机械三维建模及3D打印课程教学模式研究

三维建模软件在机械行业中越来越受到重视,相关软件的教学也成为机械大类专业的核心课程。以CREO 3.0为例,探讨了机械类三维建模课程的教学内容等到,并且进一步说明了作者在教学实践中的模式,在课程体系、教学资源建设、教学手段等方面都提出了新的理念和做法。     

A Review of 3D Printing Technologies for Soft Polymer Materials

Soft polymer materials, which are similar to human tissues, have played critical roles in modern interdisciplinary research. Compared with conventional methods, 3D printing allows rapid prototyping and mass customization and is ideal for processing soft polymer materials. However, 3D printing of soft polymer materials is still in the early stages of development and is facing many challenges including limited printable materials, low printing resolution and speed, and poor functionalities. The present review aims to summarize the ideas to address these challenges. It focuses on three points: 1) how to develop printable materials and make unprintable materials printable, 2) how to choose suitable methods and improve printing resolution, and 3) how to directly construct functional structures/systems with 3D printing. After a brief introduction on this topic, the mainstream 3D printing technologies for printing soft polymer materials are reviewed, with an emphasis on improving printing resolution and speed, choosing suitable printing techniques, developing printable materials, and printing multiple materials. Moreover, the state‐of‐the‐art advancements in multimaterial 3D printing of soft polymer materials are summarized. Furthermore, the revolutions brought about by 3D printing of soft polymer materials for applications similar to biology are highlighted. Finally, viewpoints and future perspectives for this emerging field are discussed.     

Combining 3D Printing with Electrospinning for Rapid Response and Enhanced Designability of Hydrogel Actuators

Porous structures have emerged as a breakthrough of shape‐morphing hydrogels to achieve a rapid response. However, these porous actuators generally suffer from a lack of complexity and diversity in obtained 3D shapes. Herein, a simple yet versatile strategy is developed to generate shape‐morphing hydrogels with both fast deformation and enhanced designability in 3D shapes by combining two promising technologies: electrospinning and 3D printing. Elaborate patterns are printed on mesostructured stimuli‐responsive electrospun membranes, modulating in‐plane and interlayer internal stresses induced by swelling/shrinkage mismatch, and thus guiding morphing behaviors of electrospun membranes to adapt to changes of the environment. With this strategy, a series of fast deformed hydrogel actuators are constructed with various distinctive responsive behaviors, including reversible/irreversible formations of 3D structures, folding of 3D tubes, and formations of 3D structures with multi low‐energy states. It is worth noting that although poly(N‐isopropyl acrylamide) is chosen as the model system in the present research, our strategy is applicable to other stimuli‐responsive hydrogels, which enriches designs of rapid deformed hydrogel actuators.     

Robust Self-Catalytic Reactor for CO2 Methanation Fabricated by Metal 3D Printing and Selective Electrochemical Dissolution

The methanation of CO₂ has been actively pursued as a practical approach to mitigating global climate change. However, the complexity of the catalyst development process has hindered the development of new catalysts for CO₂ methanation; as a result, few catalysts are commercially available. Herein, a multifunctional self-catalytic reactor (SCR) is prepared via metal 3D printing and selective electrochemical dissolution as a method to not only simplify the catalyst development process but also fabricate active catalysts for CO₂ methanation. The combination of metal 3D printing and selective electrochemical dissolution is demonstrated as a feasible method to prepare active catalysts for the methanation of CO₂ in a short time. In addition, the use of an electrochemical method enables the formation of galvanic cells on the SCR; these cells continuously generate active sites via self-dissolution during a simple refresh process, resulting in high reusability of the SCR. The proposed method represents a new facile technique to fabricate highly reusable catalysts that exhibit superior performance for CO₂ methanation, and the results provide a guideline for preparing metal 3D-printed catalysts that will satisfy industrial demand.     

