Infill Rate Research Articles

How open‐stage melt crystallization affects tensile and shrinkage properties of 3D printed polypropylene

AbstractMelt crystallization of isotactic Polypropylene (PP) on open platform during 3D processing is critical and often challenging. Numerous factors that influence the melt extrusion of PP directly influence its crystallization and hence impact the physico‐mechanical properties of the printed parts. The present article represents a detailed investigation of the influence of 3D processing parameters on tensile and shrinkage properties of PP subject to respective melt‐crystallization behaviors. Moreover, the article also demonstrated the best experimental conditions that can produce mechanically stronger parts (even stronger than compression molded specimens used for comparison) with minimum warping. Influence of print temperature, bed temperature, print layer thickness (when the layer thickness varies by a margin of four folds), print orientation (horizontal or vertical), and infill rates was found to be highly sensitive towards melt crystallization of the PP dumbbell (which was printed as a product) hence brought about the highest variation in tensile and shrinkage properties. A print head temperature of above 220°C and a bed temperature of 60°C produced stronger dumbbells when printed with a higher layer thickness (0.20 mm/0.25 mm) in horizontal conditions with a 100% infill rate. Such specimens possessed higher tensile strength, and elongation at break values than the compression molded sample.

The Thermal and Mechanical Behaviour of Wood-PLA Composites Processed by Additive Manufacturing for Building Insulation.

This study was aimed at considering the potential of wood-based composites processed using additive manufacturing as insulators in the building sector. A polylactic acid blend with 30% wood particles was used as a feedstock material in fused filament technology. Its thermal and mechanical properties were determined for various processing conditions, including printing temperature and infill rate. The results showed a minor contraction in its tensile performance as a result of the printing process. The printing temperature had a negligible effect on its stiffness and a limited influence on the other engineering constants, such as the tensile strength and ultimate stress. The thermal properties of printed structures have been found to significantly depend on the infill rate. Although the tested 3D printed wood-PLA material exhibited good thermal properties, which were tuneable using the printing conditions, its performance was still 38% to 57% lower compared to insulators such as the glass wool of the synthetic foams used in the building sector.

3D printed cathodes for implantable abiotic biofuel cells

3D printing has recently triggered huge attention in several fields such as construction, artificial tissue engineering, food fabrication, wearable electronics, and electrochemical energy storage.This work investigates the fabrication of a 3D-printed abiotic cathode for implantable glucose/oxygen biofuel cells. The ink formulation was optimized to get printable ink with high electro-catalytic activity. Electrode macro porosity was screened in order to identify the better compromise between electrode density and electrochemical performance. A maximum current density of 260 μA/cm2 was obtained with cylindrical electrodes with linear mesh infill and a volumic infill rate of 40%.A complete biofuel cell was assembled using a 3D-printed abiotic cathode and an enzymatic anode in the form of a compressed pellet showing maximum power and current densities of 80 μW/cm2 and 320 μA/cm2, respectively. Moreover, the hybrid biofuel cell was implanted in the intraabdominal region of a rat for three months and after cell explantation, the abiotic cathode displayed a 50% decrease in the current density while the enzymatic anode did not display any residual activity.The 3D printed electrode displayed a 2–3.6 fold increase in current density when compared to homolog 2D electrodes.

Post-Ultraviolet-Curing Process Effects on Low-Velocity Impact Response of 3D Printed Polylactic Acid Parts

In this study, polylactic acid (PLA) parts produced with the 3D fused deposition modelling (FDM) technique were cured with ultraviolet irradiation (post-UV-curing) after production, and the low-velocity impact behaviour of the parts was experimentally investigated. Accordingly, PLA parts were subjected to post-UV-curing at 15-, 30-, 45-, and 60-minute periods. The impact behaviour of the specimens produced with production parameters of 200 °C printing temperature, 0.2 mm layer thickness, 50 mm/s printing speed, 100% infill rate, and 45° raster angle was compared with the raw specimens after the post-UV-curing process was applied. As a result of the impact tests, peak force, peak displacement, peak energy, and puncture energy values were obtained from the force-displacement graphs. It has been revealed that the post-UV-curing implementation increases the peak force values of PLA specimens and decreases the displacement values compared to the raw specimens. All specimens' impact behaviour improves with the post-UV-curing process; however, a decreasing trend is entered after 30 min.

