Design and Realization of 3D Printed AFM Probes

Atomic force microscope (AFM) probes and AFM imaging by extension are the product of exceptionally refined silicon micromachining, but are also restricted by the limitations of these fabrication techniques. Here, the nanoscale additive manufacturing technique direct laser writing is explored as a method to print monolithic cantilevered probes for AFM. Not only are 3D printed probes found to function effectively for AFM, but they also confer several advantages, most notably the ability to image in intermittent contact mode with a bandwidth approximately ten times larger than analogous silicon probes. In addition, the arbitrary structural control afforded by 3D printing is found to enable programming the modal structure of the probe, a capability that can be useful in the context of resonantly amplifying nonlinear tip–sample interactions. Collectively, these results show that 3D printed probes complement those produced using conventional silicon micromachining and open the door to new imaging techniques.     

基于参数化的个性3D打印产品设计研究

目的 基于用户调研,研究参数化设计结合3D打印技术在个性化智能手环表带定制设计的可行性.方法 首先阐释了国内外参数化设计研究的现状,通过解析参数化风格和相关产品案例明晰了参数化与产品设计的关系,进而总结了参数化个性定制的内涵;通过用户调研提出了参数化设计中参数的获取及参数逻辑关系建立的设计流程和设计任务;通过Rhino软件中Grasshopper的参数建模功能,从用户需求着手完成了设计实践,最终打印了3D实物模型,完成了对设计方案的评价.结果 基于用户参与情境下的参数化设计,在产品开发流程及方案呈现中能较好地体现个性化的用户需求.结论 参数化设计体现了个性化产品的设计思想,借助3D打印等增材制造技术,让这一效果得到了强化.参数化设计中的个性体现取决于数据的获取和数据逻辑关系的构建,而这可以从用户调研的结论中进行总结和提取.参数化设计、3D打印技术与个性化需求三者缺一不可,既互为驱动又相互制约.     

3D打印陶瓷材料研究进展

作为新一代成型技术,3D打印技术具有操作简单、成型速度快、精度高等优点,而采用3D打印技术制备出的多功能化陶瓷零件,在建筑、工业、医学、航天航空等领域将会得到广泛的应用,其发展前景十分广阔。主要介绍了3D打印陶瓷方面的成型技术和材料,回顾了3D打印陶瓷的发展及国内外产业状况,并对可应用于3D陶瓷的打印技术和打印材料进行了展望。     

Heat conduction analysis of laser CFRP processing with IR and UV laser light

To investigate carbon fiber reinforced plastic (CFRP) composite processing, cutting experiments are performed using a Nd:YAG laser. Both ultraviolet (λ = 266 nm) and infrared (λ = 1064 nm) lights are examined to optimize the laser conditions for cutting CFRP. The experimental data are compared to the results calculated by heat conduction models. The good agreement between the experimental and calculated results indicates that the cutting quality depends on the wavelength of the cutting laser.     

3D打印氧化铝陶瓷的气氛脱脂热处理工艺研究

脱脂热处理工艺对于3D打印陶瓷的成形质量具有重要的影响。目前光固化3D打印制备得到的氧化铝生坯经过在空气中的脱脂热处理工艺后烧结最终得到的氧化铝陶瓷存在的微观裂纹等缺陷, 将导致其力学性能较差。本工作研究了基于数字光处理(Digital light processing, DLP)技术的氧化铝陶瓷打印热处理工艺, 将3D打印制备得到的氧化铝陶瓷生坯分别在空气与氩气中脱脂后比较其宏观形貌, 发现在空气下脱脂的氧化铝生坯存在微观裂纹。再将脱脂后的生坯在空气下烧结得到氧化铝陶瓷, 并对其微观形貌和宏观性能进行表征, 发现在氩气下脱脂的氧化铝陶瓷平均晶粒尺寸要比直接在空气中脱脂得到的氧化铝陶瓷平均晶粒尺寸大, 而且晶粒结构致密, 无明显气孔和杂相, 而且具有更高的抗压强度。这说明在氩气中脱脂后烧结得到的氧化铝陶瓷性能更好。在氩气中脱脂的氧化铝致密度最高可达到96.72%, 抗压强度可达到761.7 MPa, 相比于只在空气中脱脂的氧化铝陶瓷性能得到显著提升。     

3D Printed Functional and Biological Materials on Moving Freeform Surfaces

Conventional 3D printing technologies typically rely on open‐loop, calibrate‐then‐print operation procedures. An alternative approach is adaptive 3D printing, which is a closed‐loop method that combines real‐time feedback control and direct ink writing of functional materials in order to fabricate devices on moving freeform surfaces. Here, it is demonstrated that the changes of states in the 3D printing workspace in terms of the geometries and motions of target surfaces can be perceived by an integrated robotic system aided by computer vision. A hybrid fabrication procedure combining 3D printing of electrical connects with automatic pick‐and‐placing of surface‐mounted electronic components yields functional electronic devices on a free‐moving human hand. Using this same approach, cell‐laden hydrogels are also printed on live mice, creating a model for future studies of wound‐healing diseases. This adaptive 3D printing method may lead to new forms of smart manufacturing technologies for directly printed wearable devices on the body and for advanced medical treatments.     

