无支撑熔融挤压快速成形的参数研究

针对快速成形产品悬空部分的支撑问题,归纳出常见零件的5种悬空特征,分别为倾斜形、弧顶形、平顶形、开放式悬臂形、封闭式悬臂形。采种熔融挤压工艺进行加工试验,得到这5种悬空特征无需添加支撑即可成形的极限悬空参数,分别为倾斜角60°、弧顶半径4 mm、平顶长度8 mm、开放式悬臂长度3 mm、封闭式悬臂长度5 mm。成形环境温度对悬空部分的成形质量影响较大。     

虚拟样机在火炮反后坐实验台设计中的应用

某型牵引火炮后坐装置的虚拟样机动力学模型以LMS Virtual.Lab为开发环境建立.先导入PRO/E模型文件进行简化,并添加约束关系建立火炮上架以上部分的实体模型.再借助Virtual.Lab用户自定义子程序模版TSDA,通过Fortran语言编程实现后坐与复进行程函数元素的添加.以0°全装药射击对虚拟样机进行验证,采用最大值法比较比后坐位移和速度的仿真值与实验值,所得误差在工程应用范围内,满足工程应用需要.     

基于STL文件的快速成型分层算法与毗邻拓扑信息的快速提取

该文研究了实时的快速成型的分层算法,即从CAD模型转换成STL文件后,实时快速求出该模型与水平截面的轮廓线交线,为此,该文提出并建立了三角形网格的毗邻关系索引表,并构造相应的数据结构来表达STL文件的散乱三角形集合中的毗邻拓扑联系,而为了快速建立这种毗邻关系,该文进一步提出建立两套三角形网格的分组表,来缩小三角形网格的毗邻查找范围,为快速确定三角形网格的毗邻关系奠定基础。该文同时分析了该算法的时间与空间复杂度。计算实践表明,基于该文提出的毗邻关系索引表的分层算法能满足快速成型的实时要求。     

快速成型中的自适应切片方法研究

分层切片是快速成型软件系统中核心部分之一，完成将CAD实体模型离散化为层面信息的功能，提出了一种基于面积变化的自适应切片方法，并对该方法进行了实现，同时与定层厚切片方法进行了比较，表明该6算法可以有效地降低切片过程中的阶梯效应。     

快速成型和快速模具在现代工业中的应用

从快速成型和快速模具产生的历史背景开始，阐述了快速成型和快速模具的工作原理、主要方法、独有特性、重要意义和在现代工业生产中的应用。     

The iterative development of a tangible pin-board to symmetrically link physical and digital documents

There is an asymmetry in many tangible interfaces: while physical objects can be used to manipulate digital information, the reverse is often not possible—the digital world cannot push back. We introduce a new push-back tangible technology, a pin-board that physically ejects paper documents. This is realized by extending the Pin&Play technology to support ‘pouts’, addressable pin-like devices that can remove themselves from a board using muscle wire actuators. We describe how this technology has been developed through two iterations of prototyping, application and formative study. An initial study revealed how potential mismatches between the physical and digital characteristics of pouts caused difficulties with users predicting pop-out events and reasoning about the state of pouts. This led us to extend pouts to reveal more of their internal state, an approach verified through a second study. It also raises more general issues for the design of pushback tangible technologies and ubiquitous interfaces.     

Experimental studies on selective laser melting of metallic parts

Laser assisted generative production techniques like Selective Laser Melting (SLM) are novel but complex near net shape fabrication methods. The present paper describes properties of metallic specimens generated by SLM. Therefore various process parameters were observed to evaluate their influence on certain attributes of parts fabricated by Selective Laser Melting. In addition, approaches for an improvement of density, surface quality and mechanical properties are given.     

Shape deposition manufacturing of biologically inspired hierarchical microstructures

The applications of dry adhesives range from part handling in manufacturing to aids for human and robotic climbing. Nature provides inspiration in the hierarchical structures used by geckos and spiders to attach using Van der Waals forces. Among the challenges faced in creating synthetic dry adhesives are the need to conform to surfaces at length scales from centimeters to tens of nanometers and the need to create arrays of compliant asymmetric structures at the micro-scale. Initial attempts from the literature are reviewed and a new approach based on a hybrid additive/subtractive prototyping technique called shape deposition manufacturing (SDM) is proposed.