The effects of voids on structural properties of fused deposition modelled parts: a probabilistic approach

Tronvoll, Sigmund Arntsønn; Welo, Torgeir; Elverum, Christer W.

doi:10.1007/s00170-018-2148-x

Cited by 110 publications

(60 citation statements)

References 35 publications

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“…In addition, several studies demonstrate that the lowest tensile strength is achieved for vertical build orientation (loading direction aligned with the building direction) . These results converge toward the importance of optimizing the inter‐layer bond strength to limit the mechanical anisotropy and improve the tensile performance in transverse direction of FDM‐based structures . The improvement of the inter‐layer bond strength can be obtained, for instance, by ultrasonic vibration coupled to FDM process as proposed by Tofangchi et al It can be also improved by increasing the printing temperature as shown by Davis et al In most engineering applications, the part orientation is chosen to avoid vertical build configurations as the one selected in this study.…”

Section: Resultsmentioning

confidence: 87%

“…[2,18,19] These results converge toward the importance of optimizing the inter-layer bond strength to limit the mechanical anisotropy and improve the tensile performance in transverse direction of FDM-based structures. [20] The improvement of the inter-layer bond strength can be obtained, for instance, by ultrasonic vibration coupled to FDM process as proposed by Tofangchi et al [21] It can be also improved by increasing the printing temperature as shown by Davis et al [22] In most engineering applications, the part orientation is chosen to avoid vertical build configurations as the one selected in this study. The tensile strength of samples printed using horizontal build configurations can be further increased by improving the intra-layer bond strength.…”

Section: Mechanical Performancementioning

confidence: 99%

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Microstructure, Thermal and Mechanical Behavior of 3D Printed Acrylonitrile Styrene Acrylate

Guessasma

Belhabib

Nouri

2019

Macro Materials & Eng

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Fused deposition modeling (FDM) is one of the most popular additive manufacturing techniques for polymers. Despite the numerous works on the printability of various types of polymers, there is a lack in understanding the role of the microstructure on the mechanical performance of printed parts. This work aims at addressing this particular point for the case of a polymer that did not receive much attention, namely acrylonitrile styrene acrylate or ASA. This study emphasizes on the effect of the printing temperature on thermal and mechanical performance of printed ASA using differential scanning calorimetry, infra‐red measurements, mechanical testing, X‐ray micro‐tomography, and finite element computation. The experimental results demonstrate a narrow window of printability of ASA based on the thermal response of this polymer during the laying down process. In addition, both experimental and numerical results show an evident loss in the performance that represents one third of the performance of the raw material. Despite this loss, the limited amount of generated porosity and the level of tensile strength of ASA make it a good choice as a feedstock material for FDM compared to other polymers such as acrylonitrile butadiene styrene.

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Section: Resultsmentioning

confidence: 87%

Section: Mechanical Performancementioning

confidence: 99%

Microstructure, Thermal and Mechanical Behavior of 3D Printed Acrylonitrile Styrene Acrylate

Guessasma

Belhabib

Nouri

2019

Macro Materials & Eng

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“…The flow rate multiplier increased the amount of material being pushed through the nozzle (i.e., the volumetric flow rate), resulting in heavier specimens (Table 3), in which the deposited strands were better connected and overlapping; therefore, the amount of voids between strands was reduced. It was determined that voids are the main factor leading to reduced mechanical properties in FFF parts [57]; therefore, reducing voids is very important to improve the mechanical performance. This is especially visible in trials 1, 13, and 16, where this factor was set to higher values (120% and 127%) ( Figure 8).…”

Section: Statistical Analysis Of Tensile Strengthmentioning

confidence: 99%

Optimization of the 3D Printing Parameters for Tensile Properties of Specimens Produced by Fused Filament Fabrication of 17-4PH Stainless Steel

