Academic literature on the topic 'Infill percentage'

Abstract Commonly used 3D printed samples are partially infilled to reduce time and cost of printing, with mechanical properties dependent on the infill. In this work, the influence of the percentage and pattern of infill in PLA printed samples on the elastic modulus and characteristic stresses was analyzed. The elastic modulus, E, and characteristic stresses (σ 0.2, σ 4 and the maximum tensile stress) were determined for each sample using impulse excitation technique, IET, and uniaxial tensile tests. An apparent density was calculated for each pattern and infill percentage, and the mechanical parameters were studied as a function of such density. The results of IET obtained in different modes of vibration were analyzed and an apparent value of E was calculated. FEM simulations were carried out and the results were compared with the experimental ones. The mechanical properties for different infill percentages and infill patterns were studied by comparing the specific values of E and the stresses. Samples with higher infill percentages exhibit the best specific values of maximum stress and E, but the sample with 20% infill has the highest specific yield stress and a good value of the specific E from flexural vibrations.

The current study explores the effects of geometrical shapes of the infills on the 3D printed polylactic acid (PLA) plastic on the tensile properties. For this purpose, by utilizing an accessible supply desktop printer, specimens of diamond, rectangular, and hexagonal infill patterns were produced using the fused filament fabrication (FFF) 3D printing technique. Additionally, solid samples were printed for comparison. The printed tensile test specimens were conducted at environmental temperature, Ta of 23 °C and crosshead speed, VC.H of 5 mm/min. Mainly, this study focuses on investigating the percentage infill with respect to the cross-sectional area of the investigated samples. The mechanical properties, i.e., modulus of toughness, ultimate tensile stress, yield stress, and percent elongation, were explored for each sample having a different geometrical infill design. The test outcomes for each pattern were systematically compared. To further validate the experimental results, a computer simulation using finite element analysis was also performed and contrasted with the experimental tensile tests. The experimental results mainly suggested a brittle behavior for solidly infilled specimen, while rectangular, diamond, and hexagonal infill patterns showed ductile-like behavior (fine size and texture of infills). This brittleness may be due to the relatively higher infill density results that led to the high bonding adhesion of the printed layers, and the size and thickness effects of the solid substrate. It made the solidly infilled specimen structure denser and brittle. Among all structures, hexagon geometrical infill showed relative improvement in the mechanical properties (highest ultimate tensile stress and modulus values 1759.4 MPa and 57.74 MPa, respectively) compared with other geometrical infills. Therefore, the geometrical infill effects play an important role in selecting the suitable mechanical property’s values in industrial applications.

This study aims to analyze the effect of infill parameters on the tensile strength of Acrylonitrile Butadiene Styrene (ABS) filament in the 3D printing process for the manufacture of prototype cat prosthetics. ABS filament was chosen because it has good mechanical strength, resistance to high temperatures, and the ability to be further processed after printing. The infill parameters studied include infill percentage, layer thickness, and print speed. The research methodology involved making test samples with varying infill percentages, which were then tested using a tensile testing machine to measure the maximum tensile strength. The infill percentage was varied between 25%, 50%, 80%, and 100%. Tensile strength testing was conducted in accordance with ASTM D638 standards to determine the mechanical characteristics of the molded specimens and then the optimal infill parameters were applied in the design and manufacture of the cat prosthetic leg prototype, ensuring better load distribution and higher durability. The results show that the percentage density of infill has a positive correlation with the tensile strength of the specimen; an increase in infill density increases the tensile strength of the material. The findings provide practical guidance in the selection of infill parameters for tensile strength optimization in 3D printing applications using ABS filament so that it can be known that the influence of infill parameters greatly affects the strength of manufacturing.

