首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
J. López  M. Artés 《Measurement》2011,44(8):1367-1380
The optical linear encoders are the preferred choice sensors for positioning machine tools’ moveable parts. Machine tools’ errors have been traditionally focused on the analysis and performance of the machine tool structure until recent works have treated the encoder itself as a source of error. Encoder error quantification has been done for several mounting conditions in static situations, but there is a lack of information regarding the performance of the encoder under dynamic solicitations. The aim of this work is to analyze the loss of accuracy of the sensor because of vibration for different mounting conditions. A finite element model of encoder has been developed and experimental results have been analyzed using this model.  相似文献   

2.
随机振动下机械产品广义可靠性评估   总被引:2,自引:0,他引:2  
李超  王金诺  申川 《机械》2003,30(4):8-11
利用随机振动试验模拟使用环境可时构件进行可靠性考核,通过直接测量可获得薄弱部位的应变、加速度响应规律,再对相同振动条件下构件的可靠性进行评估。应力和应力循环次数是由平均功率谱密度通过离散计算得来,其计算精度由离散点间距、随机振动时间决定,因此获得的应力和应力循环次数具有模糊性。利用普通事件概率表示模糊事件概率,将模糊可靠性计算问题转化为普通可靠性计算。通过定义模糊安全状态的不同形式,建立了以状态变量表示安全状态时的广义可靠性计算模型。结合工程实际给出了算例。  相似文献   

3.
利用虚拟仪器技术设计开发了旋转轴扭振测试系统,并结合ATI2000系列扭振传感器进行了实际测量,实验结果表明该系统可实现传动轴扭振宽频率、宽转速、多通道同时测量及在线分析等功能,且操作方便、灵活性强,为今后测试和研究大型旋转机械的扭振特性及实现扭振在线监测、故障诊断等提供了理论与技术支持.  相似文献   

4.
机床基础底部铺有五层不同材料的防振层的方法来提高机床基础的防振性,能很好的消振和隔离外界振源的影响。该设计主要采用了在机床四周开挖防振沟,通过对设计要素的分析和试验,证明该设计可广泛应用于轧辊磨床的机床基础的设计,提高轧辊磨床的磨削精度。  相似文献   

5.
基于Newton力学法建立复杂旋转机械扭振的测理模型,正则变换后用Duhamel积分计算各正则坐标的响应,通过与试验测试数据相比较,验证该模型的有效性,为旋转机械的扭振计算提供新途径.  相似文献   

6.
随机振动下小子样机械产品可靠性评估   总被引:3,自引:1,他引:3  
李超  王金诺 《机械设计》2003,20(11):31-33
针对机械产品使用寿命一般比较长,用于振动试验的产品数量必须很少的特点,提出一种基于经典方法、通过增大产品承受的应力,并结合应力-强度干涉计算,建立适合极小子样产品的可靠性评估方法。研究了过载随机振动试验的实现手段。讨论了过载试验中确定过载系数上限的问题。针对某一高可靠性产品,利用随机振动试验获得薄弱部位的应力响应规律,经可靠性评估表明,如果提高输入功率谱密度约108%,只需选取4~5件进行可靠性试验即可。该方法对试验费用昂贵,小子样产品的可靠性评估,具有工程实用价值。  相似文献   

7.
杜辉  周晓明  徐利梅 《机械》2006,33(5):52-54,56
为防止共振发生,电动机的工作频率应远远小于其固有频率。基于受迫振动理论,本文提出用实验测定电动机的固有频率范围的方法,分析电动机机械振动特征,为电机减振提供有了力支持。重点论述了振动试验的夫具设计及试验过程,并对实验结果进行了分析。实验数据与理论结果较为一致,证明该实验方法是测定电动机的固有频率的有效方法。  相似文献   

