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Bending and rotational behaviour of semi-continuous composite beams

WANG Jingfeng, LI Guoqiang

《结构与土木工程前沿（英文）》 2008年第2卷第2期页码 116-122 doi: 10.1007/s11709-008-0015-9

摘要： Stresses and deflections were measured in various semi-continuous composite beams. The bending and rotational capacities of the composite connections were measured in terms of beam curvatures and deflections by using two full-scale semi-rigid composite frames with monotonic loadings. The effect of semi-rigid connections on the performance of composite beams with various loadings was compared with predictions and codes. The tests show that the semi-continuous composite beams are more economic and effective than the simple or continuous composite beams. The semi-rigid connections affect the bending capacities and beam deflections, so the connection behavior should be considered in the design of composite beams. Yielding analysis of the steel beam bottom flange has some influence on the deflection calculation of composite beams.

关键词： rotational effective deflection calculation semi-continuous composite full-scale semi-rigid

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properties of friction stir welded aluminum alloy joints based on axial force, traverse speed, and rotational

Biranchi PANDA,A. GARG,Zhang JIAN,Akbar HEIDARZADEH,Liang GAO

《机械工程前沿（英文）》 2016年第11卷第3期页码 289-298 doi: 10.1007/s11465-016-0393-y

摘要：

Friction stir welding (FSW) process has gained attention in recent years because of its advantages over the conventional fusion welding process. These advantages include the absence of heat formation in the affected zone and the absence of large distortion, porosity, oxidation, and cracking. Experimental investigations are necessary to understand the physical behavior that causes the high tensile strength of welded joints of different metals and alloys. Existing literature indicates that tensile properties exhibit strong dependence on the rotational speed, traverse speed, and axial force of the tool that was used. Therefore, this study introduces the experimental procedure for measuring tensile properties, namely, ultimate tensile strength (UTS) and tensile elongation of the welded AA 7020 Al alloy. Experimental findings suggest that a welded part with high UTS can be achieved at a lower heat input compared with the high heat input condition. A numerical approach based on genetic programming is employed to produce the functional relationships between tensile properties and the three inputs (rotational speed, traverse speed, and axial force) of the FSW process. The formulated models were validated based on the experimental data, using the statistical metrics. The effect of the three inputs on the tensile properties was investigated using 2D and 3D analyses. A high UTS was achieved, including a rotational speed of 1050 r/min and traverse speed of 95 mm/min. The results also indicate that 8 kN axial force should be set prior to the FSW process.

关键词： tensile properties ultimate tensile strength tensile elongation friction stir welding tool rotational speed genetic programming welding speed

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Design and analysis of a class of redundant collaborative manipulators with 2-dimension large rotational

Xiaodong JIN, Yuefa FANG, Dan ZHANG, Xueling LUO

《机械工程前沿（英文）》 2020年第15卷第1期页码 66-80 doi: 10.1007/s11465-019-0570-x

摘要： The parallel spindle heads with high rotational capability are demanded in the area of multi-axis machine tools and 3D printers. This paper focuses on designing a class of 2R1T (R: Rotation; T: Translation) parallel spindle heads and the corresponding collaborative 5-axis manipulators with 2-dimension (2D) large rotational angles. In order to construct 2D rotational degrees of freedom (DOF), a platform with 2-dimension revolute joints is proposed first. Based on the constraint screw theory, the feasible limbs that can be connected in the platform are synthesized. In order to provide constant rotational axis for the platform, a class of redundant limbs are designed. A class of redundant 2R1T parallel spindle heads is obtained by connecting the redundant limbs with the platform and the redundant characteristics are verified by the modified Grübler-Kutzbach criterion. The corresponding 5-axis collaborative manipulators are presented by constructing a 2-DOF series translational bottom moving platform. The inverse kinematics and the orientation workspace as well as the decoupling characteristics of this type of 2R1T parallel spindle heads are analyzed. The results show that these manipulators have large 2D rotational angles than the traditional A3/Z3 heads and can be potentially used in the application of multi-axis machine tools and the 3D printers.

关键词： parallel mechanism redundant mechanism large rotational angles machine tools 2R1T spindle head collaborative manipulator

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Soft curvature sensors for measuring the rotational angles of mechanical fingers

Haixiao LIU, Li LI, Zhikang OUYANG, Wei SUN

《机械工程前沿（英文）》 2020年第15卷第4期页码 610-621 doi: 10.1007/s11465-020-0596-0

摘要： The design, fabrication, and testing of soft sensors that measure elastomer curvature and mechanical finger bending are described in this study. The base of the soft sensors is polydimethylsiloxane (PDMS), which is a translucent elastomer. The main body of the soft sensors consists of three layers of silicone rubber plate, and the sensing element is a microchannel filled with gallium-indium-tin (Ga-In-Sn) alloy, which is embedded in the elastomer. First, the working principle of soft sensors is investigated, and their structure is designed. Second, the relationship between curvature and resistance is determined. Third, several sensors with different specifications are built in accordance with the structural design. Experiments show that the sensors exhibit high accuracy when the curvature changes within a certain range. Lastly, the soft sensors are applied to the measurement of mechanical finger bending. Experiments show that soft curvature sensors can effectively reflect mechanical finger bending and can be used to measure the bending of mechanical fingers with high sensitivity within a certain working range.

