's working performance are proposed. AMESim is used to establish the system simulation model to obtain the system composite motion, variable LS differential pressure control, and variable pressure differential control of the pressure compensation valve performance. The simulation results show that the system achieves the essential functions of a conventional load-sensitive system. The variable LS differential pressure control and the variable pressure differential control of the pressure compensation valve are feasible. They can effectively improve the performance of agricultural machinery to adapt to working conditions. It can effectively reduce the system energy consumption and provide a theoretical basis for the intellectualization of electric agricultural machinery.
传统的农业机械负载敏感液压驱动底盘系统使用发动机和负载敏感泵的组合,不能根据工作条件调整控制策略。它不符合当前节能减排的趋势。为此,提出了一种采用永磁同步电机和定量泵相结合的农业机械电液负载敏感液压驱动底盘系统。为了提高农业机械的工作性能,提出了一种变LS压差控制和压力补偿阀的变压差控制方法。利用AMESim建立系统仿真模型,得到系统复合运动、变LS压差控制、变压差控制的压力补偿阀性能。仿真结果表明,该系统实现了传统负载敏感系统的基本功能。可变LS压差控制和压力补偿阀的可变压差控制是可行的。它们可以有效地提高农业机械的性能以适应工作条件。可以有效降低系统能耗,为电动农业机械的智能化提供理论依据。
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引用次数: 0
Comparative Analysis of Temperature Field and Stress Field of TC4 Ti-tanium Alloy Joint Between CMT and MIG Welding CMT焊与MIG焊TC4钛合金接头温度场与应力场对比分析
IF 0.7 4区 工程技术 Q4 MECHANICS Pub Date : 2022-12-05 DOI: 10.5755/j02.mech.31491
Rui Zhang, X. Gu, Yuxian Meng, Lijuan Zhu
A model was used for the cold metal transfer (CMT) welding based on the volume heat flux distribution of double ellipsoids loaded with time intervals. The temperature field and stress field of TC4 titanium alloy were numerically simulated by ANSYS software. The distribution laws of temperature, residual stress and post-weld deformation during CMT and MIG welding were studied and compared. It was found that the maximum temperature of the molten pool in CMT welding was fluctuating and rising during the loading process, while the temperature of the molten pool in MIG welding was rising smoothly and the maximum temperature was higher than that in CMT welding. The welding stress field was analyzed by thermal-stress coupling analysis. The stress distribution simulated based on the MIG welding heat source was similar to CMT welding, but the maximum von Mises stress was greater than that of CMT welding. Due to the cooling shrinkage, both of them would produce angular deformation after welding. And the maximum angular deformation simulated based on the MIG welding heat source was greater than that of CMT welding. It was proved by welding simulation that CMT welding could reduce welding heat input and residual stress and deformation after welding.
基于双椭球体体积热通量随时间间隔的分布,建立了冷态金属转移焊接模型。利用ANSYS软件对TC4钛合金的温度场和应力场进行了数值模拟。研究并比较了CMT和MIG焊接过程中温度、残余应力和焊后变形的分布规律。研究发现,在加载过程中,CMT焊接熔池的最高温度呈波动上升趋势,而MIG焊接熔池温度平稳上升,最高温度高于CMT焊接。采用热应力耦合分析方法对焊接应力场进行了分析。基于MIG焊接热源模拟的应力分布与CMT焊接相似,但最大von Mises应力大于CMT焊接。由于冷却收缩,两者在焊接后都会产生角变形。基于MIG焊接热源模拟的最大角变形大于CMT焊接。焊接仿真结果表明,CMT焊接可以减少焊接热输入,减少焊后残余应力和变形。
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引用次数: 1
Damage Model of Bridge Bearing and Its Influence on Train-Track-Bridge Dynamic System 桥梁轴承损伤模型及其对列车-轨道-桥梁动力系统的影响
IF 0.7 4区 工程技术 Q4 MECHANICS Pub Date : 2022-12-05 DOI: 10.5755/j02.mech.30995
Xinmeng Ke, Fusheng Li, Zhaowei Chen
Bridge bearing damage is unavoidable in railway engineering. This work presents an investigation on the damage model of bridge bearing and its influence on the dynamic responses of the high-speed train-track-bridge system. Primarily, the mathematical description of bridge bearing damage model is explained in detail, which is then compared with the traditional linear model. Then a 3D train-track-bridge dynamic model considering bearing damage is established based on the train-track-bridge dynamic interaction theory. Adopting the model, the influences of single-point-damage and multi-point-damage on the dynamic behaviors of the coupled system are deeply investigated. Results show that the calculated obtained by the proposed model and the traditional linear model are different, especially in frequency-domain. Compared to results of traditional linear model, the results obtained by the proposed model are smaller due to the additional damping effect. Bridge bearing damage has almost no influence on the train vibrations, while has great effect on bridge vibrations. The damage in z-direction mainly affects the vertical vibrations, while damage in y-direction mainly influences the lateral vibrations. Among all the damaged bearings in this work, the influence of damage in x-direction has the least influence on the system. The damage in the fixed bearing is larger than that in other bearings, indicating that more attentions should be paid to the health monitoring of fixed bearings in railway engineering.
