共查询到20条相似文献,搜索用时 15 毫秒
1.
Atomic force microscope and electron back-scattering diffraction measurement methods were used to study the effects of friction on surface asperity flattening and surface texture during the uniaxial planar compression of annealed aluminum alloy. With an increase in gauged reduction, surface asperity tended to be flattened. Friction could boost the surface asperity flattening process by reducing the flow stress in deformation. The development of surface asperity features demonstrated that friction can effectively hinder the development of the Goss orientation component {011} <100> and clearly promote the generation of brass orientation {011} <100> orientation. Regardless of whether the sample was compressed with lubricant or not, a few S orientation component {123} <634> formed in sample edge area. 相似文献
2.
纯铝单向压缩过程的晶体塑性有限元模拟 总被引:1,自引:0,他引:1
在率相关晶体塑性理论框架下,分别将Taylor模型和有限单元模型两种多晶模型嵌入有限元程序ABAQUS中,实现了纯铝单向压缩过程的晶体塑性有限元模拟。直接将电子背散射衍射(EBSD)获取的晶粒初始取向输入UMAT子程序,预测了单向压缩1050纯铝过程的力学响应与变形织构演化。结果表明:模拟力学响应结果与试验结果有较好的一致性,同时也存在一定偏差。随着真应变的增加,压缩丝织构(〈110〉织构)趋于锋锐,模拟结果与EBSD试验测得的织构演化结果能较好地吻合。 相似文献
3.
4.
试验研究了静态接触中表面纹理对塑性变形界面微凸体平坦化的影响。运用抛光技术制备了两种试件表面:单向纹理表面和各向同性表面。采用HDM-20端面摩擦试验机,分别在有、无润滑油条件下对试件进行了压缩试验。用JM-6200型光学显微镜观测试件表面形貌结构的变化;用Talysurf CCI Lite测量三维表面参数,并选取S_a、S_(al)、S_(tr)、S_(dr)和S_(dq)等参数来定量描述试件表面形貌结构的变化。结果表明,试件表面纹理对微凸体平坦化行为具有明显的影响,无润滑油时各向同性表面微凸体平坦化程度大于单向纹理表面,但有润滑油时刚好相反;表面纹理对微凸体平坦化的影响使得三维表面参数发生了规律性变化。基于机械流变模型的分析表明,封闭润滑油坑的出现导致了有润滑油时表面纹理影响微凸体平坦化行为。通过封闭润滑油坑特征的提取,验证了分析的正确性。 相似文献
5.
6.
一种三维有限元网格的快速消隐算法 总被引:1,自引:0,他引:1
提出了一种利用三维有限元网格相关性实现三维有限元网格快速消隐算法。该算法通过对单元面的排序直接剔除了内部完全不可见网格 ,避免了大量的线、面查找计算 ;通过单元面的深度排序 ,避免了消隐算法中的大量求交和比较计算 ,从而达到大大减小计算量、实现快速消隐的目的。本文所提出的消隐方法速度快、稳定性好 ,在实际应用中取得了满意的效果。 相似文献
7.
Finite Element Modelling of Lamb Waves Propagation in 3D Plates and Brass Tubes for Damage Detection
Structural health monitoring (SHM) is becoming very significant for preventing catastrophic failures and uninterrupted operation. Due to continuous developments in SHM Lamb wave technique, finite element simulation is emerging as an initial step to be performed to visualize the potential solution to problem. The present study focus on the simulation of Lamb wave response using finite element method and its application to crack detection and identification in 3D aluminium plates and brass tubes using commercially available finite element package ABAQUS. Phase velocity and group velocity dispersion curve are initially plotted for aluminium and brass material. Subsequently simulation of distinct specimens with and without presence cracks is performed. Simulation results were validated and compared with actual results and were found to be in reasonably good agreement. A damage index parameter i.e. amplitude ratio is defined to notice the effect of crack dimensions variation. Interaction of Lamb waves with rectangular, semi-elliptical and semi-circular cracks (shallow to deep) is studied in detail. Also the application of signal processing techniques such as Spectrogram analysis, Fourier transform and Hilbert transform is also reported in this paper. 相似文献
8.
9.
Fretting fatigue is a combination of two complex mechanical phenomena, namely, fretting and fatigue. Fretting appears between components that are subjected to small relative oscillatory motion. Once these components undergo cyclic fatigue load at the same time, fretting fatigue occurs. Fretting fatigue is an important issue in aerospace structural design. Many studies have investigated fretting fatigue behavior; however, the majority have assumed elastic deformation and very few have considered the effect of plasticity. The main goal of this study is to monitor the effect of different fretting fatigue primary variables on localized plasticity in an aluminum alloy (Al 2024-T3) test specimen. In order to extract the stress distribution at the contact interface under elasto-plastic conditions, a modified finite element contact model was used. The contact model was verified through comparison with an elastic analytical solution. Then, a bilinear elasto-plastic isotropic hardening model with a von Mises yield surface was implemented to simulate the material behavior of the aluminum alloy. The effect of different fretting fatigue primary variables, such as axial stress, contact geometry, and coefficient of friction, on localized plasticity was investigated. Finally, the relationship between the location of maximum localized plasticity and Ruiz fretting damage parameter with the crack initiation site is discussed. 相似文献
10.