Rapid 3D Printing of Electrohydraulic (HASEL) Tentacle Actuators

A comprehensive material system is introduced for the additive manufacturing of electrohydraulic (HASEL) tentacle actuators. This material system consists of a photo‐curable, elastomeric silicone‐urethane with relatively strong dielectric properties (ε_r ≈ 8.8 at 1 kHz) in combination with ionically‐conductive hydrogel and silver paint electrodes that displace a vegetable‐based liquid dielectric under the application of an electric field. The electronic properties of the silicone material as well as the mechanical properties of the constitutive silicone and hydrogel materials are investigated. The hydraulic pressure exerted on the dielectric working fluid in these capacitive actuators is measured in order to characterize their quasi‐static behavior. Various design features enabled by 3D printing influence this behavior—decreasing the voltage at which actuation begins or increasing the force density in the system. Using a capacitance change of >35% across the actuators while powered, a demonstration of self‐sensing inherent to HASELs is shown. Antagonistic pairs of the 3D printed actuators are shown to exert a blocked force of over 400 mN. An electrohydraulic tentacle actuator is then fabricated to demonstrate the use of this material and actuation system in a synthetic hydrostat. This tentacle actuator is shown to achieve motion in a multi‐dimensional space.     

城市三维空间模型快速构建方法研究

对城市三维空间模型建立方法的研究现状进行总结,提出城市三维空间模型的快速重建方案:采用一次性生成约束TIN构建地形模型,利用数字影像提取建筑物模型,通过CSG体素生长法对建筑物实施建模。在模型的建立过程中,首次将3种方法综合使用,实现了城市三维空间模型快速显示。     

一种平面图像立体化的新方法

基于对人类心理立体视觉和生理立体视觉的理论分析和实验研究,发现在一幅平面图像的各个图像单元中引入随机交叉视差异和随机非交叉视差异之后,其双眼深度暗示效果会明显增强的立体视觉现象,并由此提出了一种新颖且实用的在仅含有心理立体视觉深度暗示的平面图像中随机加入双眼视差异的平面图像立体化方法.     

3D Printed Actuators: Reversibility,Relaxation, and Ratcheting

Additive manufacturing strives to combine any combination of materials into 3D functional structures and devices, ultimately opening up the possibility of 3D printed machines. It remains difficult to actuate such devices, thus limiting the scope of 3D printed machines to passive devices or necessitating the incorporation of external actuators that are manufactured differently. Here, 3D printed hybrid thermoplast/conducter bilayers are explored, which can be actuated by differential heating caused by externally controllable currents flowing through their conducting faces. The functionality of such actuators is uncovered and it is shown that they allow to 3D print, in one pass, simple flexible robotic structures that propel forward under step‐wise applied voltages. Moreover, exploiting the thermoplasticity of the nonconducting plastic parts at elevated temperatures, it is shown that how strong driving leads to irreversible deformations—a form of 4D printing—which also enlarges the range of linear response of the actuators. Finally, it is shown that how to leverage such thermoplastic relaxations to accumulate plastic deformations and obtain very large deformations by alternatively driving both layers of a bilayer; this is called ratcheting. The strategy is scalable and widely applicable, and opens up a new approach to reversible actuation and irreversible 4D printing of arbitrary structures and machines.     

一种基于体素的三维重建方法

文章给出的一种基于体素的三维重建算法，采用面片作为体素，通过判断不同视点处输入图像纹理颜色的一致性来重建三维模型。算法利用场景分块重建来简化遮挡问题，降低了时间复杂度；算法提出了面片步长的计算方法．以重建具有照片级真实感的三维模型。     

Rapid Assembly of Small Materials Building Blocks (Voxels) into Large Functional 3D Metamaterials

Herein, various 3D additive manufacturing approaches are reviewed in terms of two important figures of merit: maximum voxel printing rate and minimum voxel size. Voxel sizes from several 100 µm down to the 100 nm scale are covered. Original results on multifocus two‐photon printing at around voxel printing rates of 10⁷ voxels s^?1 are presented in this context, which significantly surpass previous best values. These advances are illustrated by and applied to the making of microstructured 3D (chiral) mechanical metamaterials that are composed of more than one‐hundred‐thousand unit cells in three dimensions. Previous best values for unit cells of similar complexity are smaller by two orders of magnitude.     

