浅谈偏置面齿轮齿面方程及三维建模

为满足面齿轮设计效率和制造精度要求,以偏置式面齿轮传动系统为研究对象,根据微分几何和齿轮啮合原理,建立了理想状况下的面齿轮齿面数学模型。采用MATLAB语言编程,计算出齿面特征点坐标,并导入proe生成三维实体模型。该方法可使繁琐复杂的面齿轮建模变得准确易行。     

非圆齿轮三维造型设计系统的开发

基于非圆形节曲线的非圆齿轮设计和计算要比圆齿轮复杂得多。由于非圆齿轮各轮齿的形状不尽相同,因此无法使用阵列、镜像等方法进行建模。目前的三维机械CAD软件还不能直接进行非圆齿轮实体建模。文章利用Visual Basic语言对三维软件SolidEdge进行二次开发,实现了齿轮的根切校验、凸性校验、压力角计算等功能,建立了非圆齿轮的三维建模系统,为非圆齿轮三维建模参数化设计提供了一种方法。生成的齿轮三维实体可用于装配设计、运动仿真及计算机辅助教学中。     

基于逆向工程的发动机叶片数字化设计验证

对发动机叶片实体建模中的关键问题进行了分析,并采用关节臂激光扫描仪进行了装配模式下发动机叶片的逆向扫描,运用Geomagie Qualify软件实现了叶片型面三维误差比较以及叶片截面指标计算分析,为发动机叶片的数字化设计验证提供了参考.     

CAD系统中产品设计三维实体建模方法的研究

三维建模是应用CAD系统进行产品设计的重要步骤。现在市场上已有不少的CAD系统，但是不同系统中的三维建模方法却是基本相同的。在这些三维建模的方法中，往往对用户施加了许多的限制，使得用户无法建立复杂的三维实体。笔者提出了一种新的三维建模方法－折叠法，应用这种方法的概念和原理，可以开发出先进的三维建模CAD系统。折叠二维平面图形构成三维实体是作者提出的一种新概念。     

SolidWorks中的非圆齿轮实体建模方法研究

非圆齿轮因其节曲线为非圆形,目前的三维CAD软件还无法直接进行实体建模.研究了非圆齿轮轮齿设计方法及计算方程,采用Visual Basic语言进行SolidWorks二次开发,论述了系统开发的具体过程.以常用的椭圆齿轮为例实现了参数化实体建模.     

空分设备冷箱内管道设计及应力分析浅析

简述了利用PDMS进行冷箱内管道设计的步骤和利用三维实体建模进行管道设计的优点;阐述了利用CAESARII软件进行应力分析的重要性和操作步骤以及对分析结果的判定和调整。     

铁路钢轨受力分析模型比较研究

为了更准确地分析钢轨应力和列车荷载作用下的受力特性,该文将钢轨看作三维实体,并考虑扣件支承面积的影响,将其视为均布弹簧,建立了更接近实际的力学模型,分析了钢轨在竖向力作用下的应力和位移,并对枕上应力进行了求解,将结果与传统的点支承梁简化模型进行比较,指出了两者之间的相似之处和差异性;同时指出,三维实体方式建模更有利于指导钢轨和轨枕的细部设计。     

环面蜗杆类零件虚拟设计研究

针对环面蜗杆类零件齿面形成的特点,提出了一种进行虚拟设计,生成空间三维图形的简洁方法——参教化“虚拟加工”实体建模。基于AutocAD软件平台,应用LISP语言开发设计程序,并以环面蜗杆和弧面分度凸轮为例进行了实例计算。在此基础上,进一步研究了该类零件二维工程视图和各种断面图形的提取方法。文中提出的参数化实体建模方法,对深入研究一般复杂曲面的实体生成问题具有指导意义。     