假肢接受腔3D打印模型的正逆向混合建模

针对传统工艺制作假肢接受腔依赖于石膏取型,以及金属阳四爪连接盘与假肢接受腔依赖于人工手动加工连接的问题,提出了一种基于SLA3D打印技术的假肢接受腔制作方法。通过仿真分析软件迭代设计得到承压合理的接受腔模型;通过正逆向混合建模,将光敏树脂接受腔和金属阳四爪连接盘复合。结果表明：3 mm厚的光敏树脂材料符合假肢接受腔的应用要求;切片层厚为0.2 mm时,光敏树脂接受腔和金属阳四爪连接盘的复合效果最佳。用SLA 3D打印假肢接受腔是可行性的。     

Analytical and numerical modeling of mechanical properties of orthogonal 3D CFRP

This study proposes an analytical and numerical model, for the prediction of mechanical properties of orthogonal 3D reinforcement composite materials, taking into account their structural parameters (mechanical properties of the components and geometrical architecture). This first step of this work requires the definition of the composite representative elementary volume (REV). Microscope studies made possible to visualize the architectural aspect of the internal structure. From these observations two types of REV, adapted to the types of modeling (analytical and by finite elements FE), were defined. The first one takes into account the whole of material in its thickness thus integrating the characteristics of the layers and the vertical reinforcements. The second one, strongly simplified in order to minimize the costs of calculations, is used in the FE approach. Moreover the analytical model is extended to the prediction of the ultimate properties by using the tonsorial criterion 3D of Tsai. The results obtaining from these modeling are compared with experimental results. This comparison highlights the interest and the limits of each approach according to the effect of the choice of the REV.     

3D Point Cloud Analysis for Detection and Characterization of Defects on Airplane Exterior Surface

Three-dimensional surface defect inspection remains a challenging task. This paper describes a novel automatic vision-based inspection system that is capable of detecting and characterizing defects on an airplane exterior surface. By analyzing 3D data collected with a 3D scanner, our method aims to identify and extract the information about the undesired defects such as dents, protrusions or scratches based on local surface properties. Surface dents and protrusions are identified as the deviations from an ideal, smooth surface. Given an unorganized point cloud, we first smooth noisy data by using Moving Least Squares algorithm. The curvature and normal information are then estimated at every point in the input data. As a next step, Region Growing segmentation algorithm divides the point cloud into defective and non-defective regions using the local normal and curvature information. Further, the convex hull around each defective region is calculated in order to englobe the suspicious irregularity. Finally, we use our new technique to measure the dimension, depth, and orientation of the defects. We tested and validated our novel approach on real aircraft data obtained from an Airbus A320, for different types of defect. The accuracy of the system is evaluated by comparing the measurements of our approach with ground truth measurements obtained by a high-accuracy measuring device. The result shows that our work is robust, effective and promising for industrial applications.     

Stress Reduction of 3D Printed Compliance‐Tailored Multilayers

Multilayered multi‐material interfaces are encountered in an array of fields. Here, enhanced mechanical performance of such multi‐material interfaces is demonstrated, focusing on strength and stiffness, by employing bondlayers with spatially‐tuned elastic properties realized via 3D printing. Compliance of the bondlayer is varied along the bondlength with increased compliance at the ends to relieve stress concentrations. Experimental testing to failure of a tri‐layered assembly in a single‐lap joint configuration, including optical strain mapping, reveals that the stress and strain redistribution of the compliance‐tailored bondlayer increases strength by 100% and toughness by 60%, compared to a constant modulus bondlayer, while maintaining the stiffness of the joint with the homogeneous stiff bondlayer. Analyses show that the stress concentrations for both peel and shear stress in the bondlayer have a global minimum when the compliant bond at the lap end comprises ≈10% of the bondlength, and further that increased multilayer performance also holds for long (relative to critical shear transfer length) bondlengths. Damage and failure resistance of multi‐material interfaces can be improved substantially via the compliance‐tailoring demonstrated here, with immediate relevance in additive manufacturing joining applications, and shows promise for generalized joining applications including adhesive bonding.     

