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Abstract The effect of the particle sizes (307, 259, 172, and 50 μm) on rheological properties and printing performance for a food-ink dispersion system that 20% (w/w) of spinach powder was incorporated in 10% (w/w) xanthan gum mixture was investigated. Scanning electron microscopy images demonstrated that the larger particle size (307 μm and 259 μm) possess a skeletal-like and cellular structure, and are more porous than the smaller particle size (up to 172 μm). The increase of particle size significantly affected the composition and bulk density (ranged from 0.15 for 50 μm to 0.22 for 307 μm) of the spinach powder. Reduction in particle size resulted in the increase of water and oil holding capacity, but did not affect the water solubility index. Increasing particle size promoted a rise of the values of the storage modulus and loss modulus systematically. The shear modulus of spinach dispersion was ranged from 2.97 ± 1.26 kPa for finest size (50 μm) to 6.43 ± 1.41 kPa for a particle size of 307 μm and increased with increasing particle size. All dispersions were printed smoothly regardless of the particle size. The results obtained in this study suggest that increasing the particle size of the incorporated food powder can achieve efficient mechanical strength increase and a limit the incorporated powder content, simultaneously, due to its excessive increase. This may be useful in determining parameters which required to prepare the food-ink system such as the milling time and the maximum incorporation content of the food powder. Highlights • The effect of the particle size on rheological properties and printing performance for a food-ink was investigated. • A larger particle size promoted shape stability during the printing process. • Adjusting particle size yielded a promising means to desired nutritional value and printing performance. [ABSTRACT FROM AUTHOR]

3D concrete printing can be used to build many complex structures. However, due to its material properties in the fresh state, it is difficult to construct overhanging structures without supports. In order to unleash the true capability of 3D concrete printing, a support structure is required to support any overhanging fresh material, which is usually removed during post-processing. This study demonstrates the feasibility of adjusting the printing parameters to print the main structure and support structure using a single type of building material. It was found that the solidity ratio, which is defined as the ratio between actual and expected filament sizes, was significantly affected by the nozzle travel speed and material volume flow rate. Furthermore, a gap distance characterisation test was carried out to find the maximum distance that the filament can cross over without a significant slump. The results were combined to determine the different printable regions for different operations. An overhang structure was printed to verify the results obtained for the different printing operations. This technique allows complex structure to be built without the need for human intervention throughout the printing process. [ABSTRACT FROM AUTHOR]

Binder jetting is expected to become the universal process for preparing ceramic parts because it can overcome multiple problems, such as the difficulty to prepare complex-shaped ceramic parts and the shrinkage of the sintering process, which appear in conventional ceramic preparation process. This paper introduces principles, steps, and applications of binder jetting printing ceramics. Furthermore, five key factors of binder jetting printing ceramics (powders, binders, printing parameters, equipment, and post-treatment process) have been investigated. Accordingly, effects of powders (including shape, particle size and distribution, and additives), binders (including binding method, droplet-formation mechanism, and droplet-infiltration kinetics), printing parameters (including layer thickness, saturation, solid binder, and printing orientation), equipment, and post-treatment (including de-powdering process, and densification process) on density, roughness, strength, accuracy, and resolution of ceramic parts have been discussed and summarized. This paper provides detailed analysis of techniques and mechanisms of binder jetting of ceramics, giving guidance on how to handle raw materials and select various processing parameters for achieving desired performance. [ABSTRACT FROM AUTHOR]

This study assesses the feasibility of printing implantable devices using 3D printing Fused deposition modeling (FDM) technology. The influence of the deposition temperature, the deposition rate and the layer thickness on the printing process and the physical properties of the devices were evaluated. The filaments were composed of neat poly(lactic acid) (PLA) and blends of different plasticizers (polyethylene glycol 400 (PEG 400), triacetine (TA), acetyltriethyl citrate (ATEC) and triethyl citrate (TEC)) at 10% (w/w). The assessment of thermomechanical characteristics and morphology of both filaments and devices (cylinders and dog bones) were performed. The influence of each parameter was evaluated using a design of experiment (DoE) and the significance of the results was discussed. A large amount of data about the evaluation of FDM process parameters are already available in the literature. However, specific insights needed to be increased into the impact of the use of PLA and plasticized PLA raw material on the feasibility of printing devices in three dimensions. To conclude, the ductility was improved with a high layer thickness, low temperature and using ATEC. Whereas, adhesion was promoted with an increase in temperature, a lower layer thickness and adding TA. [ABSTRACT FROM AUTHOR]

