scholarly journals Dynamic Molding Deposition: The additive manufacturing in partially ordered system

2021 ◽  
Author(s):  
Christophe Marquette ◽  
Edwin-Joffrey Courtial ◽  
Arthur Colly
Keyword(s):  
Additive Manufacturing ◽  
High Viscosity ◽  
Material Composition ◽  
Support Structures ◽  
Complex Objects ◽  
Powder System ◽  
Partially Ordered ◽  
Injection Material ◽  
Composite Objects

Abstract Additive manufacturing (AM) is now identified as a powerful bundle of fabrication techniques. Limitations were identified to be mostly related to the availability of reformulated materials compatible with existing AM technologies. What if we were able to dynamically generate sacrificial molds with unlimited architectures and material composition? We have discovered such a process, called Dynamic Molding Deposition (DMD) in partially ordered powder system and demonstrated its capacity to produce highly complex objects with 100 µm resolution, without any building plate or support structures. The DMD compatible materials were shown to be almost infinite, from low to high viscosity, from thermoplastic to elastomers. Our process enables us to build unexpected composite objects made up of injection material and powder grains from the dynamic mold. This feature opens the path to a complete new field of research and applications.

Differential Performance Signature Qualification for Additively Manufactured Parts

2018 ◽  
Author(s):  
John G. Michopoulos ◽  
John C. Steuben ◽  
Athanasios P. Iliopoulos
Keyword(s):  
Additive Manufacturing ◽  
Graphical Representation ◽  
Functional Performance ◽  
Complex Objects ◽  
Aircraft Landing ◽  
Differential Performance ◽  
Aircraft Landing Gear ◽  
Am Processes ◽  
Comparison Measures ◽  
Quantities Of Interest

Additive Manufacturing (AM) technologies and associated processes, enable successive accretion of material to a domain, and permit manufacturing of highly complex objects which would otherwise be unrealizable. However, the material micro- and meso-structures generated by AM processes can differ remarkably from those arising from conventional manufacturing (CM) methods. Often, a consequence of this fact is the sub-standard functional performance of the produced parts that can limit the use of AM in some applications. In the present work, we propose a rapid functional qualification methodology for AM-produced parts based on a concept defined as differential Performance Signature Qualification (dPSQ). The concept of Performance Signature (PerSig) is introduced both as a vector of featured quantities of interest (QoIs), and a graphical representation in the form of radar or spider graph, representing the QoIs associated with the performance of relevant parts. The PerSigs are defined for both the prequalified CM parts and the AM-produced ones. Comparison measures are defined and enable the construction of differential PerSigs (dPerSig) in a manner that captures the differential performance of the AM part vs. the prequalified CM one. The dPerSigs enable AM part qualification based on how their PerSigs are different from those of prequalified CM parts. After defining the steps of the proposed methodology, we describe its application on a part of an aircraft landing gear assembly and demonstrate its feasibility.

scholarly journals Suitability of Recycled PLA Filament Application in Fused Filament Fabrication Process

2021 ◽  
Vol 15 (4) ◽  
pp. 491-497
Author(s):  
Tomislav Breški ◽  
Lukas Hentschel ◽  
Damir Godec ◽  
Ivica Đuretek
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Polylactic Acid ◽  
Design Of Experiment ◽  
Experimental Approach ◽  
Manufacturing Processes ◽  
Support Structures ◽  
Fused Filament Fabrication ◽  
Layer Height ◽  
Printing Parameters

Fused filament fabrication (FFF) is currently one of the most popular additive manufacturing processes due to its simplicity and low running and material costs. Support structures, which are necessary for overhanging surfaces during production, in most cases need to be manually removed and as such, they become waste material. In this paper, experimental approach is utilised in order to assess suitability of recycling support structures into recycled filament for FFF process. Mechanical properties of standardized specimens made from recycled polylactic acid (PLA) filament as well as influence of layer height and infill density on those properties were investigated. Optimal printing parameters for recycled PLA filaments are determined with Design of Experiment methods (DOE).

scholarly journals On preventing the dripping effect of overhang constraints in topology optimization for additive manufacturing

2021 ◽  
Author(s):  
Alain Garaigordobil ◽  
Rubén Ansola ◽  
Igor Fernandez de Bustos
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Prevention Strategy ◽  
Alternative Strategy ◽  
Manufacturing Processes ◽  
Support Structures ◽  
Local Minimizers ◽  
Constraint Function ◽  
Temporary Support