Masonry infills are usually treated as nonstructural elements in buildings, and their interaction with the bounding frame is often ignored in analysis and design of reinforced concrete structures. The main aim of this study is to develop a seismic fragility curves showing the probability of exceeding a damage limit state for a given structure type subjected to a seismic excitation. For the purpose of this study, three distinct buildings namely, seven-story, eleven-story and sixteen-story, with typical floor plan were proposed as the case study. Each building cases are explicitly modeled as a bare frame and HCB infilled model with varying percentage of infill configurations. All building models under the case study were analyzed using Seismo-Struct software to assess seismic vulnerabilities. Non-linear dynamic time history and pushover analysis were employed to generate fragility curves. 30 generated artificial accelerograms were employed in the nonlinear dynamic time history analysis. Accordingly, for developing a fragility curve, nonlinear dynamic analyses of 30 building models for each case are conducted and the maximum roof displacement (ID) for each ground motion is recorded. Results of the study showed that bare frame has a highest probability of failure and building models with a larger percentage of infill configurations have lesser failure probability than slightly infilled building models. Basically these infills have significant contribution in arresting large lateral deflections and results in lower and most tolerable story displacements under excited earthquake motion and eventually reducing the structure’s probability of failure at life safety and collapse prevention limit states

The paper presents investigations of the mechanical properties of PLA plastic samples produced by a 3D printer under tension. The dependence of the maximum load on the selected 3D printing parameters (infill patterns and infill percentage) is compared. Octet, Zig Zag, Triangles and Grid infill pattern and infill percentage 50% and 90% are used. Keywords: 3D printing, infill, tension.

Injection molding (IM) normally made from steel, such as STAVAX because of its ability to withstand molding forces such as clamping, injection, and holding force. Beside of this ability, the fabrication of steel insert requires machining as such CNC machining and electro discharge machining (EDM). In contrast, a 3D printed mold insert can overcome of these constraints as it can be printed in less time and cost compared to conventional method of insert fabrication. In this research, a mold insert is fabricated using a 3D printer with a key chain shape cavity. The 3D printed insert are printed using fused deposition modelling (FDM) 3D printer with a three different infill, namely 50%, 75%, and 100% infill percentage. This could determine the performance of the 3D printed insert with the infill percentage. After several test conducted at injection molding, it is found that the infill percentage could improve the insert life span. The 100% infill contributed to longer life of the insert compared to 50% and 75% infill percentage. As the molten polymer is injected into the mold, the polymer tends to fill the void of the insert with the infill percentage of 50% and 75%. As the insert with 100% infill is used, the void is eliminated, thus the cavity can be filled with the molten polymer efficiently. From this research, the capabilities of 3D printed mold insert with different infill percentage is determined.

The rapid advancement of additive manufacturing (AM) technologies has provided new avenues for creating three-dimensional (3D) parts with intricate geometries. Fused Deposition Modeling (FDM) is a prominent technology in this domain, involving the layer-by-layer fabrication of objects by extruding a filament comprising a blend of polymer and metal powder. This study focuses on the FDM process using a filament of Copper–Polylactic Acid (Cu-PLA) composite, which capitalizes on the advantageous properties of copper (high electrical and thermal conductivity, corrosion resistance) combined with the easily processable thermoplastic PLA material. The research delves into the impact of FDM process parameters, specifically, infill percentage (IP), infill pattern (P), and layer thickness (LT) on the maximum failure load (N), percentage of elongation at break, and weight of Cu-PLA composite filament-based parts. The study employs the response surface method (RSM) with Design-Expert V11 software. The selected parameters include infill percentage at five levels (10, 20, 30, 40, and 50%), fill patterns at five levels (Grid, Triangle, Tri-Hexagonal, Cubic-Subdivision, and Lines), and layer thickness at five levels (0.1, 0.2, 0.3, 0.4, and 0.5 mm). Also, the optimal factor values were obtained. The findings highlight that layer thickness and infill percentage significantly influence the weight of the samples, with an observed increase as these parameters are raised. Additionally, an increase in layer thickness and infill percentage corresponds to a higher maximum failure load in the specimens. The peak maximum failure load (230 N) is achieved at a 0.5 mm layer thickness and Tri-Hexagonal pattern. As the infill percentage changes from 10% to 50%, the percentage of elongation at break decreases. The maximum percentage of elongation at break is attained with a 20% infill percentage, 0.2 mm layer thickness, and 0.5 Cubic-Subdivision pattern. Using a multi-objective response optimization, the layer thickness of 0.152 mm, an infill percentage of 32.909%, and a Grid infill pattern was found to be the best configuration.