This work aims to study the influence of protective coatings on the water absorption and mechanical properties of 3D printed poly-lactic acid (PLA) parts. The PLA parts were fabricated with different levels of the 3D printing process parameters, aiming to define samples with distinct strength and ductility/toughness characteristics. Water absorption tests following the standard ASTM D570-98 were performed on uncoated and coated PLA specimens. The effectiveness of two protective coatings based on acrylic and polyurethane varnish on reducing water absorption was evaluated. Both protective coatings have shown being effective on preventing water absorption by the PLA, with polyurethane presenting the best performance reducing water absorption by 38%. Tensile tests were carried out to determine the ultimate tensile strength, elastic modulus, yield tensile strength, fracture strain and toughness of specimens, before and after the application of protective coatings. The polyurethane protective coating also benefits the tensile properties of PLA parts, increasing the strength and ductility/toughness characteristics of specimens up to 24%. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) is an emerging technique for the production of various unique and complex food items. Printing materials and recipes should be optimized to improve the quality and efficiency of 3D printing. This paper presents the development of a novel food formulation for 3D printing. This formulation is based on a complex mixture system that comprises egg white protein (EWP), gelatin, cornstarch, and sucrose. The effects of EWP addition on the rheological, lubrication, and texture properties and the microstructure of the mixture system were investigated. The results of the rheological and tribology studies show that a 5.0% (w/w) EWP mixture system is ideal for use in 3D printing. The addition of a certain concentration of EWP could improve the hardness and springiness of gel samples. The improvement in these properties facilitates the timely flow-out of the printing material from the nozzle and improves the viscosity of the printing material. The latter effect helps maintain the shape of the printing material during printing. Furthermore, the printing parameters for the optimal geometric accuracy and dimensions of the printed mixture system were determined and are 1.0 mm nozzle diameter, 70 mm/s nozzle moving speed, and 0.004 cm3/s extrusion rate. This work suggests that 3D printing based on the EWP complex system is a promising method for producing food objects with complex shapes. [ABSTRACT FROM AUTHOR]

The present study established a maximum standard for printing quality and developed a preliminary ideal index to print three-dimensional (3D) construct using the Gly-Arg-Gly-Asp (GRGD) peptide modified Pluronic-F127 hydrogel (hereafter defined as 3DG bioformer (3BE)) as bioink. In addition, the biocompatibility of 3BE for 3D printing applications was carefully investigated. For biocompatibility study and ideal printing parameter, we used the formulation of 3BE in three different concentrations (3BE-1: 25%, 3BE-2: 30%, and 3BE-3: 35%). The 3BE hydrogels were printed layer by layer as a cube-like construct with all diameters of the needle head under the same feed (100 mm/s). The printing parameters were determined using combinations of 3BE-1, 3BE-2, and 3BE-3 with three different standard needle sizes (Φ 0.13 mm, Φ 0.33 mm, and Φ 0.9 mm). The printed constructs were photographed and observed using optical microscopy. The cell viability and proliferation were evaluated using Live/Dead assay and immunofluorescence staining. Results showed that a stable of printed line and construct could be generated from the 3BE-3 combinations. Cytotoxicity assay indicated that the 3BE hydrogels possessed well biocompatibility. Bioprinting results also demonstrated that significant cell proliferation in the 3BE-3 combinations was found within three days of printing. Therefore, the study discovered the potential printing parameters of 3BE as bioink to print a stable construct that may also have high biocompatibility for cell encapsulation. This finding could serve as valuable information in creating a functional scaffold for tissue engineering applications.

In this article, the optimization of printing properties on a new, flexible ceramic substrate is reported for sensing and antenna applications encompassing internet of things (IoT) devices. E-Strate® is a commercially available, non-rigid, thin ceramic substrate for implementing in room temperature and high-temperature devices. In this substrate, the printing parameters like drop spacing, number of printed layers, sintering temperature, and sintering time were varied to ensure an electrically conductive and repeatable pattern. The test patterns were printed using silver nanoparticle ink and a Dimatix 2831 inkjet printer. Electrical conductivity, high-temperature tolerance, bending, and adhesion were investigated on the printed samples. The three-factor factorial design analysis showed that the number of printed layers, sintering temperature, sintering time, and their interactions were significant factors affecting electrical conductivity. The optimum printing parameters for the thin E-Strate® substrate were found to be 20 μm drop spacing, three layers of printing, and 300 °C sintering temperature for 30 min. The high-temperature tolerance test indicated a stable pattern without any electrical degradation. Repetitive bending, adhesion test, and ASTM tape tests showed adequate mechanical stability of the pattern. These results will provide insight for investigators interested in fabricating new IoT devices.

