1,757 research outputs found
From 3D Models to 3D Prints: an Overview of the Processing Pipeline
Due to the wide diffusion of 3D printing technologies, geometric algorithms
for Additive Manufacturing are being invented at an impressive speed. Each
single step, in particular along the Process Planning pipeline, can now count
on dozens of methods that prepare the 3D model for fabrication, while analysing
and optimizing geometry and machine instructions for various objectives. This
report provides a classification of this huge state of the art, and elicits the
relation between each single algorithm and a list of desirable objectives
during Process Planning. The objectives themselves are listed and discussed,
along with possible needs for tradeoffs. Additive Manufacturing technologies
are broadly categorized to explicitly relate classes of devices and supported
features. Finally, this report offers an analysis of the state of the art while
discussing open and challenging problems from both an academic and an
industrial perspective.Comment: European Union (EU); Horizon 2020; H2020-FoF-2015; RIA - Research and
Innovation action; Grant agreement N. 68044
Multiresolution Layered Manufacturing
PURPOSE: Two-photon polymerization (TPP) has become one of the most popular techniques for stereolithography at very high resolutions. When printing relatively large structures at high resolutions, one of the main limiting factors is the printing time. The goal of this work is to present a new slicing algorithm to minimize printing times. DESIGN/METHODOLOGY/APPROACH: Typically, slicing algorithms used for TPP do not take into account the fact that TPP can print at a range of resolutions (i.e. with different heights and diameters) by varying parameters such as exposure time, laser power, photoresist properties, and optical arrangements. This work presents Multiresolution Layered Manufacturing (MLM), a novel slicing algorithm that processes 3D structures to separate parts manufacturable at low resolution from those that require a higher resolution. FINDINGS: MLM can significantly reduce the printing time of 3D structures at high resolutions. The maximum theoretical speed-up depends on the range of printing resolutions, but the effective speed-up also depends on the geometry of each 3D structure. RESEARCH LIMITATIONS/IMPLICATIONS: MLM opens the possibility to significantly decrease printing times, potentially opening the use of TPP to new applications in many disciplines such as microfluidics, metamaterial research or wettability. ORIGINALITY/VALUE: There are many instances of previous research on printing at several resolutions. However, in most cases, the toolpaths have to be manually arranged. In some cases, previous research also automates the generation of toolpaths, but they are limited in various ways. MLM is the first algorithm to comprehensively solve this problem for a wide range of true 3D structures.NANO3D (a BEWARE Fellowship from the Walloon Region, Belgium, part of the Marie Curie Programme of the ERC). IAP 7/38 MicroMAST (Interuniversity Attraction Poles Programme from the Belgian Science Policy Office, the Walloon Region and the FNRS)
Digital design of medical replicas via desktop systems: shape evaluation of colon parts
In this paper, we aim at providing results concerning the application of desktop systems for rapid prototyping of medical replicas
that involve complex shapes, as, for example, folds of a colon. Medical replicas may assist preoperative planning or tutoring in
surgery to better understand the interaction among pathology and organs. Major goals of the paper concern with guiding the
digital design workflow of the replicas and understanding their final performance, according to the requirements asked by the
medics (shape accuracy, capability of seeing both inner and outer details, and support and possible interfacing with other organs).