关键词： soft sensor Ga-In-Sn alloy strain sensing curvature sensing mechanical finger bending

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一种新型转子式陀螺的分辨率为0.47″的转子微偏转角度检测方法 Article

Hai LI, Xiao-wei LIU, Rui WENG, Hai-feng ZHANG

《信息与电子工程前沿（英文）》 2017年第18卷第5期页码 591-598 doi: 10.1631/FITEE.1500454

摘要：差分电容检测被广泛应用于振动陀螺仪质量块的位移测量，然而由于结构、理论以及接口电路等因素的限制其在转子式陀螺所需的转子偏转角度检测方面还尚未取得较高分辨率。本文提出了一种差分电容检测结构，用以测量一种新型转子式陀螺转子的偏转角度。本文建立了结构电容与转子偏转角度之间关系的数学模型，分析了差分电容与结构参数之间的关系，并获得了初步优化的尺寸参数。设计了一款低噪声读出接口电路将差分电容的变化转换为电压信号。对陀螺仪的转台测试结果表明，该角度检测结构的最小可分辨的偏转角度小于0.47″（0.00013°），三次多项式补偿后检测结构的非线性可达0.33%，并可进一步提高。结果表明该检测结构和电路有助于实现该陀螺仪的高精度。

关键词：微角度检测；差分电容结构；转子式陀螺

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Development of an analytical model to estimate the churning losses in high-speed axial piston pumps

《机械工程前沿（英文）》 2022年第17卷第2期 doi: 10.1007/s11465-021-0671-1

摘要： The axial piston pumps in aerospace applications are often characterized by high-speed rotation to achieve great power density. However, their internal rotating parts are fully immersed in the casing oil during operation, leading to considerable churning losses (more than 10% of total power losses) at high rotational speeds. The churning losses deserve much attention at the design stage of high-speed axial piston pumps, but accurate analytical models are not available to estimate the drag torque associated with the churning losses. In this paper, we derive the analytical expressions of the drag torque acting on the key rotating parts immersed in oil, including the cylinder block and the multiple pistons in a circular array. The calculated drag torque agrees well with the experimental data over a wide range of rotational speeds from 1500 to 12000 r/min. The presented analytical model provides practical guidelines for reducing the churning losses in high-speed axial piston pumps or motors.

关键词： axial piston pump rotating parts high rotational speed churning losses drag torque

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Scrutiny of non-linear differential equations Euler-Bernoulli beam with large rotational deviation by

M. R. AKBARI,M. NIMAFAR,D. D. GANJI,M. M. AKBARZADE

《机械工程前沿（英文）》 2014年第9卷第4期页码 402-408 doi: 10.1007/s11465-014-0316-8

摘要：

The kinematic assumptions upon which the Euler-Bernoulli beam theory is founded allow it to be extended to more advanced analysis. Simple superposition allows for three-dimensional transverse loading. Using alternative constitutive equations can allow for viscoelastic or plastic beam deformation. Euler-Bernoulli beam theory can also be extended to the analysis of curved beams, beam buckling, composite beams and geometrically nonlinear beam deflection. In this study, solving the nonlinear differential equation governing the calculation of the large rotation deviation of the beam (or column) has been discussed. Previously to calculate the rotational deviation of the beam, the assumption is made that the angular deviation of the beam is small. By considering the small slope in the linearization of the governing differential equation, the solving is easy. The result of this simplification in some cases will lead to an excessive error. In this paper nonlinear differential equations governing on this system are solved analytically by Akbari-Ganji’s method (AGM). Moreover, in AGM by solving a set of algebraic equations, complicated nonlinear equations can easily be solved and without any mathematical operations such as integration solving. The solution of the problem can be obtained very simply and easily. Furthermore, to enhance the accuracy of the results, the Taylor expansion is not needed in most cases via AGM manner. Also, comparisons are made between AGM and numerical method (Runge-Kutta 4th). The results reveal that this method is very effective and simple, and can be applied for other nonlinear problems.

