scholarly journals A Review of Stereolithography: Processes and Systems

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1138 ◽  
Author(s):  
Jigang Huang ◽  
Qin Qin ◽  
Jie Wang
Keyword(s):  
Additive Manufacturing ◽  
Technological Innovation ◽  
High Accuracy ◽  
Materials Selection ◽  
Liquid Resin ◽  
3D Objects ◽  
The Past ◽  
Selection For ◽  
System Configurations ◽  
Magnetically Assisted

Being the earliest form of additive manufacturing, stereolithography (SLA) fabricates 3D objects by selectively solidifying the liquid resin through a photopolymerization reaction. The ability to fabricate objects with high accuracy as well as a wide variety of materials brings much attention to stereolithography. Since its invention in the 1980s, SLA underwent four generations of major technological innovation over the past 40 years. These innovations have thus resulted in a diversified range of stereolithography systems with dramatically improved resolution, throughput, and materials selection for creating complex 3D objects and devices. In this paper, we review the four generations of stereolithography processes, which are scanning, projection, continuous and volumetric stereolithography. For each generation, representative stereolithography system configurations are also discussed in detail. In addition, other derivative technologies, such as scanning–projection, multi-material, and magnetically assisted stereolithography processes, are also included in this review.

Alumina-Forming Austenitic Alloys for Advanced Recuperators

2007 ◽  
Author(s):  
Bruce A. Pint ◽  
John P. Shingledecker ◽  
Michael P. Brady ◽  
Philip J. Maziasz
Keyword(s):  
Alumina Scale ◽  
Turbine Engines ◽  
Exhaust Gas ◽  
Materials Selection ◽  
The Past ◽  
Austenitic Alloys ◽  
Order Of Magnitude ◽  
Selection For ◽  
Sufficient Strength ◽  
Magnitude Increase

Materials selection for thin-walled recuperators has been extensively investigated over the past decade. In the latest generation of recuperated turbine engines, type 347 stainless steel has been replaced by higher alloyed steels and Ni-base chromia-forming alloys. However, high (linear) rates of chromia evaporation in exhaust gas fundamentally limits the oxidation lifetime of these chromia-forming alloys. One solution is to use alumina-forming alloys that are more resistant to this environment. The lower scale growth kinetics and resistance to evaporation in the presence of water vapor suggests an order of magnitude increase in lifetime for alumina-forming alloys. A significant problem with this strategy was the large drop in creep strength with the addition of sufficient Al to form an external alumina scale. However, new Fe-base austenitic compositions have been developed with sufficient strength for this application above 700°C.

scholarly journals Cavity vat photopolymerisation for additive manufacturing of polymer-composite 3D objects

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Joel Bachmann ◽  
Philip Obst ◽  
Lukas Knorr ◽  
Stefan Schmölzer ◽  
Gabriele Fruhmann ◽  
...  
Keyword(s):  
Composite Material ◽  
Additive Manufacturing ◽  
Manufacturing Processes ◽  
Solid Object ◽  
Thermal Curing ◽  
Covalent Bonds ◽  
Liquid Resin ◽  
3D Objects ◽  
Hard Shell ◽  
Dual Curing

AbstractVat photopolymerisation describes resin-based additive manufacturing processes in which ultraviolet light is used to layer-wise solidify liquid resin into a desired 3D shape. If the starting resin is a dual-curing formulation the object is also thermally cured to attain its final properties, obtaining either an elastomer or a thermoset. Here, we introduce cavity vat photopolymerisation, in which one photopolymer resin produces a composite material of an elastomer and thermoset. Cavities of any geometry are purposefully designed in the solid object and then filled with liquid resin during printing due to negative pressure. Thermal curing then solidifies the resin in the cavities into an elastomer, forming a distinct interface held together by strong covalent bonds. Hybrid specimens indicate improved damping, reduced fragmentation upon fracture and increased local elasticity, and we suggest several hard-shell/soft-core applications that might benefit.

scholarly journals SVM based pattern recognised islanding detection approach in a multiple distributed generation system