In the last decades, one of the most critical issues concerning the control on the processing, structure and properties of nanocomposites is related to the dispersion of nanofiller in the polymer matrix and internal interactions resulting in percolation. In this study, we investigate the rheological behavior in oscillatory and steady shear flow of poly(lactic) acid based nanocomposites incorporating 0 – 12 wt% graphene nanoplates (GNP) and multi-walled carbon nanotubes (OH-MWCNT). The effect of the filler contents and aspect ratio on the viscosity and viscoelastic response is evaluated. Three rheological techniques are used for estimation of rheological percolation threshold. Due to different aspect ratio and state of dispersion of GNP and MWCNTs the percolation threshold differs significantly for both compositions ϕp ≤ 1.5 wt% for MWCNT/PLA and ϕp ≤ 5 wt% for GNP/PLA. The larger the aspect ratio of nanofiller, the lower is the rheological percolation threshold. The visualized structure by TEM analysis confirms the rheological predictions for both type composites. The index of flow was estimated by the power law slope of the flow curves and a better dispersion was assumed for MWCNTs in comparison with GNPs due to the surface modification. Based on the rheological percolation threshold and the flow index, nanocomposites were classified in three groups: Newtonian, percolated composites and elastic solids. Both characteristics are used to select the printing parameters for the three groups of nanocomposites, suitable for fused deposition modeling (FDM).

In food ink systems in which the particles are dispersed in a hydrocolloid matrix, the source of the particles and the particle content are the main factors affecting the printability and rheological properties of the system. In this study, different contents (10% and 30% w/w) of vegetable (broccoli, spinach, or carrot) powders were added to hydrocolloid matrices with different hydration properties, and their influence on the printability and rheological properties was investigated. At low powder contents (10%), slight differences in the printability and rheological values were observed between the different vegetable sources in all hydrocolloids. When the powder content was increased to 30%, the hydrocolloid with the lowest water hydration capacity, hydroxypropyl methylcellulose, showed the greatest differences in rheology and printability when different vegetable sources were used. Xanthan gum, with its higher water hydration capacity, inhibited the swelling of the particles, thus minimizing the increase in the rheological values at high volume fractions of powder and reducing the differences in printability between different vegetable sources. Confocal laser scanning microscopy analysis of the vegetable inks showed that xanthan gum inhibited swelling of the particles regardless of the vegetable powder source. The mixtures using xanthan gum could be smoothly extruded from the nozzle due to their low extruded hardness (2.96 ± 0.23 to 3.46 ± 0.16 kg), and the resulting objects showed high resolution without collapse over time. Practical Application: The powder‐based texturization technology introduced in this study provides a standardized method of preparing food ink that can be universally applied to all food materials that can be powdered. In addition, the present invention can be applied to a 3D printing technique in which a powder and a hydrocolloid matrix are independently stored and mixed immediately before printing. This technique can minimize the inherent rheological differences between formulations with different food sources and compositions. [ABSTRACT FROM AUTHOR]

Background: Interest in additive manufacture has grown significantly in recent years, driving a need for printable materials that can sustain high strains and still fulfill their function in applications such as tissue engineering, regenerative medicine field, food engineering and field of aerospace, etc. As an emerging and promising technology, 3Dprinting has attracted more and more attention with fast manipulation, reduce production cost, customize geometry, increase competitiveness and advantages in many hot research areas. Many researchers have done a lot of investigations on printable materials, ranging from a single material to composite material. Main content: This review focuses on the contents of printable edible inks. It also gathers and analyzes information on the effects of printable edible ink material properties on 3D print accuracy. In addition, it discusses the impact of printing parameters on accurate printing, and puts forward current challenges and recommendations for future research and development. [ABSTRACT FROM AUTHOR]