3D打印制备多孔结构的研究与应用现状

多孔结构材料具有优异的物理、力学性能,应用领域广泛。目前,已开发出的多孔结构的制备方法种类繁多,然而仅少数可实现批量生产,大多数方法工艺较为复杂,并且在制备过程中难以对多孔结构进行有效控制,以致所得多孔结构仍存在某些性能方面的不足。3D打印技术的发展与应用为多孔结构的制备带来了新的途径,所制备的多孔结构可同时具备宏观孔隙和微观孔隙,其骨架及宏观孔隙可以根据需要进行设计。可用于制备多孔结构的3D打印方法主要有利用激光能量的选择性激光烧结法(SLS)、选择性激光熔化法(SLM)和激光近净成形法(LENS)等方法,利用电子束能量的电子束熔化(EBM)法,喷射粘结剂的三维印刷(3DP)法,材料挤出类中的熔融沉积成形(FDM)法和三维浆丝沉积(3DF)法,以及间接3D打印法。近年来,国内外学者对采用这些方法制备多孔结构开展了一定的研究,以期找到适合具体情况的3D打印方法及相应合理的工艺规范,从而提高制件的性能。采用SLS、SLM和LENS法,通过控制激光扫描轨迹和粉末烧结程度可以获得材料的宏观和微观孔隙。SLS法可制备的多孔结构材料种类较广,SLM和LENS法主要用于制备金属多孔结构。EBM法与SLM法类似,但EBM法需要在真空环境下成形,可用于制备Ti等活泼金属材料。适用于3DP法的粉末材料种类更广,可选用不同的粘结剂和相应的后处理方法,其工艺灵活性大。FDM法一般用于低熔点热塑性材料,通过熔融挤出而堆积成宏观多孔结构。3DF法以粉末浆料的形式挤出成形,适用的材料种类比FDM法广,得到的结构具有宏观和微观孔隙。FDM和3DF法的打印精度和孔隙尺寸受喷嘴打印能力的限制。间接法先利用某种便捷的3D打印方法制备出多孔结构原模,再将该原模经粉末冶金、浇注等方法制得所需的多孔结构材料,这样可以避免3D打印直接制备某些材料的多孔结构在结构特征方面受到的限制。上述这些方法中,由于激光和电子束的能量集中,故SLM和EBM法制备的多孔结构相对于其他方法更精细。3D打印制备多孔结构时孔隙的形成机理可以总结为:制件内打印轨迹未到达的区域形成的宏观设计孔隙、制件骨架内的粘结剂被加热分解或被溶解而去除后形成的孔隙、气体溶解在烧结过程中的熔融金属内形成的孔隙、激光扫描熔迹之间形成的孔隙、粉末颗粒间堆积空隙形成的孔隙。本文对3D打印制备多孔结构的研究与应用现状进行了综述,概述了制备多孔结构的几种主要的3D打印方法,总结了其孔隙的形成机理,介绍了3D打印多孔结构的应用现状,指出了未来需要开展的研究。     

熔融沉积法3D打印制备氧化锆陶瓷及其力学性能研究

在传统熔融沉积方法的基础上,采用颗粒混合料和螺杆挤出机构3D打印制备了致密和多孔氧化锆陶瓷,系统研究了颗粒原料的打印性能、坯体显微结构特征和陶瓷材料的力学性能。研究结果表明,该方法可以实现倾角达165°和跨度为5.5mm的无支撑结构的打印成型。研究了两种打印路径对致密氧化锆陶瓷抗弯强度及抗弯强度Weibull模数的影响,结果表明与传统单线填充模式相比,"单线+矩形"复合填充模式可以得到更高致密度和更优力学性能的陶瓷(抗弯强度达到637.8 MPa, Weibull模数达到9.10)。研究了不同气孔率多孔氧化锆陶瓷的压缩力学行为,结果表明陶瓷的抗压强度和气孔率之间存在复合指数规律,低气孔率时异面压缩的应力–应变曲线只呈现弹性阶段,高气孔率时出现弹性阶段和坍塌阶段,均未出现密实阶段。     

Highly Reproducible Physiological Asymmetric Membrane with Freely Diffusing Embedded Proteins in a 3D‐Printed Microfluidic Setup

