Cem Alparslan

Geranium psilostemon Ledeb. is a rhizomatous perennial whose cultivation performance under low-altitude conditions requires further investigation. This study evaluated survival, vegetative growth and meter-estimated total leaf chlorophyll content across five growing media in a single experiment conducted in an open-top section of a greenhouse facility. Rhizomes collected from a natural clump at 1375 m elevation in Maçka, Trabzon, Türkiye, were cultivated at 53 m elevation in peat, cocopeat, river silt, forest soil and an equal-volume mixture of these materials, with 30 individually potted rhizomes per treatment. Following approximately one year of cultivation, seven measurements were conducted between May and August 2024. Plant height, crown diameter, leaf number and chlorophyll content were recorded alongside substrate temperature, moisture, pH and electrical conductivity. Data were examined using exploratory ANOVA, post hoc comparisons, correlation analysis and artificial neural network (ANN) modeling. River silt and peat supported the highest survival percentages (83.3% and 80.0%, respectively), whereas survival in cocopeat was 10.0%. Peat produced the highest mean plant height and crown diameter, while river silt and peat had the highest mean leaf chlorophyll content. Chlorophyll content showed weak negative associations with substrate temperature (20.8–45.9 °C) and pH (5.30–10.20), and a weak positive association with electrical conductivity (0.00–0.31 mS cm⁻¹). ANN modeling showed limited-to-moderate discrimination for survival status (ROC-AUC = 0.6653) and limited predictive performance for continuous traits, with plant height yielding the highest R² (0.3192). These findings provide an initial basis for growing-media selection for low-altitude cultivation of G. psilostemon, with further independent trials needed to evaluate their consistency.

Fused deposition modeling (FDM) is one of the most extensively used additive manufacturing (AM) techniques. This study contributes to the knowledge enhancement related to AM by presenting the details of experimental investigation conducted on FDM of three different materials i.e. polylactic acid (PLA), acrylonitrile butadiene styrene (ABS) and carbon fiber (ePA-CF) and providing the common optimum fabrication parameters for FDM of PLA, ABS and ePA-Cf materials. A detailed analysis of the effect of two important FDM parameters, namely infill pattern (IP) and layer thickness (LT), on mechanical properties of the fabricated samples from the materials, has been done. The best mechanical properties of the PLA sample were obtained with LT of 0.15 mm and hexagon pattern, of the ABS sample were obtained with LT of 0.15 mm and triangle pattern, and of the ePA- CF sample were observed at LT of 0.15 mm and hexagon pattern. It was determined that elongation, yield (YS) and tensile strength (TS) decreased with increasing LT in all materials’ samples. While the fracture surfaces of PLA samples were smooth, and the layer lines were evident. Whereas the fracture surfaces of ABS samples were rough, and the lines were less distinct than PLA. On the other side, the fracture surfaces in ePA-CF samples had a fibrous structure. The voids formed between layers were seen the most in PLA and the least in ePA-CF samples. LT of 0.15 mm and hexagon IP. It was observed that the best results in terms of mechanical properties were obtained under LT of 0.15 mm and IP of hexagon conditions.

Understanding the finishing behavior of hybrid structures produced by additive manufacturing based on FDM is critically important in systems where phases with different thermal and mechanical properties coexist. In this study, the drilling performance of hybrid structures with a PLA/17-4 PH/PLA layer arrangement was comprehensively investigated in terms of thrust force, moment, surface roughness, temperature variation, vibration behavior, and surface integrity. For this purpose, a total of 16 drilling tests were performed on 56 × 56 × 15 mm hybrid specimens with 100% infill density, in a full factorial configuration, at cutting speeds (V) of 80–170 m/min and feed rates (f) of 0.04–0.16 mm/rev. The middle layer was used in the as-printed green state as a 17-4 PH metal-filled filament containing metal particles and binder, without any debinding or sintering step. The results showed that increasing feed rate increased thrust force, moment, and surface roughness in all layers, whereas increasing cutting speed decreased these values and promoted a more stable drilling regime. The middle 17-4 PH layer exhibited lower surface roughness than the outer PLA layers, while thermal measurements indicated limited variation at the hole entrance and higher temperature accumulation at the hole exit. The most favorable drilling condition within the studied hybrid configuration was obtained at 170 m/min and 0.04 mm/rev, whereas the least favorable condition was obtained at 80 m/min and 0.16 mm/rev. Overall, the combination of high cutting speed and low feed rate provided the most suitable drilling window for the studied hybrid structure. The findings also indicated that surface quality was more strongly associated with cutting load and high-frequency vibration components than with vibration level alone.

