Infill selection for 3D printed radiotherapy immobilisation devices

The advent of additive manufacturing has revolutionized the prototyping, design, and manufacturing of new and innovative products. Through the use of Fused Deposition Modeling (FDM), parts can be manufactured using different sparse infill percentages (the percentage of void space within a printed object) and sparse infill patterns (the lattice structure of material within the object). Through the manipulation of these variables, the same material and part can have different compressive and flexural properties. In addition to sparse infill, the thermoplastics used in fused deposition modeling can be reinforced with carbon fiber strands to create a printable composite material capable of strengthening and stiffening parts without increasing the amount of material used. This experiment evaluated the yield stress performance of 3DXTech’s CarbonX PETG+CF filament printed at varying infill densities and infill patterns in hopes of characterizing the minimum structural properties of commonly used lattice structures. The infill patterns were evaluated at 15%, 35%, 50%, and 75% along with a baseline 100% infill with no internal pattern. The two-dimensional infill patterns (infill patterns that do not vary along the z-axis) rectilinear and triangles along with the three-dimensional infill patterns (infill patterns that vary along the z-axis) cubic, gyroid, and 3D honeycomb were tested on the surface perpendicular to the print orientation in order to test the minimum compressive strength of each specimen. All test specimens used were derived from the same STL document and manufactured by Bambo Lab’s X1 Carbon at a resolution of 0.2mm with a nozzle temperature of 260 oC, and the printer was programmed using the g-code created by Bambu Lab’s Bambu Studio slicing software. For each infill density and infill pattern, four test specimens were tested to failure using the Shimadzu Autograph AGX-V2 and its associated software. The yield strength, absolute strength, and stress vs. strain graph of each specimen were derived from the data collected along with photography and projectional radiography of the failure mode. The findings of this research can be summarized as three-dimensional infill patterns being characterized as having larger yield stresses than two dimensional infill patterns along their weakest face, increasing infill density universally increases the yield stress of the object, and objects of higher infill densities buckle at the middle of the specimen, acting as uniform bodies, while lower infill densities tend to buckle at the top and bottom of the specimen. More research is needed to further characterize the effects of stress on PETG-CF lattice structures, but this research can be used to guide the selection of print parameters depending on expected compressive loads.

Additive manufacturing such as 3D printing is considered as a highly convenient manufacturing process since it enables to create any 3D objects. It is known that different materials, printing techniques, and printing parameters are affecting the mechanical properties of the printed objects. However, studies on the mechanical properties of the 3D printed structure are still limited. In this work, investigation of the relationship between two printing parameters, i.e. infill pattern and infill density were conducted on the Polylactic Acid (PLA) material. Three infill densities, 25%, 50%, and 75%, and three infill patterns, grid, tri-hexagon, and concentric, were chosen. The tensile test, ASTM D638, was employed to obtain the material properties based on these two printing parameters. An open-source 3D printing slicer software, Cura, was used to manufacture the tensile specimens. The Young’s modulus, yield strength, and ultimate strength were recorded and examined. The results showed that the tensile properties increase as infill density increases. Of the three-printing pattern, the concentric has the highest values of tensile properties regardless of the infill densities. This finding can be used as a reference for creating a finite element model (FEM) as well as predicting the optimum tensile properties with respect to the printing parameters.

Fused deposition modeling (FDM) is an additive manufacturing process that builds parts layer by layer, selectively depositing melted material in a predetermined path. Two of the principal 3D-print settings that can be modified with FDM are infill density and infill pattern. This project examined the impact of both of these settings on the stiffness of beams printed using FDM. To obtain stiffness values, an accelerometer connected to an oscilloscope was first attached to beams before flicking them in order to determine their resonant frequencies. These data points, along with length, thickness, and density measurements, were then used to calculate each beam's stiffness using Euler–Bernoulli beam theory. An analysis of the results showed that both infill density and infill pattern had a significant impact on the stiffness of beams, suggesting that these print settings are important factors to keep in mind when designing parts to be 3D-printed using FDM.

