•Hybrid Structure, as geometrical hybrid of octet and rhombic dodecahedron, formulated to achieve the combination of their corresponding advantages.•Dynamic compressive responses of three polymeric ...lattices examined experimentally, as lattices for energy absorption expected to shield an object from impact in practical applications.•Selective laser sintered lattices collapse catastrophically under impact, although attaining favourable quasi-static performances.•Fused deposition modelled lattices exhibit good energy absorption characteristics under both quasi-static and dynamic compression.•Rate dependence observed in FDM lattices, accompanied with severer deformation localisation and strut failure.
Lightweight polymeric lattices, which display good energy absorption characteristics during crushing, are increasingly employed in impact protection applications. Lattices based on an octet, rhombic dodecahedron (RD) and a novel hybrid structure (HS), were fabricated by Selective Laser Sintering (SLS), and their dynamic responses were investigated via a drop-weight tester. Their stress-strain responses and crushing patterns were compared with quasi-static responses obtained using a universal testing machine. The experimental results show that SLS-fabricated lattices display good energy absorption performance under quasi-static compression, but collapse catastrophically when subjected to impact. To investigate the cause for the distinct responses under different deformation speeds, the quasi-static and dynamic tensile properties of the cell strut material were also examined. SLS-fabricated specimens are notably more brittle than those fabricated by another commonly used technique – Fused Deposition Modelling (FDM). Consequently, lattices fabricated by FDM were also tested. Unlike their SLS counterparts, FDM-fabricated lattices exhibit good energy absorption characteristics under both quasi-static and dynamic compression, as well as typical rate dependence, whereby the stress level increases with deformation speed. Compared with the traditional octet and RD, the novel HS lattice design shows superior energy absorption characteristics for all tests.
•Mechanical properties of Fused Deposition Modelling (FDM) components depending on process parameters.•Effects generated by the contouring on the tensile strength and on the stiffness of FDM ...components.•Closed-form analytical model for the prediction of the mechanical properties of FDM components.•Validation of the model by comparison to experimental data.
The Fused Deposition Modelling process is a highly efficient Rapid Prototyping approach that makes it possible to rapidly generate even much complicated parts. Unfortunately, the Fused Deposition Modelling is affected by several parameters, whose setting may have a strong impact on the components strength. This paper is devoted to the study of the effects generated by the Fused Deposition Modelling production parameters on the tensile strength and on the stiffness of the generated components, tackling the question from both the experimental and the numerical points of view. For this purpose, an analytical model was developed, which is able to predict the strength and the stiffness properties, based on the number of contours deposited around the component edge and on the setting of the other main parameters of the deposition process. The fundamental result of the paper consists in the possibility of predicting the mechanical behaviour of the Fused Deposition modelled parts, once the raster pattern (dimensions, number of contours, raster angle) has been stated. The effectiveness of the theoretical model has been verified by comparison to a significant number of experimental results, with mean errors of about 4%.
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•Discussion of 3D to 4D transition and its associated processes for printing.•Decoded the world of shape memory effect in materials for 4D Printing.•Potential of stimuli in 4D ...printing have been reviewed.•Parametric evaluation of materials for 4D Printing and its influences on final properties.
The idea of 3D printing ever since 1980’s has agitated the research domains challenging the conventional techniques with its inordinate efficiency in the utility of material, superior surface resolution and single step production which are applied in biomedical, electronics, self-healing and most prominently in biomimetic applications. However, this additive technique could not be controlled to produce intricate structure, to suppress strain controlled dimensional change, and anisotropic behavior. This complexity and inflexible design that had barricaded their dimension were vanquished by 4D printing with its dynamic structures. The fourth dimension conferred vitality to the design using stimulus to drive the transformation in smart materials (Shape Memory Effect or SME). Smart materials are environmentally sensitive materials comprising of polymers, alloys, hydrogels, ceramics and composites, activated by heat (pre-strain), water (absorption), electromagnetic radiations (Infrared, IR), magnetic field, ohmic parameters (current and voltage), solvent and pH. 4D printing attempts to counterfeit natural processes (flower blooming, leaf cirrus (tendrils), and sunflower movement) in drug delivery, wearable electronics, fashion wares, self-transmuting origami structures, sensors and other engineering applications. This review engulfs the evolution, burgeoning advancements and life cycle prediction of 4D printing with focusing on the smart materials and associated features like stimuli response along with future scope and challenges.
