A development of three-dimensional surface measurement on cylinder

We developed a new measuring equipment of three-dimensional surface on cylinder. This system can measure all of surface forms from cylindrical form error to local surface asperity profile continuously. The system consists of static air bearings mainly and gets discrete data in cylindrical coordinates. Any areal data are regressed by some references and expressed by contour maps. This system is useful for estimation of roller bearing, etc.     

Calibration of translational tables for use in three-dimensional surface topography measurement systems

Translational tables now form a vital part in three-dimensional surface topography systems. In some systems typically, one translational table is used to provide measurements in one of the axes and the translational motion provided by the gearbox of the system is used to provide the other axis. In other systems, two translational tables are used to provide all the movement for data acquisition from the surface. In these systems, the stylus is held stationary during the measurement. It is clear from the above, that irrespective of the motion mechanism employed, the measurement depends heavily on the accuracy and repeatability of positioning of the translational tables. There are, as yet, no standards specifically prepared for calibrating translational tables and this can lead to problems with traceability.This paper sets out to define and assess procedures for determining the accuracy and repeatability of positioning translational tables in the x- and y-axes by using as an example, two tables that work on different principles: (1) a lead screw stepper motor driven table; and (2) a brushless linear motor driven table. Each of these systems has its particular problems. The system proposed, is based on the standard techniques employed for machine tool calibration and provides a basis for assessing and quantifying table errors that are likely to significantly affect the logging and characterization of surface data in three-dimensions (3D). In this paper the displacement and velocity characteristics of the tables are examined as well as dynamic stability, lead screw error, backlash, and repeatability of positioning. The paper also assesses the suitability of the two systems for use in static and on-the-fly data collection.     

Direct measurement procedure for three-dimensional local crack driving force using synchrotron X-ray microtomography

X-ray microtomography has been utilized for the observation of ductile fractures in an aluminum alloy with an Al/Al–Si dual phase structure. A procedure for analyzing a series of tomographic images is proposed for extracting the variation in the local crack-tip opening displacement (CTOD), and its feasibility is confirmed. Complicated crack growth behavior and the formation of uncracked ligaments ahead of a crack tip are observed in the alloy owing to the marked difference in local fracture toughness between the two phases. The proposed technique has provided a quantitative interpretation for such phenomena. It is clarified that a conventional measurement significantly overestimates the CTOD level. The transition behavior in CTOD has been revealed over a certain distance across an interface between the two phases, suggesting the existence of scaling effects that influence the microstructure/fracture relationship. Overall the current method could offer a highly effective way of assessing three-dimensional local fracture behavior.     

不同条件下三维边坡失稳规律的数值模拟

采用强度折减法研究二维和三维边坡的失稳机理。通过大量的算例,分析边界条件、强度参数和坡顶超载的三维效应,并与二维计算方法的结果进行对比,确定二维和三维计算方法的适用范围。数值模拟的计算结果表明,三维效应对滑体宽度很敏感;而对于特定的边坡几何尺寸,三维效应则受无量纲参数c/（γHtanφ）的影响。对于坡顶承受荷载的无限长边坡,边坡失稳模式主要受到荷载的影响。而对于同时受到物理边界和坡顶超载作用的边坡,失稳模式会受到两者的影响;随着荷载长度的增加,边界条件的影响更加显著。进而提出二维和三维的边坡稳定分析图,可以快速、可靠地确定二维和三维安全系数,且不需要任何迭代。最后,基于边坡三维效应和边坡稳定分析图的研究,总结一套简单实用的边坡计算流程,判断何时该采用二维或三维计算方法。     

The measurement and analysis of the three-dimensional form of curved surfaces

In an attempt to reduce manufacturing costs, contact lenses are manufactured using a cast moulding technique. If quality is to be maintained, it is essential that the mould components are manufactured to very high standards, with particular emphasis being placed on the curvature of the optical surfaces. If these surfaces are to be: accurately measured and described, then they must be considered in three dimensions. Several different :measurement instruments have been considered for this purpose, and three-dimensional numerical algorithms developed for assessment of the data from these instruments.     

Hardware variability in the three-dimensional measurement of autobody steel panel surfaces

Automotive panel manufacture is an important industrial activity. Research in this area has recently been assisted by an European Community funded research programme on three-dimensional characterisation of steel sheet. This paper describes the results of the first part of the programme in which the emphasis is on a Round Robin Test of the partners measuring equipment. Software was identified as being one of the major causes of variability. It is concluded that standard and stable algorithms are a necessity to ensure reliable interchange of data.     

The application of three-dimensional surface measurement techniques to characterizing grinding wheel topography

Two differing grinding wheels were dressed under similar conditions and their resulting surface topographies were measured using three-dimensional contacting profilometery techniques. Through the use of newly developed three-dimensional numerical surface characterization parameters, aerial estimations of the number of static cutting points and static cutting grains were made, and the results compared with those obtained by other workers. The techniques used proved useful for both qualitative and quantitative analysis of the wheel topography. The results obtained compared favourably with those of other workers. The effects of sampling strategy on the results are discussed and optimum sampling conditions suggested.     

Determination of tribological conditions within hot stamping

Innovative hot sheet metal forming technologies are gaining an increasing significance in the scope of application of more and more innovative high and ultra high strength steels in the automotive industry. With respect to a numerical process design beside the mechanical and the thermal material characteristics the friction coefficient represents an important input parameter for finite element (FE) simulation. Within the scope of this paper an evaluation method for the determination of the friction coefficient μ for the direct hot stamping process of boron-manganese steels will be presented. Therefore cup deep drawing tests at elevated temperatures following the time-temperature-characteristic of the hot stamping process are carried out. For the calculation of the friction coefficient the approach according to Siebel for the modeling of the maximum drawing force is used.     

