基于Stewart的表面粗糙度随形测量技术研究

在生产加工、测量控制过程中,许多问题的解决需要建立在对机械零件表面的几何特性和构造的准确认识的基础上。传统的分析主要是对单个轮廓的表面几何特性进行描述,而实际的零件却是三维立体的,通过对单个轮廓的分析来推断工件表面的三维几何特性,存在很大的不确定因素。因此,把检测范围从二维扩展     

三维表面偏斜度与陡度的规律研究

使用ADE公司的非接触式表面三维形貌仪对粗糙度标准样板进行系统测试,研究分析了三维表面偏斜度与陡度的规律。结果表明：三维表面偏斜度、陡度与表面的摩擦磨损性能有重要的对应关系,它们是表面微观结构形状的描述,与表面的精度无直接关系;对应不同结构的表面,三维表面偏斜度与陡度在数值上出现了一定的规律性,随机性较强的表面的工作性能明显优于周期性较强的表面,这给我们更加准确地根据零件的使用要求选择不同的加工方法或选择表面结构类型提供了依据;三维表面偏斜度与陡度明显优于二维,三维参数取点于整个区域,更能反映表面微观的特征,测量值更加稳定、可靠。     

具有指定统计参数的粗糙表面的加工和复制

表面微／纳米结构和各种功能特性密切相关,为了更加定量地分析结构参数和功能特性的内在相互依赖关系,需要首先获得具有指定统计粗糙度参数（例如表面均方根粗糙度、偏斜度、峰度、自相关长度等）的三维粗糙表面。本文主要进行可控表面统计参数的粗糙结构的设计、加工和复制研究。为了提高设计精度,特别是对于具有大自相关长度的表面,在非线性共轭梯度法中引入了遗传算法（GA）。经优化设计后,利用聚焦离子束（FIB）在硅基底上加工了一系列具有不同高度分布和自相关长度的三维粗糙表面。最后,用转印的方法将这些结构复制到聚二甲基硅氧烷（PDMS）薄膜,并且应用参数评价和频谱分析等对模板和复制结构之间的原子力显微镜（AFM）测量结果评价比较。可控表面统计参数的粗糙表面加工及复制可为后续进行粗糙结构相关的表面功能特性定量分析研究提供支持。     

水中规则波纹表面球回声特性研究

运用声呐目标回声特性预报的板块元方法,研究了平面波入射水中规则波纹(正弦平方曲线波纹)表面球体的目标回声特性。分析了表面波纹高度、周期、入射平面波频率和入射方位角对声目标强度空间分布和频率响应特性的影响规律。讨论了不同频段目标强度空间分布特性的形成机理,得到了表面波纹参数与目标强度频率响应和空间分布特性的近似定量关系。通过水槽实验测量得到了3D打印的规则波纹表面尼龙球目标强度的频率响应和空间分布特性,测量结果与理论计算结果吻合较好。掌握规则波纹表面球体回声特性,有助于开展利用声学超构材料对散射声场调控的研究。     

表面粗糙度三维测量和评定的研究

本文论述了应用相移干涉原理测量三维表面粗糙度,给出了测量系统的组成,实现相移的微位移器件压电陶瓷应用,三维表面粗糙度评定参数的确定。     

毛化表面的三维表面形貌在线测量仪

表面形貌影响着毛化钢板的使用性能和轧制工艺,在冷轧毛化钢板的生产中要实时监控.本文介绍了一种便携式的三维表面形貌测量仪,具有三维形貌测量和图像分析的功能,能够在线测量毛化钢板和轧辊的表面形貌.接触式位移传感器基于激光干涉原理,结合二维水平位移工作台,可实现大面积高精度的三维形貌测量.同时分析了该仪器的技术性能,并进行了试验测试,给出了测量结果.     