The increasing interest in sustainable materials has led to the development of bio-based composites for additive manufacturing applications. This study aimed to investigate the influence of key printing parameters and new-generation infill patterns together on the maximum compressive force of PLA-wood bio-composites produced by Material Extrusion. By optimizing this material, low-cost wood-like products can be produced. New-generation 3D infill patterns (octet, cubic-subdivision, and lightning which is a biomimetic infill pattern) infill densities, printing temperatures, and layer heights were selected as variables/factors, and the Taguchi method was applied for design of the experiment. The signal-to-noise ratio and Analysis of Variance were used to evaluate the statistical significance and contribution of each parameter to the mechanical response. The signal-to-noise ratio indicated that the optimal printing settings were as follows: printing temperature, 205 °C; infill density, 80%; infill pattern, octet; and layer height, 0.2 mm (7123.4 N). ANOVA results showed that infill density was the most significant factor affecting maximum compressive force at 60%, while infill pattern also exhibited a notable effect. According to these results, infill density and infill pattern are the most important factors for achieving high compressive strength. These findings suggest that optimizing infill architecture and density can improve the mechanical performance of PLA-wood composites, also they can offer assistive design guidelines for lightweight and eco-friendly components.

This study focuses on the investigation of infill patterns and their influence on the mechanical behavior of sandwich structures fabricated using the Fused Deposition Modeling (FDM) technique. Polylactic Acid (PLA) was chosen as the primary material, known for its favorable mechanical properties and biodegradability. Six different infill patterns, including Cubic, Line, Triangular, Trihexagonal, Octet, and Gyroid, were employed to fabricate sandwich structures with varying infill densities (20%, 30%, and 40%). The samples were subjected to edgewise compressive strength tests, and the force-displacement curves were analyzed to evaluate the performance of the structures. The results revealed that the Cubic infill pattern exhibited superior strength in all infill densities, while other patterns showed variations in performance. Moreover, the analysis of damage types indicated different failure modes, such as core shear and facesheet buckling, depending on the infill pattern and density. These findings contribute to understanding the role of infill patterns in enhancing the mechanical properties of sandwich structures fabricated via FDM.

3D printing has been shown to be a highly effective approach for the reproducible manufacturing of composite carbon electrodes. Various printing parameters have been effectively shown to enhance the electrochemical performance of 3D‐printed electrodes through reducing contact resistance; however, most of these studies have been conducted using 100% infill electrodes. Our study explored how the infill pattern and printing orientation can impact the electrochemical performance of reduced infill carbon black/polylactic acid (CB/PLA) electrodes. We printed 30% infill CB/PLA electrodes in linear, grid, triangle, and wiggle infill patterns in both horizontal and vertical orientations and evaluated the performance using cyclic voltammetry, conductivity imaging, and contact angle measurements. CB/PLA electrodes made using a grid infill pattern in horizontal orientation and a linear infill pattern with vertical orientation had the highest current and lowest difference between the anodic and cathodic peak potentials for an inner‐sphere redox probe. This study provides vital insight that the choice of infill pattern is important when printing in different orientations. The findings presented have significant implications on effective choice of printing parameters when crafting 3D‐printed electrodes and electronic components.

Warping remains a critical challenge in fused deposition modeling (FDM) of thermoplastic composites, leading to dimensional inaccuracies and compromised mechanical properties in printed parts. Existing studies have predominantly examined individual factors that affect warpage, such as infill specifications and printing orientation, without a comprehensive assessment of their combined effects. This study addresses this gap by employing a transient thermomechanical simulation approach in Digimat-AM, which integrates material crystallinity evolution, fiber orientation effects, and toolpath-dependent thermal history to enhance warpage prediction accuracy. A short carbon fiber-reinforced polyamide 12 composite was selected as the material system due to its complex thermal behavior, including the negative thermal expansion coefficient of carbon fibers. An unmanned aerial vehicle (UAV) camera holder was used as a case study, where the effects of the infill density, the infill pattern, the printing orientation, and the raster angle on warpage and mechanical performance were systematically analyzed. The high-fidelity simulation method in Digimat-AM was utilized to predict warpage, while experimental validation was performed through tensile and bending tests. Analysis of variance was applied to optimize the process parameters. The results demonstrated that a 90% infill density, a triangular infill pattern, a flat printing orientation, and a 90° raster angle significantly reduced warpage, achieving a deviation angle of as low as 0.04°. Furthermore, the combination of 90% infill density, concentric infill pattern and 90° raster angle improved tensile strength (45.58 MPa) and stiffness (2.57 GPa), confirming improved mechanical integrity.