Experimental and finite element analyses on the vibration behavior of 3D-printed PET-G tapered beams with fused filament fabrication

PurposeThis study aims to reveal the influences of three-dimensional (3D) printing parameters such as layer heights (0.1 mm, 0.2 mm and 0.4 mm), infill rates (40, 70 and 100%) and geometrical property as tapered angle (0, 0.25 and 0.50) on vibrational behavior of 3D-printed polyethylene terephthalate glycol (PET-G) tapered beams with fused filament fabrication (FFF) method.Design/methodology/approachIn this performance, all test specimens were modeled in AutoCAD 2020 software and then 3D-printed by FFF. The effects of printing parameters on the natural frequencies of 3D-printed PET-G beams with different tapered angles were also analyzed experimentally, and numerically (finite element analysis) via Ansys APDL 16 program. In addition to vibrational properties, tensile strength, elasticity modulus, hardness, and surface roughness of the 3D-printed PET-G parts were examined.FindingsIt can be stated that average surface roughness values ranged between 1.63 and 6.91 µm. In addition, the highest and lowest hardness values were found as 68.6 and 58.4 Shore D. Tensile strength and elasticity modulus increased with the increase of infill rate and decrease of the layer height. In conclusion, natural frequency of the 3D-printed PET-G beams went up with higher infill rate values though no critical change was observed for layer height and a change in tapered angle fluctuated the natural frequency values significantly.Research limitations/implicationsThe influence of printing parameters on the vibrational properties of 3D-printed PET-G beams with different tapered angles was carried out and the determination of these effects is quite important. On the other hand, with the addition of glass or carbon fiber reinforcements to the PET-G filaments, the material and vibrational properties of the parts can be examined in future works.Practical implicationsAs a result of this study, it was shown that natural frequencies of the 3D-printed tapered beams from PET-G material can be predicted via finite element analysis after obtaining material data with the help of mechanical/physical tests. In addition, the outcome of this study can be used as a reference during the design of parts that are subjected to vibration such as turbine blades, drone arms, propellers, orthopedic implants, scaffolds and gears.Social implicationsIt is believed that determination of the effect of the most used 3D printing parameters (layer height and infill rate) and geometrical property of tapered angle on natural frequencies of the 3D-printed parts will be very useful for researchers and engineers; especially when the importance of resonance is known well.Originality/valueWhen the literature efforts are scanned in depth, it can be seen that there are many studies about mechanical or wear properties of the 3D-printed parts. However, this is the first study which focuses on the influences of the both 3D printing parameters and tapered angles on the vibrational behaviors of the tapered PET-G beams produced with material extrusion based FFF method. In addition, obtained experimental results were also supported with the performed finite element analysis.

Biocompatible 3D printed yttria-stabilized zirconia parts using direct ink writing

Metals such as titanium or Cr-Co alloys have been the most widely used materials in biomedical applications that require high mechanical properties, like implants. However, these materials present the disadvantage of releasing ion metals into the body. As an alternative, prostheses made of ceramic materials have been developed, as they produce less debris and have better durability. The aim of the present work is to test the biocompatibility of 3D-printed yttria-stabilized zirconia parts by culturing human bone-marrow-derived mesenchymal stem cells. Two different scaffols were 3D printed having a liner infill pattern, with 80 % and 95 % infill rate respectively. Results on surface roughness and biocompatibility tests confirmed that 3 mol % yttria-stabilized zirconia is a highly promising material as it presented high biocompatibility. In adition, similar results were obtained with or without the use of a type I collagen coating., which suggest that coating could be avoided when on zirconia substraes.

Simulation of Fused Deposition Modeling of Glass Fiber Reinforced ABS Impact Samples: The Effect of Fiber Ratio, Infill Rate, and Infill Pattern on Warpage and Residual Stresses

It is known that products made of polymer materials or especially polymer materials with glass fiber and carbon fiber are used in many different areas such as automotive, aerospace, and defense. At this point, studies in the literature have gained momentum due to the combination of fiber-reinforced polymer materials emerging as a result of technological developments and industrial demands, and the fused deposition modeling (FDM) method providing the production of parts in desired sizes and complexity. Residual stresses and distortions occurring in polymer-based composite parts produced with FDM are among the problems that should be minimized. In this study, the influences of fiber ratio (%10, %15, and %20), infill rate (%20, %50, and %80), and infill pattern (line, honeycomb, and triangle) on the residual stresses and warpages generating in impact test specimens produced from glass fiber reinforced ABS filaments by fused deposition modeling were tried to be determined with the Digimat 2021 program. As a result of the findings, it was determined that the distortion values decreased and the thermal residual stress values went up with the increase in fiber ratio and infill rate. In addition, it can be reported that the distortions that bring out as a result of the separation of the produced parts from the production platform are caused by the high deformations condensing at the lower corner points of the parts.

