scholarly journals Stitchless support-free 3D printing of free-form micromechanical structures with feature size on-demand

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Linas Jonušauskas ◽  
Tomas Baravykas ◽  
Dovilė Andrijec ◽  
Tomas Gadišauskas ◽  
Vytautas Purlys
Keyword(s):  
3D Printing ◽  
Free Form ◽  
Complex Structures ◽  
Production Lines ◽  
Feature Size ◽  
Voxel Size ◽  
Translation Velocity ◽  
Micromechanical Structures ◽  
Simultaneous Movement ◽  
Good Agreement

AbstractFemtosecond laser based 3D nanolithography is a powerful tool for fabricating various functional micro- and nano-objects. In this work we present several advances needed to push it from the laboratory level use to the industrial production lines. First, linear stage and galvo-scanners synchronization is employed to produce stitch-free mm-sized structures. Furthermore, it is shown that by varying objective numerical apertures (NA) from 1.4 NA to 0.45 NA, voxel size can be tuned in the range from sub μm to tens of mm, resulting in structuring rates between 1809 μm3/s and 313312 μm3/s at 1 cm/s translation velocity achieved via simultaneous movement of linear stages and scanners. Discovered voxel/throughput scaling peculiarities show good agreement to ones acquired with numerical modeling. Furthermore, support-free 3D printing of complex structures is demonstrated. It is achieved by choosing pre-polymer that is in hard gel form during laser writing and acts as a dissolvable support during manufacturing. All of this is combined to fabricate micromechanical structures. First, 1:40 aspect ratio cantilever and 1.5 mm diameter single-helix spring capable of sustaining extreme deformations for prolonged movement times (up to 10000 deformation cycles) are shown. Then, free-movable highly articulated intertwined micromechanical spider and squids (overall size up to 10 mm) are printed and their movement is tested. The presented results are discussed in the broader sense, touching on the stitching/throughput dilemma and comparing it to the standard microstereolithography. It is shown where multiphoton polymerization can outpace standard stereolithography in terms of throughput while still maintaining superior resolution and higher degree of freedom in terms of printable geometries.

scholarly journals Polarization-insensitive 3D conformal-skin metasurface cloak

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
He-Xiu Xu ◽  
Guangwei Hu ◽  
Yanzhao Wang ◽  
Chaohui Wang ◽  
Mingzhao Wang ◽  
...  
Keyword(s):  
3D Printing ◽  
Incident Light ◽  
Three Dimensional ◽  
Free Form ◽  
Polarization Insensitive ◽  
Wavelength Scale ◽  
First Time ◽  
Printing Techniques ◽  
Flat Ground ◽  
Good Agreement

AbstractElectromagnetic metasurface cloaks provide an alternative paradigm toward rendering arbitrarily shaped scatterers invisible. Most transformation-optics (TO) cloaks intrinsically need wavelength-scale volume/thickness, such that the incoming waves could have enough long paths to interact with structured meta-atoms in the cloak region and consequently restore the wavefront. Other challenges of TO cloaks include the polarization-dependent operation to avoid singular parameters of composite cloaking materials and limitations of canonical geometries, e.g., circular, elliptical, trapezoidal, and triangular shapes. Here, we report for the first time a conformal-skin metasurface carpet cloak, enabling to work under arbitrary states of polarization (SOP) at Poincaré sphere for the incident light and arbitrary conformal platform of the object to be cloaked. By exploiting the foundry three-dimensional (3D) printing techniques to fabricate judiciously designed meta-atoms on the external surface of a conformal object, the spatial distributions of intensity and polarization of its scattered lights can be reconstructed exactly the same as if the scattering wavefront were deflected from a flat ground at any SOP, concealing targets under polarization-scanning detections. Two conformal-skin carpet cloaks working for partial- and full-azimuth plane operation are respectively fabricated on trapezoid and pyramid platforms via 3D printing. Experimental results are in good agreement with numerical simulations and both demonstrate the polarization-insensitive cloaking within a desirable bandwidth. Our approach paves a deterministic and robust step forward to the realization of interfacial, free-form, and full-polarization cloaking for a realistic arbitrary-shape target in real-world applications.

scholarly journals Modular crawling robots using soft pneumatic actuators

2020 ◽  
Author(s):  
Nianfeng Wang ◽  
Bicheng Chen ◽  
Xiandong Ge ◽  
Xianmin Zhang ◽  
Wenbin Wang
Keyword(s):  
3D Printing ◽  
Numerical Models ◽  
Pneumatic Actuators ◽  
Axial Elongation ◽  
Control Schemes ◽  
Good Agreement

