铁谱磨粒形态分形特征参数提取方法研究

阐述了分形与分形维数的定义，给出了铁谱磨粒分形维数和无标度区间的计算原理。编制了磨粒图像处理及磨粒分维计算的计算程序，并以片状磨粒为实例，提取了该磨粒的轮廓分维特征、磨粒表面纹理特征、表面纹理方向特征与磨粒表面间隙度特征四个特征值，为有效识别磨粒提供科学依据。     

曲波域铁谱磨粒图像特征提取方法研究

曲波变换具有多尺度分析能力,与小波变换相比可更好地表达图像的曲线特征.为有效描述铁谱磨粒的形貌特征,提出一种曲波域图像特征提取方法.利用曲波变换将磨粒图像进行分解,得到不同尺度的曲波系数;根据曲波系数统计分布特点,采用广义高斯分布模型对细尺度和精细尺度曲波系数分布进行建模;提取粗尺度曲波系数的均值、标准差、能量和熵等统计特征,以及细尺度和精细尺度曲波系数的广义高斯分布模型参数描述磨粒特征.将提取的特征用于发动机典型磨粒识别,识别成功率达到了88.9%,表明该方法所提特征能很好地表达铁谱磨粒的形貌特征.     

基于链码的金属磨粒分形参数计算

介绍了基于链码的磨粒分形参数及其计算方法，采用编写的磨粒识别程序，对不同磨损阶段测得的磨粒分布数进行分析，可以得到磨粒二重分形参数和拐点数值，发现磨粒分布分形维数的变化与磨损状态改变相对应。该方法用于磨粒分形特征与磨损状态相关性规律的研究识别，简便快捷。     

磨粒类型识别研究

提出了一种有效的磨粒类型识别方法，该方法除了选用传统的磨粒形态特征参数，将表面粗糙度和表面纹理指数也作为重要的磨粒识别参数，选用面积、长度、圆度、纤维比率、体态比、边界分形维数、表面粗糙度．Sa．Sq，和表面纹理指数（Stdi）等9个参数，采用人工神经网络来识别磨粒类型，应用示例表明效果良好，提高了磨粒类型识别的精确度。     

片状磨粒、块状磨粒和层状磨粒轮廓分形维数研究

选取计盒维数法作为计算磨粒轮廓分形维数方法,采用磨粒相片、实验法和现场收集3种方法收集了片状磨粒、块状磨粒和层状磨粒各600个样本,并在500和800倍放大倍数下进行了轮廓分形维数计算.结果表明,这3种磨粒轮廓分形维数分布为正态分布,在放大800倍数时具有最好的统计分形;研究结果可用于磨粒自动识别和磨损状态实时检测.     

发动机铁谱磨粒分析与磨粒识别研究

从发动机摩擦副及其摩擦磨损特点着手，提出了用于发动机磨损状态监测与诊断的主要10类磨粒，依据其识别特征提出了用于磨粒识别的14个磨粒形状、表面纹理与颜色特征；最后应用BP网络分层识别策略进行了磨粒识别。     

基于在线铁谱图像的磨损机理智能辨识

基于状态的维护(Condition based maintenance,CBM)理念为机器健康状态维护提出了实时监测的新挑战。现有研究由于缺乏在线信息获取手段,磨损状态监测逐渐成为CBM的技术瓶颈。基于特征磨粒的磨损机理判断方法已经被广泛应用在离线磨损分析中,但是在线磨损机理的表征依然是一个很大的问题。针对基于在线铁谱图像的磨损机理开展研究。为了在一副在线铁谱图像中获得分离的磨粒图像,研究磨粒在在线铁谱传感器中的沉积机理。研究结果表明,磨粒链是图像中的主要形态,这是由于先前沉积的磨粒产生的局部磁场所致。设计一种依靠自适应调节沉积时间的在线磨粒沉积方法。运用该方法可以在在线铁谱图像中获得分离的磨粒,为特征磨粒的特征辨识提供了便利。参考分析铁谱知识,提取特征磨粒的4种形态学特征(当量尺寸、长径比、形状因子和分形维数)以综合表征4种典型磨损机理,包括正常、切削、疲劳、严重滑动磨损。采用反馈式人工神经网络构建自动磨损机理辨识模型。采用离线铁谱图像样本验证所建模型,结果表明该模型可以识别在线磨粒图像中的特征磨粒。对在线磨损机理表征方法进行了有意义的探索,所得研究成果将为在线磨损状态表征提供可行方法。     

