Mechanics and Mechanical Engineering最新文献

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Synthetic jet actuator with two opposite diaphragms 具有两个相对隔膜的合成射流致动器

Q3 Engineering

Mechanics and Mechanical Engineering

Pub Date : 2020-09-01 DOI: 10.2478/mme-2020-0004

E. Smyk, S. Wawrzyniak, K. Peszyński

Abstract The synthetic jet actuators are one of the most investigated types of actuators used in heat transfer and active flow control. The energetic efficiency of actuators is a key parameter determining the possibility of device use. The actuators with two or more diaphragms have higher efficiency than the actuators with only one. The paper presents the investigations of the acoustic synthetic jet actuator with two opposite diaphragms. In the paper, synthetic jet velocity, Reynolds number and the energetic efficiency as a function of oscillating actuator frequency, for a different cavity, orifice configuration and one real input power P0 = 2 W were studied. The possibility of theoretical calculation of first and second resonance frequency were checked. The coupling ratio for actuators was calculated. The maximum energetic efficiency was η = 8.67% and Reynolds number Re = 8503. The possibility of using the same dependencies and rules during the design of actuators with two opposite diaphragms as in the case of actuators with one diaphragm was demonstrated. The results may be useful in the design of the actuators of the two membranes.

摘要合成射流执行器是目前研究最多的用于传热和主动流动控制的执行器之一。执行器的能量效率是决定装置使用可能性的关键参数。具有两个或多个膜片的执行器比只有一个膜片的执行器效率更高。本文研究了双相对膜片声合成射流作动器。本文研究了不同腔型、孔型和实际输入功率P0 = 2w时，合成射流速度、雷诺数和能量效率随执行器振荡频率的变化规律。验证了理论计算第一共振频率和第二共振频率的可能性。计算了各作动器的耦合比。最大能效率η = 8.67%，雷诺数Re = 8503。演示了在设计具有两个相反膜片的执行器时使用与具有一个膜片的执行器相同的依赖关系和规则的可能性。研究结果可为两种膜的致动器的设计提供参考。

引用次数: 10

The effect of dynamics of the swash plate–slippers–piston assembly on friction torques in bearings in compressor of cooling aggregate 斜盘-滑块-活塞总成动力学对冷却集料压缩机轴承摩擦力矩的影响

Q3 Engineering

Mechanics and Mechanical Engineering

Pub Date : 2020-09-01 DOI: 10.2478/mme-2020-0006

M. Woźniak, T. Szydłowski, K. Siczek

Abstract The swash plate type compressor utilized in car air conditioning devices and cooling system was analyzed in this study. Proper dynamic behavior of the components in such a compressor affected the correct functioning of the whole system. The aim of the study was to identify the characteristics of the main motion components in the swash plate–slippers–piston assembly of the compressor and to estimate the friction torques in its bearings. Some models of this assembly are elaborated and presented in the paper. The main components of slipper complex motion were identified, such as reciprocal motion along the axis of piston, rotation around piston axis, and short-time rotation around its own axis. Friction torque in axial bearing was higher than in journal bearing and varied with the rotational angle. Friction torques in journal bearings varied with the rotational angle and had different courses for two bearings of the compressor.

摘要对汽车空调装置及冷却系统中使用的斜盘式压缩机进行了分析。在这种压缩机中，部件的正确动态行为影响到整个系统的正确运行。研究的目的是确定压缩机斜盘-滑靴-活塞总成的主要运动部件的特性，并估计其轴承的摩擦力矩。文中详细介绍了该装配的一些模型。确定了滑靴复合运动的主要组成部分:沿活塞轴的往复运动、绕活塞轴的旋转运动以及绕自身轴的短时旋转运动。轴向轴承的摩擦力矩大于滑动轴承，且摩擦力矩随旋转角度的变化而变化。轴颈轴承的摩擦力矩随压缩机两个轴承的旋转角度而变化，且具有不同的行程。

引用次数: 0

Robotic machining in correlation with a 3D scanner 与3D扫描仪相关的机器人加工

Q3 Engineering

Mechanics and Mechanical Engineering

Pub Date : 2020-09-01 DOI: 10.2478/mme-2020-0003

K. Kurc, A. Burghardt, D. Szybicki, P. Gierlak, Wojciech Łabuński, M. Muszyńska, J. Giergiel

Abstract The article presents an original method of communication and data exchange in a robotic machining station consisting of two robots, a positioner and a 3D optic scanner. The task of one of the robots, equipped with a 3D optic scanner, was to receive point cloud of a detail (mould) attached to the positioner table. After detail digitalisation, the received point cloud was adjusted to (compared with) a model detail in the form of a CAD file in the Atos Professional software. In the software, casting material excesses were received in places selected on the detail. Values of the excesses and their coordinates were saved in the script and sent to the robot controller using TCP/IP protocol. The other of robots, equipped with the force control addition and the option of obtaining various processing tools, received sent excess and its coordinates. The other robot adjusted the processing parameters to random excesses, the value of which was received from measurements of the optic scanner of the first robot.