3D打印专利技术的国内主要申请人分析

对3D打印技术进行了简介,并且根据设定的关键词、IPC分类号等对涉及3D打印技术的中国已公开专利进行检索,列出了国内前14位申请人,通过对其中5位申请人的专利申请的情况(申请类型、申请状态等)的统计分析,总结其各自的专利申请的特点,并进行了各申请人之间的比较及建议,对我国相关企业的研发和专利申请提出了建议.     

3D Conformal Printing and Photonic Sintering of High‐Performance Flexible Thermoelectric Films Using 2D Nanoplates

Flexible thermoelectric (TE) devices hold great promise for energy harvesting and cooling applications, with increasing significance to serve as perpetual power sources for flexible electronics and wearable devices. Despite unique and superior TE properties widely reported in nanocrystals, transforming these nanocrystals into flexible and functional forms remains a major challenge. Herein, demonstrated is a transformative 3D conformal aerosol jet printing and rapid photonic sintering process to print and sinter solution‐processed Bi₂Te_2.7Se_0.3 nanoplate inks onto virtually any flexible substrates. Within seconds of photonic sintering, the electrical conductivity of the printed film is dramatically improved from nonconductive to 2.7 × 10⁴ S m^?1. The films demonstrate a room temperature power factor of 730 µW m^?1 K^?2, which is among the highest values reported in flexible TE films. Additionally, the film shows negligible performance changes after 500 bending cycles. The highly scalable and low‐cost fabrication process paves the way for large‐scale manufacturing of flexible devices using a variety of high‐performing nanoparticle inks.     

工艺亭子三维造型与3D打印

3D打印是最近几年开始流行的一种快速成形技术,它以数字模型文件为基础,通过逐层打印的方式来构造物体。被认为推动了第三次工业革命进程的3D打印技术,涉及信息技术、材料科学、精密机械等多个方面。投入民用工业是近年来的事,多用于大型制造业。本文以工艺亭子为载体,介绍3D打印技术,并通过UP打印机完成工艺亭子的3D打印。通过3D打印过程分析得出目前3D打印技术的优势和不足。     

3D打印的小型化超宽带盘锥天线

在传统双锥天线的结构上,将双锥天线的上圆锥用圆盘替代,形成由一盘一锥构成的倒置盘锥结构的小型化超宽带盘锥天线。该天线满足新型天线的超宽工作频带、小型化、水平全向辐射的性能需求。该天线在实现超宽带性能的同时,也实现了天线的小型化和轻量化。利用电磁仿真软件CST STUDIO SUITE 2017对天线结构设计和参数优化后,采用3D打印技术加工制作了天线样品,其直径仅为74 mm(0. 17λ),高度仅为97. 37 mm(0. 23λ),其中λ为天线工作频段低端对应波长。仿真和测试结果表明,当S11(Return Loss)≤-10 d B时,天线的工作频段为0. 7~17. 1 GHz,相对带宽为184. 3%,其水平全向辐射性能良好,最大增益为6. 63 d Bi,且该天线结构简单,易于加工,具有一定的工程应用价值。     

A Hierarchical 3D Graft Printed with Nanoink for Functional Craniofacial Bone Restoration

An ideal craniofacial bone repair graft shall not only focus on the repair ability but also the regeneration of natural architecture with occlusal loads-related function restoration. However, such functional bone tissue engineering scaffold has rarely been reported. Herein, a hierarchical 3D graft is proposed for rebuilding craniofacial bone with both natural structure and healthy biofunction reconstruction. Inspired by the bone healing process, an organic–inorganic nanoink with ultrasmall calcium phosphate oligomers and bone morphogenetic protein-2 incorporated is developed for spatiotemporal guidance of new bone. Based on such homogeneous nanoink, a biomimetic graft, including a cortical layer containing Haversian system, and a cancellous layer featured with triply periodic minimum surface macrostructures, is fabricated via projection-based 3D printing method, and the layers are loaded with distinct concentrations of bioactive factors for regenerating new bone with gradient density. The graft exhibits excellent osteogenic and angiogenic potential in vitro, and accelerates revascularization and reconstructs neo-bone with original morphology in vivo. Benefiting from such natural architecture, loading force is widely transferred with reduced stress concentration around the inserted dental implant. Taken from native physiochemical and structural cues, this wstudy provides a novel strategy for functional tissue engineering through designing function-oriented biomaterials.     