This paper presents the development of a new 3D printing food constructs based on fish surimi gel system. This study investigated the influence of NaCl addition on rheological property, gel strength, water holding capacity (WHC), water distribution and microstructure of surimi gel to be used as a material for 3D printing. The obtained results from rheological studies showed that the surimi gels made with 1.5 g NaCl/100 g surimi mixture can be used for 3D printing. NaCl addition is helpful for the slurry to flow out from the nozzle in time and then get viscous post-deposition for holding its shape. Moreover, the effects of the printing parameters on the geometrical accuracy and dimension of the printed surimi gel were also studied. In this particular printing system, the 2.0 mm nozzle diameter, 5.0 mm nozzle height, 28 mm/s nozzle moving speed and 0.003 cm 3 /s extrusion rate were the optimal parameters to print 3D samples with fine resolution, better matching with the target geometry, fewer point defects and no compressed deformation. The overall results suggested that the 3D printing based on surimi gel system is a promising method for producing complexed-shape food patterns. [ABSTRACT FROM AUTHOR]

Low-cost metal additive manufacturing remains difficult but would be of great practical value. To prepare slurry distributed evenly and stably, the present study thoroughlymixed metal powder, as a basematerial, with corresponding monomers, crosslinking agents, dispersant, initiator, and catalysts. A complex three-dimensional structure of iron powder slurry was built using a pneumatic injection additive manufacturing system. The effects of the injection pressure, platform speed, and nozzle diameter on the width of printed lines were studied. The stability of the width of a single printed line was investigated. It was found that the line width increases with an increase in the injection pressure or nozzle diameter and decreases with an increase in the moving speed of the platform. A reasonable drying, debinding, and sintering schedule was established, and the microstructures of dried, debinding, and sintered parts were analyzed. The sintered parts were denser than dried and debinding parts. The pneumatic injection additive manufacturing technology adopted in this study has the advantages of lowmanufacturing costs and a wide range of printing materials, and is applicable in the additive manufacturing of iron powder and a variety of other metal powders, thus widening the range of materials used in additive manufacturing. [ABSTRACT FROM AUTHOR]

This paper evaluates the potential of short carbon fibres as a reinforcement material in order to improve the fatigue resistance of PLA. The fatigue behaviour has been analysed through rotational bending fatigue tests. The influence of printing parameters, such as layer thickness, printing temperature and printing speed, on the mechanical behaviour, dimensional accuracy and macrogeometrical deviations of printed parts have also been analysed as they can too interfere with the mechanical behaviour of the parts. The results show that there is no improvement on the mechanical behaviour of the printed parts with the incorporation of short carbon fibres. On the contrary, the fatigue behaviour worsens due to the poor adhesion between the short carbon fibres and the PLA matrix. Fatigue life is reduced by 6% compared to PLA. Focusing only on the printing parameters, it is shown that at the highest temperature allowed, the fatigue behaviour improves a 12%. The Printing speed is the least influential variable, with the layer thickness having the greatest influence, increasing fatigue life by 15% comparing 0.1 mm and 0.3 mm. Therefore, the best combination would be to print with the highest temperature and the highest layer thickness, for this case study. Finally, a parametric relationship is presented in order to relate the layer thickness with the fatigue behaviour. [Display omitted] [ABSTRACT FROM AUTHOR]

With decades of development, Additive Manufacturing (AM) grows significantly and has been used in a wide range of applications. Although AM was introduced for production of prototypes, it is now being utilized for fabrication of functional end-use products. Therefore, structural integrity and mechanical strength of additively manufactured parts have become of significant importance. The rise of potentials of AM process motivate research and industry to use modeling techniques to support the process and product development by reducing costly and time consuming experiments. In the current study, we have demonstrated two simulation case studies: (a) modeling of AM process, and (b) modeling of additively manufactured parts. Simufact additive manufacturing software is used which provides simulation solution for all metal manufacturing process. Simufact is used to examine the development of residual stresses during the thermal treatment in selective laser melting process. We also used commercial Finite Element (FE) software Abaqus to simulate structural integrity of additively manufactured adhesive joints. We demonstrated how FE modeling can be employed to reveal the impact of printing parameters of the adherends of the joints on to their mechanical performances and their cohesive fracture. The outcome of this study can be utilized for implementation of simulation and computational modeling into the future designs of additively manufactured components. [ABSTRACT FROM AUTHOR]