椭圆类齿轮参数化设计与运动仿真系统的开发

非圆齿轮因其节曲线为非圆形,计算复杂,设计困难,目前的三维设计软件都无法直接进行实体建模。根据非圆齿轮的设计理论,利用Visual Basic 6.0良好的界面设计功能和计算能力对SolidWorks进行二次开发,设计出椭圆类齿轮参数化设计与运动仿真系统,实现了椭圆类齿轮的三维参数化建模与运动仿真。论述了系统的开发过程,运行实例表明系统界面友好,设计正确。解决了椭圆类齿轮设计中的复杂计算和三维实体造型难的问题,可提高设计精度、缩短产品开发周期,保证产品质量。     

基于绝对坐标法的柴油机曲轴柔性多体系统的动力学仿真

该文基于柔性多体动力学理论,在自主研发的多体系统程序中,建立了某大型船用柴油机曲轴的柔性多体动力学仿真模型。其中采用基于绝对节点坐标的三维实体单元和基于有限段法的梁单元分别对曲柄和主轴颈进行建模,利用约束方程将发动机曲柄连杆机构的各部件进行组装,并考虑了轴承的弹性和非线性。对曲轴进行了约束模态分析和动力学仿真分析,计算了主轴承的载荷和轴颈的位移,得到了曲轴的动应力分布规律并进行了其强度校核。结果表明基于绝对节点坐标法的柔性多体系统的动力学建模和仿真计算的实现为柴油机的改进和设计提供了理论依据。     

基于相位测量的摄像机标定方法

提出一种新的摄像机标定方法,该方法基于2D共面参照物摄像机标定方法和相移技术.首先由摄像机记录已知相位分布的平面,通过相移计算出相位分布.对任意标定平面,两个正交相位分布与平面坐标的对应关系已知,由此可以建立像素坐标与2D平面坐标的一一对应关系.将该已知相位分布的平面在空间中放置不同的位置,分别完成上述测量,即可根据2D共面参照物摄像机标定方法完成摄像机的高精度标定.该方法避开了复杂的标定特征点提取,大大增加了2D标定数据量,提高了标定精度.实验和计算机模拟表明,该方法简单、可靠和精度高.     

飞机座舱显示界面目标图符的设计和评价

针对飞行员需要快速辨认等问题,设计了飞机座舱显示界面的目标图符,并采用匹配测试和排序测试实验来评价设计的优劣。在实验和实验分析的基础上得到以下结果:敌机的目标图符采用红色、实心、三角形识别性较好;对友机和僚机的目标图符采用绿色或蓝色、实心、圆形识别性较好;对于不明飞机目标图符采用黄色、实心、方形识别性较好。该评价方法对于界面设计具有一定的参考价值。     

基于直线与平面投影自动识别其位置及相互关系的研究

点线面的两面投影包含其空间完整的几何信息。根据正投影的机理，建立了点线面屏幕坐标与空间关系的转换关系。基于直线与平面的两面投影、投影原理及几何定理提出直线和平面相对于投影面的位置及彼此间相互关系识别的几个算法，并在AutoCAD新一代开发环境ARX下用VC 加以实现。     

Wavefront watermarking of technical and biological samples using digital random phase modulation and phase retrieval

A technique for digital watermarking of smooth object wavefronts using digital random phase modulation and multiple-plane iterative phase retrieval is demonstrated experimentally. A complex-valued watermark is first encrypted using two random phase masks of known distributions before being superposed onto a set of host wavefront intensity patterns. Encryption scaling factor and depth of randomization of the masks are optimized such that the amplitude and phase watermarks are decrypted successfully and are not distorting the host wavefront. Given that the watermarked intensity patterns and the numerous decryption keys are available (i.e. distances between recording planes, light source wavelength, pixel size, random phase masks and their distances to the planes are all known), increasing the number of watermarked patterns used results in enhanced quality of decrypted watermarks. The main advantage of wavefront watermarking via the phase retrieval approach compared to the holographic approach is the avoidance of reference wave-induced aberration. Watermarking of wavefronts from lenses and unstained human cheek cells demonstrate the effectiveness of the technique.     

