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51.
Wire + Arc Additive Manufacturing 总被引:1,自引:0,他引:1
S. W. Williams A. C. Addison J. Ding G. Pardal P. Colegrove 《Materials Science & Technology》2016,32(7):641-647
Depositing large components (>10?kg) in titanium, aluminium, steel and other metals is possible using Wire + Arc Additive Manufacturing. This technology adopts arc welding tools and wire as feedstock for additive manufacturing purposes. High deposition rates, low material and equipment costs, and good structural integrity make Wire+Arc Additive Manufacturing a suitable candidate for replacing the current method of manufacturing from solid billets or large forgings, especially with regards to low and medium complexity parts. A variety of components have been successfully manufactured with this process, including Ti–6Al–4V spars and landing gear assemblies, aluminium wing ribs, steel wind tunnel models and cones. Strategies on how to manage residual stress, improve mechanical properties and eliminate defects such as porosity are suggested. Finally, the benefits of non-destructive testing, online monitoring and in situ machining are discussed. 相似文献
52.
Wenyuan Li Zhiyong Chen Jianrong Liu Shaoxiang Zhu Guoxin Sui Qingjiang Wang 《材料科学技术学报》2019,35(5):790-798
Rolling texture and its effect on tensile properties of Ti60 alloy plates were investigated in the present study. The plates wereβ-rolled at 1070℃ and(α+β)-rolled at 980℃, using uni-directionally rolling(UDR) and cross-directionally rolling(CDR) processes, respectively.β-rolled plates exhibited weak textures, which were attributed to the dispersive orientations of secondary α during the β→α phase transformation. Strong deformation textures formed in(α+β)-rolled plates as a result of slipping mechanisms: the strong T-type texture in UDR plate was related to {10 1 0}[11 2 0] slipping, while the B-type texture in CDR plate was relevant with {0001}[11 2 0] slip. Strong T-type textures led to anisotropic tensile properties. B-type textures would decrease such an anisotropy. The(α+β)-CDR process was found to be a candidate process for reducing anisotropy of Ti60 alloy plates. 相似文献
53.
汪世益 《安徽工业大学学报》1998,(3)
论证了轴承信号中高频谱峰群的存在,指出了高频谱峰群中含有轴承元件疲劳剥落缺陷的重要信息,对轴承的故障诊断具有重要意义. 相似文献
54.
该文阐述了ORACLE数据库的特点及其访问方式,并介绍了ORACLE数据库及其所带的Form,Reports在开发大H型钢轧线二级系统中的应用。 相似文献
55.
A rolling robot is developed that possesses an elliptically shaped outer surface with the ability to change shape as it rolls, resulting in a gravity-powered torque imbalance that accelerates or brakes the robot’s motion. Angular position and velocity are measured onboard and used as feedback control to trigger and define shape change actuation. Goal of the control is to direct the robot to follow a given step angular velocity profile. An equation of motion for the rolling robot is derived and solved numerically, and simulations are compared to velocity data from roll trials of the actual robot. Results show that when the robot is given a set of advantageous initial conditions, it is able to accelerate from rest, maintain constant average velocity, and brake its motion in order to follow a desired velocity profile with significant accuracy. 相似文献
56.
齐滨 《自动化与仪器仪表》2011,(2):79-79,83
提出了中厚板轧机轧制力计算模型,并在此基础上,对数学模型进行在线自适应,使计算得到的轧制力更接近于实测值。 相似文献
57.
全连续式冷轧工艺的发展对冷轧带钢的生产带来了重大的变革。然而能形成全连续轧制的条件也是有一定限度的,本文即是结合我国引进的宝钢2030mm轧机从入口段带钢运行条件导出带长与速度的关系式,从主电机功率的利用率分析了全连轧与常规轧制的差异。 相似文献
58.
本文给出一种借助于二维神经网络构成的混合系统,用它来完成几种方向估计算法,这些算法包括:最大似然法,交替投影最大似然法,Marcos等人提出的无需特征分解的“传播算法”。利用神经网络对某些算法的快速性,该系统为实时实现目标的精确定位提供了一条新的,有效的途径。 相似文献
59.
《Ergonomics》2012,55(10):1361-1371
The coefficient of rolling resistance (C r) for pneumatic tyres is dependent on hysteresis loss from tyre deformation which is affected by the vertical force applied to the tyres (F v) and the tyre inflation pressure (P r). The purpose of this paper was to determine the relative influence of five different levels of P r and four different levels of F v on C r and to examine the relationships of C r with P r and F v during cycling locomotion. F v was modified through carriage of additional mass by the subject. C r was determined with the coasting deceleration method from measurements performed in a level hallway. Iterations minimizing the sum of the squared difference between the actual deceleration distance and a predicted deceleration distance were used to determine C r. This latter distance was computed from a derivation based on Newton's second law applied to the forces opposing motion. C r was described by a hyperbolic function of P r (C r = 0.1071 P r ?0.477, r 2 = 0.99, p < 0.05), decreasing 62.4% from 150 kPa (Cr= 0.0101) to 1200 kPa (Cr = 0.0038). F v was related to C r by a polynomial function (C r = 1.92.10?8 F v 2 ?2.86.10?5 F v + 0.0142, r 2 = 0.99, p = 0.084), with an added mass of 15 kg (C r = 0.0040) resulting in an 11.4% increase in C r compared with no added mass (C r = 0.0035). From this study, it is concluded that the relationships of P r and F v with C r for cycling are non-linear. Furthermore, a simulation model shows that changes in P r and F v of the magnitude examined here have an important effect on competitive cycling performance. 相似文献
60.
Jafar Zarei 《Expert systems with applications》2012,39(1):68-73
This paper proposes a systematic procedure based on a pattern recognition technique for fault diagnosis of induction motors bearings through the artificial neural networks (ANNs). In this method, the use of time domain features as a proper alternative to frequency features is proposed to improve diagnosis ability. The features are obtained from direct processing of the signal segments using very simple calculation. Three different cases including, healthy, inner race defect and outer race defect are investigated using the proposed algorithm. The ANNs are trained with a subset of the experimental data for known machine conditions. Once the network is trained, efficiency of the proposed method is evaluated using the remaining set of data. The obtained results indicate that using time domain features can be effective in accurate diagnosis of various motor bearing faults with high precision and low computational burden. 相似文献