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Journal ArticleDOI

Additive manufacturing of PLA structures using fused deposition modelling: Effect of process parameters on mechanical properties and their optimal selection

15 Jun 2017-Materials & Design (Elsevier)-Vol. 124, Iss: 124, pp 143-157

Abstract: Fused deposition modelling is a rapidly growing additive manufacturing technology due to its ability to build functional parts having complex geometries. The mechanical properties of a built part depend on several process parameters. The aim of this study is to characterize the effect of build orientation, layer thickness and feed rate on the mechanical performance of PLA samples manufactured with a low cost 3D printer. Tensile and three-point bending tests are carried out to determine the mechanical response of the printed specimens. Due to the layer-by-layer process, 3D printed samples exhibit anisotropic behaviour. Upright orientation shows the lowest mechanical properties. On the other hand, on-edge and flat orientation show the highest strength and stiffness. From a layer thickness and feed rate point of view, it is observed that ductility decreases as layer thickness and feed rate increase. In addition, the mechanical properties increase as layer thickness increases and decrease as the feed rate increases for the upright orientation. However, the variations in mechanical properties with layer thickness and feed rate are of slight significance for on-edge and flat orientations, except in the particular case of low layer thickness. Finally, the practicality of the results is assessed by testing an evaluation structure.
Topics: Ductility (50%)
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Journal ArticleDOI
30 Jul 2017-Chemical Reviews
TL;DR: Polymers are by far the most utilized class of materials for AM and their design, additives, and processing parameters as they relate to enhancing build speed and improving accuracy, functionality, surface finish, stability, mechanical properties, and porosity are addressed.
Abstract: Additive manufacturing (AM) alias 3D printing translates computer-aided design (CAD) virtual 3D models into physical objects. By digital slicing of CAD, 3D scan, or tomography data, AM builds objects layer by layer without the need for molds or machining. AM enables decentralized fabrication of customized objects on demand by exploiting digital information storage and retrieval via the Internet. The ongoing transition from rapid prototyping to rapid manufacturing prompts new challenges for mechanical engineers and materials scientists alike. Because polymers are by far the most utilized class of materials for AM, this Review focuses on polymer processing and the development of polymers and advanced polymer systems specifically for AM. AM techniques covered include vat photopolymerization (stereolithography), powder bed fusion (SLS), material and binder jetting (inkjet and aerosol 3D printing), sheet lamination (LOM), extrusion (FDM, 3D dispensing, 3D fiber deposition, and 3D plotting), and 3D bioprinting....

1,309 citations

Journal ArticleDOI
Hozhabr Mozafari1, Pengfei Dong1, Haitham Hadidi1, Michael P Sealy1  +1 moreInstitutions (1)
20 Dec 2018-Materials
TL;DR: The results showed that the interphase layer provided a smooth transition of elastic modulus from steel particles to the polymeric matrix, and a 10% volume fraction of steel particles could enhance the elasticModulus of PLLA polymer by 31%.
Abstract: The objective of this study is to characterize the micromechanical properties of poly-l-lactic acid (PLLA) composites reinforced by grade 420 stainless steel (SS) particles with a specific focus on the interphase properties. The specimens were manufactured using 3D printing techniques due to its many benefits, including high accuracy, cost effectiveness and customized geometry. The adopted fused filament fabrication resulted in a thin interphase layer with an average thickness of 3 µm. The mechanical properties of each phase, as well as the interphase, were characterized by nanoindentation tests. The effect of matrix degradation, i.e., imperfect bonding, on the elastic modulus of the composite was further examined by a representative volume element (RVE) model. The results showed that the interphase layer provided a smooth transition of elastic modulus from steel particles to the polymeric matrix. A 10% volume fraction of steel particles could enhance the elastic modulus of PLLA polymer by 31%. In addition, steel particles took 37% to 59% of the applied load with respect to the particle volume fraction. We found that degradation of the interphase reduced the elastic modulus of the composite by 70% and 7% under tensile and compressive loads, respectively. The shear modulus of the composite with 10% particles decreased by 36%, i.e., lower than pure PLLA, when debonding occurred.