关键词： AGM critical load of columns large deformations of beam nonlinear differential equation

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Vibratory behaviors of Jeffcott system on cylindrical roller bearings

Hao WU, Jianwen WANG, Qi AN

《机械工程前沿（英文）》 2009年第4卷第3期页码 305-309 doi: 10.1007/s11465-009-0036-7

摘要： A Jeffcott rotor system of cylindrical roller bearings is studied in detail. Its critical speed is calculated by a new calculation method with roller bearing stiffness and damping. The influences of bearing parameters, such as the roller length, rotor mass, distance between the bearings and the kinematics viscosity of oil on the system critical speed are numerically studied, and the influences of an oil film and damping on the critical speed are also studied. Regular curves of the relationship between the geometric parameters and the system critical speed are obtained. The results show that with increasing roller length and radial load, the critical speed increases; and with increasing rotor mass and the distance between the bearings and the kinematics viscosity, the critical speed decreases. This means that an oil film will decrease the critical rotational speed of the rotor system.

关键词： roller bearing bearing-rotor system design value critical rotational speed

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Investigation of vortical flows over oscillating body using fast Lagrangian vortex method

Baoshan ZHU ,

《能源前沿（英文）》 2009年第3卷第3期页码 297-306 doi: 10.1007/s11708-009-0010-4

摘要： A computational method facilitating long-time and high-resolution unsteady vortical flows is developed with the advantages of the discrete vortex methods. Both the velocity and pressure distribution of the flow field are calculated by integral formulations in combination with a fast summation algorithm. The vorticity field is described by Lagrangian representation, which is well suited to the moving boundary. Viscosity diffusion of the vorticity is considered with the core spreading model corrected by an adaptive splitting and merging algorithm. The effectiveness of the present method is examined by comparing the numerical results of unsteady separated flows which pass a cylinder and a thin cambered blade undergoing rotational oscillations with available experimental results. Interesting results about vortex shedding patterns and lock-in characteristics are provided for the thin cambered blade.

关键词： unsteady vortical flows fast vortex method vortex shedding rotational oscillation thin cambered blade

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Dynamic response of a long span suspension bridge and running safety of a train under wind action

GUO Weiwei, XIA He, XU You-lin

《结构与土木工程前沿（英文）》 2007年第1卷第1期页码 71-79 doi: 10.1007/s11709-007-0007-1

摘要： A dynamic analysis model of a wind-train-bridge system is established. The wind excitations of the system are the buffeting and self-excited forces simulated in time domain using measured aerodynamic coefficients and flutter derivatives. The proposed formulations are then applied to a long rail-cum-road suspension bridge. The dynamic responses of the bridge and the train under wind action are analyzed. The results show that the lateral and rotational displacements of the bridge are dominated by wind, while the vertical by the gravity loading of the moving train. The running safeties of the train vehicles are much affected by wind. Under wind conditions of 30 40 m/s, the offload factors, derail factors and overturn factors of the train vehicles exceed the safety allowances, to which great attention should be paid.

关键词： rotational offload vertical m/s attention

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Implementation of total Lagrangian formulation for the elasto-plastic analysis of plane steel frames exposed to fire

Bing XIA, Yuching WU, Zhanfei HUANG

《结构与土木工程前沿（英文）》 2012年第6卷第3期页码 257-266 doi: 10.1007/s11709-012-0163-9

摘要： In this paper, the co-rotational total Lagrangian forms of finite element formulations are derived to perform elasto-plastic analysis for plane steel frames that either experience increasing external loading at ambient temperature or constant external loading at elevated temperatures. Geometric nonlinearities and thermal-expansion effects are considered. A series of programs were developed based on these formulations. To verify the accuracy and efficiency of the nonlinear finite element programs, numerical benchmark tests were performed, and the results from these tests are in a good agreement with the literature. The effects of the nonlinear terms of the stiffness matrices on the computational results were investigated in detail. It was also demonstrated that the influence of geometric nonlinearities on the incremental steps of the finite element analysis for plane steel frames in the presence of fire is limited.

关键词： co-rotational total Lagrangian geometrical nonlinearity fire elasto-plastic

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海洋二号卫星大惯量旋转部件干扰力矩抑制技术

周勇,李正军,马超,王小宁

《中国工程科学》 2014年第16卷第3期页码 43-49

摘要：

海洋二号（HY-2A）卫星要求微波散射计和微波辐射计实现扫描过程中所产生的力矩波动不能影响卫星姿态稳定度。这两个载荷使用永磁同步电动机矢量控制，对负载直接驱动；通过电机本体采用齿槽转矩优化设计、采用固定角度计时法消除量化误差、相电流测量误差控制、逆变器死区补偿等措施，抑制转矩波动。通过电机本体和控制策略进行联合精确模型仿真，分析了系统的转矩波动。由在轨遥测数据分析可得，实现了大惯量旋转部件的精确控制。