3D printing technology was capable of fabricating phantoms to enhance quality assurance in radiation therapy. The ideal phantom has properties equivalent to the real tissue. However, 3D Printing has the limits to mimicking the attenuation properties of various tissues because during 3D printing there can be only one type of material. The purpose of this study was to evaluate the effect of infill percentage and infill patterns of 3D printing technology to simulate various types of tissue. This study used 25 samples measuring 5 × 5 × 1 cm3 from PETG material. The 20 samples were printed using variations infill percentages from 5 - 100% and the infill pattern in lines. The five samples were then printed with the infill percentage constant at 50% and used the infill pattern triangles, grid, gyroid, octet, and concentric. We used Computed Tomography (CT) to determine the Hounsfield Unit (HU) value for each sample and evaluated the suitability of each sample for phantom applications in radiation therapy and radiology. However, none of the samples was able to simulate compact bone. As a result, we found that PETG material could simulate the properties of soft tissue, fat, lung, kidney, liver, pancreas, and spongy bone. Thus, the study had shown promising potential for the fabrication of the anthropomorphic phantom of radiation therapy.

This article introduces a multi-objective optimization approach for determining the best 3D printing parameters (layer thickness and infill percentage) to efficiently produce PLA and ABS parts, extensively analyzing mechanical behavior under tests for different traits such as tensile strength, compression, flexural, impact, and hardness. The value analysis method is used to optimize settings that balance use value (Vi- represented by mechanical characteristics) and production cost (Cp). Findings reveal that the infill percentage significantly influences the Vi/Cp ratio for tensile, compression, and hardness tests, while flexural tests are influenced by layer thickness. Impact strength is influenced nearly equally by both factors, with material-specific variations. The desirability function proved useful for optimizing processes with multiple responses, identifying the optimal parameters for the FDM process: a layer thickness of 0.15 mm with 100% infill percentage for PLA, a layer thickness of 0.20 mm with 100% infill percentage for annealed PLA, and a layer thickness of 0.15 mm with 100% infill percentage for ABS. Overall, this study guides efficient 3D printing parameter selection through a technical-economic optimization based on value analysis.

This paper contributes a concurrent topological structure and cross-infill angle optimization method for material extrusion type additive manufacturing (AM). This method features in modeling the process-induced material anisotropy through microscopic geometric modeling obtained by scanning electron micrographs. Numerical homogenization is performed to evaluate the equivalent effective properties of the 100-percentage cross-infilled local microstructures, and by introducing fitting functions, the relationship between equivalent effective material properties and varying cross-infill angles is empirically constructed. Then, optimization problems involving cross-infill angles as design variables are formulated, including concurrent optimization formulation. Numerical and experimental studies are conducted to illustrate the effectiveness of the proposed method. Both the numerical and experimental results demonstrate that the structural stiffness obtained by our proposed method has evidently improved.