Smart Energy Bricks: Ti3C2@Polymer Electrochemical Energy Storage inside Bricks by 3D Printing

Three-dimensional (3D) printing technology has a pronounced impact on building construction and energy storage devices. Here, the concept of integrating 3D-printed electrochemical devices into insulation voids in construction bricks is demonstrated in order to create electrochemical energy storage as an integral part of home building. The low-cost 3D-printed supercapacitor (SC) electrodes are created using graphene/polylactic acid (PLA) filament in any desired shape such as 3D cylindrical- (3Dcy), disk- (3Ddc), and 3D rectangular- (3Drc) shaped electrodes. To obtain excellent capacitive performance, a Ti₃C₂@polypyrrole (PPy) hybrid is uniformly electroplated on the surface of 3D-printed electrodes. These Ti₃C₂@PPy-coated 3D-printed electrodes exhibit outstanding electrical conductivity, capacitive performance, cycle life, and power density. The bricks themselves act as an excellent scaffold for electrochemical energy devices as they are electrically insulating, fire-resistant, and contain substantial unused thermal insulation voids. A 3Drc Ti₃C₂@PPy SC is integrated into a real brick to showcase a smart house energy storage system that allows to reserve power in the bricks and use it as a power backup source in the event of a power outage in the elevator. This concept provides a platform for future truly smart buildings built from added value “smart brick” energy storage systems.     

基于秩1约束的三维重建方法

假设相机为正投影模型,提出了一种基于秩1约束的三维重建方法,该方法并不是直接求解空间结构点和投影矩阵,而是求解空间结构点的深度及投影矩阵。本文利用空间结构点可以由第1幅图像点及深度构成的特性,构造了一个秩为1的矩阵,利用该矩阵求取空间结构点的深度,最后完成三维重建。模拟实验和真实实验数据结果表明,该重建方法具有较高的重建精度。      

基于智能化方法的入侵检测系统

入侵检测是防火墙之后的第二道安全闸门,它在不影响网络性能的情况下对网络进行监测,对内部攻击、外部攻击和误操作进行实时保护。本文对入侵检测和入侵检测系统基础知识进行简要介绍,接着分析入侵检测系统的智能化方法,着重对数据挖掘和专家系统两种技术进行详细介绍,最后分析入侵检测系统目前存在的缺陷,并对它的发展趋势进行预测分析。     

3D Printing of Bilineage Constructive Biomaterials for Bone and Cartilage Regeneration

Owing to the different biological properties of articular cartilage and subchondral bone, it remains significant challenge to construct a bi‐lineage constructive scaffold. In this study, manganese (Mn)‐doped β‐TCP (Mn‐TCP) scaffolds with varied Mn contents are prepared by a 3D‐printing technology. The effects of Mn on the physicochemical properties, bioactivity, and corresponding mechanism for stimulating osteochondral regeneration are systematically investigated. The incorporation of Mn into β‐TCP lowers the lattices parameters and crystallization temperatures, but improves the scaffold density and compressive strength. The ionic products from Mn‐TCP significantly improve the proliferation of both rabbit chondrocytes and mesenchymal stem cells (rBMSCs), as well as promote the differentiation of chondrocytes and rBMSCs. The in vivo study shows that Mn‐TCP scaffolds distinctly improve the regeneration of subchondral bone and cartilage tissues as compared to TCP scaffolds, upon transplantation in rabbit osteochondral defects for 8 and 12 weeks. The mechanism is closely related to the Mn²⁺ ions significantly stimulated the proliferation and differentiation of chondrocytes through activating HIF pathway and protected chondrocytes from the inflammatory osteoarthritis environment by activating autophagy. These findings suggest that 3D‐printing of Mn‐containing scaffolds with improved physicochemical properties and bilineage bioactivities represents an intelligent strategy for regenerating osteochondral defects.