三维表面粗糙度的均方根斜率评定

基于分形几何理论,通过分析随机表面的轮廓谱矩和表面谱矩的特性,提出了三维粗糙表面的均方根斜率评定方法,并用平磨样块试验证实了该法的正确性。     

基于棋盘光栅Ronchi检验法的微变液面测量

提出了基于棋盘光栅Ronchi检验法的微变表面形貌测量方法,可同时测量被测表面形貌两个正交方向的斜率,因而可通过一幅变形棋盘光栅图重构被测表面形貌。使用取微分极值的方法可简单有效地实现变形棋盘光栅图两个正交方向信息的分离和提取。根据所提出的测量方法和数据提取算法建立了微变表面形貌测量系统并对静态和动态表面形貌进行了测量。结果表明,所建立系统的分辨率＜0.1 μm,测量范围＞50 μm,符合有关研究中对微变液面的测量需求。     

On-machine measurement of a cylindrical surface with sinusoidal micro-structures by an optical slope sensor

This paper describes the measurement of a cylindrical surface with sinusoidal micro-structures over a large area on a diamond turning machine. The sinusoidal micro-structures, which are fabricated on the periphery surface of a cylinder by the fast tool servo-based diamond turning, are superposition of periodic sine-waves along the cylinder axis and the cylinder circumference with amplitudes of 100 nm and wavelengths of 100 μm, respectively. An optical two-dimensional (2D) slope sensor with a multi-spot light beam is developed for measurement of the 2D local slopes of the sinusoidal micro-structured surface. A cylindrical lens is employed in the sensor for removing the influence of the curvature of the cylinder surface. Experiments of fabrication and measurement of the sinusoidal micro-structured surface on an ultra-precision diamond turning machine are carried out.     

A simple datum for measurement of the Abbott curve of a profile and its first derivative

The methods used in some recent work to predict boundary friction from surface slopes require that the variation of rms slope with bearing area be calculated: an Abbott curve of the first derivative of the profile. It is shown that this curve can be distorted if a conventional filter is used to set the datum, in the same way as the Abbott curve itself. Better results can be obtained for both the standard Abbott curve and the Abbott curve of slopes if an envelope through the peaks of the profile is used as the datum, rather than a digital filter.     

A study of the surface parameters of ground and lapped metal surfaces,using specular and diffuse reflection of laser light

Laser light, with a photocell giving a logarithmic response, is used to measure the specular and diffuse reflection from ground and ground and lapped metal surfaces. Theory suggests that the probability distribution of roughness heights determines the specular reflection, while the distribution of surface slopes determines the diffuse reflection. For specular reflection the theory gives useful results even in the range of grazing incidence (70° or 80°) which must be used for the roughness range 0.2 to 1.5 μm.The optical and profilometer results suggest skewed non-Gaussian probability distributions, and a theoretical model which may account for such distributions is suggested. The diffuse light results show that, except for the roughest specimens, the slope distribution is also non-Gaussian. The standard deviation of the slopes increases with roughness, and the relation between them is obtained.     

Calibration for the sensitivity of multi-beam angle sensor using cylindrical plano-convex lens

A highly sensitive and compact multi-beam angle sensor (MBAS), which utilizes the principle of operation of an autocollimator, was developed to detect the differential of the local slope components (angle difference) of a point on the mirror surface and using Fourier series, we can obtain the profile data from the angle difference. In order to investigate the application of the MBAS for high precision aspheric surface measurements, two types of calibration methods using plane mirror and cylindrical plano-convex lens has been proposed to measure the sensitivity of the MBAS. The calibration data analysis results using plane mirror agree well with the measurement results of the cylindrical plano-convex lens data. Comparison of the two methods confirms that the second method (using cylindrical plano-convex lens) is more adapted for measurement with ultra high level of uncertainty. Further, the second method is simple, corresponding to a direct calculate in the sensitive parameters aiming to minimize the cost.     

Measurement of the rotational inertia of bodies by using mechanical spectroscopy

In this paper, mechanical spectroscopy was used to study the rotational inertia of bodies. In order to verify and show its importance in relation to other techniques, measurements of the internal friction and rotational inertia of a body with liquid or sand inside were carried out. For a solid without axes and planes of symmetry, properties such as the matrix, directions and principal moments of inertia, variation of the rotational inertia for each of the coordinate planes, and the ellipsoid of inertia were determined. Force sensors and rotational motion were used in the measurements taken in an arrangement that was specifically designed for this type of measure.     

Relationships among the physical parameters required to give a linear relation between slope and intercept of Fowler-Nordheim plots.

For field emitters with a given surface condition, but different apex radii, there exists an empirical linear relationship between the slopes and intercepts of their Fowler-Nordheim plots. This behavior is quite different from that predicted by the theory with the assumption of a smooth surface. We have already characterized the possible reasons for this discrepancy; one possibility is that the emission area rapidly increases with increase in the apex radius. The previous report (Jpn. J. Appl. Phys. Part II 32 (1993) L342), however, showed a curved relation between the slope and the intercept of Fowler-Nordheim plots. In the present article, we try to extract the relationship between the emission area and the apex radius needed in order to give a linear relationship between slope and intercept of the F-N plots. As an additional result of the present analysis, the change in work function of the field emitting surface is demonstrated.     