摘要本文介绍了一种在由两个机器人、一个定位器和一个三维光学扫描仪组成的机器人加工站中进行通信和数据交换的原始方法。其中一个配备了3D光学扫描仪的机器人的任务是接收附着在定位器台上的细节（模具）的点云。细节数字化后，将接收到的点云调整为（与）Atos Professional软件中CAD文件形式的模型细节。在软件中，在细节上选择的位置接收到铸造材料过量。多余的值及其坐标保存在脚本中，并使用TCP/IP协议发送到机器人控制器。另一个机器人，配备了力控制功能和获取各种加工工具的选项，接收发送的多余部分及其坐标。另一个机器人将处理参数调整为随机过量，其值是从第一个机器人的光学扫描仪的测量中接收的。

引用次数: 3

Design of Accurate Steering Gear Mechanism 精密舵机机构设计

Q3 Engineering

Mechanics and Mechanical Engineering

Pub Date : 2020-08-12 DOI: 10.2478/MME-2018-0009

V. Babu, P. G. Rao, K. S. Rao, B. Krishna

This article focuses on the synthesis of a steering mechanism that exactly meets the requirements of steering geometry. It starts from reviewing the four-bar linkage, then discusses the number of points that a common four-bar linkage could precisely trace at most. After pointing out the limits of a four-bar steering mechanism, this article investigates the turning geometry for steering wheels and proposes a steering mechanism using servo motors and ARDUINO board. The pitch curves, addendum curves, dedendum curves, tooth profiles and transition curves of the noncircular gears are formulated and designed. Finally, kinematic simulations are executed to demonstrate the target of design

本文的重点是合成一种完全满足转向几何要求的转向机构。首先回顾了四杆机构，然后讨论了普通四杆机构最多可以精确跟踪的点数。在指出四杆转向机构的局限性之后，本文研究了方向盘的转向几何，提出了一种采用伺服电机和ARDUINO板的转向机构。编制和设计了非圆齿轮的节曲线、齿顶曲线、齿根曲线、齿廓曲线和过渡曲线。最后，通过运动学仿真验证了设计目标

引用次数: 2

Comparative evaluation of diametral tensile strength of phosphate-bonded investment (ringless) material by using air-drying method, conventional hot air oven, microwave oven, and combination of microwave and conventional oven: An in vitro study. 使用风干法、传统热风炉、微波炉以及微波炉与传统炉相结合的方法对磷酸盐粘结投资（无环）材料的直径拉伸强度进行比较评估：体外研究。

Q3 Engineering

Mechanics and Mechanical Engineering

Pub Date : 2019-07-01 DOI: 10.4103/jips.jips_45_19

Akhil Rathi, Neelam Pande, Usha Radke, Saee Deshpande, Anuj Chandak

Aim: This study evaluated and compared the diametral tensile strength (DTS) of phosphate-bonded investment (PBI) material (ringless) used in removable cast partial denture fabrication.

Settings and design: Comparative - Invitro study.

Materials and methods: The PBI material, Wirovest used in this study was subjected to four different drying methods. A total of 80 specimens were prepared in a cylindrical form; 20 specimens were air dried for 2 h, 20 specimens were dried in a conventional oven at 230°C for 1 h, 20 specimens were dried in microwave oven at 600 W for 10 min, and remaining 20 specimens were dried first in microwave oven and then in conventional oven. The dried specimens were tested at 2-h interval for diametral compression at a crosshead speed of 0.5 cm/min.

Statistical analysis used: Pairwise analysis.

Results: The microwave drying technique and drying by combination method resulted in greater DTS, respectively.

Conclusion: Within the limitation of this study, PBI specimens dried in microwave oven at 600W for 10 min increased the diametral strength and are also a time-saving procedure.

目的：本研究评估并比较了用于可摘铸造局部义齿制作的磷酸盐粘结投资（PBI）材料（无环）的直径拉伸强度（DTS）：材料和方法：本研究中使用的 PBI 材料 Wirovest 采用了四种不同的干燥方法。共制备了 80 个圆柱形试样；20 个试样在空气中干燥 2 小时，20 个试样在 230°C 的传统烤箱中干燥 1 小时，20 个试样在 600 W 的微波炉中干燥 10 分钟，其余 20 个试样先在微波炉中干燥，然后在传统烤箱中干燥。干燥后的试样以 0.5 厘米/分钟的十字头速度进行直径压缩测试，测试间隔为 2 小时：结果：结果：微波干燥技术和组合干燥法分别获得了更大的DTS：结论：在本研究的局限范围内，在 600 瓦微波炉中干燥 10 分钟的 PBI 试样可提高直径强度，同时也是一种省时的方法。