The aim of this paper is to develop a new 3D printing food constructs based on lemon juice gel system. We investigated the effect of potato starch (10, 12.5, 15, 17.5 and 20 g/100 g) on the rheological properties and mechanical properties of lemon juice gels. Besides, the influence of printing parameters (nozzle height, nozzle diameter, extrusion rate and nozzle movement speed) on the quality of printed products were also studied. The results show that it is suitable to make the size of the nozzle height the same with that of the nozzle diameter, which could not be regarded as a key factor that affects print quality. An equation is proposed to explain the relationship between extrusion rate, nozzle diameter and nozzle movement speed. In this printing system, the 1 mm nozzle diameter, 24 mm 3 /s extrusion rate and 30 mm/s nozzle movement speed were found to be the optimal parameters to print 3D constructs matching the target geometry with fine resolution, more smooth surface texture, and fewer point defects with no compressed deformation. [ABSTRACT FROM AUTHOR]

Purpose: 3D printing is a rapid prototyping technology that uses a 3D digital model to physically build an object. The aim of this study was to evaluate the peri-operative effect of 3D printing in treating complex elbow fractures and its role in physician-patient communication and determine which material is best for surgical model printing.Method: Forty patients with elbow fractures were randomly divided into a 3D printing-assisted surgery group (n = 20) and a conventional surgery group (n = 20). Surgery duration, intra-operative blood loss, anatomic reduction rate, incidence of complications and elbow function score were compared between the two groups. The printing parameters, the advantages and the disadvantages of PLA and ABS were also compared. The independent-samples t-test was used to compare the data between groups. A questionnaire was designed for orthopaedic surgeons to evaluate the verisimilitude, the appearance of being true or real, and effectiveness of the 3D printing fracture model. Another questionnaire was designed to evaluate physician-patient communication effectiveness.Results: The 3D group showed shorter surgical duration, lower blood loss and higher elbow function score, compared with the conventional group. PLA is an environmentally friendly material, whereas ABS produce an odour in the printing process. Curling edges occurred easily in the printing process with ABS and were observed in four of ten ABS models but in only one PLA model. The overall scores given by the surgeons about the verisimilitude and effectiveness of the 3D model were relatively high. Patient satisfaction scores for the 3D model were higher than those for the 2D imaging data during physician-patient discussions.Conclusion: 3D-printed models can accurately depict the anatomic characteristics of fracture sites, help surgeons determine a surgical plan and represent an effective tool for physician-patient communication. PLA is more suitable for desktop fused deposition printing in surgical modeling applications. [ABSTRACT FROM AUTHOR]

[Display omitted] During the last few years, smart materials like shape-memory polymers (SMPs) have attracted great attention from manufacturers and researchers due to their ease of formability and functionality. One of the most recent advanced techniques for manufacturing SMPs to create recoverable objects is additive manufacturing (3D printing). The factors that should be considered when printing 3D SMPs include the type of 3D printer being used, the temperature and humidity of the printing environment, and the properties of the shape memory polymer material. Other important parameters include the speed of the printing, the layer thickness, and the size and shape of the object being printed. Another aspect is the infill structure design, which could be regulated to agree with application requirements and achieve feasibility of these polymers. The most famous shapes are honeycomb, gyroid, and triangles. By carefully controlling these parameters, it is possible to achieve high-quality results when 3D printing with SMPs. Infill structure design, such as honeycomb, gyroid, and triangles, can also affect the mechanical characteristics of SMPs, including tensile, bending, and compression strength, as well as shape memory properties such as shape recovery and fixity ratios, and recovery time. Our review comprehensively discusses the influence of printing parameters on the mechanical properties of different SMPs. Future scope for research in this area includes exploring the use of new infill structures, developing techniques for printing multi-material SMPs, and investigating the use of SMPs in novel applications, such as biomedical devices and soft robotics. Overall, by summarizing and quantifying the factors that influence the properties of 3D-printed SMPs, our review provides a valuable resource for researchers and manufacturers looking to improve the production of these materials for various fields. Therefore, summarizing these factors can improve the production of such materials for various fields. The future scope of research in this field includes further exploring the influence of printing parameters on the properties of SMPs, developing new SMP formulations with improved properties, and exploring new applications of 3D-printed SMPs. [ABSTRACT FROM AUTHOR]

