scholarly journals Experimental and Computational Investigation of Lattice Sandwich Structures Constructed by Additive Manufacturing Technologies

2021 ◽  
Vol 5 (3) ◽  
pp. 95
Author(s):  
Nikolaos Kladovasilakis ◽  
Paschalis Charalampous ◽  
Konstantinos Tsongas ◽  
Ioannis Kostavelis ◽  
Dimitrios Tzetzis ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Mechanical Performance ◽  
Sandwich Structures ◽  
Volume Ratio ◽  
Dimensional Accuracy ◽  
High Porosity ◽  
Design Strategies ◽  
Fused Filament Fabrication ◽  
Geometrical Structures ◽  
Specific Distribution

Additive Manufacturing (AM) technologies offer the ability to construct complex geometrical structures in short manufacturing lead time coupled with a relatively low production cost when compared to traditional manufacturing processes. The next trend in mechanical engineering design is the adaption of design strategies that build products with lightweight lattice geometries like sandwich structures. These structures possess low mass, large surface area to volume ratio, high porosity, and adequate mechanical behavior, which are properties of great importance in scientific fields such as bioengineering, automotive, and aerospace engineering. The present work is focused on producing sandwich structures with complex lattice patterns like the Triply Periodic Minimal Surface (TPMS) Schwarz diamond structure. The specimens were manufactured with two different Additive Manufacturing procedures employing various relative densities. More specifically, Material Jetting Printing (MJP) and Fused Filament Fabrication (FFF) processes were employed to investigate the performance of Acrylonitrile Butadiene Styrene (ABS) lightweight lattice structures. These structures were examined using digital microscopy in order to measure the dimensional accuracy and the surface characteristics of the utilized AM technologies. Furthermore, three-point bending tests and finite elements analyses have been applied to investigate the mechanical performance of the proposed technologies and designs as well as the influence of the relative density on the Schwarz diamond TPMS structure. The experimental results demonstrate that the investigated structure possesses a remarkable performance in respect to its weight due to the specific distribution of its material in space.

scholarly journals Mechanical Performances of Lightweight Sandwich Structures Produced by Material Extrusion-Based Additive Manufacturing

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1740 ◽  
Author(s):  
Sebastian Marian Zaharia ◽  
Larisa Anamaria Enescu ◽  
Mihai Alin Pop
Keyword(s):  
Finite Element ◽  
Additive Manufacturing ◽  
Failure Modes ◽  
Sandwich Structures ◽  
Leading Edge ◽  
Mechanical Tests ◽  
Failure Behavior ◽  
Fused Filament Fabrication ◽  
Element Analysis ◽  
Material Extrusion

Material Extrusion-Based Additive Manufacturing Process (ME-AMP) via Fused Filament Fabrication (FFF) offers a higher geometric flexibility than conventional technologies to fabricate thermoplastic lightweight sandwich structures. This study used polylactic acid/polyhydroxyalkanoate (PLA/PHA) biodegradable material and a 3D printer to manufacture lightweight sandwich structures with honeycomb, diamond-celled and corrugated core shapes as a single part. In this paper, compression, three-point bending and tensile tests were performed to evaluate the performance of lightweight sandwich structures with different core topologies. In addition, the main failure modes of the sandwich structures subjected to mechanical tests were evaluated. The main failure modes that were observed from mechanical tests of the sandwich structure were the following: face yielding, face wrinkling, core/skin debonding. Elasto-plastic finite element analysis allowed predicting the global behavior of the structure and stressing distribution in the elements of lightweight sandwich structures. The comparison between the results of bending experiments and finite element analyses indicated acceptable similarity in terms of failure behavior and force reactions. Finally, the three honeycomb, diamond-celled and corrugated core typologies were used in the leading edge of the wing and were impact tested and the results created favorable premises for using such structures on aircraft models and helicopter blade structures.

scholarly journals A study on extruded filament bonding in fused filament fabrication

