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The optimization and evaluation of 3D-printed polylactic acid (PLA) materials for reinforcing concrete elements present a promising avenue for advancing sustainable construction methods. This study addresses the challenges associated with PLA’s dual nature—biodegradable yet mechanically limited for long-term applications—while leveraging its potential to enhance concrete reinforcement. The research identifies gaps in understanding PLA’s mechanical and chemical behavior in alkaline environments, particularly its interactions with concrete matrices. To bridge this gap, four distinct PLA variants (high-impact PLA, engineering PLA, electrical ESD PLA, and gypsum PLA) and ABS (acrylonitrile butadiene styrene) were subjected to dissolution tests in NaOH solutions (pH 12 and 12.55) and mechanical evaluation under three-point bending using digital image correlation (DIC) technology. Test specimens were prepared using optimized 3D printing strategies to ensure structural consistency and were embedded in concrete beams to analyze their reinforcement potential. Force–displacement data and GOM ARAMIS measurements revealed significant differences in mechanical responses, with peak loads ranging from 0.812 kN (high-impact PLA) to 1.021 kN (electrical ESD PLA). Notably, electrical ESD PLA exhibited post-failure load-bearing capacity, highlighting its reinforcement capability. Chemical dissolution tests revealed material-specific degradation patterns, with high-impact and Gypsum PLA showing accelerated surface changes and precipitation phenomena. Observations indicated white crystalline precipitates, likely lime (calcium hydroxide—Ca(OH)2), residue from the dissolution tests (sodium hydroxide—NaOH), or material-derived residues formed on and near PLA elements, suggesting potential chemical interactions. These findings underline the critical role of material selection and optimization in achieving effective PLA–concrete integration. While PLA’s environmental sustainability aligns with industry goals, its structural reliability under long-term exposure remains a challenge. The study concludes that electrical ESD PLA demonstrates the highest potential for application in reinforced concrete, provided its chemical stability is managed, as its peak value (1.021 kN) showed 25.7% higher load-bearing capacity than high-impact PLA (0.812 kN) and did not lose any of its structural stability in the dissolution tests. This work advances the understanding of PLA as a sustainable alternative in construction, offering insights for future material innovations and applications.

Within the scope of the work, the possible use of fused deposition modeling (FDM) technology in executing rapid prototypes of cutting tools for aluminum sheets was systematically studied. Relevant investigations have thus far mainly concentrated on tools for the 3D printing of bent and deep-drawn pieces, yet the implementation of FDM tools in cutting has been insufficiently covered. This study aims to determine the characteristics of FDM cutting tools, such as wear and tear, dimensional stability, and cutting efficiency. Various tool designs were tested under different wall thicknesses and orientations with respect to the feed of Al99.5 sheets with thicknesses of 0.22 mm and 0.3 mm. According to the results, in the best case, three-dimensional printed PLA tools performed six cuts with no burrs and an acceptable wear level due to the IT tolerances (IT9 and IT10). Tools with thicker walls and more appropriate orientations were found to be more robust. However, some designs failed when subjected to greater loads, revealing a deficiency in some of the strength properties of the material. These observations suggest that it is possible to create 3D printed tools for modeling and small-scale production at considerably cheaper and faster rates than conventional methods. Future work will integrate advanced materials and designs to enhance tool performance, further solidifying FDM as a transformative approach in industrial tool manufacturing. With this research, the authors wanted to demonstrate that FDM technology can also be used to produce a classic sheet cut, which, of course, is still of great importance for prototyping or setting up production processes. This research demonstrated that FDM printing can play a role in this area.

In this study, an experimental analysis of the thermal behavior and wear of polymer and hybrid polymer gears produced with the Fused Deposition Modeling (FDM) method was performed. Compared to conventional polymer gear manufacturing methods, the FDM process represents an energy-efficient material forming method. The low thermal conductivity of polymer gears has an impact on heating, which limits their application. The novelty of this research is an experimental analysis on hybrid polymer gears, and, for this purpose, a new hybrid polymer gear design with aluminum and steel inserts has been proposed. An in-house-developed non-mechanically closed-loop test rig was used to investigate Polyamide (PA) gears under different loads. An accelerated step load test procedure was employed, while the gears’ bulk temperature was recorded with a thermal imaging camera. The print quality affected the tooth flank surface roughness, so polymer gears with two different print qualities were initially produced. Hybrid polymer gears were produced with a higher print quality, since the print quality had an influence on the heating and wear. The correlation between the bulk temperature and wear was observed for all of the tested gears. A novel design of hybrid polymer gears with aluminum inserts achieved up to a 9 °C (17%) lower bulk temperature and a higher wear resistance.