Fused deposition modeling (FDM) is an important process among the available additive manufacturing technologies in various industries. Although there exists many works investigating the effects of ...FDM process parameters on the mechanical properties of printed materials, there are still several points need to be studied. One is the effects of process parameters on the dynamic mechanical properties of FDM-printed materials, especially in environments where the temperature often changes. The other is the mechanism by which process parameters affect the mechanical properties of printed materials. Aiming at these two points, uniaxial tensile tests and dynamic mechanical analysis are carried out respectively to characterize the tensile properties and dynamic mechanical properties of FDM-printed PLA materials under different FDM process parameters, namely printing angle, layer thickness, fill rate and nozzle temperature. Based on the experimental results explanations are given for the influence of the FDM process parameters on the mechanical properties of the printed materials.
●The effects of the four FDM process parameters on the tensile and dynamic mechanical properties of the printed PLA materials were studied experimentally.●Printing angle mainly affects the fracture mode of the FDM-printed PLA materials.●Layer thickness mainly affects the interlayer bonding strength of the printed materials and the smaller the printing angle, the greater the effect.●The fill rate mainly affects the air gap inside the printed material.●Nozzle temperature mainly affects the fluidity of extruded material.
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Additive manufacturing (AM), also known as additive manufacturing, permits the fabrication of fully customized objects with a high level of geometrical complexity at reduced ...fabrication time and cost. Besides metals and ceramics, polymers have become a widely researched class of materials for applications in AM. The synthetic versatility and adaptability, as well as the wide range of properties that can be achieved using polymer materials, have rendered polymers the most widely employed class of materials for AM methodologies. In this review, the basic principles, considering the printing mechanism as well as the advantages and disadvantages, of the most relevant polymer AM technologies are described. The particular features, properties and limitations of currently employed polymer systems in the various AM technology areas are presented and analyzed. Subsequently, 4D printing, that is the fabrication of 3D printed structures that are cabable to change with time, is discussed. A brief description of the polymeric materials and technologies under development for 4D printed structures as well as the different shape changes explored are presented. Finally, based on the characteristics of the polymers employed for each technology illustrative examples of the principal applications are discussed.
Gyroid polylactic acid (PLA) scaffolds with different unit cell sizes of 2 mm (G2), 2.5 mm (G25), and 3 mm (G3) were fabricated via fused deposition modeling for bone tissue engineering ...applications. The porosity of the PLA scaffolds ranged from 86% to 90%. The structural anisotropy value of the scaffolds was 3.80, 2.00, and 1.04 for G2, G25, and G3, respectively. Compressive test results indicated that both the dense PLA and porous PLA scaffolds showed elastic-plastic deformation behavior in both building and transverse directions. The compressive elastic modulus and yield strength of the scaffolds were 118–180 MPa and 2–8 MPa in the building direction and 106–138 MPa and 2.5–6.0 MPa in the transverse direction, respectively. The tensile elastic modulus and yield strength were 51–63 MPa and 1.5–4.5 MPa in the building direction and 11–17 MPa and 1–5 MPa in the transverse direction, respectively. The gyroid PLA scaffolds showed significantly higher values for compressive strength (up to three times) compared to other gyroid structures reported in the literature. The PLA scaffolds can be anticipated as promising scaffold biomaterials for bone tissue engineering applications by virtue of their bone-mimicking porous structure and good mechanical properties.
•PLA gyroid scaffolds with three different unit cell sizes were manufactured by fused deposition modeling.•A well-interconnected porous structure with an open porosity of ~90% was achieved.•Higher mechanical strength compared to other TPMS structures manufactured by fused deposition modeling.•The mechanical properties of the PLA scaffolds are close to those of natural cancellous bone.
