小波系数表征机械加工表面分形特征的计算方法 .pdfVIP

学兔兔 第31卷 第7期 仪 器 仪 表 学 报 VoL 3l Nm 7 2010年7月 Chinese Journal of Scientific Instrument Ju1．2010 小波系数表征机械加工表面分形特征的计算方法木 杨红平，傅卫平，王 雯，杨世强，李德信 (西安理工大学机械与精密仪器工程学院 西安 710048) 摘 要：针对表征机械加工表面轮廓形貌分形特性，提出应用小波变换系数计算分形维数的算法。基于Majumdar—Bhushan分 形函数构造典型曲线，采用工程常用的三种小波基函数，通过小波分解提取小波系数，并将在不同分解尺度和阶数下计算出的 分形维数进行对比分析和验证，选择出计算分形维数精度较高的小波基函数和分解尺度。用该方法对车削和铣削加工的结合 面实验试件表面形貌的分形维数进行计算，评价了表面形貌的分形特征。 关键词：小波变换系数；表面形貌；分形维数；机械加工表面 中图分类号：TH161．14 文献标识码：A 国家标准学科分类代码：460．351 Calculation method for fractal characteristics of machining topography surface based on wavelet coefficients Yang Hongping，Fu Weiping，Wang Wen，Yang Shiqiang，Li Dexin (Faculty of Mechanical and Precision Instrument Engineering，Xi an University of Technology，Xi art 710048，China) Abstract：In this paper，to characterize the fractal characteristics of machining topography surface，a calculation method of fractal dimensions using wavelets transform coefficients is proposed．Typical surface profiles are simulated based on the Majumdar-Bhushan fractal function．The calculated fractal dimensions are analyzed and validated using three kinds of wavelet functions commonly used in engineering with different decomposition scales and orders．The wavelet function and scale that can obtain higher calculated fractal dimension accuracy are selected．The fractal char- acteristics of the tested surfaces for turning and milling experiment parts are estimated．Results show that the pro— posed wavelet transform coefficient method is a powerful tool for the research on fractal surface． Key words：wavelet transform coefficient，Surface topography，fractal dimension，machinin