桥梁支座损坏是铁路工程中不可避免的问题。本文研究了桥梁支座的损伤模型及其对高速列车-轨道-桥梁系统动力响应的影响。首先详细阐述了桥梁轴承损伤模型的数学描述,并与传统的线性模型进行了比较。然后,基于列车-轨道-桥梁动力相互作用理论,建立了考虑轴承损伤的列车-轨道-桥梁三维动力模型。采用该模型,深入研究了单点损伤和多点损伤对耦合系统动力学行为的影响。结果表明,该模型的计算结果与传统线性模型的计算结果有很大的不同,特别是在频域上。与传统线性模型的结果相比,由于附加阻尼的影响,该模型得到的结果较小。桥梁支座损伤对列车振动几乎没有影响,而对桥梁振动有较大影响。z方向损伤主要影响竖向振动,y方向损伤主要影响横向振动。在所有损坏的轴承中,x方向的损坏对系统的影响最小。固定轴承的损伤大于其他轴承的损伤,说明在铁路工程中应更加重视固定轴承的健康监测。
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引用次数: 0
Experimental Investigation of Thermal and Humidity Dynamics in the Enclosures Made of Non-Permeable Walls 非渗透墙围护结构的湿热动力学实验研究
IF 0.7 4区 工程技术 Q4 MECHANICS Pub Date : 2022-12-05 DOI: 10.5755/j02.mech.32240
Z. Staliulionis, G. Miliauskas, L. Paukštaitis, A. Balčius
The usage of electronics in outdoor environment is growing therefore the control of moisture related failures in electronics are becoming more important. The main cause of these failures is the humidity inside electronics which may condense on the surfaces or components. To protect electronics from harsh environment, the components and electronics are encapsulated by using electronics enclosures, however it does not prevent from moisture ingress through plastic walls, gaskets, cable feedthroughs and etc. Thus, to control the humidity, it is very important to understand the humidity ingress and behaviour in the electronics enclosures. Hence, the paper concerns the study of temperature and moisture dynamics when electronics enclosure is exposed to a cyclic temperature condition according to MIL-STD-810F. Two different enclosures were selected for the experiment, namely, aluminum enclosure and glass jar. The study was carried out in a climatic chamber and the measurements of temperature and relative humidity were performed using sensors. Different effect of enclosure material was considered for humidity ingress. In aluminum enclosure, results showed that the temperature difference between different points are smaller than in case of glass jar. Different temperatures in enclosures are determined by different boundary conditions outside the enclosure caused by the climatic chamber.
电子设备在户外环境中的使用越来越多,因此控制电子设备中与湿气相关的故障变得越来越重要。这些故障的主要原因是电子设备内部的湿度可能会凝结在表面或部件上。为了保护电子设备免受恶劣环境的影响,使用电子设备外壳封装组件和电子设备,但不能防止湿气通过塑料壁、垫圈、电缆引线等进入。因此,为了控制湿度,了解电子设备外壳中的湿度进入和行为非常重要。因此,本文关注的是根据MIL-STD-810F对电子外壳暴露在循环温度条件下时的温度和湿度动力学的研究。实验选择了两种不同的外壳,即铝外壳和玻璃罐。这项研究是在气候室中进行的,使用传感器测量温度和相对湿度。考虑了外壳材料对湿度进入的不同影响。结果表明,在铝外壳中,不同点之间的温差小于玻璃罐的情况。外壳内的不同温度由气候室引起的外壳外的不同边界条件决定。
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引用次数: 0
Effects of Machining Parameters on Electrochemical Multi-Field Coupling 加工参数对电化学多场耦合的影响
IF 0.7 4区 工程技术 Q4 MECHANICS Pub Date : 2022-12-05 DOI: 10.5755/j02.mech.31499
Y. Chen, Xiang Li, Yichi Zhang, Jinyang Liu
Electrochemical machining involves three couplings between electric field, flow field and thermal field. The precipitation of hydrogen on the surface of the cathode will affect the entire electrochemical machining process and the final machining quality of the workpiece. Finite element software is used to analyze the effects of different voltages, electrolyte inlet pressure and interelectrode gap on current density, hydrogen volume fraction, conductivity and temperature distribution in this article. The research results show that the increase of processing voltage will increase the current density, hydrogen volume fraction and temperature, and decrease the conductivity of the solution. As the pressure of the electrolyte increases, the current density and conductivity increase, but the hydrogen volume fraction and temperature decrease. The current density, hydrogen volume fraction and temperature decrease, and the conductivity increases when the gap between electrodes increases. At the inlet, the current density and conductivity are relatively large, and gradually decrease along the electrolyte flow direction, while the hydrogen volume fraction and temperature are the smallest at the inlet, and gradually accumulate along the electrolyte flow direction, and reach the maximum at the outlet. Through multi-physics coupling simulation, the current density, temperature, conductivity and bubble distribution in electrochemical machining can be predicted, which can provide a theoretical basis for actual electrochemical machining process parameter selection.