et al. 2020

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Fused filament fabrication (FFF) combined with debinding and sintering could be an economical process for three-dimensional (3D) printing of metal parts. In this paper, compounding, filament making, and FFF processing of feedstock material with 55% vol. of 17-4PH stainless steel powder in a multicomponent binder system are presented. The experimental part of the paper encompasses central composite design for optimization of the most significant 3D printing parameters (extrusion temperature, flow rate multiplier, and layer thickness) to obtain maximum tensile strength of the 3D-printed specimens. Here, only green specimens were examined in order to be able to determine the optimal parameters for 3D printing. The results show that the factor with the biggest influence on the tensile properties was flow rate multiplier, followed by the layer thickness and finally the extrusion temperature. Maximizing all three parameters led to the highest tensile properties of the green parts.One of the most commonly used AM technologies for the production of metal parts is PBF. In PBF, a laser or electron beam selectively fuses metal powder or metal powder covered with a binding agent by scanning cross-sectional layers generated from a CAD file of the part on the surface of a powder bed. After one cross-section is scanned, the powder bed is lowered and a new layer of powder is added on top of the previous one; the process repeats until the part is finished [6]. One of the biggest disadvantages of PBF is that it relies on high-power lasers or high-energy electron beams, which can be very costly. In addition, the powder must be free-flowing and, therefore, it requires a specific powder distribution, which adds to the price of the material. Therefore, MEAM shows great promise as a cost-effective alternative since the shaping equipment is orders of magnitude cheaper than PBF [6], and powders with a great range of particle size distributions can be processed. In the most common type of MEAM, the building material is supplied in the form of spooled filaments and, therefore, is also known as fused filament fabrication (FFF). In most FFF machines, the filament is fed into a heating unit with a nozzle using counter-rotating rollers as a feeding system. The extrusion head is controlled to move in the XY plane, and, as it moves, material is extruded through the nozzle on a flat platform that moves in the Z-direction [5]. However, there are also MEAM systems, where the extrusion system is fixed and the printing platform moves in three axes [7], and systems where the printed head moves in three axes and the building platform is fixed [8].FFF was first developed for polymeric materials; however, for the fabrication of metal or ceramic parts, a filament made of a polymeric blend filled with a large portion of metal or ceramic particles, known as feedstock, is used. After shaping the filament into what is referred to as the green parts, the binder system is removed from the part by thermal, catalytic, or solvent extraction and then sintered to ob...

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“…Components manufactured by FDM are found to result in an anisotropic cellular material behavior [1][2][3]. For low relative density components, the internal structure, also called infill, typically consists of either rectilinear webs, as variations of a (0°, 90°) or (0°, 60°, 120°) alternating raster structures, or honeycombs.…”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, these methods do only capture the void sizes along a single surface, and through thickness variations are therefore usually neglected in further analysis. In a previous study, the statistical distribution of void sizes combined with a weakest link approach was found to be the main driver for anisotropic strength characteristics of tensile specimens in PLA [3]. The method used a microscopy picture of a center slice of a specimen to estimate the void sizes, and the distribution was then analyzed and the expected weakest link of a given sample length was predicted.…”

Section: Introductionmentioning

confidence: 99%

A new method for assessing anisotropy in fused deposition modeled parts using computed tomography data

Tronvoll

Vedvik

Elverum

et al. 2019

Int J Adv Manuf Technol

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Voids in fused deposition modeled (FDM) parts are assumed to be a key driver for their anisotropic behavior. However, these assumptions are based on investigations of voids using only 2D data (microscopy images). This paper presents a new method to measure such voids by analyzing 3D-data of from X-ray computed tomography (CT), and application of this data for assessment of mechanical parameters. The article is divided into three parts, where the first part elaborates on a proposed method to assess and characterize the void geometry throughout uniaxial printed FDM parts using CT-data. The second part presents an investigation of the void configurations in samples manufactured using different process parameters, aiming to understand how variation in extrusion rate and compensation for non-linear dynamic extrusion behavior affects the void sizes. The third part displays how the information regarding void sizes could be further related to global mechanical properties, using a multiscale finite element approach. The present method of CT-data analysis gives a clear overview of the spatial variation of the void geometry, and findings from the investigated samples suggest that the size of voids have a large non-random spatial variation, highly dependent on the turning points of the toolpaths, and also significantly affected by accumulation of excess material. Printing at a low extrusion rate increases the void sizes considerably, while implementation of an extrusion dynamics compensation algorithm was found to have low impact on the void sizes. The multiscale finite element approach predicts anisotropic elastic behavior, significantly more compliant in the vertical and transversal direction, relative to the printing direction of the infill. It also predicts a non-isotropic strain energy density throughout the specimen, where the location and magnitude of the most energy dense locations vary significantly for different directions of loading, which implicates an anisotropic behavior in terms of failure, in accordance with literature.

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The effects of voids on structural properties of fused deposition modelled parts: a probabilistic approach

Cited by 110 publications

References 35 publications

Microstructure, Thermal and Mechanical Behavior of 3D Printed Acrylonitrile Styrene Acrylate

Microstructure, Thermal and Mechanical Behavior of 3D Printed Acrylonitrile Styrene Acrylate

Optimization of the 3D Printing Parameters for Tensile Properties of Specimens Produced by Fused Filament Fabrication of 17-4PH Stainless Steel

A new method for assessing anisotropy in fused deposition modeled parts using computed tomography data

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