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PEEK不同表面粗糙度与分形维数关系研究 总被引:1,自引:0,他引:1
为探究PEEK不同表面粗糙度与分形维数之间的关系,在触针式表面轮廓仪上测量PEEK不同表面的粗糙度并采集了其轮廓曲线和数据。运用分形理论随机过程的结构函数方法,分析轮廓曲线的分形特征,并计算出不同表面粗糙度的分形维数。利用SPSS统计软件对粗糙度和分形维数关系进行拟合并得到最佳的拟合模型。结果表明:分维可以作为一个独立的表征参量来表征粗糙表面的复杂程度和粗糙度水平;PEEK的分形维数与粗糙度存在单调递减的关系,粗糙度数值越大,分形维数值越小;通过分形维数值与粗糙度之间的关系式,在一定范围内,可以通过粗糙度值计算得出分形维数值。 相似文献
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机械加工表面形貌分形特征的计算方法 总被引:10,自引:1,他引:10
提出应用小波变换计算表面形貌分形特征参数,基于Weierstrass-Mandelbrot函数(W-M函数)和Majumdar-Bhushan函数(M-B函数)这2种常用于表征和模拟机械加工表面轮廓曲线的标准分形函数,验证了小波变换计算分形维数具有很高的精度。与其它计算表面形貌分形维数的方法进行了比较,结果表明小波变换方法的稳定性和准确性好。应用小波变换计算了不锈钢和铜2种材料的机械加工表面的分形维数。 相似文献
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针对异性分形表面的建模,提出了一种以二维离散傅里叶变换为基础,以名义维数Dx,Dy为驱动参数的表面合成方法——合成维数法。通过对比名义维数与采用轮廓功率谱公式和数值分析法得到的表面计算维数的关系,验证了该方法的有效性。探讨了名义维数对x,y方向轮廓能量分布以及对表面及轮廓粗糙度的影响。一方面在轮廓功率谱分析的基础上定义了轮廓累计功率比,用于描述表面轮廓的能量分布特性,不仅促进了对名义维数和轮廓能量关系的定性理解,更能定量地解释不同维数值影响下频率和轮廓能量分布的关系。另一方面以能量分析为切入点,建立了名义维数与表面及轮廓粗糙度参数间的联系,并且依据能量守恒定律,证明并揭示了轮廓粗糙度Rqx,Rqy之间以及二者与面粗糙度Sq的关系。同时得出结论,Dx或Dy值越小,低频部分能量占比越高,反之亦然,但是x,y方向轮廓总功率始终相等,并随Dx,Dy增大而增大;Dx,Dy只影响Sq,Rqx,Rqy的绝对数值,二者的增大会引起粗糙度值增加,但并不影响Rqx,Rqy的相对关系。 相似文献
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用互相关函数判别零件表面形貌的特征 总被引:4,自引:0,他引:4
通过对不同加工方法所形成的表面形貌进行测量,得到大量的实测数据。运用随机分析方法分别求出每个零件表面形貌的互相关函数及其系数,再通过对函数与系数的分析,探讨表面形貌的特征。 相似文献
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分形维数与表面粗糙度参数的关系 总被引:13,自引:1,他引:13
将分形维数D与传统的表面粗糙度评定参数Ra和λq作了比较。实验结果表明:D与Ra的线性关系并不明显,而D与λq的相关性较好。三个参数各自反映了表面的不同特征,但不能相互替代。 相似文献
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表面微观形貌参数尺度独立性的研究 总被引:2,自引:0,他引:2
表面微观形貌的表征主要采用传统粗糙度参数和分形参数等多种参数综合描述,尺度独立性是衡量表面形貌表征参数的重要指标。研究了传统粗糙度评定参数和分形维数等表面微观形貌表征参数的尺度独立性。以准分子激光加工,平磨、外圆磨、研磨等磨削机加工表面轮廓为对象,分析了取样长度和采样间距对传统粗糙度参数和分形维数的影响。结果表明,传统粗糙度参数受取样长度和采样间距影响较大,而分形参数与尺度独立性的相关性与加工方法有关系,微细加工表面微观形貌受取样长度和采样间距的影响比机加工表面要小,准分子激光等微细加工表面的分形参数具有尺度独立性。 相似文献
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Surface topography is one of the leading factors affecting wear processes. This study investigated topographical changes of mechanical components with non-Gaussian surfaces under sliding wear. The Johnson translatory system of distributions was applied to describe different surface height distributions. A wear model that has been experimentally confirmed for sliding wear was used to describe changes of surface heights. Based on different wear particle size distributions generated during wear, variations of surface height distribution were investigated. Relationships between topographical change and original surfaces were established. Finally, the results predicted were compared with the results using a truncation wear model 相似文献
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二维表面粗糙度的分形模拟与分析 总被引:4,自引:0,他引:4
利用W-M函数对二维表面粗糙度进行模拟,并利用其功率谱计算表面粗糙度的分形维数。最后分析了分形维数与表面的支承长度率曲线的关系。 相似文献
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《Measurement》2016
Wiper insert have the characteristics of achieving an excellent surface finish and improving the productivity in turning processes. Wiper insert can provide twice feed rate while maintaining the comparable surface roughness compared to that provided by the conventional insert. In the present study, surface topographies in finish turning with conventional and wiper inserts are investigated. The key element of this work is that the cutting edge path equation in the cutting tool coordinate system is transformed into the machine tool and workpiece coordinate system by the use of spatial coordinate transformation. Following that a surface topography simulation algorithm based on the cutting edge path equation and cutting parameters is put forward. The output of this work is that both the simulated surface topography and surface roughness profile are good agreement with the experimental results. Both the simulated and the actual machined surface results show that better surface topography is obtained in finish turning with the wiper insert than that with conventional insert. Burnishing effect of the wiper insert leads to half decrease of the Ra and Rz. The actual surface profiles are no longer regular wave shapes due to ploughing effect and side flow existing in the cutting zone. In addition, a surface roughness map has also been developed to optimize the selection of wiper radius and feed rate to satisfy the requirement of surface finishing with higher productivity. From the viewpoint of cutting tool design, the wiper radius with five times larger than tool nose radius can fully come into its role. This provides a novel insight into the design of wiper insert over conventional techniques. Above all, the proposed model gives a better prediction of surface roughness in finish turning process compared to the previous empirical and regression roughness models. The prediction of surface roughness in finish turning with wiper insert is also realized. 相似文献