A numerical framework was developed in this study to investigate the influence of relevant Extrusion Deposition Additive Manufacturing (EDAM) processing conditions on the final fiber orientation, inter-bead void and cross-sectional geometry of the bead laid down as the extrudate. Specifically, four key processes of the EDAM process are studied, namely: (i) flow of 90° angle turn as the extrudate exits the nozzle and is laid down on the previous layer or the substrate, (ii) flow of the bead during compaction, (iii) flow of an extrudate deposited adjacent to the previously compacted bead, and (iv) flow of the adjacent bead during compaction. The simulations utilize an anisotropic viscous flow model implemented using the smoothed particle hydrodynamics method in Abaqus and fiber orientation vectors are evolved under the assumption of affine motion. The simulation results are compared with experiments for printed bead geometries produced and this comparison was shown to validate the modeling approach as useful for predicting fiber orientation, bead geometry, and bead-to-bead contact interface geometry. The processing parameters considered are nozzle height from the substrate, the ratio of the print speed to the extrusion speed (V b / V e), and the bead-to-bead lateral overlap distance. A series of virtual experiments were conducted, and the following observations were noted: (i) the bead printed with a high nozzle height has significantly more fiber alignment in the printing direction than the lower nozzle height, (ii) the ratio of the print speed and extrudate speed, V b / V e , of greater than unity results in greater fiber alignment than for V b / V e <1. The developed model illuminates the roles of process parameters in determining the microstructure of the printed bead and bead geometry. [ABSTRACT FROM AUTHOR]

• Main and interaction effects of printing parameters on the mechanical properties of 3D printed samples. • Failure mode analysis of fractured samples. • Fractographic features analysis according to printing parameters. • Relationship between the plastic deformation and the printing parameters. Predicting the mechanical properties or analyzing the failure mode of fused deposition modeling products is challenging due to the layer-by-layer structure and the manufacturing parameters that can interact and be potentially conflicting. Understanding the effects and potential interactions of printing parameters, such as layer thickness, printing (build) orientation, infill density, and infill pattern, is crucial to enhancing the performance of in-service parts. This study investigates the main and interaction effects of layer thickness and printing orientation on the mechanical and failure properties in the case of two levels of infill density (100% and 40%). Tensile tests on 3D Printed PLA samples were carried out for this purpose. An ANOVA analysis was performed based on the experimental results to examine these effects on the mechanical properties. The primary findings demonstrate that the selected parameters' main and interaction effects vary throughout the considered infill densities. With this variation, it is clearly stated that samples with a 100% infill density are more sensitive to interaction effects, and the ones with a 40% infill density are more sensitive to main effects. Examining the fracture surface also details the fractographic features linked to the printing parameters, such as the appearance of plastic deformation and inter-filament debonding. [ABSTRACT FROM AUTHOR]

• Printing parameters (speed, nozzle temperature, and layer thickness) have a statistically significant influence on the compressive viscoelastic properties of PLA parts. • MFCC scaffolds are superior to traditional OCS scaffolds from stiffness, yield strength, yield strain, and toughness perspectives. • Viscoelastic properties of natural bone tissue can be achieved by the variation of FDM parameters of PLA bone scaffolds. Bone tissue engineering has been recognized as a promising strategy to repair or replace damaged bone tissues. The mechanical properties of bone scaffolds play a critical role in successful bone regeneration, as it is essential to match the mechanical properties of the scaffold with the surrounding bone tissue. In this study, we investigated the effects of fused deposition modeling (FDM) process parameters, including printing speed, printing temperature, and layer thickness, on the compressive viscoelastic properties of polylactic acid (PLA) scaffolds. The compressive viscoelastic properties of bulk PLA specimens were characterized using a Zhu-Wang-Tang (ZWT) constitutive model under different compressive strain rates. A comprehensive statistical analysis comprising multivariate and univariate analysis of variance (MANOVA and ANOVA) and Tukey's post hoc analysis was utilized to quantify the effect of each FDM parameter on the viscoelastic mechanical properties of the PLA specimens. Subsequently, we fabricated modified face-centered cubic (MFCC) scaffolds using FDM and varied the FDM process parameters to achieve a compressive viscoelastic response that matched the natural trabecular bone tissue. The viscoelastic performance of the MFCC scaffolds was compared with traditional orthogonal cylindrical struts (OCS) scaffolds. Our methodology contributes to the design of bone-mimetic scaffolds with optimized mechanical properties by controlling FDM process parameters. [ABSTRACT FROM AUTHOR]