2019 ◽  
Vol 25 (3) ◽  
pp. 555-565 ◽  
Author(s):  
Ana Elisa Costa ◽  
Alexandre Ferreira da Silva ◽  
Olga Sousa Carneiro
Keyword(s):  
Control Systems ◽  
Design Methodology ◽  
Mechanical Performance ◽  
Tensile Axis ◽  
Dimensional Accuracy ◽  
Fused Filament Fabrication ◽  
Bonding Quality ◽  
Content Type ◽  
Extrusion Rate ◽  
Forced Cooling

Purpose The performance of parts produced by fused filament fabrication is directly related to the printing conditions and to the rheological phenomena inherent to the process, specifically the bonding between adjacent extruded paths/raster. This paper aims to study the influence of a set of printing conditions and parameters, namely, envelope temperature, extrusion temperature, forced cooling and extrusion rate, on the parts performance. Design/methodology/approach The influence of these parameters is evaluated by printing a set of test specimens that are morphologically characterized and mechanically tested. At the morphological level, the external dimensions and the voids content of the printed specimens are evaluated. The bonding quality between adjacent extruded paths is assessed through the mechanical performance of test specimens, subjected to tensile loads. These specimens are printed with all raster oriented at 90º relative to the tensile axis. Findings The best performance, resulting from a compromise between surface quality, dimensional accuracy and mechanical performance, is achieved with a heated printing environment and with no use of forced cooling. In addition, for all the conditions tested, the highest dimensional accuracy is achieved in dimensions defined in the printing plane. Originality/value This work provides a relevant result as the majority of the current printers comes without enclosure or misses the heating and envelope temperature control systems, which proved to be one of the most influential process parameter.

Laser Additive Manufacturing of Novel Aluminum Based Nanocomposite Parts: Tailored Forming of Multiple Materials

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Dongdong Gu ◽  
Hongqiao Wang ◽  
Donghua Dai
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Microstructural Evolution ◽  
Mechanical Performance ◽  
Laser Energy ◽  
Dimensional Accuracy ◽  
Ring Structure ◽  
Multiple Materials ◽  
Depth Relationship ◽  
Tailored Forming

The present study has proved the feasibility to produce the bulk-form TiC/AlSi10Mg nanocomposite parts with the novel reinforcing morphology and enhanced mechanical properties by selective laser melting (SLM) additive manufacturing (AM) process. The influence of linear laser energy density (η) on the microstructural evolution and mechanical performance (e.g., densification level, microhardness, wear and tribological properties) of the SLM-processed TiC/AlSi10Mg nanocomposite parts was comprehensively studied, in order to establish an in-depth relationship between SLM process, microstructures, and mechanical performance. It showed that the TiC reinforcement in the SLM-processed TiC/AlSi10Mg nanocomposites experienced an interesting microstructural evolution with the increase of the applied η. At an elevated η above 600 J/m, a novel regularly distributed ring structure of nanoscale TiC reinforcement was tailored in the matrix due to the unique metallurgical behavior of the molten pool induced by the operation of Marangoni flow. The near fully dense TiC/AlSi10Mg nanocomposite parts (>98.5% theoretical density (TD)) with the formation of ring-structured reinforcement demonstrated outstanding mechanical properties. The dimensional accuracy of SLM-processed parts well met the demand of industrial application with the shrinkage rates of 1.24%, 1.50%, and 1.72% in X, Y, and Z directions, respectively, with the increase of η to 800 J/m. A maximum microhardness of 184.7 HV0.1 was obtained for SLM-processed TiC/AlSi10Mg nanocomposites, showing more than 20% enhancement as compared with SLM-processed unreinforced AlSi10Mg part. The high densification response combined with novel reinforcement of SLM-processed TiC/AlSi10Mg nanocomposite parts also led to the considerably low coefficient of friction (COF) of 0.28 and wear rate of 2.73 × 10−5 mm3 · N−1 · m−1. The present work accordingly provides a fundamental understanding of the tailored forming of lightweight multiple nanocomposite materials system by laser AM.

scholarly journals Mechanical and Geometric Performance of PLA-Based Polymer Composites Processed by the Fused Filament Fabrication Additive Manufacturing Technique