Despite significant efforts have been directed toward reducing waste generation and encouraging alternative waste management strategies, landfills still remain the main option for Municipal Solid Waste (MSW) disposal in many countries. Hence, landfills and related impacts on the surroundings are still current issues throughout the world. Actually, the major concerns are related to the potential emissions of leachate and landfill gas into the environment, that pose a threat to public health, surface and groundwater pollution, soil contamination and global warming effects. To ensure environmental protection and enhance landfill sustainability, modern sanitary landfills are equipped with several engineered systems with different functions. For instance, the installation of containment systems, such as bottom liner and multi-layers capping systems, is aimed at reducing leachate seepage and water infiltration into the landfill body as well as gas migration, while eventually mitigating methane emissions through the placement of active oxidation layers (biocovers). Leachate collection and removal systems are designed to minimize water head forming on the bottom section of the landfill and consequent seepages through the liner system. Finally, gas extraction and utilization systems, allow to recover energy from landfill gas while reducing explosion and fire risks associated with methane accumulation, even though much depends on gas collection efficiency achieved in the field (range: 60-90% Spokas et al., 2006; Huitric and Kong, 2006). Hence, impacts on the surrounding environment caused by the polluting substances released from the deposited waste through liquid and gas emissions can be potentially mitigated by a proper design of technical barriers and collection/extraction systems at the landfill site. Nevertheless, the long-term performance of containment systems to limit the landfill emissions is highly uncertain and is strongly dependent on site-specific conditions such as climate, vegetative covers, containment systems, leachate quality and applied stress. Furthermore, the design and operation of leachate collection and treatment systems, of landfill gas extraction and utilization projects, as well as the assessment of appropriate methane reduction strategies (biocovers), require reliable emission forecasts for the assessment of system feasibility and to ensure environmental compliance. To this end, landfill simulation models can represent an useful supporting tool for a better design of leachate/gas collection and treatment systems and can provide valuable information for the evaluation of best options for containment systems depending on their performances under the site-specific conditions. The capability in predicting future emissions levels at a landfill site can also be improved by combining simulation models with field observations at full-scale landfills and/or with experimental studies resembling landfill conditions. Indeed, this kind of data may allow to identify the main parameters and processes governing leachate and gas generation and can provide useful information for model refinement. In view of such need, the present research study was initially addressed to develop a new landfill screening model that, based on simplified mathematical and empirical equations, provides quantitative estimation of leachate and gas production over time, taking into account for site-specific conditions, waste properties and main landfill characteristics and processes. In order to evaluate the applicability of the developed model and the accuracy of emissions forecast, several simulations on four full-scale landfills, currently in operative management stage, were carried out. The results of these case studies showed a good correspondence of leachate estimations with monthly trend observed in the field and revealed that the reliability of model predictions is strongly influenced by the quality of input data. In particular, the initial waste moisture content and the waste compression index, which are usually data not available from a standard characterisation, were identified as the key unknown parameters affecting leachate production. Furthermore, the applicability of the model to closed landfills was evaluated by simulating different alternative capping systems and by comparing the results with those returned by the Hydrological Evaluation of Landfill Performance (HELP), which is the most worldwide used model for comparative analysis of composite liner systems. Despite the simplified approach of the developed model, simulated values of infiltration and leakage rates through the analysed cover systems were in line with those of HELP. However, it should be highlighted that the developed model provides an assessment of leachate and biogas production only from a quantitative point of view. The leachate and biogas composition was indeed not included in the forecast model, as strongly linked to the type of waste that makes the prediction in a screening phase poorly representative of what could be expected in the field. Hence, for a qualitative analysis of leachate and gas emissions over time, a laboratory methodology including different type of lab-scale tests was applied to a particular waste material. Specifically, the research was focused on mechanically biologically treated (MBT) wastes which, after the introduction of the European Landfill Directive 1999/31/EC (European Commission, 1999) that imposes member states to dispose of in landfills only wastes that have been preliminary subjected to treatment, are becoming the main flow waste landfilled in new Italian facilities. However, due to the relatively recent introduction of the MBT plants within the waste management system, very few data on leachate and gas emissions from MBT waste in landfills are available and, hence, the current knowledge mainly results from laboratory studies. Nevertheless, the assessment of the leaching characteristics of MBT materials and the evaluation of how the environmental conditions may affect the heavy metals mobility are still poorly investigated in literature. To gain deeper insight on the fundamental mechanisms governing the constituents release from MBT wastes, several leaching experiments were performed on MBT samples collected from an Italian MBT plant and the experimental results were modelled to obtain information on the long-term leachate emissions. Namely, a combination of experimental leaching tests were performed on fully-characterized MBT waste samples and the effect of different parameters, mainly pH and liquid to solid ratio (L/S,) on the compounds release was investigated by combining pH static-batch test, pH dependent tests and dynamic up-flow column percolation experiments. The obtained results showed that, even though MBT wastes were characterized by relatively high heavy metals content, only a limited amount was actually soluble and thus bioavailable. Furthermore, the information provided by the different tests highlighted the existence of a strong linear correlation between the release pattern of dissolved organic carbon (DOC) and several metals (Co, Cr, Cu, Ni, V, Zn), suggesting that complexation to DOC is the leaching controlling mechanism of these elements. Thus, combining the results of batch and up-flow column percolation tests, partition coefficients between DOC and metals concentration were derived. These data, coupled with a simplified screening model for DOC release, allowed to get a very good prediction of metal release during the experiments and may provide useful indications for the evaluation of long-term emissions from this type of waste in a landfill disposal scenario. In order to complete the study on the MBT waste environmental behaviour, gas emissions from MBT waste were examined by performing different anaerobic tests. The main purpose of this study was to evaluate the potential gas generation capacity of wastes and to assess possible implications on gas generation resulting from the different environmental conditions expected in the field. To this end, anaerobic batch tests were performed at a wide range of water contents (26-43 %w/w up to 75 %w/w on wet weight) and temperatures (from 20-25 °C up to 55 °C) in order to simulate different landfill management options (dry tomb or bioreactor landfills). In nearly all test conditions, a quite long lag-phase was observed (several months) due to the inhibition effects resulting from high concentrations of volatile fatty acids (VFAs) and ammonia that highlighted a poor stability degree of the analysed material. Furthermore, experimental results showed that the initial waste water content is the key factor limiting the anaerobic biological process. Indeed, when the waste moisture was lower than 32 %w/w the methanogenic microbial activity was completely inhibited. Overall, the obtained results indicated that the operative conditions drastically affect the gas generation from MBT waste, in terms of both gas yield and generation rate. This suggests that particular caution should be paid when using the results of lab-scale tests for the evaluation of long-term behaviour expected in the field, where the boundary conditions change continuously and vary significantly depending on the climate, the landfill operative management strategies in place (e.g. leachate recirculation, waste disposal methods), the hydraulic characteristics of buried waste, the presence and type of temporary and final cover systems.

