面向三维打印的特征驱动轮廓线编辑方法

当用户评估完三维打印模型而需要修改时,目前的编辑技术需要返回原始三维模型进行修改再重新分层,效率低、易出错且编辑不直观.为此,提出面向三维打印的模型编辑方法,即用户直接编辑分层模型的轮廓线,可见即可得,其核心是特征保持的轮廓线编辑技术.首先,将每一条轮廓线分割为特征点和特征段;每个特征点具有特征保持和位移传播的功能,特征保持允许用户自由选择是否保留特征点的角度值,而位移传播则确定了编辑操作的影响范围;两者共同定义了特征点和特征段的编辑模式.然后,根据轮廓线的所有特征及其邻接关系构建一个闭合的特征链图,并结合拉普拉斯坐标的保特征性质让编辑操作在相同层和不同层内的轮廓线上传播.实验结果表明,该方法能够有效地提高面向三维打印的模型编辑效率.     

An Analysis of Academic Library 3D Printing LibGuides

3D Printing is increasingly becoming a popular service provided by academic libraries throughout the United States. Many patrons have little or no awareness of this subject matter, so library staff have created LibGuides to promote resources. One hundred LibGuides from academic libraries were analyzed to find which types of resources and which specific titles are being promoted surrounding the subject of 3D printing. Three types of resources emerged in this study: 3D printing and 3D modeling software titles, 3D model repositories, and books related to 3D printing. This article lists and analyzes 3D printing resources.     

碳离子放疗可有效抗击癌症

目前,全球仅有六个碳离子放疗中心,其中日本有三个,中国、德国和意大利各有一个。另有五个新中心在建,其中日本和中国各两个,奥地利一个。     

面向3D打印体积极小的拓扑优化技术

与传统制造所生产的产品相比,3D打印产品的成本仍相对较高.因此,如何能在不牺牲打印物体表面质量的前提下通过模型优化来减少打印材料消耗,对于降低打印成本至关重要.针对这一问题,借鉴传统渐进结构优化方法,结合Von Mises应力计算,给出一种面向3D打印体积极小的拓扑优化算法.该算法通过模型力学计算所得的最大Von Mises应力与材料允许应力之比来引导模型体积减小进化,直至最大Von Mises应力达到允许应力值为止.同时,引入多分辨率技术,由粗网格再到细网格进行优化计算,有效地提高了计算效率.与现有其他给定结构模式的方法相比,该优化结果能更好地体现模型荷载受力的传递路径.     

面向陶瓷3D打印的双尺度放样曲面建模

针对陶瓷3D打印的特点,提出基于放样曲面与周期参数曲线嵌入的双尺度轻量化交互式建模和制造工具.对于用户输入的2条封闭曲线,首先在它们之间插值生成中间截面采样点,并在免支撑、路径无干涉等陶瓷3D打印制造约束下对当前曲面形状进行调整,完成基于放样曲面的大尺度曲面建模;然后将采样点之间的直线路径用周期性曲线路径代替,通过调整...     

Printing 3D microfluidic chips with a 3D sugar printer

This study demonstrated how to quickly and effectively print two-dimensional (2D) and three-dimensional (3D) microfluidic chips with a low-cost 3D sugar printer. The sugar printer was modified from a desktop 3D printer by redesigning the extruder, so the melting sugar could be extruded with pneumatic driving. Sacrificial sugar lines were first printed on a base layer followed by casting polydimethylsiloxane (PDMS) onto the layer and repeating. Microchannels were then printed in the PDMS solvent, microfluidic chips dropped into hot water to dissolve the sugar lines after the PDMS was solidified, and the microfluidic chips did not need further sealing. Different types of sugar utilized for printing material were studied with results indicating that maltitol exhibited a stable flow property compared with other sugars such as caramel or sucrose. Low cost is a significant advantage of this type of sugar printer as the machine may be purchased for only approximately $800. Additionally, as demonstrated in this study, the printed 3D microfluidic chip is a useful tool utilized for cell culture, thus proving the 3D printer is a powerful tool for medical/biological research.     