智能化表面粗糙度检测仪

研究出一种智能化的表面粗糙度检测仪，其纵向分辨率为０．３ｎｍ，横向分辨率为１．２７μｍ，测试重复精度为０．５ｎｍ。该仪器不仅可以给出待测表面的二维截面图和三维形貌图，还能提供各种纵向、横向以及综合粗糙评定参数值。本文描述了它的测量原理及设计中的关键技术，并对测量结果作了误差评述。     

三维表面粗糙度的研究

本文介绍了三维表面粗糙度的特征参数，阐述了当今表面粗糙度的一些新的检测方法，同时编制出三维表面粗糙度特征参数的数据处理软件，为三维表面测量技术走向实用阶段奠定一定基础。     

碳/碳复合材料切削表面粗糙度的评定方法及评定参数研究

通过对航空航天领域应用的碳，碳（C／C）复合材料和硬铝材料切削表面进行三维表面粗糙度测量实验，研究了C／C复合材料切削表面粗糙度的二维评定与三维评定方法、幅度表征参数及分形表征。结果表明：对于C／C一类的复合材料需选用三维评定参数才能准确表达其切削表面粗糙度的真实特征；表面均方根偏差比表面算术平均偏差更适合作为C／C复合材料切削表面粗糙度的幅度评定参数，表面粗糙度的三维标准应优先选用表面均方根偏差作为评定参数；表面分形维数可作为C／C复合材料切削表面粗糙度的表征参数之一。     

三维表面轮廓的白光干涉垂直扫描测量方法的研究

基于白光干涉垂直扫描轮廓测量原理,研制出一种以6JA干涉显微镜为基础,配合自带计量衍射光栅测量系统的精密垂直位移工作台,从而实现大范围、高精度三维表面轮廓测量的方法.实验结果表明,采用白光干涉垂直扫描轮廓测量方法,可满足测量解析度及精度达到纳米等级的同时,其垂直测量范围可达80μm的三维表面轮廓测量要求.     

Spatial pavement roughness from stationary laser scanning

Pavement roughness is a key parameter for controlling pavement construction processes and for assessing ride quality during the life of a pavement system. This paper describes algorithms used in processing three-dimensional (3D) stationary terrestrial laser scanning (STLS) point clouds to obtain surface maps of point wise indices that characterise pavement roughness. The backbone of the analysis is a quarter-car model simulation over a spatial 3D mesh grid representing the pavement surface. With the rich data-set obtained by 3D scanning, the algorithms identify several dynamic responses and inferences (suspension, acceleration and jerk) at each point in the domain. Variability in the indices is compared for a ‘rough’ pavement and a ‘smooth’ pavement in the spatial domain for different speed simulations of the quarter-car model. Results show high spatial variability in the various roughness indices both longitudinally and transversely (i.e. different wheel path positions). It is proposed that pavement roughness characterisation using a spatial framework coupled with univariate statistics provides more details on the severity and location of pavement roughness features compared to the (1D) one-dimensional methods. This paper describes approaches that provide an algorithmic framework for others collecting similar STLS 3D spatial data to be used in advanced pavement roughness characterisation.     

烧结温度对3D打印硅基陶瓷型芯表面形貌及粗糙度的影响

单晶高温合金空心叶片是航空发动机的重要部件, 其内腔结构是采用陶瓷型芯制备的。随着航空发动机推重比提高, 型芯结构越来越复杂, 传统制备工艺受限, 光固化3D打印陶瓷型芯技术为复杂结构型芯的制备提供了一种可行方案。为了改善光固化3D打印陶瓷型芯因台阶效应导致的表面粗糙度较大的问题, 本研究利用固含量体积分数63%的硅基型芯浆料进行光固化3D打印型芯, 并在1100~1300 ℃对型芯素坯进行烧结, 对烧成的硅基陶瓷型芯的微观结构、元素分布、相组成、型芯打印面和打印堆积方向的表面形貌和粗糙度进行分析。研究发现型芯打印面平整, 无明显表面缺陷, 1100、1200和1300 ℃烧结型芯的打印面粗糙度分别为1.83、1.24和1.44 μm; 片层堆积方向的表面有片层结构特征, 片层间出现微裂纹, 1200 ℃以上烧结的型芯表面粗糙度达到空心叶片使用要求(R_a≤2.0 μm)。结果表明不同烧结温度会改变型芯烧结过程中的液相含量、莫来石生成量、莫来石生成形态和颗粒间玻璃相的分布, 从而对光固化3D打印硅基陶瓷型芯的表面粗糙度产生明显影响。光固化3D打印陶瓷型芯技术结合烧结工艺能制备出满足先进空心叶片用硅基陶瓷型芯表面要求的粗糙度。     