In this study, salmon fish bone waste from the fish processing industry was converted into an inorganic ash filler by calcination and incorporated into an SLA-compatible photopolymer resin at 4, 8, and 12 wt.%. To compensate for filler-induced optical scattering and rheological changes, the printing parameters were systematically optimized, and the optimum conditions were identified as a layer thickness of 30 µm and an exposure time of 12 s. Tensile tests performed in accordance with ASTM D638 Type IV showed that fish bone ash significantly enhanced the tensile strength of the photopolymer matrix, increasing it from 24.8 MPa for the neat resin to 37.95 MPa at 12 wt.% filler loading. In contrast, increasing filler content reduced elongation at break and promoted a more brittle fracture response. Statistical evaluation using Welch ANOVA and Games–Howell post hoc analysis confirmed that filler loading had a statistically significant effect on tensile strength (p < 0.05). FTIR analysis revealed that the filler remained chemically stable within the matrix and that the interfacial interactions were predominantly physical rather than covalent. SEM observations indicated that low and medium filler loadings improved crack deflection and energy dissipation, whereas particle agglomeration at higher loading increased the tendency for brittle fracture. These findings demonstrate that fish bone ash can be used as a sustainable bio-waste-derived reinforcement to improve the mechanical performance of SLA photopolymer composites.

This study investigates the impact response and energy absorption performance of additively manufactured PLA–geopolymer hybrid composites for potential application in road safety barriers. Hybrid Charpy specimens were fabricated with three different infill densities (20%, 60%, and 100%), combining a 3D-printed PLA outer shell with a geopolymer core. Charpy impact tests were conducted in accordance with ISO 179-1 and ASTM D6110, and the absorbed energy, specific energy absorption, and mass efficiency were determined experimentally. A phase-based analytical model was also used to estimate elastic energy contributions, while fracture surfaces were examined to identify infill-dependent damage mechanisms. To extend the material-level findings to an engineering-scale application, the observed trends were transferred to a New Jersey-type road safety barrier model and evaluated using ANSYS Explicit Dynamics. The results showed that infill density strongly affects fracture behavior and energy dissipation performance, with 60% infill providing the most balanced response in terms of energy absorption and mass/material efficiency. The originality of the present study lies in going beyond a material-scale investigation of the impact behavior of additively manufactured PLA–geopolymer hybrid structures by integrally correlating the experimental Charpy results with a theoretical energy-based framework, fracture-surface observations, and explicit dynamic finite element analysis of a New Jersey-type road safety barrier model.

Fused deposition modeling/fused filament fabrication (FDM/FFF) enables architectural tailoring of mechanical response through layer configuration and multi-material manufacturing strategies. However, the combined effects of layer arrangement, infill ratio, and packing geometry in polymer–metal hybrid structures and interfacial load transfer mechanisms are still not sufficiently elucidated. In this study, the tensile behavior of single- and multi-material structures produced using PLA and 17-4 PH stainless steel filaments was systematically investigated. A total of 24 experimental parameter sets were created with four-layer configurations (PLA, 17-4 PH, PLA/17-4 PH/PLA, and 17-4 PH/PLA/17-4 PH), three infill ratios (20%, 60%, and 100%), and two packing patterns (linear and hexagonal); the samples were tested according to the ASTM D638 standard. Mechanical data were modeled using Response Surface Methodology (RSM) and ANOVA, and the developed regression models showed high accuracy (R² > 0.95). The findings showed that tensile and yield strength are primarily controlled by the layer arrangement, while infill ratio and infill pattern have a secondary effect. The highest strength was measured in 100% infill linear PLA samples (≈10.35 MPa), and the lowest value was measured in 17-4 PH “green part” samples without sintering (≈0.92 MPa). Hybrid structures exhibited intermediate performance in the range of 2.9–4.9 MPa. ANOVA results showed that the majority of the mechanical variance was explained by the layer arrangement (70–85% contribution), while infill ratio and infill pattern had a secondary effect. Fracture surface analyses showed that high performance was associated with homogeneous filament fusion and low porosity; Studies have confirmed that poor performance is associated with delamination and interfacial separation.