三维结构分析并行自适应有限元软件PHG-Solid

介绍了所研制的一个开源三维结构分析并行自适应有限元软件PHG-Solid。它是以并行自适应有限元软件平台PHG为基础开发的,支持在纯三维结构上进行并行自适应有限元分析。与现有的商业和开源结构分析有限元软件相比,PHG-Solid的特点和优势在于:1)支持完全自动化且高度并行的自适应有限元计算;2)能稳健高效地求解大规模问题,具有很好的计算规模可扩展性;3)易于扩展,用户可根据需要添加相应的计算模块。通过几个大型数值算例来展示该软件的计算能力和并行可扩展性,其中的最大计算规模超过了5亿自由度,最大并行规模达到了1024个MPI进程。     

低成本个性化巧克力三维打印平台

针对个性化巧克力加工难、制作成本高的问题,以三维扫描、三维打印为主导技术,结合嵌入式系统,设计并实现了一套个性化巧克力三维打印系统.基于Kinect深度相机及外围驱动电路搭载其水平移动旋转,实现了稳定的三维扫描功能;为了适应巧克力材料的打印并提高其打印精度和效果,重新设计了三维打印喷头、改进了温度控制、热床等模块;对捕获几何数据进行算法优化,显著提高了计算效率.实验结果表明,与国内外同类技术平台相比,文中系统有更高精度的制作效果,且该平台人机交互性友好,有良好的巧克力个性化定制功能.     

Ribbed Support Vaults for 3D Printing of Hollowed Objects

Additive manufacturing techniques form an object by accumulating layers of material on top of one another. Each layer has to be supported by the one below for the fabrication process to succeed. To reduce print time and material usage, especially in the context of prototyping, it is often desirable to fabricate hollow objects. This exacerbates the requirement of support between consecutive layers: standard hollowing produces surfaces in overhang that cannot be directly fabricated anymore. Therefore, these surfaces require internal support structures. These are similar to external supports for overhangs, with the key difference that internal supports remain invisible within the object after fabrication. A fundamental challenge is to generate structures that provide a dense support while using little material. In this paper, we propose a novel type of support inspired by rib structures. Our approach guarantees that any point in a layer is supported by a point below, within a given threshold distance. Despite providing strong guarantees for printability, our supports remain lightweight and reliable to print. We propose a greedy support generation algorithm that creates compact hierarchies of rib-like walls. The walls are progressively eroded away and straightened, eventually merging with the interior object walls. We demonstrate our technique on a variety of models and provide performance figures in the context of fused filament fabrication 3D printing.     

基于3D打印的订单管理系统分析与设计

使用3D打印快速成型技术,为用户定制专属产品,可以快速满足用户个性化的需求,采用配置设计和调整的设计方法,可以实现模块化和系统化的设计生产。因此,笔者提出了一种基于私人定制的3D打印订单系统分析设计。该系统要解决的是为满足更多人的个性化设计需求所面临的问题,可以满足私人定制3D打印系统的基本要求。系统能根据用户的不同需求,直接下单定制和设计人员反馈意见并进行调整修改,快捷方便地为用户提供服务,此次研究的课题为私人定制的3D打印订单管理系统方面的研究提供了一定的借鉴。     

3D打印过程的计算机仿真

为实现3D打印过程的可视化仿真并获得打印过程中的温度场、应力场的变化,从而预测3D打印件的变形、翘曲、开裂等缺陷,最终达到指导和优化打印工艺的目的,通过在ABAQUS平台的Python脚本开发,首次实现了对3D打印过程的可视化仿真,并获得了打印过程的温度场历程,为后续实现温度场与应力场、位移场的耦合分析奠定了基础,使得优化打印路径和热源参数有了量化分析方法.这种全新的打印过程的可视化仿真方法也为变模型物理过程的计算机仿真提供了一种全新的思路.     

Improved Surface Quality in 3D Printing by Optimizing the Printing Direction

We present a pipeline of algorithms that decomposes a given polygon model into parts such that each part can be 3D printed with high (outer) surface quality. For this we exploit the fact that most 3D printing technologies have an anisotropic resolution and hence the surface smoothness varies significantly with the orientation of the surface. Our pipeline starts by segmenting the input surface into patches such that their normals can be aligned perpendicularly to the printing direction. A 3D Voronoi diagram is computed such that the intersections of the Voronoi cells with the surface approximate these surface patches. The intersections of the Voronoi cells with the input model's volume then provide an initial decomposition. We further present an algorithm to compute an assembly order for the parts and generate connectors between them. A post processing step further optimizes the seams between segments to improve the visual quality. We run our pipeline on a wide range of 3D models and experimentally evaluate the obtained improvements in terms of numerical, visual, and haptic quality.     