8.
This work describes the self-calibration of a high-precision open-loop mechanism. The self-calibration method is applied to a mechanical shutter for space applications, which was launched onboard the ESA-ROSETTA mission (launch: 2 March 2004). It is based on an adaptive ‘model reference’ and a ‘randomised’ search method which may be generalised to applications in which high performance and functionality are strongly interconnected. The method makes use of an adaptive ‘model-reference’ control approach [K.J. Astrom, B. Wittenmark, On self-tuning regulators Automatica 9 (1973) 185–199 [16]; K.J. Astrom, Theory and application of adaptive control, in: Proceedings of the Eighth IFAC World Conference, Kyoto, Japan, 1981 [17]; D.E. Seborg, S.L. Shah, T.F. Edgar, Adaptive control strategies for process control, AIChE Journal 6(32) (1986) 881–895 [18]] to guarantee mechanism performance. The proposed control system comprises both a deterministic adaptive part and a random-search one [K.L. Clarkson, Applications of random sampling in computational geometry, II, in: Proceedings of the Fourth Annual ACM Symposium on Computational Geometry, 1998, pp. 1–11 [19]; P.K. Agarwal, M. Sharir, Efficient randomised algorithms for some geometric optimisation problems, Discrete Computational Geometry 16 (1996) 317–337 [15]] to guarantee shutter mechanism functionality and performance over testing lifetime (5×104 cycles).  相似文献   

9.
研究了光盘轴向机械动态特性和聚焦伺服系统的关系,系统研究了影响光盘轴向偏摆各分量对总偏摆的影响,据此建立光盘轴向偏摆的数学模型。根据该模型,分析了几种有代表性的测量方法的优缺点并重点研究了它们各自的测量精度,提出了一种全新的基于激光三角法的测量方法。最后给出了测量结果和结果分析。  相似文献   

10.
Dynamic characterization of electrospindles is necessary to ensure long life, reliability and high-tech performance required in many industrial applications. Many diagnostic approaches have been developed with regard to fault detection and dynamic characterization of rotating machinery.  相似文献   

11.
This paper presents an improved analysis method for the interpretation of the vibration data measured at turbomachinery blade tips using optical laser probes. A multi-degree-of-freedom numerical simulator, which includes the structural and geometric properties of the bladed-disk assembly, the external forcing terms and the characteristics of the optical probe, has been developed to assess the reliability of the various data processing techniques to identify the natural frequencies and mode shapes of bladed-disk assemblies. It has been demonstrated that the Zablotsky—Korostelev single parameter technique, which is a de-facto standard in the aerospace industries, has inherent limitations associated with it. An improved and more rigorous method is presented for deriving the blade arrival times and a non-linear solution technique is suggested for their numerical determination. Finally, the effect of blade mistuning on the accuracy of the proposed method is also investigated.  相似文献   

12.
陆卫杰  邵晓荣 《机械设计》2006,23(12):50-51
对于由质量圆盘-扭簧组成的链式扭转振动系统,根据能量波理论,通过协调各组成环阻抗的方法,避免产生共振,达到减小振动强度的目的。  相似文献   

13.
对改造中的种分槽顶液下泵的振动原因进行了分析,提出了改进的措施,实施后达到了预期效果。  相似文献   

14.
利用误差谐波补偿法提高金属圆光栅测角精度   总被引:1,自引:0,他引:1  
提高圆光栅测角精度的方法除了提高分辨率和系统精度以外,广泛采用误差补偿方法。本文通过对新型金属圆光栅的研究,提出了一种基于软件的误差补偿方法——误差谐波补偿法。实验表明该方法可消除一定阶次内幅值和初相位不随时间变化的误差谐波,有效提高测角精度。  相似文献   

15.
针对微机电系统和无线传感器网络的迅速发展及其对清洁环保新型能源的需求,提出一种复合式振动发电装置,可实现电磁振动发电和压电振动发电。基于Ansoft有限元仿真软件,对复合式振动发电装置的电磁发电性能进行有限元仿真和结构优化。仿真结果显示,通过优化定子槽数和充磁方向,可以获得性能较优的电磁发电性能。  相似文献   

16.
This paper describes the analysis of an experimental setup for the performances evaluation of Pulsed Doppler feature in clinical ultrasound scanners. The equipment basically consist on a commercial flow phantom made by a straight tube having a known and constant cross sectional area in which a blood mimicking fluid is forced to flow at laminar conditions. Given the accuracy declared by the manufacturer (±0.7 cm/s), unsatisfactory for low flow rates, we calibrated the phantom using the gravimetric method. From the digitized images of the Pulsed Doppler spectra over time, the mean velocities have been computed with the software package developed by the authors. Moreover, to test the calibration procedure in effective conditions, we carried out performance test on five different ultrasound platforms, equipped with phased array and convex array probes with a nominal mean velocity of the blood mimicking fluid ranging from 1.1 cm/s to 12.7 cm/s. The pooled data showed an overestimation of the mean velocity, from over 200% down to about 50%, depending on nominal flow rate and ultrasound equipment. The same data, corrected via the calibration curve, showed a sensible recovery of the estimated accuracy of the tested platforms at low flow rates (<3 cm/s).  相似文献   