基于灰色信息融合技术的磨粒识别方法

传统的灰色关联度计算方法是将单特征关联系数简单的进行求和平均,在磨粒识别中其识别结果分辨率不高,容易造成误判。提出了一种基于灰色信息融合技术的磨粒识别方法,它首先将各组单特征关联系数作为多源证据,然后利用D-S证据理论进行有效融合计算灰色关联度,实际计算表明,该方法能明显提高磨粒识别结果的分辨率及准确率。     

基于磨粒表面信息的磨损表面特征评估

建立了基于磨粒表面信息的磨损表面评估方法。首先选择合理的磨粒和磨损表面特征参数，通过识别磨粒类型，获得磨损过程中具有典型性和代表性的磨粒类型，然后选取这些具有代表性的磨粒类型，得到磨粒的表面特征向量，进而来研究磨损表面和磨粒表面的映射关系，实现基于磨粒表面信息的磨损表面特征评估。实例表明，根据磨粒表面特征评估磨损表面特征是可行的。     

基于磨粒颜色特征的识别方法研究

磨粒监测是机械设备故障诊断的有效方法,其中磨粒的识别是目前研究的重点和难点,磨粒的颜色参数是识别磨粒的重要特征。基于对因子分析方法的介绍,将彩色磨粒图像提取的颜色变量减少为5个主要特征,简化了描述参数。结果表明,选择适合的HSV获得不同磨粒的空间分布,设置分割线,就可用于不同颜色的磨粒分类和识别。     

基于广义贴近度的船用柴油机磨损模式识别方法

在总结船用柴油机磨损形式的磨粒分析基础上,分析了模糊逻辑方法进行模式识别的不足,提出在船用柴油机磨损模式识别中极用基于广义贴近度的模糊模式识别方法,建立相应模式识别专家系统,并验证了识别结果的可靠性。     

柴油机主要摩擦副磨损型式的识别

本文首先提出了柴油机磨损型式识别的重要性,进而阐述了磨损型式模糊模式识别的过程,即：模糊模式识别原理,建立磨损型式的标准样板库,隶属函数的确定等等,最后给出了结论。     

油润条件下磨粒分形行为与摩擦状态相关性的研究

以45#钢-铜配副在浸油状态下进行磨损试验,采用自行构建的磨粒分析系统考察不同磨损阶段产生的磨粒形态,测量多种磨粒表征参数,并就各表征参数与摩擦力的关联性进行了对比分析.分析结果表明:磨粒群体中轮廓分形维数的分布呈正态分布;磨粒分形维数相对于其它表征参数而言,和摩擦力相关性更大.     

磨损微粒识别的模糊决策树方法

磨损微粒识别是在磨损工况监控中确定机器磨损类型的关键步骤。本文基于非单调模型推理方法，依据磨粒识别过程中所依赖特征的层次关系，建立了磨粒识别的模糊推理决策树。这一决策树开发的软件试验结果表明，本文所提出的方法在实现磨粒的自动识别方面是有效的。     

Scale-invariant analysis of wear particle morphology—a preliminary study

The importance of wear particle characterization is continuously growing, as the need for prediction and monitoring of wear increases. Accurate analysis of wear particles can, however, be limited by problems associated with particle characterization, especially of the wear particles' surface morphology. Since the shape and surface topography of wear particles often exhibit a fractal nature, fractal (scale-invariant) methods are, therefore, used in their characterization. However, the methods used to date ignore the fact that all fractal objects can be described by a small set of mathematical rules; although finding those rules which describe a particular fractal image is a difficult problem. No general solution exists to date and this paper attempts to redress this problem. A new analysis method, ‘scale-invariant analysis’, which is based on a partitioned iterated function system (PIFS), is proposed for the characterization of wear particle morphology. PIFS is a collection of contractive affine transformations. Each affine transformation transforms one part of a wear particle image onto another part of the same image. PIFSs were constructed for both computer generated and SEM images of wear particles. Results obtained in this study clearly demonstrate that the morphology of wear particles can effectively be characterized using the PIFS method.     

Tribological behavior of boundary lubricated sliding surfaces using three different spacing of surface profiles

The ball-on-disk type sliding tests with boundary lubricated steels were carried out to verity the effect of initial spacing in surface profiles on wear and scuffing. Three kinds of surface spacing, which are closely related with initial surface micro-cracks on sliding surfaces, were produced onAISI 1045 steel surfaces using different grinding and polishing processes. Frictional forces and time to scuffing were measured, and the shape and amount of wear particles were analyzed to compare the with original surface profiles. From the tests, it was confirmed that the size of wear particles are related closely to the original spacing of the surface profile. The time to failure and amount of wear were sensitive to the surface spacing. The wider surface spacing shows much longer sliding life and smaller amount of wear than the others. Time to scuffing was increased with increasing surface profile spacing. The size of wear particles increased while the wear and wear rateK were decreased with an increase in surface spacing. After the sliding tests, surface cracks of inner parts of the wear track formed due to scuffing were observed and compared among the specimens having the different surface spacing.     