Recently, there is a growing demand towards adopting 3D printing technology in various sectors due to its potential merits. The mechanical properties and surface quality of the final product are influenced by the process parameters. Therefore, this study aims to optimize the infill density and pattern beside printing speed and temperature to achieve optimum mechanical properties and surface characteristics of PLA+ 3D-printed material. The Taguchi method was applied with L9 array, and tensile and surface roughness tests were carried out to evaluate the performance of specimens in terms of the obtained ultimate tensile strength, Young’s modulus, tensile strain (%), and surface roughness. The selected parameters with their levels were as follows: printing temperature (205, 215, and 225°C), printing speed (20, 50, and 80 mm/s), infill density (30%, 60%, and 90%), and infill pattern (triangle, cubic, and concentric). The findings revealed the significant impact of the infill density followed by the infill pattern on the mechanical and surface performances of the PLA+ material. From the other side, the Taguchi method was integrated with grey relational analysis (GRA) as a multiobjective optimization to find out the optimum mechanical properties and surface characteristics of the 3D-printed PLA+ part. Accordingly, 215°C, 50 mm/s, 90%, and triangle pattern achieved optimum mechanical properties (24 MPa, 3.14 GPa, and 13.72%) and surface roughness (3.21 µm).

Nowadays, it is well known that on the ship, free space is at a premium. Unfortunately, every part on the ship has its duration before the failure, and the spare parts occupy the space. The broken part must be replaced when the failure occurs to maintain the ship's operation. Developing 3D printer technology and particular material technology, it has become possible to print a spare part that can replace broken. However, due to hazardous environments (salt, humidity, vibrations, etc.), printed parts change their properties. Electrical capacity and further dielectric permittivity is a parameter or metric that has to be monitored since it directly influences the printed part material structure. Therefore, this paper aims to research the impact of relative dielectric constant in additive manufacturing on printed ship's spare parts since infill patterns and density were changed due to a hazardous environment. The experiment, in which the three shaped material samples are created, consists of the following equipment, the Ultimaker S5 3D printer, Polylactic Acid (PLA) and Acrylonitrile-Butadiene-Styrene (ABS) materials, and LC HM 8018m. Results show relative dielectric constant changes between 1.7778 and 2.8141 for PLA and between 2.1979 and 2.9989 for ABS, depending on infill density and pattern. ANOVA test for ABS is performed to investigate how the calculated dielectric constant relates to the infill density for various infill shapes. Scores are: F = 154.3773, Fcrit = 5.1432, and p = 6.9269·10-6. ANOVA test for PLA resulted in scores F = 18.911, Fcrit = 5.1432, and p = 0.0022.

Commercial and industrial use of 3D printing has swiftly taken off as a versatile and effective method of manufacturing on both a small and large scale. Despite being adaptable, the procedure currently works with a restricted number of materials, mostly thermoplastic polymers. 3D printing fused deposition modeling (FDM) provides opportunities to produce complex components relatively quickly in small batch with a high degree of flexibility for both manufacturer and researcher. Process parameters in FDM like infill pattern, infill density, printing speed, raster angle influences the mechanical properties of a printed parts. In this research study, a novel approach on the internal structure of 3D printed parts say combined infill pattern (Triangles & Octet) on a single part has been introduced and mechanical properties like tensile test, flexural strength, compression strength and hardness were measured. Specimens were printed in Acrylonitrile butadiene styrene (ABS) as per ASTM standards by FDM technology with different infill densities of 60%, 80% and 100% by XY build orientation. SEM analysis was made to analyze the morphological and inter bonding of different infill patterns. The results show that mechanical performance was inflated by an increase in infill density.

This study proposes a novel optical fiber Bragg grating (FBG)-based load cell sensor using 3-D printing technology. It explores the impact of the infill density and pattern on the FBG’s temperature and mechanical strain sensitivity. Two FBGs were used, one for strain measurement, FBG L, and the other for temperature compensation, FBG T. Conducted measurements show that the strain-sensitive FBG L and strain-free FBG T exhibited a similar average temperature sensitivity value of around 10.5 pm/°C with a good linearity value of 99.92%. This will also allow the unstrained FBG T to effectively compensate for FBG L’s temperature changes during load measurement. Under varied load conditions, load cell sensors with lower infill density, such as 20%, displayed more significant average wavelength shift and increased strain sensitivities compared to those with higher infill density, such as 80%, due to having more voids and hollow sections within its actuator. This facilitates easier deformation, thus inducing more significant stretching on FBG L. Regarding the infill pattern, the gyroid pattern outperformed the tri-hexagon in both average wavelength shift and strain responses, showing its suitability for precise measurements under diverse loads. Therefore, this work demonstrates the critical role of the infill density and pattern in the performance of an efficient load cell sensor using FBGs.