Optimising fused filament fabrication surface roughness for a dental implant

ABSTRACT Medical applications of 3D Printing (3DP) have been investigated with dental implants and prosthetics since 2000. However, the use of 3DP in dental implants has been growing due to their ability to print scaffolds with functional characteristics. The present work optimizes a medical-dental implant 3D printed by the fused filament fabrication (FFF) technology in terms of three 3DPprocessing parameters, i.e. the infill rate (InfR), platform temperature (PlaT) and printing temperature (PriT). Furthermore, surface roughness is outlined in each case, and the parameter effects are explained while the printing time, shape quality and surface hardness are reported for the optimized implant. Additionally, a 3D printed dental implant with 0.16 mm Layer Thickness (LT) is utilized to show the pros and cons of the FFF technology versus the Poly Jet photopolymerization with 16 μm LT. Lastly, current challenges and future directions in FFF 3DP optimization issues of dental implants are also briefly outlined.

Experimental investigation of self-cleaning behaviour of 3D-printed textile fabrics with various printing parameters

Self-cleaning of textile fabrics is defined as the ability that the pollutants particles can be removed from the fabric surface without any external source. The application of the technology is beneficial to the environment since it conserves water, energy and laundry costs. In the past, it is typically obtained by chemical coatings, which develop low surface energy and high roughness on the fabric surface, allowing the pollutant particles or droplets to float over the surface rather than adhesion. These chemical coating methods are effective for fabrics manufactured by traditional woven-based textile technology. However, the recent advancements in 3D printing technology have evolved the manufacturing of textile fabrics but with equal challenges in self-cleaning as previous chemical coating-based methods are not useful for printed fabrics. A recent study has successfully established a linear regression model to demonstrate the relationship between secondary 3D printing parameters and the self-cleaning properties of different polymeric fabrics. This paper is intended to analyse the impact of the primary printing parameters on the self-cleaning attributes, including infill rate (IR), flow rate (FR), printing temperature (PT), printing speed (PS), and printing acceleration (PA). The experimental results were used to construct a regression polynomial to quantify the self-cleaning behaviour of the selected thermoplastic polyurethane (TPU) fabric. The models were validated experimentally to highlight the critical values of considered primary parameters for optimal self-cleaning behaviour. The obtained results indicated that FR was the most significant parameter, and all parameters affected the fabric's wettability almost equally.

Re-evaluation of the role of volatiles in the rupture of magma chambers and the triggering of crystal-rich eruptions

The role of volatile exsolution in triggering volcanic eruption is re-evaluated using numerical simulations of a growing and solidifying magma chamber. The modelled magma chamber is silicic, emplaced at about 2 Kbar, and H2O-saturated. The rate of volume additions to the chamber by the release of volatiles is controlled by cooling and solidification and is significantly lower than magma infilling rates. Thus, the increase in volume due to volatile exsolution is unlikely to be the primary cause of magma chamber failure unless the magma chamber is already on the brink of failure. However, the formation of buoyant H2O rich layers within the mush that surrounds the magma chamber makes the system gravitationally unstable. If the host rock is not permeable and volatiles accumulate, their buoyancy might overcome the strength of the wall resulting in dyke injection and possibly an eruption. Eruptions that are triggered or facilitated by volatiles exsolution are associated to the presence of mush in the chamber and are expected to be crystal-rich. Triggering of eruption by volatiles buoyancy explains the common occurrence of large ranges of crystals ages and protracted crystal residence times at low temperature.

A Test System for Safely Measurements of Cancer-Inducing UV-C Diodes Produced in a Simple and Cost-Effective Way by Rapid Prototyping

New technologies leading to better and more efficient light emitting diodes. The emitted radiation reaches higher energy levels and lower wavelengths especially in the UV-C spectrum. UV-C light has a cancer inducing effect on human cells. Therefore it is necessary to work in a safe way with those devices.
 This work is focused on an open-source solution for rapid 3D printing of an safe UV-C radiation measuring device. Especially for research groups or universities which can not afford big safety labs.
 After modeling and printing the prototype, a series of tests has shown the functionality of that UV-C Diode test system. By using black printing filaments and infill rates over 50 %, the transmission of light could be prevented and the system worked well.