Experimental setups to produce and to monitor model membranes have been successfully used for decades and brought invaluable insights into many areas of biology. However, they all have limitations that prevent the full in vitro mimicking and monitoring of most biological processes. Here, a suspended physiological bilayer‐forming chip is designed from 3D‐printing techniques. This chip can be simultaneously integrated to a confocal microscope and a path‐clamp amplifier. It is composed of poly(dimethylsiloxane) and consists of a ≈100 µm hole, where the horizontal planar bilayer is formed, connecting two open crossed‐channels, which allows for altering of each lipid monolayer separately. The bilayer, formed by the zipping of two lipid leaflets, is free‐standing, horizontal, stable, fluid, solvent‐free, and flat with the 14 types of physiologically relevant lipids, and the bilayer formation process is highly reproducible. Because of the two channels, asymmetric bilayers can be formed by making the two lipid leaflets of different composition. Furthermore, proteins, such as transmembrane, peripheral, and pore‐forming proteins, can be added to the bilayer in controlled orientation and keep their native mobility and activity. These features allow in vitro recapitulation of membrane process close to physiological conditions.     

Algorithmic Scheme for Concurrent Detection and Classification of Printed Circuit Board Defects

An ideal printed circuit board (PCB) defect inspection system can detect defects and classify PCB defect types. Existing defect inspection technologies can identify defects but fail to classify all PCB defect types. This research thus proposes an algorithmic scheme that can detect and categorize all 14-known PCB defect types. In the proposed algorithmic scheme, fuzzy c-means clustering is used for image segmentation via image subtraction prior to defect detection. Arithmetic and logic operations, the circle hough transform (CHT), morphological reconstruction (MR), and connected component labeling (CCL) are used in defect classification. The algorithmic scheme achieves 100% defect detection and 99.05% defect classification accuracies. The novelty of this research lies in the concurrent use of CHT, MR, and CCL algorithms to accurately detect and classify all 14-known PCB defect types and determine the defect characteristics such as the location, area, and nature of defects. This information is helpful in electronic parts manufacturing for finding the root causes of PCB defects and appropriately adjusting the manufacturing process. Moreover, the algorithmic scheme can be integrated into machine vision to streamline the manufacturing process, improve the PCB quality, and lower the production cost.     

3D打印非晶合金材料工艺及性能的研究进展

综述了3D打印制备非晶合金材料工艺及性能的研究进展,介绍了激光选区熔化和激光立体成形两种研究较多的3D打印制备非晶合金的方法,重点讨论了成形过程中工艺优化、基体预热、双激光熔化对成形非晶合金中晶态及微裂纹的影响。分析3D打印技术现有缺陷如球化、孔隙,指出今后的研究中可采用重熔、退火、粉体基体预热、改变扫描方式等手段提升性能,以期制备出致密度高、无裂纹、无晶化且性能优异的块体非晶合金。     

3D打印的兵马俑文创服装设计定制化服务研究

目的 研究3D打印技术在文创服装制作上的应用。方法 运用文献资料法、田野考察法及实践性研究,对3D打印服装的技术以及定制化服务的相关情况进行概述,研究3D打印在文创产业的定制化服务方面的可行性及优势。以3D打印图案的兵马俑文创服装的制作过程为例,证明了3D打印技术可以用于文创类服装的定制化生产、制作。结论 3D打印技术支撑的兵马俑文创服饰的定制化服务具有良好的发展前景,并且其技术已经成熟,是一个极有潜力的产业。     

Fatigue assessment of a marine structural steel and comparison with Thermographic Method and Static Thermographic Method

Fatigue properties are of fundamental importance and extremely time consuming to be assessed. The aim of this research activity is to apply the Thermographic Method (TM) and the Static Thermographic Method (STM) during fatigue and tensile tests to correlate the temperature trend to the fatigue properties of an S355 steel. The material was retrieved from an in‐service port crane. Traditional fatigue tests were performed in order to evaluate the S‐N curve with a scatter band. Step load tests were carried out deriving the fatigue limit and the Energy Parameter of the material. Static tensile tests were performed to obtain the stress at which the temperature trend deviates from the thermoelastic behavior. The fatigue properties obtained by means of the energetic methods were compared to the traditional ones showing a good agreement.     

An Examination of Various Methods of Minimising Strain Gradients in 3D Embedded Strain Gauge Analysis

This paper is a review of different methods used to reduce the effect of strain gradients in experimental models with 3D embedded strain gauged transducers. A detailed analysis of various methods used in relation to research carried out on a prosthetic hip implant is investigated. The methods to reduce these gradient effects detail the importance of the selection of the most suitable 3D transducer pattern and establishing the locations on the model where strain gradients are least problematic. It is also shown that the use of large‐scale models helps minimise the effect a gradient may have on data. Another way of avoiding strain gradients is to use axisymmetric models and embed the gauges at the same radius in the model but at a different angular orientation from the central axis. The strain gradient across the 3D embedded strain gauge transducer can be reduced using the methods described here so that significant errors in the final tensor do not materialise.