电化学加工涉及电场、流场和热场的三种耦合。阴极表面氢气的析出将影响整个电化学加工过程和工件的最终加工质量。本文采用有限元软件分析了不同电压、电解质入口压力和电极间隙对电流密度、氢体积分数、电导率和温度分布的影响。研究结果表明:加工电压的升高会使溶液的电流密度、氢体积分数和温度升高,并降低溶液的电导率。随着电解液压力的增加,电流密度和电导率增加,但氢的体积分数和温度降低。随着电极间隙的增大,电流密度、氢体积分数和温度降低,电导率提高。在进口处,电流密度和电导率较大,沿电解质流动方向逐渐减小,而氢气体积分数和温度在进口处最小,沿电解质流动方向逐渐积累,在出口处达到最大值。通过多物理场耦合仿真,可以预测电化学加工中的电流密度、温度、电导率和气泡分布,为实际电化学加工工艺参数的选择提供理论依据。
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引用次数: 1
Helical Baffle Thermohydraulic Performance Versus Segmental Baffle One 螺旋折流板与节段折流板的热水力性能比较
IF 0.7 4区 工程技术 Q4 MECHANICS Pub Date : 2022-12-05 DOI: 10.5755/j02.mech.31096
M. Yousfi
In this contribution, we reworked the Bell-Delaware technique for a HB-STHX to systematically study its thermohydraulic performance behavior in the shell side. The helical baffles are continuous quadrant sectors with five inclination angles 25°, 30°, 35°, 40° and 45° and are exanimated for six different values of Reynolds number  from  up to 40 . We have observed an increase in global heat transfer rate while a decrease in pressure loss, in continuous helical baffle case compared to segmental one. we have found that the baffle inclination 40° has the largest heat transfer coefficient, 25° gives the lowest pressure drop, whereas 45°, the largest inclination we have used, displays the greatest performance evaluation factor.
在这篇论文中,我们对HB-STHX的Bell-Delaware技术进行了重新设计,系统地研究了它在壳侧的热液性能行为。螺旋挡板是连续的象限扇形,有5个倾角25°、30°、35°、40°和45°,并可检测6种不同的雷诺数值,最高可达40。我们观察到,与分段式挡板相比,连续式螺旋挡板的整体传热率增加,压力损失减少。我们发现挡板倾角为40°时传热系数最大,25°时压降最小,而倾角为45°时性能评价因子最大。
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引用次数: 0
The Effect of Mixing Recirculated Flue Gas with Primary or Secondary Air during Biomass Combustion in Grate-Firing Boiler as the Primary Measure for NOx Reduction 炉排锅炉生物质燃烧过程中再循环烟气与一次或二次风混合作为NOx减排主要措施的效果
IF 0.7 4区 工程技术 Q4 MECHANICS Pub Date : 2022-12-05 DOI: 10.5755/j02.mech.31475
Giedrius Jomantas, K. Buinevičius
Due to the pollutant regulations of the Directive (EU) 2015/2193, the need to reduce the emissions of pollutant compounds such as NOx is of a great importance for industrial boilers. This study was performed to determine the effect of primary measures in reducing said pollutants by mixing primary or secondary air with FGR and supplying the mixture for combustion. The studies were conducted on low-scale industrial biomass grate-firing furnace and boiler stand of 25 kW. Sunflower husk pellets, shredded pine bark and wood pellets were combusted during these experiments and emissions of NOx in their combustion products were analyzed. The most significant reduction of emissions was achieved by mixing primary air and FGR and supplying it to the primary combustion zone – under the grate. The emissions of NOx were reduced by 29% and 15% for shredded pine bark and sunflower husk pellets respectively. The emissions of shredded pine bark were reduced enough to meet the standards of the EU Directive, unlike those of sunflower husk pellets. The possible ways to reach greater reduction of NOx by using primary measures are implementing staged combustion, supplying pure FGR and/or mixing agriculture waste with fuels containing less N in its composition.
由于指令(EU)2015/2193的污染物法规,减少NOx等污染物化合物的排放对工业锅炉来说非常重要。进行这项研究是为了确定通过将一次或二次空气与FGR混合并提供混合物用于燃烧来减少所述污染物的主要措施的效果。在小型工业生物质炉排燃烧炉和25kW锅炉台上进行了试验研究。在试验过程中,对葵花皮颗粒、松皮碎和木屑颗粒进行了燃烧,并对其燃烧产物中的NOx排放进行了分析。通过混合一次空气和FGR并将其供应到炉排下的一次燃烧区,实现了最显著的减排。松皮碎颗粒和向日葵壳颗粒的NOx排放量分别减少了29%和15%。松皮碎片的排放量减少到足以满足欧盟指令的标准,这与向日葵壳颗粒不同。通过使用主要措施实现更大程度减少NOx的可能方法是实施分级燃烧、提供纯FGR和/或将农业废物与成分中含氮较少的燃料混合。
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引用次数: 0
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Mechanika
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