Recent progress in 4D printing of stimuli-responsive polymeric materials

4D printing is proposed based on the additive manufacturing of stimuli-responsive materials and structures, which can realize shape changing upon external stimuli. This article reviews the 4D printing methods and actuating performances of 4D printing structures based on shape memory polymers, hydrogels, liquid crystal elastomers, and electroactive polymers. This article shows that the shape morphing properties of single materials are limited, while 4D printing of composites can integrate the various driving modes of different smart materials. In the end, challenges facing 4D printing such as broadening the scope of smart materials, improving printing processes, the compatibility of printing different materials have been discussed.     

有机碳黑复合导电纤维混纺面料的设计

利用14 tex涤纶/棉/碳黑(T/C/CB 65/35/20D3F)复合导电纱作为经纱设计了一款以平纹地经起花为组织的混纺导电纤维面料.选择合理的产品原料,设计合适的面料规格及织造工艺参数,所开发的面料兼具抗静电性、穿戴舒适性和美观性.用此款导电纤维面料做成静电防护工作服,可以延长集成电路类电子器件的寿命、降低生产成...     

Monocular trajectory intersection method for 3D motion measurement of a point target

This article proposes a monocular trajectory intersection method, a videometrics measurement with a mature theoretical system to solve the 3D motion parameters of a point target. It determines the target’s motion parameters including its 3D trajectory and velocity by intersecting the parametric trajectory of a motion target and series of sight-rays by which a motion camera observes the target, in contrast with the regular intersection method for 3D measurement by which the sight-rays intersect at one point. The method offers an approach to overcome the technical failure of traditional monocular measurements for the 3D motion of a point target and thus extends the application fields of photogrammetry and computer vision. Wide application is expected in passive observations of motion targets on various mobile beds.     

植物三维结构参数化建模系统的设计与实现

基于植物生长规律及其拓扑结构特点，将参数化绘图技术应用于植物三维结构仿真，以提高植物拓扑结构生成的速度．在Windows平台上，使用OpenGL图形接口，结合植物三维形态建模实际需要，采用面向对象编程技术，设计并实现了一个集植物形态模拟及可视化、场景动态渲染、植物生长动画等功能的植物三维结构可视化模拟系统．重点介绍了参数化建模原理、L系统算法的改进、各种植物构造模型的模拟、系统的模块设计及用户界面的实现，最后给出了系统应用的具体例子．     

4D printed shape memory polymers and their structures for biomedical applications

Shape memory polymers are smart materials that produce shape changes under external stimulus conditions. Four-dimensional (4D) printing is a comprehensive technology originate from deformable materials and three-dimensional (3D) printing technology. At present, 4D printed shape memory polymers and shape-changing structures have been applied in various fields, especially in the field of biomedical science. 4D printing technology has made a breakthrough of personalized customization in the traditional medical field, providing a new direction for the further development of the biomedical field. In this review, the recent research and development of shape memory polymer, 3D printing technology, 4D printed shape memory polymers and shape-changing structures in biomedical area are present. The examples and applications of 4D printed shape memory polymers and their structures in the area of biomedical are also introduced. Based on 4D printing, stimulated by different conditions, 3D printed objects can be fabricated into various biomedical applications such as cell scaffolds, vascular stents, bone scaffolds, tracheal stents and cardiac stents by different 3D printing techniques. Finally, the application prospects, existing technical restriction and future development directions of 4D printed shape memory polymers and their structures in the biomedical field are summarized.     

Experiments and simulation of low-velocity impact characteristics on carbon fiber composite lattice core sandwich structures

Since composite sandwich structures are susceptible to low-velocity impact damage,a thorough characterization of the loading and damage process during impact is important.In the present paper,the low-velocity impact response of carbon fiber composites lattice structures is investigated by experimental and numerical methods.Impact tests on composite plates are performed using an instrumented drop-weight machine(Instron 9250HV)and a new damage mode is observed.A three-dimensional finite element model is built by ABAQUS/Explicit and user subroutine(VUMAT)to predict the peak loading and simulate the complicated damage problem.The numerical predictions are in good agreement with the experimental results.     

一种微型光电纤维检测仪的设计

为了方便在现场观测纺织纤维的形态及种类，开发了一种便携式新型光电纤维检测仪．文中详细介绍了仪器的设计原理，结构实现，并介绍了其应用实例，展示了用该检测仪所取得的图像数据．     

碳纤维复合材料周铣加工过程的数值模拟研究

为了对碳纤维铣削过程进行研究,建立了碳纤维复合材料三维周铣加工的有限元计算模型,并研究了切削层简化及材料去除等建模关键技术。通过将周铣力施加到碳纤维复合材料的有限元计算模型,研究了铣削力对碳纤维复合材料的周铣加工过程。通过数值模拟获得了碳纤维复合材料铣削过程中的应力分布情况,数值模拟为碳纤维复合材料切削参数及刀具参数优化研究提供了参考。     

多UCAV协同打击多目标实时三维航迹规划

为提高无人作战飞机(Unmanned combat aerial vehicle,UCAV)协同实时航迹规划的实时性和可操作性,针对多架UCAV协同执行对地作战任务过程中的协同实时航迹规划问题,提出一种基于自学习策略和Lévy飞行的正弦余弦优化算法(Sine cosine optimization algorithm ...     