人工神经网络在铁谱技术磨粒识别中的应用

铁谱技术在机械设备状态监测中得到了广泛的应用，磨粒识别是铁谱分析的一个关键环节，本文提出了一种基于神经网络的磨粒识别方法，利用前馈型神经网络模型对七种典型磨损磨粒进行了实例分析识别，取得了令人满意的结果。     

Ceramic wear maps

Ceramic wear maps have been developed to elucidate the complex interactions of the operating parameters, environments, and wear mechanisms. This paper summarizes these interactions for four ceramics, alumina, yttria-doped zirconia, silicon carbide and silicon nitride. Wear maps of these ceramics are systematically constructed using measured data under dry sliding, water, and paraffin lubricated conditions. For each material, different wear level regions acid wear transition zones are identified as a function of operating conditions and lubrication conditions. Wear mechanism studies performed within each wear region give rise to the wear mechanism maps. These maps facilitate material comparison and selection. The knowledge of wear, wear transitions, and wear mechanisms for a material pair enables realistic wear model development. One outcome of this approach is the recognition that a single wear model for a material pair cannot cover all operating conditions and environments.

As wear maps are constructed today, they are material pair specific. Within a material pair, there are microstructural dependence and surface properties influence. These parameters can change substantially for a given chemical composition of the material. How to incorporate these factors into the wear map research remains an issue. The search for a universal parameter such as the “asperity temperature” in Ashby's wear map continues in spite of mounting evidence that this may not be practical or feasible. But the hope remains that some parameters can be identified to normalize a large number of materials, operating conditions, and environments for tribological applications. Systematic wear maps are the first steps in this direction.     

Characterisation of wear debris from UHMWPE on zirconia ceramic, metal-on-metal and alumina ceramic-on-ceramic hip prostheses generated in a physiological anatomical hip joint simulator

There is currently much interest in the characterisation of wear debris from different types of artificial hip joints. There have been numerous studies on the wear of UHMWPE in hip joint simulators, but relatively few studies on the wear of alternative materials such as metal-on-metal (MOM) and ceramic-on-ceramic (COC). The aim of this study was to compare the wear volumes and wear debris generated from zirconia ceramic-on-UHMWPE, MOM and COC hip joints under identical conditions in the same hip joint simulator.

All prostheses showed an initial higher ‘bedding in’ wear rate, which was followed by a lower steady state wear rate. The zirconia ceramic-on UHMWPE prostheses showed the highest wear rates (31±4.0 mm³/million cycles), followed by the MOM (1.23±0.5 mm/million cycles), with the COC prostheses showing significantly (P<0.01) lower wear rates at 0.05±0.02 mm³/million cycles. The mode (±95% confidence limits) of the size distribution of the UHMWPE wear debris was 300±200, 30±2.25 nm for the metal particles, and 9±0.5 nm for the ceramic wear particles. The UHMWPE particles were significantly larger (P<0.05) than the metal and ceramic wear particles, and the metal particles were significantly larger (P<0.05) than the ceramic wear particles. A variety of morphologies and sizes were observed for the UHMWPE wear particles, including submicrometer granules and large flakes in excess of 50 μm. However, the wear particles generated in both the MOM and COC articulations were very uniform in size and oval or round in shape.

This investigation has demonstrated substantial differences in volumetric wear. The in vitro wear rates for the zirconia-on-UHMWPE and MOM are comparable with clinical studies and the UHMWPE and metal wear particles were similar to the wear debris isolated from retrieved tissues. However, the alumina/alumina wear rate was lower than some clinical retrieval studies, and the severe wear patterns and micrometer-sized particles described in vivo were not reproduced here.

This study revealed significant differences in the wear volumes and particle sizes from the three different prostheses. In addition, this study has shown that the alternative bearing materials such as MOM and COC may offer a considerable advantage over the more traditional articulations which utilise UHMWPE as a bearing material, both in terms of wear volume and osteolytic potential.     

Evaluation of fretting wear based on the frictional work and cyclic saturation concepts

It is time consuming or even impossible to simulate the whole process of fretting wear, since it always involves millions of cyclic loadings. This paper focuses on the modeling and evaluation method of fretting wear for the typical bridge type fretting test with a flat pad. The frictional work on the contact interface is chosen as the parameter to evaluate the fretting wear. To verify the fretting wear model, the predicted wear profile is compared with that obtained by the experimental results. Fretting wear always includes plastic deformations due to the edge stress singularity. The effect of cumulative plastic deformation is also taken into account in the wear model. The role of the coefficient of friction at the contact interface on the fretting wear has also been discussed.