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引用次数: 0

Application of Genetic Algorithm Technique for Machining Parameters Optimization in Drilling of Stainless Steel 遗传算法技术在不锈钢钻孔加工参数优化中的应用

Q3 Engineering

Mechanics and Mechanical Engineering

Pub Date : 2019-06-01 DOI: 10.2478/mme-2019-0036

T. Kannan, B. Kumar, G. Kannan, M. Umar, Mohammad Chand Khan

Abstract This work is aimed at developing relations between the pertinent variables that affect drilling process of stainless steel using artificial neural network. The experiments were conducted on vertical CNC machining centre. The parameters used were spindle speed and feed rate. The effect of machining parameters on entry burr height, exit burr height and surface roughness was experimentally evaluated for different spindle speeds and feed rates. A model was established between the drilling parameters and experimentally obtained data using ANN. The predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the burr height and surface roughness in drilling of stainless steel. Genetic algorithm (GA) technique was used in this work to identify the optimized drilling parameters. Confirmation test was conducted with the optimized parameters and it was found that confirmation test results were similar to that of GA-predicted output values.

摘要本工作旨在利用人工神经网络建立影响不锈钢钻孔过程的相关变量之间的关系。实验在立式数控加工中心上进行。使用的参数是主轴转速和进给速度。在不同主轴转速和进给速度下，实验评估了加工参数对毛刺高度、毛刺高度和表面粗糙度的影响。利用人工神经网络建立了钻孔参数与实验数据之间的模型。预测值与实测值相当接近，表明所建立的模型可以有效地预测不锈钢钻孔过程中的毛刺高度和表面粗糙度。采用遗传算法(GA)技术确定最优钻井参数。对优化后的参数进行验证试验，验证试验结果与ga预测输出值基本一致。

引用次数: 4

Resonance of Nanoscale Beam due to Various Sources in Modified Couple Stress Thermoelastic Diffusion with Phase Lags 具有相位滞后的修正耦合应力热弹性扩散中不同源纳米光束的共振

Q3 Engineering

Mechanics and Mechanical Engineering

Pub Date : 2019-06-01 DOI: 10.2478/mme-2019-0006

Rajneesh Kumar, S. Devi, Veena Sharma

Abstract This paper deals with the study of thermoelastic thin beam in a modified couple stress with three-phase-lag thermoelastic diffusion model subjected to thermal and chemical potential sources. The governing equations are derived by using the Euler-Bernoulli beam assumption and eigenvalue approach. The Laplace transform technique is employed to obtain the expressions for displacements, lateral deflection, temperature change, axial stress and chemical potential. A particular type of instantaneous and distributed sources is taken to show the utility of the approach. The general algorithm of the inverse Laplace transform is developed to compute the results numerically. The numerical results are depicted graphically to show the effects of phase lags, with and without energy dissipation on the resulting quantities. Some special cases are given.

摘要本文研究了在热、化学势源作用下，具有三相滞后热弹性扩散模型的修正耦合应力下的热弹性薄梁。利用欧拉-伯努利梁假设和特征值法推导了控制方程。采用拉普拉斯变换技术，得到了位移、横向挠度、温度变化、轴向应力和化学势的表达式。采用一种特定类型的瞬时和分布式源来展示该方法的实用性。为了对结果进行数值计算，提出了拉普拉斯逆变换的通用算法。数值结果用图形表示，以显示相位滞后、有无能量耗散对结果量的影响。给出了一些特殊情况。

引用次数: 5

Development of a cryogenic condenser and computation of its heat transfer efficiency based on liquefaction of nitrogen gas 基于氮气液化的低温冷凝器的研制及其传热效率计算

Q3 Engineering

Mechanics and Mechanical Engineering

Pub Date : 2019-06-01 DOI: 10.2478/mme-2019-0039

D. R. Chowdhury, N. Chakraborty, S. Sarkar

Abstract The typical cryogenic condenser described here transfers the refrigerating effect from its inner side to its outer side through the wall of the condenser. The separate close refrigeration cycle operates on Reverse Stirling Cycle using hydrogen or helium as working fluid. The nitrogen gas gets liquefied when it comes in contact with the cold outer surface of the condenser. We have successfully developed a cryogenic condenser using copper of electrolytic grade for a liquefaction duty of 10 liters of liquid nitrogen per hour. Condenser effectiveness is evaluated by assembling it in Cryogenerator model, ZIF-1002 and by noting the liquefaction rate. Both the results are satisfactory. Selection of material, fabrication, testing of the condenser developed for a Cryogenerator have been described in the paper to assess its suitability for a Cryogenerator based on Reverse Stirling cycle liquefier.