This study investigates the mechanical properties and biocompatibility of eight commercially available filaments tailored for Fused Deposition Modeling (FDM) additive manufacturing. Test specimens were fabricated using original PRUSA MK4 printers, with ten samples from each selected polymer. Mechanical evaluations through static tensile and three-point bending tests revealed that PETG Carbon and PA+15CF exhibited superior tensile and flexural strengths, making them highly suitable for applications requiring high mechanical resilience. Biocompatibility assessments in line with the ISO 10993-5:2009 and ISO 10993-12:2021 standards indicated that all materials except FiberFlex 40D Fiberlogy were non-cytotoxic, supporting their potential in biomedical applications. The experimental data established material constants within the Johnson–Cook strength model, which effectively predicted the mechanical behaviors of monotonic materials like FiberFlex 40D, PETG, HIPS, TPU, and PA+15CF Rosa 3D, with maximum fitting errors not exceeding 2.6%. However, the model was inadequate for non-monotonic materials like PLA and PETG, resulting in higher errors and less accurate simulations. Scanning electron microscope (SEM) analyses provided insights into fracture mechanisms, correlating fracture surface characteristics with mechanical performance. This comprehensive study advances the understanding of mechanical properties in thermoplastic materials for 3D printing, validates numerical models for certain materials, and confirms material suitability for biomedical use.

This paper presents a comparative study focused on a modal parameters estimation of specimens manufactured by the FDM technique using a fixed embedded vibrometer based on the laser Doppler principle and roving hammer-impact method. Part of this paper is devoted to testing a fixed circular plate with a honeycomb infill pattern while varying the number of excitation points (DOFs), the number of analysis lines of fast Fourier transformation (FFT), and the locations or numbers of reference degrees of freedom (REFs). Although these parameters did not significantly affect the values found for the natural frequencies of the structure, there were changes in the estimates of the mode shapes (affected by the low number of DOFs), in the height and sharpness of the peaks of the CMIF functions (caused by the increased number of FFT lines), and in the number of identified modes (influenced by the chosen location(s) of REFs), respectively. Subsequently, the authors compared the results of experimental modal analyses carried out under the same conditions on three circular plates with honeycomb, star, and concentric infill patterns made of PLA. The results confirm that specimens with honeycomb or star infill patterns have a higher stiffness than those with concentric infill patterns. The low values of the damping ratios obtained for each structure indicate a strong response to excitation at or near their natural frequencies.

Additive manufacturing has been widely used in various industries, including the healthcare sector. Over the last few decades, AM has been playing an important role in the medical field in different areas, including surgical planning, implants, and educational activities. For surgical applications, AM can help surgeons practice and plan an operation until they are confident with the process. This can help to reduce operational risk and time. In addition, it can help to demonstrate the problem to other colleagues. AM has also been used to produce 3D models to teach students and doctors about human anatomy. This paper aims to comprehensively review the diverse applications of additive manufacturing within the domains of surgical planning and medical education. By focusing on the multifaceted roles played by AM in these critical areas, a contribution to the growing body of knowledge that underscores the transformative potential of this technology in shaping the future of healthcare practices is sought to be made.

As additive manufacturing (AM) processes become integrated with artificial intelligence systems, the time and cost of the fabrication process decrease. In this study, the raster angle, an important parameter in the manufacturing process, was examined using fused deposition modeling (FDM), an AM method. The optimal value of this parameter varies depending on the designed product geometry. By changing the raster angle, the distribution of stresses and strains within the printed object can be modified, potentially influencing the mechanical behavior of the object. Thus, the correct estimation of the raster angle is essential for obtaining parts with high mechanical properties. The focus of this study is to reduce the fabrication time and cost of products by intertwining machine learning (ML) systems with mechanical systems. Its novelty is that ML has never been applied for FDM raster angle estimation. The estimation and modeling of the raster angle were performed using five different ML algorithms. These algorithms include a support vector machine (SVM), Gaussian process regression (GPR), an artificial neural network (ANN), decision tree regression (DTR), and random forest regression (RFR). Data for training were generated using various shapes and geometries, then trained in the MATLAB software, and a prediction model between the input parameters and the raster angle was created. The predicted model was evaluated using five performance criteria. The RFR model predicts the raster angle in the FDM test data with R-squared (R2) = 0.92, an explained variance score (EVS) = 0.92, a mean absolute error (MAE) = 0.012, a root mean square error (RMSE) = 0.056, and a mean squared error (MSE) = 0.0032. These values are R2 = 0.93, EVS = 0.93, MAE = 0.010, RMSE = 0.051, and MSE0.0025 for the training data. RFR is significantly superior to the other prediction algorithms. The proposed model predicts the optimum raster angle for any geometry.