Drainage and refill of an Antarctic Peninsula subglacial lake reveal an active subglacial hydrological network

Abstract. The presence of subglacial lakes and subglacial hydrological networks under the East and West Antarctic ice sheets is now relatively well understood, whilst their influence on ice dynamics is the subject of ongoing research. In contrast, little is known about subglacial lakes and hydrological networks under the Antarctic Peninsula Ice Sheet and how these are influencing glacier behaviour. Here we describe the rapid drainage and slow refill of a subglacial lake under Mars Glacier using remote sensing and aerogeophysics. Results suggest drainage of the subglacial lake occurred prior to 2011, resulting in the collapse of the overlying ice into the newly formed subglacial cavity. The cavity has been refilling since this time, with peak rates of infilling associated with seasonal surface meltwater activity. We review evidence for similar features elsewhere in the Antarctic Peninsula and discuss whether their appearance marks a threshold shift in glacier thermal regimes and the activation or enhancement of their subglacial hydrological networks by surface meltwater. Collectively, these features show coupling of climate processes and the bed of the region's glaciers highlighting their ongoing vulnerability to climate change.

Effect of infill pattern on fatigue characteristics of 3D printed polymers

The effect of the structure that is printed inside an object, known as infill pattern, on fatigue life of 3D printed specimens made of ABS was investigated in this paper. There are several infill pattern geometries, each with benefits and compromises between material usage, printing time or mechanical strength of the obtained part. Standard specimens with 100 % infill rate and rectilinear 0° and 90°, grid 0°–90° and ± 45°, triangular 60°, fast honeycomb, full honeycomb and wiggle infill patterns were tested. Following the completion of tensile tests to determine the ultimate tensile strength (UTS) of specimens, axial fatigue tests for each combination of infill pattern were conducted to measure the fatigue life for 90 %, 75 %, 60 %, 45 % and 40 % UTS. Comparative evaluation of the measured values revealed the strong influence of the printing patterns upon fatigue life. A simple mathematical model of the fatigue proprieties has been proposed for each infill patterns, statistical data shows that the proposed model ensures reasonably accurate prediction of fatigue life. The examination of fracture areas using electronic microscopy indicated the microstructural interaction between filaments underlying the main failure mechanisms, crazing, delamination and disbonding of the filaments and layers and their fracture. The results indicate that pattern with inclined filaments about tensile axis (grid±45°, rectilinear 0° and triangular 60°) have the maximum fatigue life compared with those with most of the filaments perpendicular to tensile direction (fast honeycomb, full honeycomb and rectilinear 90°). The pattern like grid 0°–90° and wiggle are very close to the first group, having filaments inclined (wiggle) or along and perpendicular to the tensile direction (grid 0°–90°).

Production of compression and flexural test samples in 3D printer with PLA polymeric biomaterial and bone compression with appropriate properties

In this study, it is planned to design and develop a structure close to the real bone strength properties by using PLA (polylactic acid) material. 3D printers have started to take place in our daily lives with today's developing technology and are preferred because of their ease of production and low cost. It has been determined that the PLA biomaterial can be used as a bone substitute in the body. The samples produced have different filling ratios and different internal structures. In the study, the effects of changes in the internal structure on the mechanical properties were investigated. Bone geometry is considered as an important factor among the parameters affecting biomechanical properties. In order to determine the mechanical properties of PLA filament material, bending and compression samples were prepared as 3 pieces for each test. The aim of this study is to determine whether it can be used as bone in the body by measuring the mechanical properties of biocompatible PLA polymer material. In the current work, the quality of the 3d printer and the material used in production directly affects the mechanical properties. In bones in the human body, trabecular bone has 80% porosity and cortical bone 10% infill. In this study, it was tried to obtain structures with properties close to real bone strength by using test specimens with different infill rates. It has been determined from the obtained data that PLA polymer material can be developed and meet the mechanical values in bone.

Infill Strategy in 3D Printed PLA Carbon Composites: Effect on Tensile Performance.

Tuning the infill pattern is one of the key features in additive manufacturing to optimise part weight. In this work, the effect of the infill strategy, including rate and pattern type, is studied on the mechanical performance of polylactic acid (PLA)-carbon composite. In particular, three types of patterns and four filling levels are combined. These combinations are evaluated by tensile loading applied on dogbone specimens. In addition, the underlined deformation mechanisms are further explored using filament-based finite element model. The numerical simulation is built from sliced models and converted into 3D meshes to predict tensile performance. The results show that the infill rate has a nonlinear effect on the density of PLA–carbon composites, and its magnitude depends on the complexity of the generated pattern. In addition, tensile loading is found to activate varied modes of shearing and uniaxial deformations depending on the pattern type. This leads to different profiles and rankings of the tensile performance and allows the infill strategy to significantly affect the part performance, along with its density.

