3D打印连续纤维复合材料丝材的成形规律

针对3D打印连续纤维增强热塑性树脂复合材料,研究了热塑性树脂在螺杆挤出过程中的流动机理和在纤维界面的浸渍行为,揭示了螺杆转速和牵引速度对复合丝材成形直径和纤维含量的影响规律。提出使用实际浸渍时间和理论完全浸渍时间来共同表征树脂对纤维的浸渍程度,观察复合丝材断面的形貌可知,高浸渍程度的丝材内部空隙较少,树脂和纤维结合更紧密。进行3D打印成形测试,当丝材的浸渍程度从17.25%提高到40.02%,样件的拉伸强度可从132 MPa提高到160 MPa,提高约21%。对样件进行动态力学性能分析(DMA)测试,试验结果表明浸渍程度高的复合材料成形件具有高的存储模量和损耗模量,表明其纤维和基体间的界面结合程度得到了提高和改善。     

我国印染助剂30年发展进程

我国助剂工业始于20世纪50年代,70年代开始发展,品种遍及漂、染、印、整,基本上满足纺织印染需要.但不论产量还是品种数量都还远远落后于工业发达国家.90年代开始,产量大幅上升,品种亦趋齐全,有些品种的研究和开发逐渐缩短了与国外的差距.随着纺织品与服装的高档化,对印染助剂质量与品种提出了更高的要求,促使国内助剂工业开发更多新产品以满足需求.     

Rapid Biofabrication of Printable Dense Collagen Bioinks of Tunable Properties

Recent convergence of the 3D printing of tissue‐like bioinks and regenerative medicine offers promise in the high‐throughput engineering of in vitro tissue models and organoids for drug screening and discovery research, and of potentially implantable neo‐tissues with tailored structural, biological, and mechanical properties. However, the current printing approaches are not compatible with collagen, the native scaffolding material. Herein, a unique biofabrication approach that uses automated gel aspiration‐ejection (GAE) is reported to potentially overcome these challenges. Automated‐GAE generates highly defined, aligned, dense collagen gel bioinks of various geometries (i.e., cylindrical, quadrangular, and tubular), dimensions, as well as tunable microstructural and mechanical properties that modulate seeded cellular responses. By densifying initial naturally derived reconstituted collagen hydrogels incorporating cells, automated‐GAE generates mini‐tissue building blocks with tailored protein fibril density and alignment, as well as cell loading, density and orientation according to the intended use. Surprisingly, a simple mathematical relationship defining the bioink compaction factor is found to be highly effective in predicting the initial and temporal properties of the bioinks in culture. Therefore, automated‐GAE will potentially also enable a fourth dimension to biofabrication, where cell–cell communications and cell‐extracellular matrix interactions as a function of time in culture can be predicted and modeled.     

Mechanical Assembly of Thermo‐Responsive Polymer‐Based Untethered Shape‐Morphing Structures

Shape‐morphing robotic structures can provide innovative approaches for various applications ranging from soft robotics to flexible electronics. However, the programmed deformation of direct‐3D printed polymer‐based structures cannot be separated from their subsequent conventional shape‐programming process. This work aims to simplify the fabrication process and demonstrates a rapid and adaptable approach for building stimulus‐responsive polymer‐based shape‐morphing structures of any shape. This is accomplished through mechanically assembling a set of identical self‐bending units in different patterns to form morphing structures using auxiliary hard connectors. A self‐bending unit fabricated by a 3D printing method can be actuated upon heating without the need for tethered power sources and is able to transform from a flat shape to a bending shape. This enables the assembled morphing‐structure to achieve the programmed integral shape without the need for a shape‐programming process. Differently assembled morphing structures used as independent robotic mechanisms are sequentially demonstrated with applications in biomimetic morphing structures, grasping mechanisms, and responsive electrical devices. This proposed approach based on a mechanical assembling method paves the way for rapid and simple prototyping of stimulus‐responsive polymer‐based shape‐morphing structures with arbitrary architectures for a variety of applications in deployable structures, bionic mechanisms, robotics, and flexible electronics.     