Determination of the optimum conditions for ion nitriding of AISI 5140 steel

AISI 5140 low alloy steel was ion nitrided under different process parameters including time (1, 4, 8 and 12 h), temperature (400, 450, 500 and 550 °C) and gas mixture ratio (0.05, 0.33, 1 and 3 N₂/H₂). By determining the fatigue strength, surface hardness, compound layer thickness and case depth, the optimum working conditions were determined by using a Taguchi design of experiment. After ion nitriding process, it is aimed to maximize fatigue strength, surface hardness and case depth as well as to minimize compound layer thickness. While the optimum conditions were determined, due to the goals (above aims) more than one being, the trade-off among goals was considered. First of all, each goal was optimised, separately. Then, all the goals were optimised together, considering the priority of the goals, and the optimum results were obtained at 0.05 N₂/H₂ gas mixture ratio, at the temperature of 450 °C and for 12 h process time.     

In-situ measurement of three-dimensional deformation behaviour of sheet and tools during stamping using borescope

An in-situ measurement approach for three-dimensional deformation of sheet and tools during stamping using borescopes was developed. The borescope, consisting of a small CCD camera with a flexible cable, was connected to personal computer and placed inside a small space between the tool cavities to measure the deforming behaviour of the sheet. The deformation behaviour of the sheet and punch, the real springback and wrinkling in shrink flanging were measured. The deformed shape of the sheet measured by the borescope was in good agreement with that measured by the laser displacement sensor. In addition, three-dimensional deforming behaviour was measured by a stereoscopic method using two borescopes. It was found that the borescopes are effective in in-situ measurement of three-dimensional deformation behaviour of the sheet and tools.     

合理焊接顺序在避免焊趾裂纹中的应用实例

通过实例介绍如何采用合理的焊接顺序来避免焊趾裂纹的产生。在焊接结构上,焊趾是主要的潜在裂纹源。一些表面裂纹可能在焊趾上先后成核、扩展,最终沿深度方向贯穿板厚。焊趾裂纹的产生与焊缝的受力状态有关。这种裂纹因位于焊缝的应力集中区内,受到高应力的作用,同时还受到附加弯矩的作用。合理的焊接顺序能够极大地减少焊缝中的残余应力和变形,此外活马板的使用能够使焊缝自由收缩,也可减小焊缝中的应力,避免焊趾裂纹的产生。     

A statistical sampling approach for measurement of fracture toughness parameters in a 4330 steel by 3-D femtosecond laser-based tomography

A new approach using statistically random material volume sampling has been developed to model the variability of fracture toughnesses in steels. A recently developed femtosecond laser-based serial sectioning (FSLSS) technique was utilized to collect 3-D datasets showing the distribution of titanium nitride (TiN) phases in a 4330 high strength steel. Random volumes were sampled from widely spaced regions within the bulk steel specimen. Plastic zone sized volumes were sampled from the 3-D reconstructions to produce statistically representative volume elements containing TiN particles. Fracture toughness was calculated for 48 different plastic zone sized volumes using two different toughness models. Weibull analysis was performed to relate the modeled fracture toughness to the probability of occurrence. Variability in the fracture toughness gave a Weibull modulus of m = 1.4–1.5, similar to the variability measured in 22 bulk sample specimens analyzed by Ruggieri et al. for a similar steel.     

Determination of sampling errors in natural stone plates through Single Linkage Cluster Method

In this study, the variations in the thicknesses of the plates cut from natural stone blocks with a circular saw block cutter machine have been investigated using Range (R) control charts. Erratic data caused by sampling errors in range values were encountered when these charts are examined. Erratic data among the range values were determined by Single Linkage Cluster Method and were eliminated from the processes. After the erratic data were sorted out, the parameters concerning the R control charts were recalculated and the charts were reconstructed. Using the reformed R control charts, it was shown that the processes are better than the previous R control charts. Finally, it was determined that the erratic data caused by sampling errors could reliably be estimated by the Single Linkage Cluster Method.     

Determination of fiber bridging stress profile by debond length measurement

A new technique is developed for measuring the fiber bridging stress in fiber-reinforced ceramic matrix composites (FCMCs). This technique is based on the direct measurement of the debond length associated with a bridged matrix crack in a composite. Theoretical formulations are developed to relate the debond length measurement (DLM) to the applied stress and fiber bridging stress. Subsequently, the DLMs of a bridged crack are used to calculate the bridging stress profile. Simultaneously, the crack opening displacements (CODs) are also measured from which the fiber bridging stress is determined independently. A comparison of the fiber bridging stress obtained from DLM and COD is made. Finally, a new bridging law is proposed and verified based on this study.     

Determination of permissible deviations of the two-sided arc welding conditions

Methods for determining the permissible deviations of welding conditions are investigated. The sensitivity parameters do not provide information on the relative risk of different types of perturbation of the parameters. A relative coefficient of transfer of perturbations is proposed which can be used to estimate the susceptibility of the welding parameter to perturbations and does not require any controlling effect of the system. An example of the application of the methods of determining the requirements for the accuracy of the parameter and the conditions for two-sided argon-shielded arc welding of sheets made of high-alloy steel without edge preparation is described.     

Determination of optimal cutting conditions using design of experiments and optimization techniques

In process planning or NC part programming, optimal cutting conditions are to be determined using reliable mathematical models representing the machining conditions of a particular work-tool combination. The development of such mathematical models requires detailed planning and proper analysis of experiments. In this paper, the mathematical models for TiN-coated carbide tools and Röchling T4 medium carbon steel were developed based on the design and analysis of machining experiments. The models developed were then used in the formulation of objective and constraint functions for the optimization of a multipass turning operation with such work-tool combinations.