In particular, after the analysis of these requirements, we apply digital design for colon replicas, adopting two desktop systems. ,e
experimental results confirm that the proposed preprocessing strategy is able to conduct to the manufacturing of colon replicas
divided in self-supporting segments, minimizing the supports during printing. ,is allows also to reach an acceptable level of final
quality, according to the request of having a 3D presurgery overview of the problems. ,ese replicas are compared through reverse
engineering acquisitions made by a structured-light system, to assess the achieved shape and dimensional accuracy. Final results
demonstrate that low-cost desktop systems, coupled with proper strategy of preprocessing, may have shape deviation in the range
of ±1 mm, good for physical manipulations during medical diagnosis and explanation
Virtual assembly rapid prototyping of near net shapes
Virtual reality (VR) provides another dimension to many engineering applications. Its immersive and interactive nature allows an intuitive approach to study both cognitive activities and performance evaluation. Market competitiveness means having products meet form, fit and function quickly. Rapid Prototyping and Manufacturing (RP&M) technologies are increasingly being applied to produce functional prototypes and the direct manufacturing of small components. Despite its flexibility, these systems have common drawbacks such as slow build rates, a limited number of build axes (typically one) and the need for post processing. This paper presents a Virtual Assembly Rapid Prototyping (VARP) project which involves evaluating cognitive activities in assembly tasks based on the adoption of immersive virtual reality along with a novel non-layered rapid prototyping for near net shape (NNS) manufacturing of components. It is envisaged that this integrated project will facilitate a better understanding of design for manufacture and assembly by utilising equivalent scale digital and physical prototyping in one rapid prototyping system. The state of the art of the VARP project is also presented in this paper
A level set based method for fixing overhangs in 3D printing
3D printers based on the Fused Decomposition Modeling create objects
layer-by-layer dropping fused material. As a consequence, strong overhangs
cannot be printed because the new-come material does not find a suitable
support over the last deposed layer. In these cases, one can add some support
structures (scaffolds) which make the object printable, to be removed at the
end. In this paper we propose a level set method to create object-dependent
support structures, specifically conceived to reduce both the amount of
additional material and the printing time. We also review some open problems
about 3D printing which can be of interests for the mathematical community
Printing non-Euclidean solids
Geometrically frustrated solids with non-Euclidean reference metric are
ubiquitous in biology and are becoming increasingly relevant in technological
applications. Often they acquire a targeted con- figuration of incompatibility
through surface accretion of mass as in tree growth or dam construction. We use
the mechanics of incompatible surface growth to show that geometrical
frustration develop- ing during deposition can be fine-tuned to ensure a
particular behavior of the system in physiological (or working) conditions. As
an illustration, we obtain an explicit 3D printing protocol for arteries, which
guarantees stress uniformity under inhomogeneous loading, and for explosive
plants, allowing a complete release of residual elastic energy with a single
cut. Interestingly, in both cases reaching the physiological target requires
the incompatibility to have a topological (global) component.Comment: 5 pages, 4 figure
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Techno-Economic Analysis of Hybrid Layered Manufacturing
Subtractive manufacturing (CNC machining) has high quality of geometric and
material properties but is slow, costly and infeasible in some cases; additive
manufacturing (RP) is just the opposite. Total automation and hence speed is
achieved in RP by compromising on quality. Hybrid Layered Manufacturing
(HLM) developed at IIT Bombay combines the best features of both these
approaches. It uses arc welding for building near-net shapes which are finish
machined to final dimensions. High speed of HLM surpasses all other processes
for tool making by eliminating NC programming and rough machining. The
techno-economic viability of HLM process has been proved through a real life
case study. Time and cost of tool making using HLM promises to be substantially
lower than that of CNC machining and other RP methods. Interestingly, the
material cost in HLM was also found to be lower. HLM is a cheaper retrofitment
to any 3 or 5 axis CNC milling machine or machining center.Mechanical Engineerin
Recoater-induced distortions and build failures in selective laser melting of thin-walled Ti6Al4V parts
Additively manufactured thin-walled structures through selective laser melting (SLM) are of great interest in achieving carbon-neutral industrial manufacturing. However, residual stresses and warpages as well as recoater crashes often occur in SLM, leading to the build failure of parts, especially for large-scale and lightweight geometries. The challenge in this work consists of investigating how the recoater affects the warpage and (sometimes) causes the failure of different thin-walled Ti6Al4V parts (wall thickness of 1.0 mm). All these parts are printed on the same platform using a commercial SLM machine. After the loose powder removal and before the cutting operation, a 3D-scanner is used to obtain the actual warpage of each component. Next, an in-house coupled thermo-mechanical finite element model suitable for the numerical simulation of the SLM process is enhanced to consider the recoater effects. This numerical framework is calibrated to predict the thin-walled warpage as measured by the 3D-scanner. The combination of numerical predictions with experimental observations facilitates a comprehensive understanding of the mechanical behavior of different thin-walled components as well as the failure mechanism due to the recoater. The findings show that the use of a higher laser energy input causes larger residual stresses and warpage responsible for the recoater crashes. Finally, potential solutions to mitigate the warpage and the recoater crashes in the SLM of lightweight structures are assessed using the validated model.This research was funded by the Spanish Ministry of Economy and Competitiveness, through the Severo Ochoa Programme for Centers of Excellence in R&D (CEX2018-000797-S). This work has been supported by the Ministry of Science, Innovation and Universities (MCIU), Spain via the PriMuS project (Printing pattern based and MultiScale enhanced performance analysis of advanced Additive Manufacturing components, No. PID2020-115575RB-I00) and by the Light3D project (No. 001-P-001646) as part of the BASE3D network by ACCIÓ (Generalitat de Catalunya). The support from the China Scholarship Council (No. 201906290011) is also gratefully acknowledged.Peer ReviewedPostprint (published version
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