Additive manufacturing (AM) has transformed traditional manufacturing processes, revolutionizing the production of complex, customized, and high-performance components. The role of advanced materials developed specifically for AM technologies is critical to the success of this transformation. This review comprehensively covers advanced material classes such as metal-based alloys, ceramics, high-performance polymers, composite systems, smart materials, and functionally gradient materials (FGMs). The compatibility of each material group with AM processes, its mechanical and functional properties, post-production requirements, and application potential are detailed. Furthermore, the compatibility between material selection processes and manufacturing technologies is comparatively evaluated in terms of application-specific performance outcomes. Supported by recent case studies selected from the literature, this review discusses prominent applications, particularly in the aerospace, biomedical, and automotive sectors. Current challenges such as microstructural control, post-process optimization, environmental sustainability, and multi-material manufacturing are also addressed, and future research areas such as AI-assisted material design and nano-additive systems are highlighted. As a result, the integration of advanced material development and AM processes stands out as the key determinant in the production of functional, durable and sustainable products.

Additive manufacturing (AM) has rapidly evolved into a groundbreaking technology in biomedical engineering, offering unprecedented capabilities for fabricating patient-specific, anatomically complex structures with high precision. This review presents a comprehensive and critical overview of recent innovations in AM-applied biomaterials, focusing on the integration and application of hydrogels, biopolymers, ceramics, metals, and composite systems. These materials, each with unique biological and mechanical attributes, are pivotal in advancing regenerative medicine, tissue engineering, and the development of next-generation medical implants and devices. Special emphasis is placed on hydrogel-based bioinks and photopolymerizable networks used in 3D bioprinting, which offer tunable properties, excellent biocompatibility, and the ability to mimic extracellular matrix environments. Furthermore, the synergistic design of structural and functional materials in AM platforms is explored to address critical challenges such as mechanical durability, degradation kinetics, immunomodulation, and dynamic cell–matrix interactions. By synthesizing current progress in material science, biofabrication strategies, and translational pathways, this review highlights the transformative potential of AM in shaping the future of personalized and precision medicine—bridging the gap between innovative material design and clinically viable biomedical solutions.

This study investigates the machinability of Continuous Fiber-Reinforced Thermoplastic Composite (CFRTP) produced via Material Extrusion (MEX) additive manufacturing, focusing on drilling as a critical post-processing step in hybrid manufacturing. CFRTP components, fabricated from 3K carbon fibers and a PLA matrix, were subjected to systematic drilling tests under varying cutting speeds (50–110 m/min) and feed rates (0.06–0.24 mm/rev). Thrust force (Fz) and torque (Mz) were recorded using a high-precision dynamometer to evaluate the influence of cutting parameters on mechanical loads and damage mechanisms. Results indicate that increasing the feed rate significantly increases Fz and Mz, promoting fiber pull-out, delamination, and edge deformation, particularly at hole entry and exit regions. Conversely, higher cutting speeds reduce Fz and Mz due to thermal softening of the PLA matrix, enabling more controlled fiber–matrix interaction. Microscopic analyses revealed that damage severity correlates strongly with mechanical load levels. While high feed rates caused pronounced surface irregularities and matrix smearing, low feed rates combined with high cutting speeds yielded smoother hole morphology and preserved fiber–matrix integrity. The study concludes that optimal drilling conditions for CFRTP materials involve low feed rates and high cutting speeds, minimizing mechanical loads and suppressing damage formation. These findings provide a scientific basis for precision finishing strategies in hybrid manufacturing, enhancing dimensional accuracy and structural reliability of CFRTP components for advanced engineering applications.