CJME | 2018年第2月刊最受关注论文推荐
DOI: 10.1186/s10033-018-0214-9
Symmetric Equations for Evaluating Maximum Torsion Stress of Rectangular Beams in Compliant Mechanisms.
Gui-Min Chen • Larry L. Howell
Abstract: There are several design equations available for calculating the torsional compliance and the maximum torsion stress of arectangular cross-section beam, but most depend on the relative magnitude of the two dimensions of the cross-section (i.e., the thickness and the width).After reviewing the available equations, two thickness-to-width ratioin dependent equations that are symmetric with respect to the two dimensions are obtained for evaluating the maximum torsion stress of rectangular cross-sectionbeams. Based on the resulting equations, outside lamina emergent torsional joints are analyzed and some useful design insights are obtained. These equations, together with the previous work on symmetric equations for calculating torsional compliance, provide a convenient and effective way for designing and optimizing torsional beams in compliant mechanisms.
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https://cjme.springeropen.com/articles/10.1186/s10033-018-0214-9
DOI: 10.1186/s10033-018-0208-7
Dynamic Accuracy Design Method of Ultra-precision MachineTool.
Guo-Da Chen • Ya-Zhou Sun • Fei-Hu Zhang • Li-Hua Lu • Wan-Qun Chen • Nan Yu
Abstract: Ultra-precision machine tool is the most important physical tool to machining the workpiece with the frequency domain error requirement, in the design process of which the dynamic accuracy design (DAD) is indispensable and the related research is rarely available. In light of above reasons, a DAD method of ultra-precision machine tool is proposed in this paper, which is based on the frequency domain error all ocation. The basic procedure and enabling knowledge of the DAD methodis introduced. The application case of DAD method in the ultra-precisionflycutting machine tool for KDP crystal machining is described to show the procedure detailedly. In this case, the KDP workpiece surface has there quirements in four different spatial frequency bands, and the emphasis for this study is put on the middle-frequency band with the PSD specifications. There sults of the application case basically show the feasibility of the proposed DAD method. The DAD method of ultra-precision machine tool can effectively minimize the technical risk and improve the machining reliability of the designed machine tool. This paper will play an important role in the design and manufacture of new ultra-precision machine tool.
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https://cjme.springeropen.com/articles/10.1186/s10033-018-0208-7
探花
DOI: 10.1186/s10033-018-0203-z
Impact of Impeller Stagger Angles on Pressure Fluctuationfor a Double-Suction Centrifugal Pump.
Da-Chun Fu • Fu-Jun Wang • Pei-Jian Zhou • Ruo-Fu Xiao • Zhi-Feng Yao
Abstract: Pressure fluctuation may cause high amplitude of vibration of double-suction centrifugal pumps, but the impact of impeller stagger angles is still not well understood. In this paper, pressure fluctuation experiments are carried out for five impeller configurations with different stagger angles by using the same test rig system.Results show that the stagger angles exert negligible effects on the characteristics of head and efficiency. The distributions of pressure fluctuations are relatively uniform along the suction chamber wall, and the maximum pressure fluctuation amplitude is reached near the suction inlet tongueregion. The pressure fluctuation characteristics are affected largely by impeller rotation, whose dominant frequencies include impeller rotation frequency and its harmonic frequencies, and half blade passage frequency. The stagger angle exerts a small effect on the pressure fluctuations in the suction chamber while a great effect on the pressure fluctuation in volute casing, especially on the aspect of decreasing the amplitude on blade passage frequency. Among the tested cases, the distribution of pressure fluctuations in the volute becomes more uniform than the other impeller configurations and the level of pressure fluctuation may be reduced by up to 50% when the impeller stagger angle is close to 24° or 36°. The impeller structure pattern needs tobe taken into consideration during the design period, and the halfway staggered impeller is strongly recommended.
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https://cjme.springeropen.com/articles/10.1186/s10033-018-0203-z
榜眼
DOI: 10.1186/s10033-018-0218-5
Model Based Adaptive Control and Disturbance Compensation for Underwater Vehicles.
Hai Huang • Guo-ChengZhang • Ji-Yong Li • QiangZhang • Jin-Yu Xu • Hong-De Qin
Abstract: Underwater vehicles are being emphasized as highly integrated and intelligent devices for a significant number of oceanic operations. However, their precise operation is usually hindered by disturbances from a tether or manipulator because their propellers are unable to realize a stable suspension. A dynamic multi-body model-based adaptive controller was designed to allow the controller of the vehicle to observe and compensate for disturbances from atether or manipulator. Disturbances, including those from a tether or manipulator, are deduced for the observation of the controller. An analysis of atether disturbance covers the conditions of the surface, the underwater area, and the vehicle end point. Interactions between the vehicle and manipulator are mainly composed of coupling forces and restoring moments. To verify the robustness of the controller, path-following experiments on a streamlined autonomous underwater vehicle experiencing various disturbances were conducted in Song Hua Lake in China. Furthermore, path-following experiments for a tetheredopen frame remote operated vehicle were verified for accurate cruising with acontroller and an observer, and vehicle and manipulator coordinate motioncontrol during the simulation and experiments verified the effectiveness of thecontroller and observer for underwater operation. This study provide sinstructions for the control of an underwater vehicle experiencing disturbances from a tether or manipulator.
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https://cjme.springeropen.com/articles/10.1186/s10033-018-0218-5
状元
DOI: 10.1186/s10033-018-0204-y
Fabrication of Microlens Array and Its Application– A Review.
Wei Yuan •Li-Hua Li• Wing-Bun Lee• Chang-Yuen Chan
Abstract: Microlens arrays are the key component in the next generation of 3D imaging system, for it exhibits some good optical properties such as extremely large field of view angles, low aberration and distortion, high temporal resolution and infinite depth of field. Although many fabrication methods or processes are proposed for manufacturing such precision component, however, those methods still need to be improved. In this review,those fabrication methods are categorized into direct and indirect method and compared in detail. Two main challenges in manufacturing microlens array are identified: how to obtain a microlens array with good uniformity in a largearea and how to produce the microlens array on a curved surface? In order to effectively achieve control of the geometry of a microlens, indirect methods involving the use of 3D molds and replication technologies are suggested. Further development of ultra precision machining technology is needed to reduce the surface fluctuation by considering the dynamics of machine tool in tool path planning. Finally, the challenges and opportunities of manufacturing microlensarray in industry and academic research are discussed and several principle conclusions are drawn.
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https://cjme.springeropen.com/articles/10.1186/s10033-018-0204-y
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