This research paper provides an in-depth examination of the mechanical characteristics of 3D-printed specimens made from acrylonitrile butadiene styrene (ABS) and resins akin to ABS, with a focus on two widely used 3D printing methodologies: fused deposition modeling (FDM) and stereolithography (SLA). The study investigates how variations in 3D printing technology and infill density impact mechanical parameters such as Young’s modulus, tensile strength, strain, nominal strain at break, maximum displacement, and maximum force at break. Tensile testing was conducted to assess these critical parameters. The results indicate distinct differences in mechanical performance between FDM- and SLA-printed specimens, with SLA consistently showing superior mechanical parameters, especially in terms of tensile strength, displacement, and Young’s modulus. SLA-printed specimens at 30% infill density exhibited a 38.11% increase in average tensile strength compared to FDM counterparts and at 100% infill density, a 39.57% increase was observed. The average maximum displacement for SLA specimens at 30% infill density showed a 14.96% increase and at 100% infill density, a 30.32% increase was observed compared to FDM specimens. Additionally, the average Young’s modulus for SLA specimens at 30% infill density increased by 17.89% and at 100% infill density, a 13.48% increase was observed, highlighting the superior mechanical properties of SLA-printed ABS-like resin materials. In tensile testing, FDM-printed specimens with 30% infill density showed an average strain of 2.16% and at 100% infill density, a slightly higher deformation of 3.1% was recorded. Conversely, SLA-printed specimens at 30% infill density exhibited a strain of 2.24% and at 100% infill density, a higher strain value of 4.15% was observed. The comparison suggests that increasing the infill density in FDM does not significantly improve deformation resistance, while in SLA, it leads to a substantial increase in deformation, raising questions about the practicality of higher infill densities. The testing data underscore the impact of infill density on the average nominal strain at break, revealing improved performance in FDM and significant strain endurance in SLA. The study concludes that SLA technology offers clear advantages, making it a promising option for producing ABS and ABS-like resin materials with enhanced mechanical properties.

With the increasing adoption of Additive Manufacturing in the industry, driven by its efficiency, productivity, and project profitability, materials have undergone significant evolution to enhance process performance and part properties. One of the processes employed to enhance these properties involves the incorporation of various types of reinforcements. This aims to ensure that the material acquires a proportion of the properties of the added reinforcement. Consequently, the options for material selection expand depending on the application. Hence, there is a need to understand how specific reinforcements modify the properties of these materials. For this reason, this study investigates the modification of mechanical properties in a PETG matrix through the incorporation of short carbon fiber (CF) reinforcements, driven by their industrial relevance. To achieve this, the Fused Filament Fabrication (FFF) process will be utilized to produce a series of standardized specimens made of both PETG and CF-reinforced PETG, with variations in layer height and extrusion temperature. Subsequently, these specimens will undergo mechanical evaluation in tension and compression, following the relevant standards for each case. Finally, distinctions between both materials will be analyzed, based on the data obtained from tensile and compression tests. The incorporation of carbon fiber reinforcement shows a detrimental effect, leading to a decrease in the material’s stress (39.23 N/mm2 vs. 48.41 N/mm2 for the conventional material). As expected, due to the nature of the reinforcement (short fibers), the deformation of the material also decreases (2.13% compared to 2.9%).

A novel L-FDM technique that builds upon the fundamentals of the FDM additive manufacturing process has been developed. It includes a mechanism that directly incorporates a chemical substance and alters polymer fibers throughout the fine process. This method eliminates the need for additional extrusion operations and compounding equipment to introduce chemical additives and solvents. This advancement opens up new opportunities for printers to be used in chemical labs to test new or known chemical substances. The paper outlines the technological assumptions, potential applications, and practical examples of direct filament modification using the L-FDM technique. The modifications made to the mechanical properties of the printed objects were confirmed through thermal analysis techniques (DSC), water contact angle measurements, electron microscopy (SEM-EDS), and mechanical analysis.