关键词：大惯量力矩波动量化误差死区精确模型

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Research on transmission principle and kinematics analysis for involute spherical gear

PAN Cun-yun, WEN Xi-sen, YANG Kun-yu, XU Xiao-jun, LIU Min, YAO Qi-shui

《机械工程前沿（英文）》 2006年第1卷第2期页码 183-193 doi: 10.1007/s11465-006-0010-6

摘要： A new kind of transmission-type spherical gear called ring involute spherical gear mechanism is introduced. Compared to the famous TRALLFA spherical gear, this new spherical gear has an involute tooth profile, and a ring tooth that is distributed continuously on the surface of the sphere. This allows the gear to overcome two disadvantages of the TRALLFA spherical gear: the drive principle error and the manufacturing difficulty. The new transmission and the formation principle of the tooth s surface of the new spherical gear mechanism are first introduced, then another mechanism, called disk rack, is introduced, which is derived from the spherical gear mechanism when one of the spherical gear s tooth number reaches infinity. To make the research more convenient, every part of the new spherical gear mechanism is named. In the following sections, some problems are discussed, such as the assembly form, the construction characteristics, the correct meshing condition, the continuum transmission condition and so on. Furthermore, the paper deduces the surface formula of the conjugate teeth profiles, which proves that the conjugate teeth profiles is also one of the ringed involute spherical gear. In order to analyze the relationship between two coordinate systems, which is attached respectively to the diving spherical gear and the driven spherical gear, the orientation cosine matrix method is utilized. By series rotational transformation, the kinematics model and inverse kinematics model are deduced. Using the method for calculating the transmission ratio of planet gear train, the relationship of the two oscillating angle between output axis and the bracket is established. Based on the research, the kinematics graphic simulation of spherical gear mechanism and disk rack are made respectively. The results prove correctness of the kinematics model.

关键词： rotational transformation orientation Furthermore conjugate number

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光刻机小型复合节流静压气浮导轨微结构参数设计 Article

温众普, 吴剑威, 邢坤鹏, 张银, 李结安, 谭久彬

《工程（英文）》 2021年第7卷第2期页码 226-237 doi: 10.1016/j.eng.2019.09.012

摘要：

在光刻机可变狭缝系统（VS）中，紧凑型复合节流静压气浮导轨是实现高精度、高加速度运动的首选结构。研究表明，导轨气浮工作面上加工浅腔、凹槽等微结构可以改善负载性能。然而，微结构微米级变化对导轨性能的影响尚不清晰。文中采用作者提出的网格自适应法，定量研究了微结构四个参数的影响，揭示了微结构变化对导轨负载性能的影响规律，并利用这些规律对微结构参数进行设计。设计方法的特点在于：通过调节浅腔参数，使承载力、刚度和转动刚度的工作点都统一起来。采用文中的设计流程和调整方法，可以在一定程度上缓解供气压力的限制和各项负载性能间的相互制约。实验结果表明，采用该方法所设计导轨的转动刚度达到2.14 × 10⁴ Nm·rad^–1，提高了69.8%。在ArF光刻机上的VS上对气浮导轨进行加速扫描实验，平均扫描加速度达到67.5 m·s^–2，
达到了设计要求。

关键词：光刻机复合节流静压气浮导轨微结构工作点转动刚度

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水力空化反应器的最新进展——空化机理、反应器设计与应用 Review

Haoxuan Zheng, Ying Zheng, Jesse Zhu

《工程（英文）》 2022年第19卷第12期页码 180-198 doi: 10.1016/j.eng.2022.04.027

摘要：

水力空化因其能效高、操作成本低、能够诱导化学反应并可规模化等优势，被认为是一种很有前途的工艺强化技术。近十年来，人们对水力空化及其主要变量的基本认识取得了一些进展，为水力空化在自由基诱导化学反应过程中的应用提供了基础。在这里，我们对这些研究工作进行了广泛回顾，包括水力空化的基本原理、空化反应器的设计、空化诱导的反应增强及相关的工业应用。比较了两种类型的水力空化反应器，即固定式和旋转式水力空化反应器。讨论了水力空化反应器的设计参数及其在实验室和中试尺度上的反应器性能，并就其最佳操作和几何条件提出了建议。本文首次回顾了目前市场上的商业空化反应器。水力空化的独特特点已广泛应用于各种化学反应，如氧化反应和废水处理，以及如乳化液生成和组分提取等物理过程。文中也详细讨论了自由基和气泡内爆的作用。

关键词：水动力空化作用空化核羟基自由基固定/旋转水动力空化反应器反应增强空化应用