BackgroundWe examined the biomechanical performance of a three-dimensional (3D)-printed vertebra on pedicle screw insertional torque (IT), axial pullout (APO), and stiffness (ST) testing.Materials and methodsSeventy-three anatomically identical L5 vertebral body models (146 pedicles) were printed and tested for IT, APO, and ST using single-threaded pedicle screws of equivalent diameter (6.5 mm), length (40.0 mm), and thread pitch (2.6 mm). Print properties (material, cortical thickness [number of shells], cancellous density [in-fill], in-fill pattern, print orientation) varied among models. One-way analysis of variance was performed to evaluate the effects of variables on outcomes.ResultsThe type of material significantly affected IT, APO, and ST (P < 0.001, all comparisons). For acrylonitrile butadiene styrene (ABS) models, in-fill density (25-35%) had a positive linear association with APO (P = 0.002), ST (P = 0.008), and IT (P = 0.10); similarly for the polylactic acid (PLA) models, APO (P = 0.001), IT (P < 0.001), and ST (P = 0.14). For the nylon material type, in-fill density did not affect any tested parameter. For a given in-fill density, material, and print orientation, the in-fill pattern significantly affected IT (P = 0.002) and APO (P = 0.03) but not ST (P = 0.23). Print orientation also significantly affected IT (P < 0.001), APO (P < 0.001), and ST (P = 0.002).Conclusions3D-printed vertebral body models with specific print parameters can be designed to perform analogously to human bone on pedicle screw tests of IT, APO, and ST. Altering the material, in-fill density, in-fill pattern, and print orientation of synthetic vertebral body models could reliably produce a model that mimics bone of a specific bone mineral density.

The study herein combines the use of fused filament fabrication (FFF) with finite element analysis (FEA) to enhance the understanding of certain manufacturing parameters (i.e. material, infill density, infill pattern, and outer vertical shell) in the design process of a lumbar fusion cage. Three FFF materials with distinct mechanical properties namely polycarbonate (PC), acrylonitrile butadiene styrene (ABS), and polylactic acid (PLA) were tested. Three infill densities (i.e. 25%, 50%, 75%) were investigated along with two different infill patterns (i.e. rectangular and honeycomb). Compressive modulus and compressive yield strength values obtained from standard mechanical analysis were used as input for FEA to assess numerically the mechanical performance of a lumbar fusion cage under physiological static loading. The findings suggest that both infill density and infill pattern influence the quality of the finished part in terms of both printing accuracy and mechanical response. FEA results indicate that both PC and ABS can be safely adopted to fabricate a porous lumbar cage with a 50% honeycomb infill density and a honeycomb infill pattern. This paper demonstrates that 3D printing assisted FEA can be used to predict the performance of a lumbar cage design with varying manufacturing parameters and potentially reduce product design and development time.

This study investigates the influence of printing parameters—layer height, infill density, and infill pattern—on the mechanical performance and surface damage behavior of PLA components fabricated via Fused Filament Fabrication (FFF). The focus is on evaluating how these parameters affect force–displacement characteristics and crack initiation under Erichsen indentation testing. Fifteen parameter combinations were tested using three‐layer heights (0.10, 0.15, 0.20 mm), five infill densities (10%–90%), and seven infill patterns (Grid, Triangles, Cubic, Octet, Concentric, ZigZag, and Cross). Force–displacement curves, peak force, displacement, and energy absorption were analyzed. Post‐test surface damage was correlated with mechanical results to assess crack propagation and failure behavior. Results showed that increasing layer height raised maximum force but reduced ductility. Higher infill densities enhanced load‐bearing capacity but limited deformation, particularly above 70%. Triangles and Cubic patterns provided superior strength and controlled crack propagation, while Cross and Concentric patterns exhibited early failure. Surface damage analysis revealed that high infill density combined with optimal pattern design guided cracks more symmetrically. This work offers an experimental assessment of how FFF parameters affect both mechanical and failure behavior of PLA under indentation, contributing valuable insights for improving the structural performance of additively manufactured parts.

3D printing, commonly referred to as Additive Manufacturing (AM), enables the creation of both simple and complex three-dimensional objects. While AM encompasses a variety of manufacturing techniques, Fused Filament Fabrication (FFF), is the most prevalent method. FFF constructs 3D models layer-by-layer by extruding molten material in a specified pattern. This paper examines the fracture properties of components produced through the FFF process. To achieve this, Single Edge Notched Bend (SENB) specimens were fabricated from polylactic acid (PLA) thermoplastic material. Various printing parameters were explored, including infill density (40, 70, and 100%), infill patterns (grid, cubic, and concentric), and printing directions (0, 45, and 90°). Three-point bending (3PB) tests were conducted at room temperature (25 °C) in accordance with ASTM D5045-14 standards. The 3PB results indicate that the mode I fracture toughness values are significantly affected by the printing parameters examined, with the greatest variations linked to infill density, followed by infill pattern and printing direction. Additionally, the fracture mechanisms associated with SENB specimens produced under different parameters exhibited distinct characteristics.