This article presents a novel 3D printing technique called L-FDM (liquid for fused deposition modeling), which is based on the deposition of molten thermoplastic material. The new method allows for the direct introduction of chemicals and polymer filament modifications during the printing process. In contrast to traditional incremental methods, L-FDM eliminates the need for extra granulating, extrusion, and processing equipment, making it possible to introduce chemical additives to the polymer matrix directly. This opens up exciting possibilities for chemical laboratories to test and experiment with new and known chemicals through 3D printing. The article discusses the technical aspects of L-FDM and its potential applications and provides practical examples of direct filament modifications using the technique. The results of these modifications were verified using a colorimeter, electron microscopy (SEM/EDS), and optical microscopy.

An approach for improving and maintaining consistent fusion quality of the deposited material during FDM 3d-printing is proposed. This approach is based on the nozzle temperature control during the printing process to adjust the polymer extrusion temperature with a speed and accuracy adequate to the FDM process. High frequency induction heating of the lightweight nozzle (

This research paper aims to improve the quality of 3D printed parts made of the wax filament by implementing the Taguchi orthogonal array process optimization method. The manufactured parts can be used as cost-effective investment casting patterns. With the Taguchi method, it was concluded that the nozzle temperature has the most effect on the dimensional accuracy of printed parts. In addition, thermal, mechanical, and rheological characterization were performed on the wax filament, revealing several important findings. For instance, the rheological studies identified the low viscosity of melted wax at printing temperatures. This resulted in the rough surface of the printed parts. To improve the surface roughness, a post-processing procedure was implemented using a white spirit as a surface smoothing agent.

This article deals with the design and testing of mobile robots equipped with drive systems based on omnidirectional tracks. These are new mobile systems that combine the advantages of a typical track drive with the advantages of systems equipped with omnidirectional Mecanum wheels. The omnidirectional tracks allow the robot to move in any direction without having to change the orientation of its body. The mobile robot market (automated construction machinery, mobile handle robots, mobile platforms, etc.) constantly calls for improvements in the manoeuvrability of vehicles. Omnidirectional drive technology can meet such requirements. The main aim of the work is to create a mobile robot that is capable of omnidirectional movement over different terrains, and also to conduct an experimental study of the robot’s operation. The paper presents the construction and principles of operation of a small robot equipped with omnidirectional tracks. The robot’s construction and control system, and also a prototype made with FDM technology, are described. The trajectory parameters of the robot’s operation along the main and transverse axes were measured on a test stand equipped with a vision-based measurement system. The results of the experimental research became the basis for the development and experimental verification of a static method of correcting deviations in movement trajectory.

Auxetic structures possess a negative Poisson ratio (ν < 0) as a result of their geometrical configuration, which exhibits enhanced indentation resistance, fracture toughness, and impact resistance, as well as exceptional mechanical response advantages for applications in defense, biomedical, automotive, aerospace, sports, consumer goods, and personal protective equipment sectors. With the advent of additive manufacturing, it has become possible to produce complex shapes with auxetic properties, which could not have been possible with traditional manufacturing. Three-dimensional printing enables easy and precise control of the geometry and material composition of the creation of desirable shapes, providing the opportunity to explore different geometric aspects of auxetic structures with a variety of different materials. This study investigated the geometrical and material combinations that can be jointly tailored to optimize the auxetic effects of 2D and 3D complex structures by integrating design, modelling approaches, 3D printing, and mechanical testing. The simulation-driven design methodology allowed for the identification and creation of optimum auxetic prototype samples manufactured by 3D printing with different polymer materials. Compression tests were performed to characterize the auxetic behavior of the different system configurations. The experimental investigation demonstrated a Poisson’s ration reaching a value of ν = −0.6 for certain shape and material combinations, thus providing support for preliminary finite element studies on unit cells. Finally, based on the experimental tests, 3D finite element models with elastic material formulations were generated to replicate the mechanical performance of the auxetic structures by means of simulations. The findings showed a coherent deformation behavior with experimental measurements and image analysis.

This paper reports the synthesis of a new printable ABS–MWCNT composite filament, for use in fused deposition modeling (FDM), using an extrusion technique. Acrylonitrile butadiene styrene (ABS) and multi-walled carbon nanotubes (MWCNTs) were the initial materials used for fabricating the filaments. The MWCNTs were dispersed in ABS resin, then extruded through a single-shaft extruder in filament form, with MWCNT contents of 0.5%, 1%, 1.5%, 2%, 3% or 4% by weight. After extrusion, the diameter of the filaments was about 1.75 mm, making them appropriate for FDM. The as-synthesized filaments were then used in FDM to print out samples, on which tensile tests and other analyses were carried out. The results demonstrate that the sample with 2% MWCNTs had the highest strength value, 44.57 MPa, comprising a 42% increase over that of the pure ABS sample. The morphology and dispersion of MWCNTs in the composite were observed by field emission scanning electron microscopy (FESEM), demonstrating the uniform distribution of MWCNTs in the ABS matrix. The thermal behavior results indicated no significant change in the ABS structure; however, the melt flow index of the filaments decreased with an increase in the MWCNT content.