AbstractCrawling robots have elicited much attention in recent years due to their stable and efficient locomotion. In this work, several crawling robots are developed using two types of soft pneumatic actuators (SPAs), namely, an axial elongation SPA and a dual bending SPA. By constraining the deformation of the elastomeric chamber, the SPAs realize their prescribed motions, and the deformations subjected to pressures are characterized with numerical models. Experiments are performed for verification, and the results show good agreement. The SPAs are fabricated by casting and developed into crawling robots with 3D-printing connectors. Control schemes are presented, and crawling tests are performed. The speeds predicted by the numerical models agree well with the speeds in the experiments.

scholarly journals ADDITIVE MANUFACTURING - APPLICATION OPPORTUNITIES FOR THE AVIATION INDUSTRY

2015 ◽  
Vol 6 (2) ◽  
pp. 63-86
Author(s):  
Dipesh Dhital ◽  
Yvonne Ziegler
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Computer Aided Design ◽  
Free Form ◽  
Aviation Industry ◽  
Layer By Layer ◽  
Printing Technology ◽  
3D Printing Technology ◽  
Subtractive Manufacturing ◽  
Aided Design

Additive Manufacturing also known as 3D Printing is a process whereby a real object of virtually any shape can be created layer by layer from a Computer Aided Design (CAD) model. As opposed to the conventional Subtractive Manufacturing that uses cutting, drilling, milling, welding etc., 3D printing is a free-form fabrication process and does not require any of these processes. The 3D printed parts are lighter, require short lead times, less material and reduce environmental footprint of the manufacturing process; and is thus beneficial to the aerospace industry that pursues improvement in aircraft efficiency, fuel saving and reduction in air pollution. Additionally, 3D printing technology allows for creating geometries that would be impossible to make using moulds and the Subtractive Manufacturing of drilling/milling. 3D printing technology also has the potential to re-localize manufacturing as it allows for the production of products at the particular location, as and when required; and eliminates the need for shipping and warehousing of final products.

scholarly journals 4D Printing: A Review on Recent Progresses

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 796 ◽  
Author(s):  
Honghui Chu ◽  
Wenguang Yang ◽  
Lujing Sun ◽  
Shuxiang Cai ◽  
Rendi Yang ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Three Dimensional ◽  
Complex Structures ◽  
Future Prospects ◽  
4D Printing ◽  
Stimulation Method ◽  
Shape Property ◽  
External Stimuli

Since the late 1980s, additive manufacturing (AM), commonly known as three-dimensional (3D) printing, has been gradually popularized. However, the microstructures fabricated using 3D printing is static. To overcome this challenge, four-dimensional (4D) printing which defined as fabricating a complex spontaneous structure that changes with time respond in an intended manner to external stimuli. 4D printing originates in 3D printing, but beyond 3D printing. Although 4D printing is mainly based on 3D printing and become an branch of additive manufacturing, the fabricated objects are no longer static and can be transformed into complex structures by changing the size, shape, property and functionality under external stimuli, which makes 3D printing alive. Herein, recent major progresses in 4D printing are reviewed, including AM technologies for 4D printing, stimulation method, materials and applications. In addition, the current challenges and future prospects of 4D printing were highlighted.

Experimental verification of textured mechanical seal designed using multi-objective optimization

2019 ◽  
Vol 71 (6) ◽  
pp. 766-771 ◽  
Author(s):  
Xiuying Wang ◽  
Michael Khonsari ◽  
Siyuan Li ◽  
Qingwen Dai ◽  
Xiaolei Wang
Keyword(s):  
Leakage Rate ◽  
Free Form ◽  
Optimization Approach ◽  
Multi Objective Optimization ◽  
Mechanical Seals ◽  
Content Type ◽  
Multi Objective ◽  
Load Carrying ◽  
And Control ◽  
Good Agreement

Purpose This study aims to simultaneously enhance the load-carrying capacity and control the leakage rate of mechanical seals by optimizing the texture shape. Design/methodology/approach A multi-objective optimization approach is implemented to determine the optimal “free-form” textures and optimal circular dimples. Experiments are conducted to validate the simulation results. Findings The experimental coefficient of friction (COF) and leakage rate are in good agreement with the calculated results. In addition, the optimal “free-form” texture shows a lower COF and a lower leakage in most cases. Originality/value This work provides a method to optimize the surface texture for a better combination performance of mechanical seals.

Prediction and Measurement of Lamb Wave from Debondings at Structural Features in Composite Laminates

2013 ◽  
Vol 558 ◽  
pp. 139-148 ◽  
Author(s):  
Ching Tai Ng ◽  
Martin Veidt
Keyword(s):  
Lamb Wave ◽  
Composite Laminates ◽  
Wave Scattering ◽  
Three Dimensional ◽  
Scattered Wave ◽  
Structural Features ◽  
Complex Structures ◽  
Detection Techniques ◽  
Fe Simulations ◽  
Good Agreement