Surface roughness and the sensitivity of D-shaped optical fibre sensors

In this paper, the surface roughness characteristic of D-shaped optical fibre sensors with its effects on the sensitivity has been studied. The ULTRAPOL end and edge polishing system was used with some modifications to fabricate the D-shaped sensors with planar sensing zone from the single-mode optical fibres. The mean surface roughness of 343, 96, 25 and 9?nm was estimated at the sensing zone of the D-shaped sensors which were sequentially polished with 30, 9, 3 and 0.5?µm grit size polishing films, respectively. From the experimental results, it has been observed that surface roughness of the sensing zone does not exhibit the significant effects on the output signal strength, whereas the sensitivity of the D-shaped sensors nonlinearly related with the surface roughness of the sensing zone. The designed D-shaped optical fibre sensors have potential applications in biomedical and chemical industries.     

燃气轮机拉杆转子考虑接触效应的扭转振动模态分析

燃气轮机转子一般是由多个层叠的轮盘通过拉杆组合而成,各轮盘接触面由磨削加工形成。粗糙度测试结果表明磨削加工的实验拉杆转子轮盘面具有两个不同分形结构的区域。利用结构函数法计算了这种双重分形面的轮廓曲线的分形维数D1、D2和分形粗糙度参数G1、G2 。采用双重分形几何描述接触表面的拓扑结构,并根据赫兹接触理论导出接触微凸体的切向接触刚度。弹塑性双重分形面的切向接触刚度等于所有微观弹性接触点的切向接触刚度的总和。粗糙层是由相接触的微凸体所构成的,其抗扭刚度模化为接触转子轮盘间的一个抗扭弹簧。通过三维有限元模态分析和实验模态分析得到了拉杆转子在不同预紧力下的扭振模态频率。通过上述计算和实验结果识别了粗糙层的抗扭刚度,实验测试结果和理论计算结果相一致,这表明上述接触层抗扭刚度的双重分形模型实合理的,可以有效地考虑接触效应对拉杆转子扭转振动模态频率的影响。     

航空钛合金板胶接表面粗糙度的超声测量

采用一种新的超声频谱法快速测量航空钛合金板经喷砂预处理后的胶接表面粗糙度,并引入表面面积均方根粗糙度系数Sr来表征材料表面三维微观形貌．以航空Ti-6Al—4V钛合金胶接板为测量试样,超声换能器接收测试试样表面的反射回波,并计算得到AR参数谱．以反射脉冲AR参数谱和声波镜面反射理论为基础,建立了有关脉冲波声反射系数和表面均方根粗糙度系数Sr的数学模型．利用表面粗糙度系数理论模型．数值计算反射回波的理论频谱曲线,并与实测反射回波AR谱进行拟合．利用最小值搜索算法,处于最佳拟合时的表面粗糙度系数Sr即为试样胶接表面的测量结果．实验表明,超声反射频谱法测量结果与轮廓仪测量结果符合得很好,该测量方法在材料或零部件表面粗糙度在线测量中具有广泛的应用前景．     

Influence of nanostructure on titanium corrosion resistance in fluoridated medium

ABSTRACT

Nanocrystalline titanium, mainly owing to its high corrosion resistance, mechanical strength to density ratio and biocompatibility, has a great application potential in dental implantology. However, fluoridated agents commonly used for oral hygiene could have a destructive influence on the titanium protective passive films and lead to the formation of local corrosion damages. In this work, the effect of nanostructuring on titanium corrosion resistance in the concentration of F^? which is typical for toothpastes, was evaluated by different electrochemical and surface characterisation techniques. It was found that nanostructure influences beneficially on titanium corrosion resistance in fluoride solution. Furthermore, the lower increase in nanocrystalline titanium surface roughness in corrosion solutions indicates better stability of passive film formed on its surface.