450 citations

Journal ArticleDOI
01 Aug 2018-Polymer Testing
Abstract: Designing and manufacturing functional parts for fields such as engineering and medicine is a major goal of Fused Deposition Modeling (FDM). These activities should be supported by knowledge on how different settings of process parameters impact the mechanical behavior of the products. However, obtaining this information is a quite complex task given the large variety of possible combinations of materials-3D printers-slicing software-process parameters. Thus, the importance of reviewing the current research on this topic for identifying practical and useful aspects, key process parameters and limitations, but also for understanding to what extent the results of these researches are relevant and can be applied in further studies and real applications. A systematic literature search was performed based on classification according to the type of 3D printing polymer. The most significant process parameters considered as influencing FDM specimens' tensile, compression, flexural or impact strengths are discussed considering the results presented in the literature. A necessary distinction between the mechanical properties of material and testing specimens (as given by producers and by experiments) and the mechanical behavior of a FDM end-part is also made.

295 citations

Journal ArticleDOI
Abstract: Additive Layer Manufacturing (ALM) process is used in the present investigation to manufacture long fibre reinforced composite parts using the MarkOne® 3D-printer. In ALM, a continuous filament (including a tow of fibres) of composite material is injected by the printer, at high temperature, over a plain tool, forming the part while the material is cooled down. The used composite filament is formed by a PA (Nylon™) matrix and carbon or glass fibre reinforcements. Previous works have shown an improvement on the mechanical properties of a part, when some zones include a nylon based composite reinforcement using ALM. Nevertheless, the characterization of fully made nylon-based ALM composite material parts has not been reported. Thus, the aim of this investigation is the experimental characterization of composite nylon-based coupons. The plane strength and stiffness properties of the composites are obtained, both for tensile and compression load states. Results showed that the obtained mechanical properties for ALM composites are not yet comparable to those obtained by traditional methods (pre-pregs). This fact may be explained by the high porosity found in ALM coupons as well as a low fibre volume obtained. Nevertheless, the mechanical properties improvement in comparison to non-reinforced nylon parts is remarkable.

182 citations

Journal ArticleDOI
Abstract: Fused deposition modelling (FDM) is a promising additive manufacturing technology and an alternative of conventional processes for the fabrication of fibre reinforced composites due to its ability to build functional parts having complex geometries. Continuous fibre reinforced thermoplastic composites (CFRTPCs) are becoming more significant in industrial applications due to their inherit advantages such as excellent mechanical performance, recycling and potential lightweight structures [1,2]. However, a major concern affecting the efficient use of 3D printed composites is the effect of impact damage on the structural integrity, compared to conventional pre-preg composites. The aim of this study is to evaluate the effect of build orientation, layer thickness and fibre volume content on the impact performance of 3D printed continuous carbon, glass, and Kevlar® fibre reinforced nylon composites, manufactured by FDM technique. Charpy impact tests are carried out to determine impact strength. SEM images of fractured surfaces are examined to assess failure mechanics of the different configurations. It is observed that the effect of layer thickness of nylon samples on the impact performance was different for flat and on-edge samples. Impact strength increases as layer thickness increases in flat samples but, conversely, it decreases in on-edge samples, depicting a more brittle fracture. In addition, the results show that impact strength increases as fibre volume content increases in most cases. Glass fibre reinforced samples exhibits the highest impact strength and carbon fibre reinforced samples the lowest one and similar to nylon performance. Furthermore, on-edge reinforced samples exhibit higher values of impact strength than flat reinforced samples. Finally, the results obtained demonstrate that impact strength exhibited by 3D printed composites are significantly higher than the usual 3D printed thermoplastics and, in some cases, even better than common pre-preg materials.