三维阶梯结构微混合器设计、制作及性能分析

为改善微纳尺度下流体的混合效果,在聚甲基丙烯酸甲酯(PMMA)基底材料上,设计制造了一款新型三维阶梯结构微混合器.混合器由一个T-型进样沟道和6个三维阶梯混合单元组成,采用超精密雕刻机在PMMA基片制作微米级结构,利用有机溶剂混溶浸泡法,在低温常压条件下键合得到.数值仿真结果表明:混合器效率受到台阶结构尺寸和流体速度的影响,当0.1≤Re≤5时,混合腔横截面的浓度方差σ0.1,接近充分混合;当流速在1~20 m L/h范围内时,将混合器用于微量溶液p H的调节取得了理想的结果.     

4D打印形状记忆聚合物及其复合材料的研究现状和应用进展

形状记忆聚合物材料是一种在外界环境刺激下可发生形状变化的智能材料,基于这种智能材料的可变形结构在生物医疗、航空航天等诸多领域显示出巨大的应用潜力.4D打印技术的问世为智能材料的进一步发展带来新的机遇,同时为微创医疗、智能机器人、柔性电子等高科技产业开创了全新的和智能化的发展方向.本文首先介绍4D打印技术的兴起和发展,以及5种新兴聚合物打印技术（光辅助打印、磁辅助打印、连续纤维打印、容积3D打印、多材料多喷头打印）的研发;其次从热、电、磁、光驱动4个方面综述了近几年4D打印形状记忆聚合物及其复合材料的研究进展及潜在应用,总结了适用于4D打印的形状记忆聚合物及其复合材料的制备方式及性能;然后介绍了基于形状记忆聚合物复合材料的4D打印结构在生物医疗、航空航天、智能器件及仿生领域的应用研究;最后指出4D打印在打印技术、打印材料、驱动方式和应用验证4个方面存在的问题及未来发展方向.     

4D产品的空间数据库结构设计

主要研究了4D产品(DEM、DOM、DRG、DLG)空间数据库结构设计,将4D产品通过空间数据库引擎 ArcSDE存储在大型商业关系数据库管理系统Oracle8i中。在Oracle中可以建立不同的关系表来存储一些4D 产品。由于采用关系数据库管理空间数据符合OpenGIS规范,这将增加空间数据的互操作性,并能使GIS融入 IT技术的主流。     

面内二维零膨胀混杂复合材料层合板设计

为使FRP结构在太空交变温度场下的热稳定性能要求,研究了面内二维零热膨胀混杂复合材料层合板设计理论.采用细观力学方法和经典层合板理论,分析层合板的纤维含量、混杂比及其铺层角等对层合板热膨胀系数的影响规律.建立了层内混杂复合材料层合板面内二维热膨胀系数设计理论.理论分析和实验结果表明,合理设计复合材料层合板的纤维含量、混杂比及其铺层,可以实现面内二维零膨胀.     

碳纤维三维编织复合材料预制件厚度的测量

提出了一种利用电涡流传感器进行碳纤维三维编织复合材料预制件厚度测量的研究方法，给出了测量系统的测量原理、硬件组成及软件设计框图，并对测得的厚度值进行了分析．实验证明，使用该系统测量的数据准确，精度高．     

复合材料桥纤维拔出的断裂动力学模型

在一无限的正交各向异性体的弹性平面上,对具有桥纤维平行自由表面的一个内部中央裂纹,提出了复合材料桥纤维拔出的动态模型.通过简化Keldysh-Sedov混合边界值问题的动态模型,呈现一简单和容易的解析解.求得了正交异性体中动态扩展裂纹受非均匀力作用问题的解析解,并利用这一解,通过迭加最终求得该模型的解.     

过刊装订封面打印程序设计

指出了传统打印过刊装订封面方式的缺点,分析了利用编程实现打印过刊装订封面的优点和方法,介绍了用Visual FoxPro6.0编程实现的步骤,着重介绍了渐进检索、特殊字符排版、动态调整字体及控制打印机的实现方法.     

过刊装订封面打印程序设计

指出了传统打印过刊装订封面方式的缺点,分析了利用编程实现打印过刊装订封面的优点和方法,介绍了用VisualFoxPro6 0编程实现的步骤,着重介绍了渐进检索、特殊字符排版、动态调整字体及控制打印机的实现方法.     

3D复合材料纤维搭桥对圆形脱层屈曲的影响

用能量法求解了绑结层合板和编织层合板等3D复合材料中纤维搭桥的椭圆形表面脱层屈曲问题，搭桥纤维被视为连续分布于脱层表面，可提供与脱层屈曲挠度成正比的恢复力的线性弹簧，算例表明，纤维搭桥对提高临界屈曲载荷的作用十分明显。     

桩基工程3D打印混凝土材料工程性质研究

通过开展桩基工程3D打印混凝土材料工程性质试验研究,提出采用42.5R快硬硫铝酸盐水泥、小粒径的建筑干砂和石子为主要材料,通过坍落度试验和抗压试验,得出水灰比越大,材料的坍落度越大;砂率越大,材料的坍落度先降低后增大,最终确定当水灰比为0.39和砂率为0.536时,流动性相对较好;同时通过添加葡萄糖酸钠缓凝剂来控制材料的凝结时间,当占比0.71%时,材料能够保持较长时间塑性,有利于较好控制拌和后混凝土的凝结时间;通过添加聚羧酸减水剂来增大材料的流动性和抗压强度,当添加比为0.48%时效果最佳。通过一系列的室内试验,制备出一种适用于桩基工程3D打印的新型混凝土材料。     

Mechanical properties and shape memory behavior of 4D printed functionally graded cellular structures

The properties of functionally graded(FG) cellular structures vary spatially, and the varying properties can meet the requirements of different working environments. In this study, we fabricated FG cellular structures with shape memory effect by 4D printing and evaluated the compressive performance and shape memory behavior of these structures with temperature through experimental analysis and finite element simulations. The results show that the maximum energy absorption gradually decreases but...