AbstractThis article falls within the scope of topology optimization for Additive Manufacturing processes and proposes an alternative strategy to prevent the phenomenon known as the Dripping Effect. The Dripping Effect is when an overhang constraint is imposed on topology optimization processes for Additive Manufacturing and is defined as the formation of oscillatory contour trends within the prescribed threshold angle. Although these drop-like formations constitute local minimizers of the constraint function, they do not provide a printable feature, and, therefore, they neither eliminate the need to form temporary support structures. So far, there has been no general agreement on how to prevent the Dripping Effect, so this work aims to introduce a strategy that effectively prevents it, and that at the same time may be easy to extrapolate to other types of geometric overhang restrictions. This paper provides a study of the origin of the Dripping Effect and gives detailed instructions on how the proposed prevention strategy is applied. In addition, several benchmark examples where the Dripping Effect is prevented are shown.

Computational Study of Reinforcement Mechanisms of Cuttlefish Bone Inspired Structure for 3D Printing

2021 ◽  
Author(s):  
Brandon Bethers ◽  
Yang Yang
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Computational Study ◽  
High Energy ◽  
Simulation Software ◽  
Support Structures ◽  
Common Support ◽  
Potential Applications ◽  
Manufacturing Techniques ◽  
Traditional Manufacturing

Abstract Cuttlebone, the internal shell structure of a cuttlefish, presents a unique labyrinthian wall-septa design that promotes high energy absorption, porosity, and damage tolerance. This structure offers us an inspiration for the design of lightweight and strong structures for potential applications in mechanical, aerospace and biomedical engineering. However, the complexity of the cuttlebones structural design makes its fabrication by traditional manufacturing techniques not feasible. The advances in additive manufacturing (3D printing) make highly complex structures like cuttlebone possible to manufacture. In this work, the authors sought to establish comparative data between cuttlebone structures and some common support structures used in additive manufacturing. The structures compared to cuttlebone in this work include the cubic, honeycomb and triangular support structures. This was accomplished by using CAD modeling and simulation software. This study found that the cuttlefish structures had higher average stress values than the others but similar average strain values. This leads to a higher modulus of elasticity for the cuttlebone structures. The data suggests that further research into cuttlebone structures could produce future designs that improve upon the current well-established additive manufacturing support structures. Further study will be performed for the 3D printing of cuttlebone inspired structures by using various types of materials, such as soft and rigid polymers, functional ceramics, composites, and metals.

Micromachined Ultrasonic Print-Head for Deposition of High-Viscosity Materials

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
J. Mark Meacham ◽  
Amanda O’Rourke ◽  
Yong Yang ◽  
Andrei G. Fedorov ◽  
F. Levent Degertekin ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Three Dimensional ◽  
High Viscosity ◽  
The Novel ◽  
Glycerol Water ◽  
Print Head ◽  
Cavity Resonances ◽  
Allowable Range ◽  
Novel Method ◽  
Manufacturing Techniques

The recent application of inkjet printing to fabrication of three-dimensional, multilayer and multimaterial parts has tested the limits of conventional printing-based additive manufacturing techniques. The novel method presented here, termed as additive manufacturing via microarray deposition (AMMD), expands the allowable range of physical properties of printed fluids to include important, high-viscosity production materials (e.g., polyurethane resins). AMMD relies on a piezoelectrically driven ultrasonic print-head that generates continuous streams of droplets from 45 μm orifices while operating in the 0.5–3.0 MHz frequency range. The device is composed of a bulk ceramic piezoelectric transducer for ultrasound generation, a reservoir for the material to be printed, and a silicon micromachined array of liquid horn structures, which make up the ejection nozzles. Unique to this new printing technique are the high frequency of operation, use of fluid cavity resonances to assist ejection, and acoustic wave focusing to generate the pressure gradient required to form and eject droplets. We present the initial characterization of a micromachined print-head for deposition of fluids that cannot be used with conventional printing-based rapid prototyping techniques. Glycerol-water mixtures with a range of properties (surface tensions of ∼58–73 mN/m and viscosities of 0.7–380 mN s/m2) were used as representative printing fluids for most investigations. Sustained ejection was observed in all cases. In addition, successful ejection of a urethane-based photopolymer resin (surface tension of ∼25–30 mN/m and viscosity of 900–3000 mN s/m2) was achieved in short duration bursts. Peaks in the ejection quality were found to correspond to predicted device resonances. Based on these results, we have demonstrated the printing of fluids that fall well outside of the accepted range for the previously introduced printing indicator. The micromachined ultrasonic print-head achieves sustained printing of fluids up to 380 mN s/m2, far above the typical printable range.