158 citations

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Journal ArticleDOI
Sung-Hoon Ahn1, Michael Montero2, Dan Odell2, Shad Roundy2  +1 moreInstitutions (2)
Abstract: Rapid Prototyping (RP) technologies provide the ability to fabricate initial prototypes from various model materials. Stratasys Fused Deposition Modeling (FDM) is a typical RP process that can fabricate prototypes out of ABS plastic. To predict the mechanical behavior of FDM parts, it is critical to understand the material properties of the raw FDM process material, and the effect that FDM build parameters have on anisotropic material properties. This paper characterizes the properties of ABS parts fabricated by the FDM 1650. Using a Design of Experiment (DOE) approach, the process parameters of FDM, such as raster orientation, air gap, bead width, color, and model temperature were examined. Tensile strengths and compressive strengths of directionally fabricated specimens were measured and compared with injection molded FDM ABS P400 material. For the FDM parts made with a 0.003 inch overlap between roads, the typical tensile strength ranged between 65 and 72 percent of the strength of injection molded ABS P400. The compressive strength ranged from 80 to 90 percent of the injection molded FDM ABS. Several build rules for designing FDM parts were formulated based on experimental results.

1,557 citations

Journal ArticleDOI
Fuda Ning1, Weilong Cong1, Jingjing Qiu1, Junhua Wei1  +1 moreInstitutions (2)
Abstract: Additive manufacturing (AM) technologies have been successfully applied in various applications. Fused deposition modeling (FDM), one of the most popular AM techniques, is the most widely used method for fabricating thermoplastic parts those are mainly used as rapid prototypes for functional testing with advantages of low cost, minimal wastage, and ease of material change. Due to the intrinsically limited mechanical properties of pure thermoplastic materials, there is a critical need to improve mechanical properties for FDM-fabricated pure thermoplastic parts. One of the possible methods is adding reinforced materials (such as carbon fibers) into plastic materials to form thermoplastic matrix carbon fiber reinforced plastic (CFRP) composites those could be directly used in the actual application areas, such as aerospace, automotive, and wind energy. This paper is going to present FDM of thermoplastic matrix CFRP composites and test if adding carbon fiber (different content and length) can improve the mechanical properties of FDM-fabricated parts. The CFRP feedstock filaments were fabricated from plastic pellets and carbon fiber powders for FDM process. After FDM fabrication, effects on the tensile properties (including tensile strength, Young's modulus, toughness, yield strength, and ductility) and flexural properties (including flexural stress, flexural modulus, flexural toughness, and flexural yield strength) of specimens were experimentally investigated. In order to explore the parts fracture reasons during tensile and flexural tests, fracture interface of CFRP composite specimens after tensile testing and flexural testing was observed and analyzed using SEM micrograph.

819 citations

Journal ArticleDOI
01 Jan 2010-Materials & Design
Abstract: Fused deposition modelling (FDM) is a fast growing rapid prototyping (RP) technology due to its ability to build functional parts having complex geometrical shape in reasonable time period. The quality of built parts depends on many process variables. In this study, five important process parameters such as layer thickness, orientation, raster angle, raster width and air gap are considered. Their influence on three responses such as tensile, flexural and impact strength of test specimen is studied. Experiments are conducted based on central composite design (CCD) in order to reduce experimental runs. Empirical models relating response and process parameters are developed. The validity of the models is tested using analysis of variance (ANOVA). Response surface plots for each response is analysed and optimal parameter setting for each response is determined. The major reason for weak strength may be attributed to distortion within or between the layers. Finally, concept of desirability function is used for maximizing all responses simultaneously.

773 citations

Journal ArticleDOI
01 Jun 2014-Materials & Design
Abstract: The recent development of the RepRap, an open-source self-replicating rapid prototyper, has made 3-D polymer-based printers readily available to the public at low costs (

734 citations

Journal ArticleDOI
Abstract: Fused deposition modeling (FDM) is one of the most popular additive manufacturing technologies for various engineering applications. FDM process has been introduced commercially in early 1990s by Stratasys Inc., USA. The quality of FDM processed parts mainly depends on careful selection of process variables. Thus, identification of the FDM process parameters that significantly affect the quality of FDM processed parts is important. In recent years, researchers have explored a number of ways to improve the mechanical properties and part quality using various experimental design techniques and concepts. This article aims to review the research carried out so far in determining and optimizing the process parameters of the FDM process. Several statistical designs of experiments and optimization techniques used for the determination of optimum process parameters have been examined. The trends for future FDM research in this area are described.

608 citations

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