Ferrography Wear Digitized Images, The Fractal Dimension

The ferrography technique is a diagnosis technology based on the identification of wear particle, and is the most effective method for wear particles condition monitoring and wear fault diagnosis. Because of the diversity and complexity of the wear particle, the current wear particle identification is mainly finished by experts, and the identification accuracy depends on the person's experience and knowledge level, making it hard for ferrography to get further popularizing and applying, yet no objectively and comprehensive description of wear particle quantitative parameters. The microscopic observation shows that the wear particle has multi-scale fractal features. With the introduction of the theory of fractal geometry, and the computer image processing technology development, it makes quantitative analysis and automatic identification of wear particle become possible. Based on the fractal theory and previous studies, the thesis analyzes the ball particle, the chip particle, the cutting particle, the blocky particle and the laminar particle. The main contents of the thesis are as follows:1.The ferrography wear particle digital image is processed, mainly including gray-scale transform, smoothing filter, sharpening filter and threshold segmentation. Through this process, the original wear particle digital image can be automatic transformed into the binary digital image.2.The digital wear sample image acquisition system is designed and developed, a-certain of samples of five kinds of typical wear particle are prepared through the experiment. The software program of the integration of image processing and calculation of image fractal dimension is developed based on the MATLAB software platform. The correctness and reliability of the software is verified by calculating the image of known fractal dimension, such as Peano cure and Sierpinski carpet.3.The image fractal dimension of ball particle, chip particle, cutting particle, blocky particle and laminar particle are calculated. The distribution of the image fractal dimension is ascertained though a certain number of samples'statistical analysis, and the result can provide reference for the wear particle automatic recognition. 4.Based on the theory of the wear particle group, the cutting particle group, laminar particle group and the both particles group are analyzed, then the presented change law of the image fractal dimension with the number and the kind of wear particle is discussed.5.The presented change law of the image fractal dimension in the rolling bearing's break-in wear stage, normal wear stage and abnormal wear stage is analyzed through the experiment. The result can provide a basis for the rolling bearing's wear state detecting and fault diagnosis.