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1924 ◽  
Author(s):  
José María Reverte ◽  
Miguel Ángel Caminero ◽  
Jesús Miguel Chacón ◽  
Eustaquio García-Plaza ◽  
Pedro José Núñez ◽  
...  
Keyword(s):  
Carbon Fibre ◽  
Mechanical Performance ◽  
Dimensional Accuracy ◽  
Point Of View ◽  
Fused Filament Fabrication ◽  
Sem Images ◽  
Tensile Performance ◽  
Interlaminar Shear ◽  
Strength And Stiffness ◽  
Short Carbon

In this work, the effect of short carbon fibre (CF) on the mechanical and geometric properties of 3D printed polylactic acid (PLA) composite parts processed using the Fused Filament Fabrication (FFF) technique have been analysed. Tensile, flexural and interlaminar shear strength (ILSS) tests were performed to obtain the mechanical performance of the different samples. The surface quality and geometric accuracy of the printed specimens were also evaluated. Finally, Scanning Electron Microscope (SEM) images of the printed samples are analysed. The results revealed that the addition of carbon fibres effectively improved all assessed mechanical properties of PLA-CF composites as compared to the neat PLA. In particular, Flat PLA-CF samples showed an average increase in tensile performance of 47.1% for the tensile strength and 179.9% for the tensile stiffness in comparison to the neat PLA. From the flexural behaviour point of view, Flat PLA-CF samples revealed an increase in average flexural strength and stiffness of 89.75% and 230.95%, respectively in comparison to the neat PLA. Furthermore, PLA-CF samples depicted the best ILSS performance. In general, the use of short carbon fibre as reinforcement did not affect the dimensional accuracy of the PLA-CF samples, and even improved the surface roughness in certain cases, particularly in Flat and On-edge orientations.

scholarly journals Additive Manufacturing of PLA-Based Composites Using Fused Filament Fabrication: Effect of Graphene Nanoplatelet Reinforcement on Mechanical Properties, Dimensional Accuracy and Texture

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 799 ◽  
Author(s):  
Miguel Caminero ◽  
Jesús Chacón ◽  
Eustaquio García-Plaza ◽  
Pedro Núñez ◽  
José Reverte ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Impact Strength ◽  
Dimensional Accuracy ◽  
Fused Filament Fabrication ◽  
Graphene Nanoplatelet ◽  
Graphene Composite ◽  
General Terms ◽  
3D Printed ◽  
Composite Samples

Fused filament fabrication (FFF) is a promising additive manufacturing (AM) technology due to its ability to build thermoplastics parts with advantages in the design and optimization of models with complex geometries, great design flexibility, recyclability and low material waste. This technique has been extensively used for the manufacturing of conceptual prototypes rather than functional components due to the limited mechanical properties of pure thermoplastics parts. In order to improve the mechanical performance of 3D printed parts based on polymeric materials, reinforcements including nanoparticles, short or continuous fibers and other additives have been adopted. The addition of graphene nanoplatelets (GNPs) to plastic and polymers is currently under investigation as a promising method to improve their working conditions due to the good mechanical, electrical and thermal performance exhibited by graphene. Although research shows particularly promising improvement in thermal and electrical conductivities of graphene-based nanocomposites, the aim of this study is to evaluate the effect of graphene nanoplatelet reinforcement on the mechanical properties, dimensional accuracy and surface texture of 3D printed polylactic acid (PLA) structures manufactured by a desktop 3D printer. The effect of build orientation was also analyzed. Scanning Electron Microscope (SEM) images of failure samples were evaluated to determine the effects of process parameters on failure modes. It was observed that PLA-Graphene composite samples showed, in general terms, the best performance in terms of tensile and flexural stress, particularly in the case of upright orientation (about 1.5 and 1.7 times higher than PLA and PLA 3D850 samples, respectively). In addition, PLA-Graphene composite samples showed the highest interlaminar shear strength (about 1.2 times higher than PLA and PLA 3D850 samples). However, the addition of GNPs tended to reduce the impact strength of the PLA-Graphene composite samples (PLA and PLA 3D850 samples exhibited an impact strength about 1.2–1.3 times higher than PLA-Graphene composites). Furthermore, the addition of graphene nanoplatelets did not affect, in general terms, the dimensional accuracy of the PLA-Graphene composite specimens. In addition, PLA-Graphene composite samples showed, in overall terms, the best performance in terms of surface texture, particularly when parts were printed in flat and on-edge orientations. The promising results in the present study prove the feasibility of 3D printed PLA-graphene composites for potential use in different applications such as biomedical engineering.