This study examines the impact of printing parameters on fused filament fabrication (FFF) parts using PLA and ABS filament. It aims to determine the ideal conditions for increasing the strength of these materials. The study uses Taguchi's method to determine the effects of infill percentage, wall line count, and infill pattern on the materials' mechanical characteristics. PLA is found to be more rigid and have higher tensile strength than ABS. The optimal combination of manufacturing parameters can result in higher PLA strength.

Additive manufacturing (AM) is a process of generating prototypes or usable parts with minimum amount of material, technology, and time. The forerunner for technology and material for AM are Fused Deposition Method (FDM) and Polylactic Acid (PLA), respectively. There are numerous works in FDM devoted to studying the effect of processing conditions on the part strength. However, no significant effort has been made to develop an understanding of the effects of the nozzle diameter, extrusion temperature, infill percentage, infill pattern, and the number of outer shells in minimizing print time & raw materials without sacrificing significant part strength. This research intends to conduct a multi-objective approach in identifying significant factors that will affect the target response. It was observed that nozzle diameter, wall thickness and infill density are the significant factors that may affect strength, build time and material consumption. In Scanning Electron Microscope (SEM) results, it was observed that the more voids seen at fracture would result to lesser strength. Lastly, a regression equation was generated to guide future researchers and end-users in predicting response in consideration of the factors (or parameters) involved in this experiment.

Abstract We study a new class of infill patterns, that we call wallpaper-infills for additive manufacturing based on space-filling shapes. To this end, we present a simple yet powerful geometric modeling framework that combines the idea of Voronoi decomposition space with wallpaper symmetries defined in 2-space. We first provide a geometric algorithm to generate wallpaper-infills and design four special cases based on selective spatial arrangement of seed points on the plane. Second, we provide a relationship between the infill percentage to the spatial resolution of the seed points for our cases thus allowing for a systematic way to generate infills at the desired volumetric infill percentages. Finally, we conduct a detailed experimental evaluation of the of these four cases to study their mechanical behavior under tensile loading.