D. Andreika D. Herlach V. A. Zhukov T. N. Mamedov A. V. Stoikov U. Zimmermann 《Instruments and Experimental Techniques》2005,48(4):535-537
A cell for the uniaxial compression of crystals at pressures of up to 5 kbar and used in µ−SR experiments to investigate aluminum acceptor impurities in silicon is described. The dimensions of the samples under study were ∼9.5 × 9.5 × 20 mm. The pressure was monitored with calibrated resistor strain gauges.__________Translated from Pribory i Tekhnika Eksperimenta, No. 4, 2005, pp. 122–124.Original Russian Text Copyright © 2005 by Andreika, Herlach, Zhukov, Mamedov, Stoikov, Zimmermann. 相似文献
11.
本文在合理建立平面包络环面蜗杆标架的基础上 ,准确推导啮合方程和蜗杆接触线计算公式 ,并制定相应的计算机算法。在AutoCAD2 0 0 0平台上 ,运用VisualBasic开发工具编程绘制了平面包络环面蜗杆的三维离散模型。在此基础上可进一步开发三维实体模型 相似文献
12.
13.
A new model of surface flattening is developed for cold metal rolling in the mixed regime. Longitudinal surface roughness is modeled by two separate wavelengths. The new model follows the asperity crushing analysis of Sutcliffe (1999) for unlubricated rolling but additionally includes a hydrodynamic model to account for the effect of the lubricant. The effect of various parameters including speed, reduction in strip thickness, roughness wavelength and lubricant properties is examined. The results show similar behavior to previous models of mixed lubrication, with a speed parameter As having the most influence, and confirm the results for unlubricated rolling that the short wavelength components of the surface roughness persist more than the long wavelength components. The predicted changes in roughness are in good agreement with experiments. 相似文献
14.
Finite element modeling of 3D turning of titanium 总被引:1,自引:1,他引:0
Rui Li Albert J. Shih 《The International Journal of Advanced Manufacturing Technology》2006,29(3-4):253-261
The finite element modeling and experimental validation of 3D turning of grade two commercially pure titanium are presented.
The Third Wave AdvantEdge machining simulation software is applied for the finite element modeling. Machining experiments
are conducted. The measured cutting forces and chip thickness are compared to finite element modeling results with good agreement.
The effects of cutting speed, a limiting factor for productivity in titanium machining, depth of cut, and tool cutting edge
radius on the peak tool temperature are investigated. This study explores the use of 3D finite element modeling to study the
chip curl. Reasonable agreement is observed under turning with small depth of cut. The chip segmentation with shear band formation
during the Ti machining process is investigated. The spacing between shear bands in the Ti chip is comparable with experimental
measurements. Results of this research help to guide the design of new cutting tool materials and coatings and the studies
of chip formation to further advance the productivity of titanium machining. 相似文献
15.
16.
采用三维设计软件SolidWorks建立数控平面磨床床身 ,导入ANSYS软件后进行三维有限元分析 ,并与以往的二维有限元分析计算作比较 ,为床身的改造和优化提供了重要的依据 相似文献
17.
P. Saravanakumar K.K. Manesh M. Singaperumal B. Ramamoorthy 《Precision Engineering》2009,33(1):99-106
Friction in servo hydraulic assemblies reduces the response characteristics of the system. The friction is influenced by various factors including the geometry (form and surface errors) of the sliding surfaces. In this work, functionally significant 3D surface parameters from the Birmingham parameters are investigated for reduced friction. A 3D surface modelling approach is presented using random process modelling as the basis. An exponential decay areal autocorrelation function is used to model the grinding and honing processes which are commonly employed for the manufacture of the hydraulic assemblies. Honed surface is modelled with the crosshatches of appropriate angle. Method of surface modelling is validated using the data obtained through measurements on a practical surface. Different surface maps with varying surface parameters of the ground and honed surfaces are generated. The fluid continuum gap geometries of the hydraulic assemblies are modelled using these surface maps as envelopes. Pressure distribution, velocity and viscous friction force are used as measurands of the frictional characteristics. Using computational fluid dynamics (CFD) approach, these measurands are evaluated for different functionally significant Birmingham parameters. Based on further analysis, negative skewness, lower kurtosis values, higher valley fluid retention index were found to have lower frictional characteristics. 相似文献
18.
19.
V. V. Dyakin O. V. Umergalina V. Ya. Raevskii 《Russian Journal of Nondestructive Testing》2005,41(8):502-513
The field of an arbitrary finite defect in a 3D semispace is calculated. This problem is solved by reduction to a 2D case that yields an integral equation on the surface of the defect alone. Calculation formulas for a spherical defect are presented. Results of calculations using these formulas for the case of a uniform external field normal or tangential to the surface of a magnetic semispace are presented in a graphical form. 相似文献
20.
利用改进的单胞模型对三维四向编织C/QY9511复合材料的拉伸行为进行有限元模拟,得到其在固定编织角下拉伸模量随纤维体积含量变化的曲线,并与实验值进行比较;结果表明,随着纤维体积含量的增加,其拉伸模量也在增加. 相似文献