In this study, the fatigue limit of powder bed fusion-laser beam (PBF-LB) 316L prepared by various printing power intensities was studied. After finding the PBF-LB printing parameters giving the best fatigue limit, the fatigue crack initiation (FCI) behavior of dense PBF-LB 316L manufactured by the parameters corresponding to the best fatigue limit was investigated. To this end, the fatigue limit was evaluated by self-heating experiments, and a novel method based on the acoustic emission (AE) technique was suggested to assess the FCI stage during the whole fatigue process. In addition, the AE source mechanism was studied to validate the proposed method, and the fatigue behavior and the fatigue cracking mechanism were deeply clarified through detailed characterizations of microstructures and metallurgical defects. The results indicate that the fatigue limit of dense PBF-LB 316L is affected by a combined effect of the subgrain size and gas pores. However, for the defective PBF-LB 316L, the LOF (lack of fusion) defects induced by low printing power play a crucial role in deteriorating the fatigue limit mainly by promoting FCI. Besides, the printing parameter corresponding to the best fatigue limit is found to be 60 J/mm3 in terms of the volume energy density (VED). Furthermore, as for the FCI behavior, it is shown that the percentage of the FCI stage of dense PBF-LB 316L ranges from 12.4% to 45.3% during the whole fatigue process, and the fatigue crack scale after FCI is on a micro level (from 3.8 to 46.6 μm). Moreover, areas around the fine grains (FGs) and coarse grains (CGs) regions and the junctions between ferrite and austenite are the sites where fatigue cracks are prone to initiate. • Fatigue limits of various powder bed fusion-laser beam 316L are investigated. • The parameters giving the best fatigue limit have been found. • A new method using acoustic emission is developed for fatigue crack initiation detection. • The thorough characterization of fatigue cracks after initiation is carried out. [ABSTRACT FROM AUTHOR]

The additive manufacturing of natural fibre-reinforced polymers is a pivotal method in developing sustainable engineering solutions. Using the fused filament fabrication method, the current study investigates the additive manufacturing of hemp-reinforced polybutylene succinate (PBS) alongside its mechanical characterization. Two types of hemp reinforcement are considered: short fibres (max. length smaller than 2 mm) and long fibres (max. length smaller than 10 mm), which are compared against non-reinforced (pure) PBS. A detailed analysis is performed regarding the determination of suitable 3D printing parameters (overlap, temperature, nozzle diameter). In a comprehensive experimental study, additionally to general analyses regarding the influence of hemp reinforcement on the mechanical behaviour, the effect of printing parameters is determined and discussed. Introducing an overlap in the additive manufacturing of the specimens results in improved mechanical performance. The study highlights that the Young's modulus of PBS can be improved by 63% by introducing hemp fibres in conjunction with overlap. In contrast, hemp fibre reinforcement reduces the tensile strength of PBS, while this effect is less pronounced considering overlap in the additive manufacturing process.

Fused deposition modeling (FDM) processed Poly-ether-ether-ketone (PEEK) materials are widely used in aerospace, automobile, biomedical, and electronics industries and other industries due to their excellent mechanical properties, thermal properties, chemical resistance, wear resistance, and biocompatibility, etc. However, the manufacture of PEEK materials and parts utilizing the FDM process faces the challenge of fine-tuning a list of process parameters and heat treatment conditions to reach the best-suiting mechanical properties and microstructures. It is non-trivial to make the selection only according to theoretical analysis while counting on a vast number of experiments is the general situation. Therefore, in this paper, the extrusion rate, filling angle, and printing orientation are investigated to adjust the mechanical properties of 3D-printed PEEK parts; then, a variety of heat treatment conditions were applied to tune the crystallinity and strength. The results show that the best mechanical performance is achieved at 1.0 times the extrusion rate, varied angle cross-fillings with ±10° intervals, and vertical printing. Horizontal printing performs better with reduced warpage. Additionally, both crystallinity and mechanical properties are significantly improved after heat treatment, and the best state is achieved after holding at 300 °C for 2 h. The resulting tensile strength is close to 80% of the strength of injection-molded PEEK parts.

The presented article deals with analyses and testing appropriate parameters for the production of components manufactured with rapid prototyping technology - Easy- 3DMaker printer. The quality of the printed component with a specific shape is analyzed. The analyzed materials are ABS Printplus and PLA Printplus. These materials are printed at different temperatures and speeds. combinations of different settings were tested in order to find the best conditions for printing with different nozzles. The quality of individual printed samples is assessed visually and by touch. The efficiency in terms of print time under various conditions was also analyzed. The main benefit of testing is the establishment of appropriate conditions for printing components on a Easy3DMaker printer. The article does not focus on mechanical properties of the examined samples. [ABSTRACT FROM AUTHOR]