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The change in surface topography caused by friction and wear influences the wear properties and service life of mechanical seal. To investigate the wear properties of mechanical seals and obtain the variation in surface topography, it is practical to carry out accelerating experiments by increasing the load, speed, or temperature of the medium than safe life tests in the field device. Based on the assumption that the same fractal roughness corresponds to the same wear properties, the pi theorem was introduced to derive the relationship of wear under experimental and actual conditions. By providing detailed values of constants in the pi theorem through accelerating experiments, a fractal model was established to predict the life expectancy of mechanical seals. Under the state of mixed friction, measured values of surface topography for experimental stationary rings and data on a mechanical seal ring's service life in the field device were in accordance with those of the model. The establishment of the fractal model provides conditions for the performance study of long-period operating mechanical seals. 相似文献
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不同材料的准分子激光微细加工机制 总被引:1,自引:0,他引:1
采用准分子激光加工方法,在相同的工艺参数下加工了Al2O3陶瓷、不锈钢、Q235等脆性和塑性材料。通过扫描电子显微镜(SEM)获得加工表面微观形貌图像和采用表面轮廓仪测得形貌统计参数。分析得出,准分子激光的加工机理是光化学和热效应作用等多种因素影响的综合体现;加工不同材质的材料时,准分子激光具有不同的加工机制,对于脆性材料以光解剥离(APD)为主,而对于塑性材料则以热效应为主。 相似文献
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W. Wayne Chen Q. Jane Wang Yuchuan Liu Wei Chen Jiao Cao Cedric Xia Raj Talwar Rick Lederich 《Tribology Letters》2007,28(1):27-38
Interaction of nominally flat engineering surfaces that leads to a large contact area exists in many mechanical systems. Considering
periodic similarity of surface geometry, a numerical three-dimensional elasto-plastic contact model can be used to simulate
the contact behaviors of two nominally flat surfaces with the assistance of the continuous convolution and Fourier transform
(CC-FT) algorithm. This model utilizes the analytical frequency response functions (FRF) of elastic/plastic responses of materials
and provides contact performance results, including the average surface gap, the contact area ratio, and the volume of plastically
deformed material, which may be defined as performance variables. Following the digital filtration technology, rough surfaces
can be numerically generated with specified autocorrelation length and the first four orders of statistical moments. A group
of contact simulations are conducted with various working conditions. The effects of topographic and material properties on
the contact behaviors are discussed. With a multi-variables regression method, empirical formulas are developed for the performance
variables as functions of surface statistical characteristics, material properties, a hardening parameter, and the applied
load in terms of pressure. 相似文献
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An Investigation of the Surface Topography of Ball Burnished Mild Steel and Aluminium 总被引:1,自引:1,他引:0
M. Némat A. C. Lyons 《The International Journal of Advanced Manufacturing Technology》2000,16(7):469-473
An experimental analysis was undertaken on ball burnished mild steel and aluminium using a purpose built burnishing tool. The analysis was designed to assess the effects of burnishing feed, force and speed and the number of tool passes on the surface roughness and surface hardness of a mild steel and an aluminium workpiece. In some cases, experiments showed that improvements of as much as 70% in surface quality were obtained when varying the mix of parameters. 相似文献