3D打印技术原理及发展应用

近些年,随着人类科学和社会的不断进步,对加工制造技术也提出了更高的要求,3D打印技术作为一种新型的快速加工成型技术开始逐渐发展成熟起来,在生物医学、建筑、工业设计、美术制作等领域得到了不同程度的应用。本文综述了3D打印技术的发展过程,详细介绍了3D打印技术的基本原理和实现过程,分析了3D打印技术在仿真建模与工艺流程上的具体实现方法,比较了3D打印技术和其它打印技术的优缺点,最后对3D打印技术的发展和未来进行了一定程度的展望。     

Saliency‐Preserving Slicing Optimization for Effective 3D Printing

We present an adaptive slicing scheme for reducing the manufacturing time for 3D printing systems. Based on a new saliency‐based metric, our method optimizes the thicknesses of slicing layers to save printing time and preserve the visual quality of the printing results. We formulate the problem as a constrained ?₀ optimization and compute the slicing result via a two‐step optimization scheme. To further reduce printing time, we develop a saliency‐based segmentation scheme to partition an object into subparts and then optimize the slicing of each subpart separately. We validate our method with a large set of 3D shapes ranging from CAD models to scanned objects. Results show that our method saves printing time by 30–40% and generates 3D objects that are visually similar to the ones printed with the finest resolution possible.     

3D打印中的几何计算研究进展

3D打印技术改变了传统的减式材料制造模式,带来了制造工艺和生产模式的变革,有力地推动了3D数字化相关技术与研究的发展.文中从3D打印的社会背景与理论背景出发,介绍了3D打印技术的分类、原理与过程.以此为基础,对近几年的3D打印中的几何计算问题给出了全面的综述,根据问题特点将其分为几何优化、结构分析、材料表面效果定制、机构设计、自支撑结构设计、内部结构设计等六大类,并对每一类作了详细的分类介绍,最后对其发展方向作了初步展望.     

全彩3D打印颜色再现方法

全彩3D打印具有快速再现彩色原型的优势, 已经开始广泛应用于医疗、工业、食品等多个领域. 这些领域对3D打印产品的颜色再现精度要求越来越高, 如何提高全彩3D打印产品的颜色再现质量成为研究热点问题之一. 本文对全彩3D打印的颜色再现方法进行了较为全面的论述. 在对全彩3D打印实现方式分类的基础上, 重点对全彩3D打印颜...     

基于模态分析的三维模型全局结构优化

传统的结构优化方法需要预先给定受力条件,所得结构只保证在所给条件下最优,而在其他外力下可能较为脆弱.实际应用中物体可能受到各种外力,这时在单个受力条件下的优化方法无法保证结构的全局性能,一般通过加大材料的使用量来满足应用需求.文中提出的优化方法能够加强物体在各种可能受力条件下的全局强度,使物体的强度趋于各向同性以抵御各种不同的外力.该方法基于物体结构的模态分析检测结构中的脆弱区域,并通过刚度矩阵特征值的优化实现脆弱区域的加强;同时基于瑞利商的概念,提出一种高效可行的求解算法.实验结果表明,该方法可有效地提高物体的全局强度.     

Structural similarity-based rate control algorithm for 3D video

Multimedia Tools and Applications - Human vision easily identifies the structural degradation in a video and thus perceptual quality improvement is necessary. To adjust the video quality to match...     

喷射式3D打印过程微滴沉积位置建模与预测

微滴沉积位置的准确性是影响喷射成型器件形貌精度的主要因素之一,为了对微滴沉积位置进行控制,需要建立微滴沉积位置的动态预测模型。建立了微滴在下落、沉积过程中的运动与传热模型,并通过数值仿真和实验研究了单个微滴以及两个相邻微滴在沉积动态过程中的形心位置变化,结果表明,相比于数值仿真模型,所建立的理论预测模型对单个微沉积位置预测误差为0.45%,相邻两个微滴间的沉积距离预测误差为0.5%,并通过实验进行了对比验证,表明所建理论模型具有足够高的位置预测精度,可用于微滴喷射3D打印过程中微滴沉积位置及打印轨迹在线控制的参考。