Carbon fiber-reinforced plastic composites have been intensively used for many applications due to their attractive properties. The increasing demand of carbon fiber-reinforced plastic composites is ...driving novel manufacturing processes to be in short manufacturing cycle time and low production cost, which is difficult to realize during carbon fiber-reinforced plastic composites fabrication in common molding processes. Fused deposition modeling, as one of the additive manufacturing techniques, has been reported for fabricating carbon fiber-reinforced plastic composites. The process parameters used in fused deposition modeling of carbon fiber-reinforced plastic composites follow those in fused deposition modeling of pure plastic materials. After adding fiber reinforcements, it is crucial to investigate proper fused deposition modeling process parameters to ensure the quality of the carbon fiber-reinforced plastic parts fabricated by fused deposition modeling. However, there are no reported investigations on the effects of fused deposition modeling process parameters on the mechanical properties of carbon fiber-reinforced plastic composites. In the experimental investigations of this paper, carbon fiber-reinforced plastic composite parts are fabricated using a fused deposition modeling machine. Tensile tests are conducted to obtain the tensile properties. The effects of fused deposition modeling process parameters on the tensile properties of fused deposition modeling-fabricated carbon fiber-reinforced plastic composite parts are investigated. The fracture interfaces of the parts after tensile testing are observed by a scanning electron microscope to explain material failure modes and reasons.
The 3D printing (or additive manufacturing, AM) technology is capable to provide a quick and easy production of objects with freedom of design, reducing waste generation. Among the AM techniques, ...fused deposition modeling (FDM) has been highlighted due to its affordability, scalability, and possibility of processing an extensive range of materials (thermoplastics, composites, biobased materials, etc.). The possibility of obtaining electrochemical cells, arrays, pieces, and more recently, electrodes, exactly according to the demand, in varied shapes and sizes, and employing the desired materials has made from 3D printing technology an indispensable tool in electroanalysis. In this regard, the obtention of an FDM 3D printer has great advantages for electroanalytical laboratories, and its use is relatively simple. Some care has to be taken to aid the user to take advantage of the great potential of this technology, avoiding problems such as solution leakages, very common in 3D printed cells, providing well-sealed objects, with high quality. In this sense, herein, we present a complete protocol regarding the use of FDM 3D printers for the fabrication of complete electrochemical systems, including (bio)sensors, and how to improve the quality of the obtained systems. A guide from the initial printing stages, regarding the design and structure obtention, to the final application, including the improvement of obtained 3D printed electrodes for different purposes, is provided here. Thus, this protocol can provide great perspectives and alternatives for 3D printing in electroanalysis and aid the user to understand and solve several problems with the use of this technology in this field.
Fused layer modeling (FLM) or fused deposition modeling (FDM) can be used to produce polymer components with a cellular structure. The existence of cells (voids) in FLM parts degrades mechanical ...properties. This study was done to understand the influence of two printing parameters, layer height (0.1 mm and 0.3 mm) and extrusion temperature (200 °C and 250 °C), on the Izod impact strength of polypropylene (PP). Morphological analysis showed that smaller layer height and higher extrusion temperature generally resulted in smaller cell size but larger cell density. Printed PP components were lighter than injection molded PP parts. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses confirmed that both α and β type crystals existed in printed PP. PP printed at 250 °C had lower impact strength while components printed at 200 °C had similar impact strength to injection molded PP.
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•This is the first research to study polypropylene (PP) by fused layer modeling (FLM) from a cellular plastic perspective.•Izod impact strength of PP from FLM can be similar to injection molded PP by controlling the processing parameters.•Increase in β-cystal content was the major source for improved Izod impact strength during FLM.
Since the concept of four-dimensional (4D) printing first emerged from additive manufacturing technologies in 2013, there has been growing interest from researchers worldwide to harness its benefits ...for advanced manufacturing and materials design. 4D printing has the potential to extend the processing of objects beyond complex geometries by giving dynamic properties to static printed structures, which can change over time. The shapes and/or properties of printed objects can change under various stimuli, including heat, light, pH, moisture, electricity, and magnetic field, and these changes can be pre-designed and well-controlled. 4D printing thus permits the creation of variable and controllable geometries by incorporating the time dimension. In recent years, the rapid technical developments in smart materials and new printing methods have greatly expanded the scope of 4D printing. This article reviews important 4D printing technologies in conjunction with the underlying polymer science and engineering. The challenges and future opportunities in 4D printing are also discussed.
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