本文介绍的典型低温冷凝器通过冷凝器壁将制冷效果从其内侧传递到外侧。单独的封闭式制冷循环在使用氢气或氦气作为工作流体的反向斯特林循环上运行。氮气与冷凝器的冷外表面接触时会液化。我们已经成功地开发了一种使用电解级铜的低温冷凝器，液化能力为每小时10升液氮。冷凝器的有效性是通过将其组装在低温发生器型号ZIF-1002中并记录液化率来评估的。两个结果都令人满意。本文介绍了为低温发生器开发的冷凝器的材料选择、制造和测试，以评估其适用于基于反向斯特林循环液化器的低温发生器。

引用次数: 0

Load-carrying capacity of the GFRP and CFRP composite beams subjected to three-point bending test – numerical investigations GFRP和CFRP组合梁三点弯曲承载力的数值研究

Q3 Engineering

Mechanics and Mechanical Engineering

Pub Date : 2019-06-01 DOI: 10.2478/mme-2019-0037

D. Banat

Abstract The subject of this article is the finite element method (FEM) simulation of the multi-layered rectangular composite beam subjected to three-point bending test. The study is focused on the composite beams made of glass or carbon fibre-reinforced laminates (glass fibre-reinforced polymer [GFRP] and carbon fibre-reinforced polymer [CFRP]) for which different laminate stacking were addressed. Three beam geometries with various length-to-thickness ratios included short beam shear (SBS) test, provided the beam is short relative to its thickness, which maximised the induced shear stresses. Simulation included the application of Tsai–Hill, Hoffman, Tsai–Wu, Hashin and Puck failure criteria to perform the composite beam failure analysis wherein the matrix and fibre failure were considered separately. Numerical failure studies also aimed to verify the beam failure modes and the participation of stress tensor elements in material failure.

摘要本文的主题是对多层矩形组合梁进行三点弯曲试验的有限元模拟。该研究的重点是由玻璃或碳纤维增强层压板（玻璃纤维增强聚合物[GFRP]和碳纤维增强聚合物[CCFRP]）制成的复合梁，针对不同的层压板堆叠进行了研究。具有不同长度与厚度比的三种梁几何形状包括短梁剪切（SBS）试验，前提是梁相对于其厚度较短，从而最大化了诱导的剪切应力。模拟包括应用Tsai–Hill、Hoffman、Tsai–Wu、Hashin和Puck失效标准进行复合梁失效分析，其中分别考虑了基体和纤维失效。数值失效研究还旨在验证梁的失效模式以及应力张量单元在材料失效中的参与。

引用次数: 6

Investigation of the effect of thermal stress on the interface damage of hybrid biocomposite materials 热应力对杂化生物复合材料界面损伤影响的研究

Q3 Engineering

Mechanics and Mechanical Engineering

Pub Date : 2019-06-01 DOI: 10.2478/mme-2019-0034

S. Sadat, A. Mokaddem, B. Doumi, M. Berber, A. Boutaous

Abstract In this paper, we have studied the effect of thermal stress on the damage of fiber-matrix interface of a hybrid biocomposite composed of two natural fibers, Hemp, Sisal, and Starch matrix. Our genetic modeling used the nonlinear acoustic technique based on Cox’s analytical model, Weibull’s probabilistic model, and Lebrun’s model describing the thermal stress by the two coefficients of expansion. The stress applied to our representative elementary volume is a uni-axial tensile stress. The numerical simulation shows that the Hemp- Sisal/Starch hybrid biocomposite is most resistant to thermal stresses as compared with Hemp/Starch biocomposite. It also shows that hybrid biocomposite materials have a high resistance to applied stresses (mechanical and thermal) compared to traditional materials and biocomposite materials. The results obtained in our study coincide perfectly with the results of Antoine et al., which showed through experimental tests that natural fibers perfectly improve the mechanical properties of biocomposite materials.

摘要本文研究了热应力对由大麻、剑麻和淀粉基质两种天然纤维组成的杂化生物复合材料纤维-基质界面损伤的影响。我们的遗传建模使用了基于Cox分析模型、Weibull概率模型和Lebrun模型的非线性声学技术，通过两个膨胀系数来描述热应力。施加在我们的代表性基本体积上的应力是单轴拉伸应力。数值模拟表明，与大麻/淀粉生物复合材料相比，大麻-剑麻/淀粉杂化生物复合材料最能抵抗热应力。它还表明，与传统材料和生物复合材料相比，杂化生物复合材料对施加的应力（机械和热）具有较高的抵抗力。我们的研究结果与Antoine等人的研究结果完全一致，Antoine等通过实验测试表明，天然纤维完美地改善了生物复合材料的力学性能。

引用次数: 1

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