Abstract. The present paper aims to assess the effect of different infill percentages and patterns on the compressive mechanical properties of specimens in Polyamide PA6 reinforced with 20% glass fibers (GF) and 10% carbon fibers (CF) printed using the Fused Deposition Modeling (FDM) technology. According to the ASTM D695-15 standard, cylindrical specimens were designed and processed through slicing software, configuring infill percentages and patterns. Three different typologies of infill pattern and two infill percentages were considered: a 100% grid infill, a 50% grid infill, a 100% concentric infill and a 50% honeycomb infill were printed. Then, compression tests were performed at room temperature to evaluate the properties of the different specimens. The comparison between the stress-strain compression curves has shown that the infill percentages and patterns significantly affect the mechanical compression properties of 3D printed components.

A set of monotonic tensile tests was performed on 3-D printed plastics following ASTM standards. The experiment tested a total of 13 “dog bone” test specimens where the material, infill percentage, infill geometry, load orientation, and strain rate were varied. Strength-to-weight ratios of the various infill geometries were compared. It was found through tensile testing that the specific ultimate tensile strength (MPa/g) decreases as the infill percentage decreases and that hexagonal pattern infill geometry was stronger and stiffer than rectilinear infill. However, in finite element analysis, rectilinear infill showed less deformation than hexagonal infill when the same load was applied. Some design guidelines and future work are presented.

Abstract This work investigated the influence of raster angle and infill percentage on selected mechanical properties of two commonly used 3D Printed materials: Polyethylene Terephthalate Glycol (PETG) and High Impact Polystyrene (HIPS) at room temperature. Their Elastic Modulus, Yield Strength, and Toughness were experimentally determined and compared for infill densities of 5%, 25%, 50%, 75%, and 100%, and raster angles of 0/90, 45/45, and 30/60. The materials were printed using Fused Deposition Modeling per ASTM D638-22 standards, with a layer thickness of 0.3 mm, an initial layer speed of 35 mm/s, and an infill speed of 50 mm/s. The initial layer speed and infill speeds were 35 mm/s and 50 mm/s, respectively. The team concluded that PETG material, on average, outperformed HIPS when looking at Young’s Modulus of the printed samples. There are few instances where HIPS has a higher Young’s Modulus, i.e., 45-45 at infill 100%, 45-45 at infill 50%, and 30-60 at infill 100%. The PETG samples often exceeded the toughness of HIPS as well. As seen in the tables, there are a few cases in which HIPS has much higher toughness than the same raster and infill percentage as PETG. For instance, HIPS samples at 0-90 angles and infill percentages of 50% and 75%. Overall, the team concluded that PETG, on average, outperforms HIPS in both Young’s Modulus and toughness during the testing. PETG would be suitable for most situations, whereas HIPS would fail more often if substituted for PETG.

This study uses the Taguchi method to optimize 3D printing conditions and identify key factors influencing fabrication time and dimensional accuracy. Three input parameters—printing speed, layer height, and infill percentage—were tested at three levels using Minitab software to analyze results via Analysis of Variance (ANOVA). 3D models were designed in CAD software, exported in STL format, and processed with software for 3D printing on a 3D printer using FDM technology. Dimensional accuracy was verified with a 3D scanner. Results showed that layer height significantly affected print time, with larger heights reducing it due to fewer layers. Infill percentage also influenced print time, with lower percentages speeding up fabrication. Although printing speed mattered, it wasn't statistically significant. This research offers valuable insights for optimizing 3D printing parameters, enhancing quality and efficiency in part production.