SOPHIE: Soft and Flexible Aerial Vehicle for Physical Interaction With the Environment

This letter presents the first design of a soft and lightweight UAV, entirely 3D-printed in flexible filament. The drone's flexible arms are equipped with a tendon-actuated bending system, which is used for applications that require physical interaction with the environment. The flexibility of the UAV can be controlled during the additive manufacturing process by adjusting the infill rate <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\rho _{TPU}$</tex-math></inline-formula> distribution. However, the increase in flexibility implies difficulties in controlling the UAV, as well as structural, aerodynamic, and aeroelastic effects. This article provides insight into the dynamics of the system and validates the flyability of the vehicle for densities as low as 6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> . Within this range, quasi-static arm deformations can be considered, thus the autopilot is fed back through a static arm deflection model. At lower densities, strong non-linear elastic dynamics appear, which translates to complex modeling, and it is suggested to switch to data-based approaches. Moreover, this work demonstrates the ability of the soft UAV to perform full-body perching, specifically landing and stabilizing on pipelines and irregular surfaces without the need for an auxiliary system.

Mechanical Properties of Fused Deposition Modeling of Polyetheretherketone (PEEK) and Interest for Dental Restorations: A Systematic Review.

The aim of this systematic review was to determine the optimal printing parameters for the producing of fused deposition modeling (FDM) 3D-printed polyetheretherketone (PEEK) elements with mechanical properties suitable for dental restorations. Indeed, the mechanical properties are a critical prerequisite for the study of other parameters, such as physical, aesthetic and biological properties. An exhaustive electronic search was carried out in the PubMed, Embase and Web of knowledge databases to gather all the studies evaluating the influence of the printing parameters on the obtained mechanical properties of FDM 3D-printed PEEK elements were selected. Initially, the search resulted in 614 eligible papers. Independent screenings of the abstracts were performed by two authors to identify the articles related to the question. Twenty-nine studies were selected, of which eleven were further excluded after reading of the full text, and finally, eighteen articles were included in this review. The studies were difficult to compare due to the variability of the printing parameters and the types of PEEK. However, it seems interesting to use a high infill rate, a high chamber temperature close to that of the printing temperature and a heat post-treatment to obtain 3D PEEK elements presenting properties adapted to use as dental restorations. The analysis of the available literature suggested that the properties of PEEK could make it an interesting material in dental restorations to be performed with FDM additive manufacturing.

Study on the radiological characteristics of metal infilled filaments for three-dimensional printing according to the infill rate and pattern

Study on the radiological characteristics of metal infilled filaments for three-dimensional printing according to the infill rate and pattern

Mechanical and Thermal Properties of 3D Printed Polycarbonate

This study aims at showing the potential of additive manufacturing as a new processing route for designing future insulators in the building sector. Polycarbonate (PC) is studied as a possible candidate for designing these new insulators. This polymer offers several advantages, among them fire resistance and stability of its physical properties at high temperatures. The 3D printing of PC is attempted using fused deposition modelling technology. The printing temperature and infill rate are varied to achieve optimal mechanical and thermal characteristics. The results show that an optimal printing temperature of 280 °C is needed to achieve high tensile performance. In addition, thermal properties including thermal conductivity and effusivity increase with the increase of the infill rate in opposition to the thermal diffusivity decrease.

Numerical Investigation of the Infill Rate upon Mechanical Proprieties of 3D-Printed Materials.

The paper proposes a novel method of numerical simulation of the fused deposition molding 3Dprinted parts. The single filaments are modeled by a script using the G-code of the 3D printer. Based on experimental evaluation of the cross-sectional geometry of a printed tensile specimen, the connection between the filaments is determined and the flattening effect of the filaments can be counted. Finite element (FE) simulations considering different element lengths were validated by experimental tests. The methodology allows, on one hand, numerical estimation of the true cross-sectional area of a specimen and correction of the experimental stress-strain curves and, on the other hand, accurate determination of the E-modulus of a printed tensile specimen with different deposition densities (20%, 40%, 60%, 80% and 100% infill rate). If the right method to connect the single filaments is established and validated for a 3D printer, the mechanical properties of the 3D specimens can be predicted without physical tensile test, only using FE method, which will allow the designers to print out the parts with variable infill rate and tunable stiffness only after the FE result are suitable for their needs, saving considerably materials and time.