staircase effect
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2021 ◽  
Author(s):  
Petr Sokolov ◽  
Dmitrii Komissarenko ◽  
Georgy Dosovitskiy ◽  
Mikhail Korzhik

<div>The present study deals with the fabrication of light-reflecting materials used in pixelated scintillator detectors. For the first time, the reflecting surfaces for pixels of different sizes (from 0.8 to 3.2 mm) were obtained via a low-cost DLP 3D printing technique. The material for the reflectors was the new composite of transparent ultraviolet light-cured resin and TiO<sub>2</sub> as a light-scattering filler. It was observed that TiO<sub>2</sub> showed better performance compare to other pigments such as BaSO<sub>4</sub>, hBN or cubic zirconia. The object formation rate was about 1 cm per hour with the possibility to produce several parts simultaneously that simplifies the wrapping procedure. It was found that the regular grooves pattern of the fabricated parts (staircase effect) could increase a light collection from a scintillator. The reflective properties of such surfaces were comparable to conventional reflection coating (e.g., Teflon wrapping).<br></div>Presented at the 2019 IEEE NSS & MIC conference, Manchester, UK. 14 pages, 12 figures, 1 table. Journal reference: Optical Materials V. 108, October 2020, p. 110393.


2021 ◽  
Author(s):  
Petr Sokolov ◽  
Dmitrii Komissarenko ◽  
Georgy Dosovitskiy ◽  
Mikhail Korzhik

<div>The present study deals with the fabrication of light-reflecting materials used in pixelated scintillator detectors. For the first time, the reflecting surfaces for pixels of different sizes (from 0.8 to 3.2 mm) were obtained via a low-cost DLP 3D printing technique. The material for the reflectors was the new composite of transparent ultraviolet light-cured resin and TiO<sub>2</sub> as a light-scattering filler. It was observed that TiO<sub>2</sub> showed better performance compare to other pigments such as BaSO<sub>4</sub>, hBN or cubic zirconia. The object formation rate was about 1 cm per hour with the possibility to produce several parts simultaneously that simplifies the wrapping procedure. It was found that the regular grooves pattern of the fabricated parts (staircase effect) could increase a light collection from a scintillator. The reflective properties of such surfaces were comparable to conventional reflection coating (e.g., Teflon wrapping).<br></div>Presented at the 2019 IEEE NSS & MIC conference, Manchester, UK. 14 pages, 12 figures, 1 table. Journal reference: Optical Materials V. 108, October 2020, p. 110393.


Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2175
Author(s):  
Cheng Guo ◽  
Xiaohua Liu ◽  
Guang Liu

In recent years, many investigations have been devoted to fused deposition modeling (FDM) of high-performance polymer-polyetheretherketone (PEEK) and carbon-fiber-reinforced PEEK (CF/PEEK) for biomedical and aerospace applications. However, the staircase effect naturally brought about by FDM restricts further applications of 3D-printed PEEK and its composites in high-temperature molds, medical implants, and precision components, which require better or customized surface qualities. Hence, this work aimed to reduce the staircase effect and improve the surface quality of 3D-printed PEEK and CF/PEEK parts by dry milling of the fluctuant exterior surface. The co-dependency between 3D printing parameters (raster angle and layer thickness) and milling parameters (depth of cut, spindle speed, and feed rate per tooth) were investigated through experiments. The difference in removal mechanisms for PEEK and CF/PEEK was revealed. It was confirmed that the smearing effect enhanced the surface quality based on the morphology analysis and the simulation model. Both the raster angle of +45°/−45° and the small layer thickness could improve the surface quality of these 3D-printed polymers after dry milling. A large depth of cut and a large feed rate per tooth were likely to deteriorate the finished polymer surface. The spindle speed could influence the morphologies without significant changes in roughness values. Finally, a demonstration was performed to verify that dry milling of 3D-printed amorphous PEEK and CF/PEEK parts could lead to a high surface quality for critical requirements.


2021 ◽  
Vol 11 (11) ◽  
pp. 4825
Author(s):  
Yuan Yao ◽  
Yichi Zhang ◽  
Mohamed Aburaia ◽  
Maximilian Lackner

Conventional Fused Filament Fabrication (FFF) equipment can only deposit materials in a single direction, limiting the strength of printed products. Robotic 3D printing provides more degrees of freedom (DOF) to control the material deposition and has become a trend in additive manufacturing. However, there is little discussion on the strength effect of multi-DOF printing. This paper presents an efficient process framework for multi-axis 3D printing based on the robot to improve the strength. A multi-DOF continuous toolpath planning method is designed to promote the printed part’s strength and surface quality. We generate curve layers along the model surfaces and fill Fermat spiral in the layers. The method makes it possible to take full advantage of the multi-axis robot arm to achieve smooth printing on surfaces with high curvature and avoid the staircase effect and collision in the process. To further improve print quality, a control strategy is provided to synchronize the material extrusion and robot arm movement. Experiments show that the tensile strength increases by 22–167% compared with the conventional flat slicing method for curved-surface parts. The surface quality is improved by eliminating the staircase effect. The continuous toolpath planning also supports continuous fiber-reinforced printing without a cutting device. Finally, we compared with other multi-DOF printing, the application scenarios, and limitations are given.