2018 ◽  
Vol 7 (1.8) ◽  
pp. 228 ◽  
Author(s):  
Gundala Srinivasa Rao ◽  
G. Kesava Rao
Keyword(s):  
Distributed Generation ◽  
High Accuracy ◽  
Islanding Detection ◽  
Generation System ◽  
Detection Zone ◽  
The Past ◽  
Detection Approach

The penetration of Distributed generation (DG) ensures the increase of demand for consistent, reasonable and spotless electricity facing with some design and operational challenges such as islanding. Several active and passive methods have been suggested in the past to detect islanding. Since they suffer from the large non detection zone and a high cost. In order to defeat such issues we propose a SVM based pattern recognising approach for islanding detection in a multiple DG system. The results show that our proposed method detects islanding with high accuracy.

Materials Selection for the Injection into Vaginal Wall for Treatment of Vaginal Atrophy

2022 ◽  
Author(s):  
Rosita Pensato ◽  
Antonio Zaffiro ◽  
Mirella D’Andrea ◽  
Concetta Errico ◽  
Jean Paul Meningaud ◽  
...  
Keyword(s):  
Vaginal Wall ◽  
Vaginal Atrophy ◽  
Materials Selection ◽  
Selection For

A Literature Review on the Wire and Arc Additive Manufacturing—Welding Systems and Software

2021 ◽  
Vol 13 (8) ◽  
pp. 1391-1400
Author(s):  
Zidong Lin ◽  
Pengfei Liu ◽  
Xinghua Yu
Keyword(s):  
Additive Manufacturing ◽  
Large Scale ◽  
Tool Path ◽  
Future Research ◽  
High Deposition Rate ◽  
Efficient Technology ◽  
The Past ◽  
Material Efficiency ◽  
Systems Software ◽  
Design Generation

Wire and arc additive manufacturing (WAAM) is considered to be an economic and efficient technology that is suitable to produce large-scale and ultra-large-scale metallic components. In the past two decades, it has been widely investigated in different fields, such as aerospace, automotive and marine industries. Due to its relatively high deposition rate, material efficiency, and shortened lead time compared to other powder-based additive manufacturing (AM) techniques, wire and arc additive manufacturing (WAAM) has been significantly noticed and adopted by both academic researchers and industrial engineers. In order to summarize the development achievements of wire and arc additive manufacturing (WAAM) in the past few years and outlook the development direction in the coming days, this paper provides an overview of 3D metallic printing by applying it as a deposition method. The review mainly focuses on the current welding systems, software for tool path design, generation, and planning used in wire and arc additive manufacturing (WAAM). In the end, the state of the art and future research on wire and arc additive manufacturing (WAAM) have been prospected.

Trajectory Planning for Conformal 3D Printing Using Non-Planar Layers

2018 ◽  
Author(s):  
Aniruddha V. Shembekar ◽  
Yeo Jung Yoon ◽  
Alec Kanyuck ◽  
Satyandra K. Gupta
Keyword(s):  
Additive Manufacturing ◽  
Trajectory Planning ◽  
Industrial Robots ◽  
Complex Geometries ◽  
Robot Arm ◽  
Joint Movement ◽  
Tool Orientation ◽  
3D Objects ◽  
Planar Surfaces ◽  
Build Time

Additive manufacturing (AM) technologies have been widely used to fabricate 3D objects quickly and cost-effectively. However, building parts consisting of complex geometries with multiple curvatures can be a challenging process for the traditional AM system whose capability is restricted to planar-layered printing. Using 6-DOF industrial robots for AM overcomes this limitation by allowing materials to deposit on non-planar surfaces with desired tool orientation. In this paper, we present collision-free trajectory planning for printing using non-planar deposition. Trajectory parameters subject to surface curvature are properly controlled to avoid any collision with printing surface. We have implemented our approach by using a 6-DOF robot arm. The complex 3D structures with various curvatures were successfully fabricated, while avoiding any failures in joint movement, holding comparable build time and completing with a satisfactory surface finish.

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