基于3D打印的仪表罩壳注塑模具随形冷却水路设计

以典型产品仪表罩壳为研究对象，借助Moldflow模流仿真软件，进行产品随形冷却水路的设计，对比分析传统冷却水路与三维(3D)打印随形冷却水路设计方案的冷却分析结果，以此评估随形冷却水路在实际应用中的优势，为随形冷却水路的设计提供理论性的参考指导，并为该产品在实际生产中提供优化的模具冷却设计方案。结果表明，与传统冷却水路相比，随形冷却水路方案的冷却效率最多可提高31.6 %，产品表面温度均匀性最多可提高44.6 %。     

Ku波段基片集成波导带通滤波器的设计

设计了一款基于基片集成波导的ku波段卫星通信的带通滤波器。描述了位于SIW内部的金属通孔的等效电路模型,并分析通孔直径、位置等关键参数对滤波器性能的影响。针对基于中心位置的SIW带通滤波器带宽较窄的问题,提出偏置金属通孔SIW带通滤波器的设计方法,从而增大滤波器的带宽。并通过对改进后的基片集成波导带通滤波器的仿真,验证了设计的正确性和方法的有效性。     

瓷砖表面非常规尺寸瑕疵的检测

与普通目标检测任务不同, 瓷砖表面瑕疵检测的困难之处在于检测小尺寸和大长宽比等非常规尺寸的目标. 为了解决这两个问题, 本文提出了一种基于改进 Cascade R-CNN 的新型瓷砖表面瑕疵检测算法. 为了提高模型对小瑕疵的检测能力, 本文模型利用侧向连接结构进行上下层语义信息的融合, 使用可切换空洞率的空洞卷积来增加模型的感受野; 为了提高模型对于大长宽比瑕疵的检测能力, 本文模型在标准卷积上引入偏移域以更好提取目标特征信息. 此外, 本文模型调整 Cascade R-CNN 框架中预选锚框的大小和长宽比例. 实验结果表明, 在从瓷砖工厂收集的数据集上, 本文所提出算法的平均精度均值 (mean average precision, mAP) 达到了 73.5%, 比改进前的 Cascade R-CNN 模型提高了9.7%. 本文实验代码可从以下链接获取: https://github.com/mashibin/Ceramic-tile-defect-detection.     

激光熔覆技术的研究与应用

激光熔覆技术在金属3D打印技术中得到了广泛的应用,其中最典型的就是航空发动机叶片采用3D打印技术一次成型。将激光熔覆技术应用在第四代冷却机上,可以实现传统铸造工艺达不到的尺寸精度,强化耐热钢工件以及实现工件的快速修复再利用,可大幅提高工件的使用寿命。     

Holey carbon micro-arrays for transmission electron microscopy: a microcontact printing approach

We have used a microcontact printing approach to produce high quality and inexpensive holey carbon micro-arrays. Fabrication involves: (1) micromolding a poly(dimethylsiloxane) (PDMS) elastomer stamp from a microfabricated master that contains the desired array pattern; (2) using the PDMS stamp for microcontact printing a thin sacrificial plastic film that contains an array of holes; (3) floating the plastic film onto TEM grids; (4) evaporating carbon onto the plastic film and (5) removing the sacrificial plastic film. The final holey carbon micro-arrays are ready for use as support films in TEM applications with the fidelity of the original microfabricated pattern. This approach is cost effective as both the master and the stamps have long-term reusability. Arbitrary array patterns can be made with microfabricated masters made through a single-step photolithographic process.     

利用VB与VC混合编程实现数字印花的图像处理

织物吸收墨水能力的差异、经向和纬向的属性不同,造成数字印花过程中出现偏色和不期望条纹的现象,达不到理想的印花效果.针对这种问题提出在印花之前对图像进行合理的处理方案,即调整图像各种颜色的灰度值,将调整后的误差按不同的比例分配到经向和纬向的点上,使得在经向和纬向的点得到不同程度的补偿.介绍用VC编写动态连接库(DLL)、在VB中调用的方法来开发对数字印花的图像处理软件,以适应不同的织物,从而提高印花质量.