This paper is part of a thematic issue on Titanium.     

Fluorescence Enhancement on Large Area Self‐Assembled Plasmonic‐3D Photonic Crystals

Discontinuous plasmonic‐3D photonic crystal hybrid structures are fabricated in order to evaluate the coupling effect of surface plasmon resonance and the photonic stop band. The nanostructures are prepared by silver sputtering deposition on top of hydrophobic 3D photonic crystals. The localized surface plasmon resonance of the nanostructure has a symbiotic relationship with the 3D photonic stop band, leading to highly tunable characteristics. Fluorescence enhancements of conjugated polymer and quantum dot based on these hybrid structures are studied. The maximum fluorescence enhancement for the conjugated polymer of poly(5‐methoxy‐2‐(3‐sulfopropoxy)‐1,4‐phenylenevinylene) potassium salt by a factor of 87 is achieved as compared with that on a glass substrate due to the enhanced near‐field from the discontinuous plasmonic structures, strong scattering effects from rough metal surface with photonic stop band, and accelerated decay rates from metal‐coupled excited state of the fluorophore. It is demonstrated that the enhancement induced by the hybrid structures has a larger effective distance (optimum thickness ≈130 nm) than conventional plasmonic systems. It is expected that this approach has tremendous potential in the field of sensors, fluorescence‐imaging, and optoelectronic applications.     

Investigation on the effect of surface modification of 3D printed parts by nanoclay and dimethyl ketone

Fused deposition modeling (FDM) has emerged as one of the most utilized 3D printing technique. However, the surface properties of the FDM built parts lacks integrity due to layer by layer manufacturing technique. Therefore, post treatment is done on FDM printed parts. In the present research work, an effort has been made to improve the surface properties of the 3D printed parts by surface modification via chemical/nanoparticles. Nanoclay and dimethyl ketone were utilized for the surface modification of acrylonitrile butadiene styrene specimens. Parameters namely nanoclay content, immersion time, heat treatment and layer thickness were investigated to study their effect on surface roughness, surface hardness and dimensions. Also, the effect of nanoclay on UV absorbance of 3D printed parts was observed. Structural and morphological analysis was performed to characterize the surface of the 3D printed specimens after surface modification process. The results show that the surface roughness was reduced by 94.9%, surface hardness was increased by 9.7% while maintaining minimum dimensional deviation of ?0.03 and +0.07?mm. Also, UV absorbance was increased in 350–380?nm range. The results of the present study highlight the capability of the surface modification process for improving the surface properties of FDM parts.     

Nanofinishing of FDM-fabricated components using ball end magnetorheological finishing process

Fused deposition modeling (FDM) is among the extensively used and the most economical additive manufacturing processes. Currently, the surface finish obtained for FDM additive manufactured parts are not at par with the current industrial application. To overcome the limitation of high surface roughness of 3D printed parts, a novel finishing technique has been proposed which includes primary and secondary finishing processes. While facing and lapping has been used as primary finishing technique, the secondary finishing involves the use of ball end magnetorheological finishing (BEMRF) process. BEMRF process is an unconventional finishing process which utilizes an advanced approach to impart finish on magnetic as well as non-magnetic materials that may be flat or freeform in shape. This article presents the experimental and analytical study to finish a polylactic acid (PLA) workpiece material manufactured by FDM process and finished using the BEMRF technique. The surface roughness of the FDM component has been reduced from initial surface roughness Ra = 20 µm to final value of Ra = 81 nm by combined primary and secondary finishing processes. The effect of magnetorheological polishing (MRP) fluid’s composition and finishing time is discussed and is followed by optimization of MRP fluid for maximum percentage reduction in surface roughness.