Fused deposition modeling (FDM) is a capable technology based on a wide range of parameters. The goal of this study is to make a comparison between infill pattern and infill density generated by computer-aided design (CAD) and FDM. Grid, triangle, zigzag, and concentric patterns with various densities following the same structure of the FDM machine were designed by CAD software (CATIA V5®). Polylactic acid (PLA) material was assigned for both procedures. Surface roughness (SR) and tensile strength analysis were conducted to examine their effects on dog-bone samples. Also, a finite element analysis (FEA) was done on CAD specimens to find out the differences between printing and simulation processes. Results illustrated that CAD specimens had a better surface texture compared to the FDM machine while tensile tests showed patterns generated by FDM were stronger in terms of strength and stiffness. In this study, samples with concentric patterns had the lowest average SR (Ra) while zigzag was the worst with the value of 6.27 µm. Also, the highest strength was obtained for concentric and grid samples in both CAD and FDM procedures. These techniques can be useful in producing highly complex sandwich structures, bone scaffolds, and various combined patterns to achieve an optimal condition.

In order to improve system coverage performance, in this paper, a multi-service transmission scheme on the basis of the puncturing technique, namely layered division multiplexing extension frequency-division multiplexing (LDM-Ex-FDM), is proposed. The key idea of the proposed scheme is that the symbols punctured from the enhanced layer (EL) of fixed services will be independently transmitted on a certain number of subcarriers orthogonal to the LDM signal of the core layer (CL) and most of the EL. By doing so, the punctured symbols will be demodulated with a higher signal-to-noise ratio (SNR) on the receiver side and can be recovered well, thus improving the reception performance of the EL fixed services. Moreover, two puncturing strategies based on bit-interleaved coded modulation (BICM) symbols of the LDM-Ex-FDM scheme, namely equal interval symbol puncturing (EISP) and non-equal interval symbol puncturing (NEISP), are developed to improve the performance of the EL services. Simulation results are given to show that, when the puncturing rate in the LDM-Ex-FDM scheme is configured as 1/12, the performance of the fixed service can be improved by 1.8 dB, meanwhile the bit error rate (BER) performance of the mobile service is not affected. Thus, the overall system coverage performance can be improved. Furthermore, to reduce the computational complexity and the demodulation delay of fixed service carried in the EL, at the receiver, a direct interference cancellation (DIC) detector is proposed as well. Simulation results are given to show that, under high injection level and high modulation order, the proposed DIC scheme is able to achieve almost the same BER performance as that of the traditional successive interference cancellation (SIC) scheme while with lower computational complexity.

Slope failure induced by sublevel caving mining is a progressive process, resulting in the large deformation and displacement of rock masses in the slope. Numerical methods are widely used to investigate the above phenomenon. However, conventional numerical methods have difficulties when simulating the process of progressive slope failure. For example, the discrete element method (DEM) for block systems is computationally expensive and possibly fails for large-scale and complex slope models, while the finite difference method (FDM) has a mesh distortion problem when simulating progressive slope failure. To address the above problems, this paper presents a finite difference modeling method using the adaptive local remeshing technique (LREM) to investigate the progressive slope failure induced by sublevel caving mining. In the proposed LREM, (1) the zone of the distorted mesh is adaptively identified, and the landslide body is removed; (2) the updated mesh is regenerated by the local remeshing, and the physical field variables of the original computational model are transferred to the regenerated computational model. The novelty of the proposed method is that (1) compared with the DEM for block systems, the proposed LREM is capable of modeling the progressive slope failure in large-scale rock slopes; (2) the proposed method is able to address the problem of mesh distortion in conventional FDM modeling; and (3) compared with the errors induced by the frequent updating of the mesh of the entire model, the adaptive local remeshing technique effectively reduces calculation errors. To evaluate the effectiveness of the proposed LREM, it is first used to investigate the failure of a simplified slope induced by sublevel caving mining. Moreover, the proposed LREM is applied in a real case, i.e., to investigate the progressive slope failure induced by sublevel caving mining in Yanqianshan Iron Mine.