从一维透视投影光流场恢复二维刚体运动和形状

研究从一维透视投影光流场恢复二维刚体运动和结构。证明利用一维透视投影光流场中最少 5个光流点可以完全确定刚体的二维角速度和角加速度 ,一般情况下有 2个解。利用一维透视投影光流场只能确定含一个未知比例因子的刚体二维平移速度、平移加速度和二维刚体的结构 ,因此可完全确定二维刚体的形状     

Depth of thermal penetration in straight grinding

Unlike the usual numerical FEM approach to determine the thermally affected layer during the grinding process, we propose a simple analytical approach to estimate the depth of thermal penetration. For this purpose, the one-dimensional definition of depth of thermal penetration is applied to the two-dimensional heat transfer models of straight grinding. A method for computing the depth of thermal penetration in these two-dimensional models is derived and compared to the one-dimensional approximation. For dry grinding, it turns out that the one-dimensional approximation is quite accurate when we consider a moderate percentage in the temperature fall beneath the surface, regardless the type of heat flux profile entering into the workpiece (i.e., constant, linear, triangular, or parabolic). In wet grinding, the latter is true if we consider a constant heat flux profile and a high Peclet number, i.e., Pe >?5. Finally, the one- and two-dimensional approaches calculating analytically the depth of thermal penetration have been compared to the temperature field numerically evaluated by a three-dimensional FEM simulation given in the literature, obtaining a quite good agreement.     

Solution of reciprocal problem of magnetic flaw detection through calculation of multipole moments of an elliptic flaw

An algorithm has been developed for calculating parameters of an effective elliptic flaw (EEF) on the base of changes in the magnetic field intensity in the air. EEF is defined as a flaw with an elliptic cross section whose magnetic moments (dipole, quadrupole, and octupole), hence the field at a large distance, are the same as those of a given flaw with an arbitrary shape. The relation between the parameters of EEF and real flaws has been established by solving Grinberg’s integral equation for internal and surface flaws of the two-dimensional configuration in a half-space filled with a linear (μ=const) ferromagnetic material. This relation was used in drawing up the solution of the reciprocal problem of magnetic flaw detection.     

接触热导率数值预测研究

假设粗糙表面轮廓高度服从高斯分布,并将两粗糙表面间的接触等效为粗糙表面与光滑刚性表面的接触。由均方根粗糙度和平均凸峰坡度得出接触点的平均半径和单位面积内的接触点个数,分别建立了用圆柱体和圆锥台来表现接触粗糙峰的两种有限元模型,对接触热导率进行了数值预测。通过对比发现,用圆柱体来表现粗糙峰的模型计算出的结果与试验吻合较好,且其误差随界面载荷的增大而减小。     

利用功率谱密度函数表征光学薄膜基底表面粗糙度

光学表面的表面粗糙度通常利用两个传统参数方根粗糙度σ和相关长度l来进行表征。主要就如何引入功率谱密度函数(PSD)表征表面微观形貌进行了初步研究。说明了一维和二维功率谱密度(PSD)函数的数学计算方法、PSD函数的物理意义,同时给出了PSD函数与传统的表面评价指标σ和l之间的关系。利用不同仪器对多种样品进行测试,在分析比较测试结果的基础上,总结了利用PSD函数评价光学表面粗糙度的优点。功率谱密度函数作为一个全面的光学表面评价参数,正得到越来越广泛的重视和应用。     

Characterization of micromachined mirror surfaces from high speed diamond fly cutting

The measurement of the surface finish of diamond “fly-cut” mirrors is discussed. By considering each surface as a series of superimposed sinusoidal gratings, the surface spectral density function (SDF) was calculated from measurements of light scattered from an He-Ne laser beam. The SDF allows examination of the roughness as a function of spatial frequency from which the r.m.s. roughness is calculated. The scattering results are compared with other methods of assessing the surface finish of the mirrors. Results from Talystep measurements compare favourably with those from the lightscattering technique for the smooth copper mirrors, the best of which had a total r.m.s. roughness of 33 Å. The apparatus developed is described. Problems encountered with stylus methods, interferometry and scanning electron microscopy are reported.     

The measurement and data analysis used to evaluate highway roughness

An overview of the measurement and data analysis techniques used to evaluate highway roughness is presented. Highway roughness is defined as the deviation of a paved surface from a true planar surface with dimensions of less than 100 m and greater than 0.1 m in wavelength and less than 100 mm and greater than 1.0 mm in amplitude, and is measured by two general types of equipment, roughness effect equipment and profilometers. Information such as operating characteristics, outputs and data analysis methods best suited to each piece of equipment is tabulated and discussed. The various methods of analysis and their application to highway safety, ride comfort, dynamic pavement loading and serviceability are also discussed. These methods of analysis have also been categorized into two general groups, those that provide a single number or index (such as root mean square (r.m.s.), slope variance, present serviceability (PSI) etc.) and those that are statistical and thus provide more detail than a single index (such as power spectral density (PSD)). The better known methods such as r.m.s., slope variance, PSD etc. are only briefly reviewed, while the methods such as PSI and amplitude-frequency distribution are presented in more detail. Finally, a summary of present research projects on new equipment and analysis methods is given.     