scholarly journals Dimensional Accuracy and Mechanical Properties of Chopped Carbon Reinforced Polymers Produced by Material Extrusion Additive Manufacturing

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3885 ◽  
Author(s):  
Evren Yasa ◽  
Kıvılcım Ersoy
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Modulus Of Elasticity ◽  
High Speed ◽  
Polymer Matrix Composites ◽  
Low Cost ◽  
Dimensional Accuracy ◽  
Fused Filament Fabrication ◽  
Material Extrusion ◽  
Pull Out

Fused Filament Fabrication (FFF), classified under material extrusion additive manufacturing technologies, is a widely used method for fabricating thermoplastic parts with high geometrical complexity. To improve the mechanical properties of pure thermoplastic materials, the polymeric matrix may be reinforced by different materials such as carbon fibers. FFF is an advantageous process for producing polymer matrix composites because of its low cost of investment, high speed and simplicity as well as the possibility to use multiple nozzles with different materials. In this study, the aim was to investigate the dimensional accuracy and mechanical properties of chopped carbon-fiber-reinforced tough nylon produced by the FFF process. The dimensional accuracy and manufacturability limits of the process are evaluated using benchmark geometries as well as process-inherent effects like stair-stepping effect. The hardness and tensile properties of produced specimens in comparison to tough nylon without any reinforcement, as well as continuous carbon-reinforced specimens, were presented by taking different build directions and various infill ratios. The fracture surfaces of tensile specimens were observed using a Scanning Electron Microscope (SEM). The test results showed that there was a severe level of anisotropy in the mechanical properties, especially the modulus of elasticity, due to the insufficient fusion between deposited layers in the build direction. Moreover, continuous carbon-reinforced specimens exhibited very high levels of tensile strength and modulus of elasticity whereas the highest elongation was achieved by tough nylon without reinforcement. The failure mechanisms were found to be inter-layer porosity between successive tracks, as well as fiber pull out.

Effect of nozzle diameter on mechanical and geometric performance of 3D printed carbon fibre-reinforced composites manufactured by fused filament fabrication

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jesús Miguel Chacón ◽  
Miguel Ángel Caminero ◽  
Pedro José Núñez ◽  
Eustaquio García-Plaza ◽  
Jean Paul Bécar
Keyword(s):  
Surface Roughness ◽  
Carbon Fibre ◽  
Mechanical Performance ◽  
Dimensional Accuracy ◽  
Nozzle Diameter ◽  
Fused Filament Fabrication ◽  
Manufacturing Costs ◽  
Content Type ◽  
3D Printed ◽  
Composite Samples

Purpose Fused filament fabrication (FFF) is one of the most popular additive manufacturing (AM) technologies due to its ability to build thermoplastic parts with complex geometries at low cost. The FFF technique has been mainly used for rapid prototyping owing to the poor mechanical and geometrical properties of pure thermoplastic parts. However, both the development of new fibre-reinforced filaments with improved mechanical properties, and more accurate composite 3D printers have broadened the scope of FFF applications to functional components. FFF is a complex process with a large number of parameters influencing product quality and mechanical properties, and the effects of the combined parameters are usually difficult to evaluate. An array of parameter combinations has been analysed for improving the mechanical performance of thermoplastic parts such as layer thickness, build orientation, raster angle, raster width, air gap, infill density and pattern, fibre volume fraction, fibre layer location, fibre orientation and feed rate. This study aims to assess the effects of nozzle diameter on the mechanical performance and the geometric properties of 3D printed short carbon fibre-reinforced composites processed by the FFF technique. Design methodology approach Tensile and three-point bending tests were performed to characterise the mechanical response of the 3D printed composite samples. The dimensional accuracy, the flatness error and surface roughness of the printed specimens were also evaluated. Moreover, manufacturing costs, which are related to printing time, were evaluated. Finally, scanning electron microscopy images of the printed samples were analysed to estimate the porosity as a function of the nozzle diameter and to justify the effect of nozzle diameter on dimensional accuracy and surface roughness. Findings The effect of nozzle diameter on the mechanical and geometric quality of 3D printed composite samples was significant. In addition, large nozzle diameters tended to increase mechanical performance and enhance surface roughness, with a reduction in manufacturing costs. In contrast, 3D printed composite samples with small nozzle diameter exhibited higher geometric accuracy. However, the effect of nozzle diameter on the flatness error and surface roughness was of slight significance. Finally, some print guidelines are included. Originality value The effect of nozzle diameter, which is directly related to product quality and manufacturing costs, has not been extensively studied. The presented study provides more information regarding the dependence of the mechanical, microstructural and geometric properties of short carbon fibre-reinforced nylon composite components on nozzle diameter.