17.
The present paper investigates experimentally the effect of external horizontal vibration on friction property of mild steel. To do so, a pin-on-disc apparatus having facility of vibrating the test samples in horizontal direction was designed and fabricated. Horizontal vibration is created along the sliding direction of vibration and perpendicular to the direction of vibration. The experimental setup has the facility to vary the amplitudes and frequencies of vibration while velocity of vibration is kept constant. During the experiment, the frequency and amplitude of vibration were varied from 0 to 500 Hz and 0 to 200 μm, respectively. Results show that the friction coefficient increases with the increase in amplitude and frequency of vibration for mild steel. The horizontal vibration can be of two types: one along the direction of sliding (longitudinal direction) and the other along the perpendicular direction of sliding (transverse direction). For both the cases, test sample slides horizontally. It is found that the magnitude of friction coefficient for longitudinal vibration is less than that for under transverse vibration. These results are analyzed by dimensional analysis to correlate the friction coefficient with sliding velocity, frequency and amplitude of vibration. The experimental results are also compared with those available in literature and simple physical explanations are provided.  相似文献   

18.
基于BSC的企业信息化绩效评价研究   总被引:2,自引:3,他引:2  
分析企业信息化绩效评价中存在的问题,提出借鉴平衡记分卡的绩效评价思路,从产出角度对企业信息化绩效进行综合评价,并设计一套定性与定量指标相结合的企业信息化绩效评价指标体系.此外,企业信息化绩效评价与人的主观认识密切相关,是一项较为复杂的思维过程,为此,提出运用层次分析法确定各评价指标的权重,进而计算企业信息化绩效指数.  相似文献   

19.
Gas-lubricated bearings are widely used in the optical lithographic manufacturing of wafers to realize nearly zero friction for the motion of the stage. As the extreme precise positioning accuracy of these equipments has reached nanometer level, and almost approaches the physical limit, the effect of the recess shape of the gas bearings cannot be neglected any longer. This paper studies the effect of the recessed shape of the bearing on the performance analysis through numerical method. The pressure distribution, as well as the loading capacity and mass flow rate for the case of different shape (no pocketed bearing, rectangular shape and spherical shape bearing, respectively) of the bearing is achieved with the well-known CFD-control element procedures in Quad meshes. The results show that the average loading capacity reduces as the following sequence: rectangular recessed bearing, spherical recessed bearing and non-recessed bearing. The mass flow rate in the bearing with spherical recess is smaller than that of with rectangular recess, and bigger than that of with non-recess. Vortexes, which can cause higher temperature in gas film, are also found in the spherical recess or rectangular recess. It means that only the bearing with non-recess is fitted to use in ultra-high precision equipments.  相似文献   

20.
This paper proposes a special application of Brillouin Optical Time Domain Analysis (BOTDA) sensors for monitoring the mechanical performance of a steel H-pile during driving process in a field in Hong Kong. First, basic calibration and the related installation method of optical fiber sensors (OFS) on pile body were introduced. Second, distributed strain profiles along the H-pile during driving process were successfully obtained from optical fiber sensors. Finally, measured strain distributions of the H-pile subjected to two loading/unloading cycles monitored by OFS were used to interpret field performance of the driven pile. Monitoring results indicate that the vertical load applied on the pile head generated significant compressive deformation, which was however mostly released by the corresponding unloading process. The 1st unloading and 2nd unloading processes released around 66% and 72% of the total compressive pile deformation, respectively. The shear stress levels mobilized between H-pile and surrounding soils were limited after each loading/unloading cycle according to the monitoring results. In addition, loading locations on the driven pile can be clearly identified from strain/stress distribution profiles. It is found from the monitoring study that BOTDA based sensors are more useful than some traditional or other point OFS (such as strain gauges or fiber Bragg grating sensors) to evaluate the average strain distribution of large scale structures.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号