2021 ◽  
Vol 903 ◽  
pp. 57-63
Author(s):  
S.M. Basha ◽  
M.M. Basha ◽  
N. Venkaiah ◽  
M.R. Shankar

Fused Deposition Modelling (FDM) is one of the additive manufacturing processes which can produce prototypes or functional components without the use of fixtures, and the lead time required is reduced drastically compared to traditional machining processes. The application of the FDM process in the biomedical and casting industries is limited by its poor surface roughness which is most generally caused by the staircase effect and chordal error of the 3D model. Owing to the drawbacks of mechanical based finishing techniques, researchers have come up with a new technique known as Vapour Smoothing (VS). In this work, past literature of the VS process of FDM components is reported and it has been seen that the VS process is giving a promising improvement in surface roughness of FDM components.


2021 ◽  
Vol 143 (5) ◽  
Author(s):  
Shubhavardhan Ramadurga Narasimharaju ◽  
Weidong Liu ◽  
Wenhan Zeng ◽  
Tian Long See ◽  
Paul Scott ◽  
...  

Abstract Additive manufacturing offers the advantage of infinite freedom to design and fabricate complex parts at reduced lead-time. However, the surface quality of additively manufactured parts remains well behind the conventionally processed counterparts. This paper aims to systematically investigate the impact of varying surface inclination angles with respect to the build direction on the resultant surface textures. A bespoke metal truncheon artifact with inclination angles varying from 0 deg to 180 deg was built by selective laser melting. Focus variation microscopy was used to measure the topography of inclined surfaces with a tilt angle of up to 132 deg. The measurement data were then analyzed to characterize the staircase effect and the particles adherent to the artifact surface. Areal surface texture parameters, including height parameters, spatial parameters, functional parameters, and feature parameters, were explored to quantify the general surface topography, the staircase effect, and the particle features. The areal surface texture characterization and particle analysis reveal the resulted surface topographies are strongly correlated with the surface inclination angles.


2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Yanyan Shi ◽  
Zhiwei Tian ◽  
Meng Wang ◽  
Xiaolong Kong ◽  
Lei Li ◽  
...  

<p style='text-indent:20px;'>Electrical impedance tomography (EIT) is a sensing technique with which conductivity distribution can be reconstructed. It should be mentioned that the reconstruction is a highly ill-posed inverse problem. Currently, the regularization method has been an effective approach to deal with this problem. Especially, total variation regularization method is advantageous over Tikhonov method as the edge information can be well preserved. Nevertheless, the reconstructed image shows severe staircase effect. In this work, to enhance the quality of reconstruction, a novel hybrid regularization model which combines a total generalized variation method with a wavelet frame approach (TGV-WF) is proposed. An efficient mean doubly augmented Lagrangian algorithm has been developed to solve the TGV-WF model. To demonstrate the effectiveness of the proposed method, numerical simulation and experimental validation are conducted for imaging conductivity distribution. Furthermore, some comparisons are made with typical regularization methods. From the results, it can be found that the proposed method shows better performance in the reconstruction since the edge of the inclusion can be well preserved and the staircase effect is effectively relieved.</p>


2021 ◽  
Vol 18 (5) ◽  
pp. 6581-6607
Author(s):  
Jimin Yu ◽  
◽  
Jiajun Yin ◽  
Shangbo Zhou ◽  
Saiao Huang ◽  
...  

<abstract><p>The image denoising model based on anisotropic diffusion equation often appears the staircase effect while image denoising, and the traditional super-resolution reconstruction algorithm can not effectively suppress the noise in the image in the case of blur and serious noise. To tackle this problem, a novel model is proposed in this paper. Based on the original diffusion equation, we propose a new method for calculating the adaptive fidelity term and its coefficients, which is based on the relationship between the image gradient and the diffusion function. It is realized that the diffusion speed can be slowed down by adaptively changing the coefficient of the fidelity term, and it is proved mathematically that the proposed fractional adaptive fidelity term will not change the existence and uniqueness of the solution of the original model. At the same time, washout filter is introduced as the control item of the model, and a new model of image super-resolution reconstruction and image denoising is constructed. In the proposed model, the order of fractional differential will be determined adaptively by the local variance of the image. And we give the numerical calculation method of the new model in the frequency domain by the method of Fourier transform. The experimental results show that the proposed algorithm can better prevent the staircase effect and achieve better visual effect. And by introducing washout filter to act as the control of the model, the stability of the system can be improved and the system can converge to a stable state quickly.</p></abstract>


Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2536 ◽  
Author(s):  
Jiangping Yuan ◽  
Chen Chen ◽  
Danyang Yao ◽  
Guangxue Chen

Material jetting is a high-precision and fast 3D printing technique for color 3D objects reproduction, but it also suffers from color accuracy and jagged issues. The UV inks jetting processes based on the polymer jetting principle have been studied from printing materials regarding the parameters in the default layer order, which is prone to staircase effects. In this work, utilizing the Mimaki UV inks jetting system with a variable layer thickness, a new framework to print a photogrammetry-based oil painting 3D model has been proposed with the tunable coloring layer sequence to improve the jagged challenge between adjacent layers. Based on contour tracking, a height-rendering image of the oil painting model is generated, which is further segmented and pasted to the corresponding slicing layers to control the overall printing sequence of coloring layers and white layers. The final results show that photogrammetric models of oil paintings can be printed vividly by UV-curable color polymers, and that the proposed reverse-sequence printing method can significantly improve the staircase effect based on visual assessment and color difference. Finally, the case of polymer-based oil painting 3D printing provides new insights for optimizing color 3D printing processes based on other substrates and print accuracy to improve the corresponding staircase effect.


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