Optimization of Part Consolidation for Minimum Production Costs and Time Using Additive Manufacturing

2019 ◽  
Vol 142 (7) ◽  
Author(s):  
Zhenguo Nie ◽  
Sangjin Jung ◽  
Levent Burak Kara ◽  
Kate S. Whitefoot
Keyword(s):  
Additive Manufacturing ◽  
Production Cost ◽  
Production Costs ◽  
Convergence Time ◽  
Cost Models ◽  
Support Structures ◽  
Test Bed ◽  
Production Time ◽  
Loop Filter ◽  
Part Consolidation

Abstract This research presents a method of optimizing the consolidation of parts in an assembly using metal additive manufacturing (MAM). The method generates candidates for consolidation, filters them for feasibility and structural redundancy, finds the optimal build layout of the parts, and optimizes which parts to consolidate using a genetic algorithm. Results are presented for both minimal production time and minimal production costs, respectively. The production time and cost models consider each step of the manufacturing process, including MAM build, post-processing steps such as support structure removal, and assembly. It accounts for costs affected by part consolidation, including machine costs, material, scrap, energy consumption, and labor requirements. We find that developing a closed-loop filter that excludes consolidation candidates that are structurally redundant with others dramatically reduces the number of candidates, thereby significantly reducing convergence time. Results show that when increasing the number of parts that are consolidated, the production cost and time at first decrease due to reduced assembly steps, and then increase due to additional support structures needed to uphold the larger, consolidated parts. We present a rationale and evidence justifying that this is an important tradeoff of part consolidation that generalizes to many types of assemblies. Subsystems that are smaller, or can be oriented with very little support structures or have low material costs or fast deposition rates can have an optimum at full consolidation; for other subsystems, the optimum is less than 100%. The presented method offers a promising pathway to minimize production time and cost by consolidating parts using MAM. In our test-bed results for an aircraft fairing produced with powder-bed electron beam melting, the solution for minimizing production cost (time) is to consolidate 17 components into four (two) discrete parts, which leads to a 20% (25%) reduction in unit production cost (time).

Computational Foundations for Using Three Degrees of Freedom Build Platforms to Enable Supportless Extrusion-Based Additive Manufacturing

2019 ◽  
Author(s):  
Prahar M. Bhatt ◽  
Rishi K. Malhan ◽  
Satyandra K. Gupta
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Manufacturing Systems ◽  
Degrees Of Freedom ◽  
Support Structures ◽  
Complex Shapes ◽  
Build Time ◽  
Time Accuracy ◽  
Three Degrees Of Freedom

Abstract Extrusion-based additive manufacturing systems usually use three degrees of freedom extrusion tools to perform the deposition operation. This requires the use of support structures to deposit structures with overhang features. The use of support structures can be avoided by adding degrees of freedom to the build platform. The elimination of build structures can offer benefits in terms of reduction of build time and elimination of postprocessing costs. This paper demonstrates that the use of three degrees of freedom build platform enables printing of complex shapes without support structures. We present computational foundations for generating paths and trajectories for synchronizing the motion of three degrees of freedom build platforms and three degrees of freedom extrusion tools. We report results on six different test parts in terms of reduction in build time, accuracy, and surface roughness.

Solid Mechanics Based Design and Optimization for Support Structure Generation in Stereolithography Based Additive Manufacturing

2015 ◽  
Author(s):  
Guanglei Zhao ◽  
Chi Zhou ◽  
Sonjoy Das
Keyword(s):  
Additive Manufacturing ◽  
Solid Mechanics ◽  
Search Algorithm ◽  
Pso Algorithm ◽  
Optimization Method ◽  
Optimized Design ◽  
Support Structures ◽  
Support Structure ◽  
Element Analysis ◽  
Structure Generation

Support structures are typically required to hold parts in place in various additive manufacturing processes. Design of support structure includes identifying both anchor locations and geometries. Extensive work has been done to optimize the anchor locations to reliably keep part in position, and minimize the contacting area as well as the total volume of the support structures. However, relatively few studies have been focused on the mechanical property analysis of the structure. In this paper, we proposed a novel design optimization method to identify the anchor geometry based on solid mechanics theory. Finite element analysis method is utilized to study the stress distribution on both the support structure and main part. Particle Swarm Optimization (PSO) algorithm with a novel constraining handling strategy is employed to optimize the design model. A gradient descent local search algorithm is utilized to quickly locate the global solution in the vicinity explored by PSO. The developed optimization framework is deployed on a bottom-up projection based Stereolithography process. The experimental results show that the optimized design can efficiently reduce the material used on support structure and marks left on the part.

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