Abstract Fused Deposition Modeling (FDM) 3D printing has evolved from a prototyping tool to a multifaceted manufacturing technique. To fully harness its capabilities, improving production repeatability, efficiency, and material quality is essential. This study explores the relationship between nozzle diameters and two common filaments: polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS). Nozzle diameter is crucial in FDM 3D printing, influencing print quality, speed, and material flow. However, the impact of varying nozzle diameters on different filaments is underexplored. Our research fills this gap, providing key insights. We found significant differences in print quality and mechanical properties across various nozzle diameters and materials. Smaller nozzles generally produce better quality prints and surface finishes but take longer. Material-specific nozzle selection is important, as some filaments work better with certain nozzle sizes. PLA performs well across various sizes, showing excellent print quality and robustness. ABS is sensitive to larger nozzles due to its high printing temperature needs. Our findings offer valuable guidelines for selecting nozzle sizes tailored to specific filaments, enhancing 3D printing efficiency, precision, and quality. These insights are particularly beneficial for industries like automotive and consumer goods, where precision and customization are crucial. Understanding nozzle diameter and filament dynamics can also lead to advanced printing algorithms and material formulations, optimizing multi-material printing and other complex applications.

Abstract This work investigates the difference in impact response of sheet extruded vs 3D printed Polyethylene Terephthalate Glycol (PETG) and High Impact Polystyrene (HIPS). The effect of a machined notch vs a 3D printed notch, the effect of the raster angle, and the role of percentage infill are also examined. IZOD impact energies at temperatures ranging from −50°C to 50°C in 5°C intervals are experimentally obtained for 3D printed and extruded specimens. 3D printed specimens tested had 25% infill, 100% infill, 60° raster angle, 90° raster angle with machined and 3D printed notches. For a 90°-raster angle, increasing infill percentage from 25% to 100% may increase the impact strength of 3D printed PETG and HIPS by 20% and 42% respectively. These gains do not seem to occur for a 60°-raster angle, neither were these gains consistent for machined notched specimens. 3D printing PETG or HIPS will generally result in materials whose DBT regions will have slopes up to 70% gentler than their sheet extruded counterparts. An increase in raster angle from 60° to 90° may reduce the DBT slope by up to 60% for either material. If an adjustment of the DBT slope is sought by altering the infill percentage for these 3D printed materials, careful attention must be paid to the raster angle used.

Abstract Additive manufacturing provides a rapid manufacturing method for a variety of materials with different applications. Thermoplastic Polyurethane (TPU) is a soft polymer material that can be 3D printed. In this work, we explore the mechanical properties of a 3D printed grid pattern structure with TPU. By changing the pattern’s cell size and wall thickness parameters, we control the density of the grid lattice and, as a result, the bulk elastic modulus of the structure. We compare simulation and physical compression tests and conclude that the bulk elastic modulus of a print is related to the infill percentage according to a cubic relationship, with higher infill percentage samples resulting in higher elastic moduli. The precise cell size and wall thickness parameter values are minor influences comparatively. The elastic moduli of the resulting samples span from 0.36 MPa with 23.44% infill to 21.83 MPa with 75% infill, compared to an elastic modulus of 64.31 MPa when printing at 100% density. We also explore other factors such as the sample size, the printer, the build orientation, and the sample geometry. The results have uses in a variety of applications, including a custom linear spring, a bistable gripper, or a soft robot finger.

Abstract Thermoplastic polyurethanes (TPU) are increasingly being used in additive manufacturing design due to their abilities to exhibit extreme elastic properties under an applied stress. In this work, processing parameters in material extrusion (ME) of TPU filaments were investigated to provide a model for component stiffness as a function of the printing conditions. This model allows designers to target processing parameters and conditions to meet constraints of stiffness within flexible components. In this study, a full factorial design of experiments methodology was employed to provide a systematic method for experimentally analyzing the influence and effect of number of outer shells, infill percentage, and infill pattern on compressive strength. Based on the data collected from these experiments, a statistical regression model is presented that can be used to predict rigidity in TPU parts manufactured through material extrusion. Based on the results of the initial model, additional investigations were carried out into impact of number of infill line intersections, exterior corners, and TPU hardness (shore 85A and 95A). It was found that shore hardness and infill percentage had the largest impact with respect to stiffness but that all factors were significant and the only interaction not significant at α = 0.05 was the two-factor interaction of infill pattern and number of external shells. The effect of exterior corners were highlighted due to their additional stiffness as they essentially act as thicker columns in the perimeter of the parts.