Comparison of velocity and turbulence profiles downstream of perforated plate flow conditioners

This paper presents the results obtained when placing different designs of perforated plate flow conditioner downstream of two common flow-disturbing installations in turn: a single 90° bend and a twisted S bend. The results comprise a series of LDV measurements of velocity and r.m.s. fluctuation velocity profiles made in two perpendicular planes at locations between 3 and 41 pipe diameters (D) downstream of the conditioners. The flow conditioners were placed at 4D downstream of the flow-disturbing installations. Measurements were also made without the inclusion of a flow conditioner for comparison. Several designs of flow conditioner give profiles within 5% of a fully developed profile 11D downstream of the conditioner; so significant reductions in lengths of meter runs should be possible. The Spearman (NEL) design performs at least as well as other contemporary designs and is available for inclusion in the relevant standards. These measurements were carried out in a water pipeline.     

Image-based river discharge estimation by merging heterogeneous data with information entropy theory

An information entropy based approach for the discharge measurements is evaluated for the gaging of the Isère river at the Grenoble university campus. Over a four month period, six discharge measurements were made using a vessel-mounted aDcp. Simultaneously, particle tracking velocimetry (PTV) from video images was used to estimate surface velocities. The surface velocities are projected along the regularly surveyed river section of the Isère-Campus gaging station. The vertical velocity profile at each stream-wise location is approximated by a 1D entropy profile. Information entropy 1D velocity vertical profile depends on two parameters which are fitted using aDcp and surface velocity measurements. The inclusion of the surface velocities reduces the dispersion of the estimated entropy parameters. The measurements show that the two parameters are linearly related with a slope that is stage dependent and thus, surface velocity dependent. From there, the information entropy theory for 1D velocity distribution offers a protocol by which surface velocities only are used to compute the discharges. The protocol is calibrated with both aDcp and surface velocity measurements. It is finally validated with several events during which only surface velocities are measured. For the high water flood event the estimated discharge falls within 2% of the one estimated with the rating curve of the gaging station.     

High-power CO(2) laser-beam monitor

A diagnostic system for measuring the beam power and quality of a high-power cw CO(2) electro-aerodynamic laser is described. A ZnSe beamsplitter was employed to split off a small fraction (0.5%) of the main laser beam for diagnostic purposes. The low-power beam was split again to provide two beams for power and energy-distribution measurements, concurrent with sample irradiation by the main beam. An electrically calibrated disk calorimeter was used to measure beam power. The temporal and spatial energy distributions were measured by means of a mechanically scanned, one-dimensional pyroelectric array. This provided a 16x16 element two-dimensional map of the beam profile at a rate of up to 10 Hz.     

一种复杂二次曲面轮廓度评定方法

为了建立复杂二次曲面轮廓度评定中计算机数据处理的理论模型和实现方法,提出了一种不要求满足小误差假设、不使用微分线形化评定二次曲面轮廓度的方法。该方法首先通过最小二乘法得到一个初始二次曲面,然后用模式搜索对初始二次曲面系数进行调整,直到找到满足最小区域原则的理想二次曲面,其目标函数值作为被测曲面的轮廓度。在计算过程中使用坐标变换将一般型的二次曲面化为标准型,既简化了轮廓度的计算,而且被测曲面可以在测量范围内任意放置。对抛物面轮廓度评定表明目标函数随着模式搜索的进行逐渐减小,模式搜索得到的抛物面轮廓度值比用最小二乘法得到的轮廓度值小得多,因此该方法更好地反映了被测二次曲面表面形状误差。     

Effect of surface topography on stress concentration factor

Neuber rule and Arola-Ramulu model are widely used to predict the stress concentration factor of rough specimens. However, the height parameters and effective valley radius used in these two models depend strongly on the resolution of the roughness-measuring instruments and are easily introduce measuring errors. Besides, it is difficult to find a suitable parameter to characterize surface topography to quantitatively describe its effect on stress concentration factor. In order to overcome these disadvantages, profile moments are carried out to characterize surface topography, surface topography is simulated by superposing series of cosine components, the stress concentration factors of different micro cosine-shaped surface topographies are investigated by finite element analysis. In terms of micro cosine-shaped surface topography, an equation using the second profile moment to estimate the stress concentration factor is proposed, predictions for the stress concentration factor using the proposed expression are within 10% error compared with the results of finite element analysis, which are more accurate than other models. Moreover, the proposed equation is applied to the real surface topography machined by turning. Predictions for the stress concentration factor using the proposed expression are within 10% of the maximum stress concentration factors and about 5% of the effective stress concentration factors estimated from the finite element analysis for three levels of turning surface topographies under different simulated scales. The proposed model is feasible in predicting the stress concentration factors of real machined surface topographies.