Methoden zur Qualitätskontrolle festgewalzter Pkw-Teile

Methods for Quality Control of Solid Rolled Automotive Parts An economically satisfactory solution has not yet been found for the quality control of solid rolled automotive components. In order to be able to reduce the time (and therefore costs) between rolling and machining, a method is needed, which controls quality direct on the rolling machine. The following up-to-date methods are presently applied in BMW plants. Control of rolling machine, grading test, internal stress test, inspection card, ground surface finish and hardness tests. Other tests are made on the steering knuckles, such as destructive chemical tests, gloss test, Barkhausen effect, dimension check, fine structure analysis and magnaflux testing. The two methods, which up to no permit a qualitative statement, namely internal stress test and Woehler fatigue test, are very involved. According to our present state of research the dimension check and fine structure analysis are good alternatives, to be able to considerably reduce the testing time between rolling and machining. The Barkhausen effect is a very elegant, non-destructive testing method to determine the grade of solid rolled components by way of comparison with sample parts.     

Grinding of Metal Matrix Composites Reinforced with Silicon-Carbide Particles

This paper studies the grindability of metal matrix composites reinforced with SiC particles. A two-level factorial experiment was set up to investigate the effects of reinforcement volume, grinding parameters, and grinding wheel materials. While increasing the force and specific energy in grinding, the SiC particles are fractured along cleavage planes rather than being machined by grinding grains. Smearing of aluminum matrix masks the effect of grinding parameters on surface finish measurement. Increasing material removal rate causes an increasing of grinding forces but a decreasing of specific energy. Diamond wheels are recommended for both rough- and fine-grinding of the tested composites.     

股骨颈空心钉手术机器人定位算法误差分析

针对股骨颈骨折空心钉手术中的空间定位问题,提出了一种基于射影变换的双平面空间定位算法,并为其建立了数学模型;在此基础上,采用蒙特卡罗法对定位算法的精度进行了理论推导,并用Matlab对系统精度进行了仿真,对仿真结果进行了分析,得到了系统精度;分组比较了定位算法中各输入量对算法精度的影响程度,并对误差分布规律进行仿真,得到误差分布规律.仿真发现当目标点处于两参考坐标系平面之内,且标记点靠近X光发射源时精度较高,本文依据上述分析结果从标尺结构、图像采集和物理量的优化等方面提出定位算法修改建议.     

Energy transfer between fluorescent dyes spaced by multilayers of cadmium salts of fatty acids

The quenching of the fluorescence of a monomethin-oxacyanine dye by a monomolecular film of a monomethin-thiacyanine is studied in Langmuir-Blodgett films. As spacers a single and a double bilayer of the cadmium salts of myristic acid up to lignoceric acid are used. The experimental data are not fitted by Förster's formula for intermolecular energy transfer as applied to a homogeneous set of donors and acceptors located in planes of ideal multilayers.     

基于Pro/E机构模块的齿轮三维实体建模研究

齿廓曲线尤其是齿根过渡曲线的构建是渐开线圆柱齿轮三维实体建模的难点,也是其关键问题。现在所采用的构建方法操作复杂,计算繁琐,且不适合不同刀具加工的齿轮模型的构建。以范成法加工齿轮的原理为理论基础,介绍在Pro/E平台下利用其机构模块的“轨迹曲线”(trace curve)功能精确构建各种刀具加工出来的渐开线圆柱齿轮齿廓曲线的方法,并以磨前滚刀加工直齿圆柱齿轮为例,详细介绍该方法的使用步骤,构建其精确的三维实体模型。该方法无需推导渐开线和过渡曲线的方程就能够方便、快捷地构建出任何刀具加工出来的齿轮模型,为基于啮合原理的复杂曲面零件的有限元建模提供了参考,特别是为复杂曲面零件的CAD/CAE建模与分析奠定了基础。     

Dispersive behaviour of humid anisotropic media

The results of dielectric measurements on a humid system consisting of filter papers which show strongly anisotropic properties in the planes and normal to the planes of the sheets, are reported. Configurations were used in which the flow of current is, respectively, normal to and in the planes and these show distinctively different behaviour. Transport in the planes provides some of the best examples of LFD ever seen by us, extending over up to eight decades of frequency; transport across the planes is influenced by less dispersive behaviour which is ascribed to the fibre-fibre contacts.