scholarly journals 3D printing of a continuous fiber-reinforced composite based on a coaxial Kevlar/PLA filament

2021 ◽  
Vol 30 ◽  
pp. 263498332110000
Author(s):  
Trenton Cersoli ◽  
Bharat Yelamanchi ◽  
Eric MacDonald ◽  
Jose Gonzalo Carrillo ◽  
Pedro Cortes
Keyword(s):  
Additive Manufacturing ◽  
High Velocity ◽  
Fiber Volume Fraction ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
High Velocity Impact ◽  
Fused Filament Fabrication ◽  
Fiber Volume ◽  
Velocity Impact ◽  
3D Printed

Additive manufacturing has allowed for the production of complex and mass customized geometries, but often at the expense of mechanical performance, a penalty which can be in part mitigated with the fabrication of composite parts. Thermoplastic structures fabricated with material extrusion additive manufacturing stand to be improved in terms of fracture toughness with the integration of continuous fibers. The present research program has investigated the production of a continuously reinforced filament to be used in open-source fused filament fabrication systems. Three different volume fractions of Kevlar fibers were incorporated into a polylactic acid (PLA) thermoplastic filament. It was observed that a 20% fiber volume fraction resulted in a doubling of the tensile strength relative to the unreinforced PLA parts. High-velocity impact tests were also performed on the reinforced printed thermoplastic material, and it was observed that the composite with the highest fiber volume fraction provided an impact energy resistance improved by a factor of four, relative to the plain PLA. The reinforced fibers have shown to restrain the penetration of the projectile at velocities similar to those that perforated the unreinforced PLA. The present work has demonstrated the production of printed composites without the need of modifying the extruding systems of a commercial 3D printer. This approach could represent an alternate and feasible process for producing continuously reinforced 3D-printed thermoplastic parts with utility for high-velocity impact applications.

scholarly journals Design of Shape Memory Thermoplastic Material Systems for FDM-Type Additive Manufacturing

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4254
Author(s):  
Paulina A. Quiñonez ◽  
Leticia Ugarte-Sanchez ◽  
Diego Bermudez ◽  
Paulina Chinolla ◽  
Rhyan Dueck ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Shape Memory ◽  
Thermomechanical Processing ◽  
Material Selection ◽  
Shape Memory Polymer ◽  
Fused Filament Fabrication ◽  
Materials Development ◽  
Thermoplastic Material ◽  
Polymer Systems ◽  
Injection Molded

The work presented here describes a paradigm for the design of materials for additive manufacturing platforms based on taking advantage of unique physical properties imparted upon the material by the fabrication process. We sought to further investigate past work with binary shape memory polymer blends, which indicated that phase texturization caused by the fused filament fabrication (FFF) process enhanced shape memory properties. In this work, two multi-constituent shape memory polymer systems were developed where the miscibility parameter was the guide in material selection. A comparison with injection molded specimens was also carried out to further investigate the ability of the FFF process to enable enhanced shape memory characteristics as compared to other manufacturing methods. It was found that blend combinations with more closely matching miscibility parameters were more apt at yielding reliable shape memory polymer systems. However, when miscibility parameters differed, a pathway towards the creation of shape memory polymer systems capable of maintaining more than one temporary shape at a time was potentially realized. Additional aspects related to impact modifying of rigid thermoplastics as well as thermomechanical processing on induced crystallinity are also explored. Overall, this work serves as another example in the advancement of additive manufacturing via materials development.

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