The interaction of the fundamental anti-symmetric Lamb wave (A0) with debondings at structural features is investigated using experimental data and finite element (FE) simulations. In this study explicit three-dimensional (3D) FE simulations are employed, which allows the study of the scattered wave along different propagation directions. Good agreement between the FE predictions and the measurements are obtained that demonstrates that the 3D FE scattering model is able to accurately predict the Lamb wave scattering characteristics at debondings. The study show that the characteristics of Lamb wave reflected from the debondings at the structure feature is much more complicated than that from defects in flat composite laminates. Parameter studies show that the backward and forward scattering coefficient of Lamb wave is a function of debonding size to wavelength ratio and debonding location. This shows the potential of employing Lamb wave to identify the size and monitor the growth of the debondings. The findings of the study provide improved physical insights into the scattering phenomena, which are important to further advance damage detection techniques for complex structures made by composite laminates.

scholarly journals Development of 3D Concrete Extrusion Nozzle for Producing Free-form Concrete Panels

2021 ◽  
Vol 12 (6) ◽  
pp. 427-436
Author(s):  
Ji-Yeong, Yun Et.al
Keyword(s):  
3D Printing ◽  
Construction Industry ◽  
Industrial Revolution ◽  
Production Equipment ◽  
Free Form ◽  
Innovative Technology ◽  
Production Sector ◽  
Construction Automation ◽  
Concrete Panels ◽  
Opening And Closing

There has been an increase in demand for free-form building through the development of advanced technologies, and the fourth industrial revolution has become a worldwide trend, thereby changing the construction industry. In particular, in the case of the free-form architecture sector, development of 3D printing technologies has been ongoing for construction automation. According to such trends, this study develops an FCP production equipment using 3D printing technologies. The FCP production equipment in this study is made up of mould equipment and 3D printer. It is different from existing 3D printing technologies so in this study 3D concrete extrusion nozzle must be developed for producing FCP. Basic design suitable to such requirements is proposed.  Applicability of the proposed design is checked and the nozzle form is concretized to draft the final drawing. In this study, slit-type opening and closing device for accurate extrusion stoppage of concrete and screw-type nozzle for adjusting pressure and extrusion speed were applied for the nozzle. This is expected to be innovative technology for the FCP production sector.

scholarly journals Multi-Material 3D Printing of a Customized Sports Mouth Guard: Proof-of-Concept Clinical Case

2021 ◽  
Vol 18 (23) ◽  
pp. 12762
Author(s):  
Alexey Unkovskiy ◽  
Fabian Huettig ◽  
Pablo Kraemer-Fernandez ◽  
Sebastian Spintzyk
Keyword(s):  
3D Printing ◽  
Free Form ◽  
Proof Of Concept ◽  
Virtual Design ◽  
Digital Workflow ◽  
Protective Function ◽  
Drop On Demand ◽  
3D Printed ◽  
Mouth Guards ◽  
Protective Performance

A multilayer mouth guard is known to have the best protective performance. However, its manufacturing in a digital workflow may be challenging with regards to virtual design and materialization. The present case demonstrates a pathway to fabricate a multilayer individualized mouth guard in a fully digital workflow, which starts with intraoral scanning. A free-form CAD software was used for the virtual design. Two various CAM techniques were used, including Polyjet 3D printing of rubber-like soft material and silicone printing using Drop-on-Demand technique. For both methods the outer layer was manufactured from more rigid materials to facilitate its protective function; the inner layer was printed from a softer material to aid a better adaptation to mucosa and teeth. Both 3D printed multilayer mouth guards showed a clinically acceptable fit and were met with patient appraisal. Their protective capacities must be evaluated in further clinical studies.

scholarly journals Property Analysis of Photo-Polymerization-Type 3D-Printed Structures Based on Multi-Composite Materials

2021 ◽  
Vol 11 (18) ◽  
pp. 8545
Author(s):  
So-Ree Hwang ◽  
Min-Soo Park
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Composite Materials ◽  
3D Printing ◽  
Bending Test ◽  
3D Printer ◽  
Complex Structures ◽  
Photo Polymerization ◽  
Anisotropic Structures ◽  
3D Printed

Additive manufacturing, commonly called 3D printing, has been studied extensively because it can be used to fabricate complex structures; however, polymer-based 3D printing has limitations in terms of implementing certain functionalities, so it is limited in the production of conceptual prototypes. As such, polymer-based composites and multi-material 3D printing are being studied as alternatives. In this study, a DLP 3D printer capable of printing multiple composite materials was fabricated using a movable separator and structures with various properties were fabricated by selectively printing two composite materials. After the specimen was fabricated based on the ASTM, the basic mechanical properties of the structure were compared through a 3-point bending test and a ball rebound test. Through this, it was shown that structures with various mechanical properties can be fabricated using the proposed movable-separator-based DLP process. In addition, it was shown that this process can be used to fabricate anisotropic structures, whose properties vary depending on the direction of the force applied to the structure. By fabricating multi-joint grippers with varying levels of flexibility, it was shown that the proposed process can be applied in the fabrication of soft robots as well.

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