Berkay Ergene

Polymer components fabricated via fused filament fabrication (FFF) are frequently exposed to friction and wear under diverse environmental conditions in various engineering applications. The tribological performance of these components is influenced by both the printing parameters employed during fabrication and subsequent post-processing and service conditions. Previous studies have generally investigated the effects of printing parameters or post-processing steps separately. However, a comprehensive evaluation of in-service performance requires the sequential consideration of these factors. This study aimed to evaluate the tribological performance of FFF-printed PLA and PLA-Wood specimens through a sequential approach considering the infill architecture, heat treatment, and subsequent water absorption. The findings indicate that the best-performing infill architecture among the investigated configurations was the rectilinear pattern at an 80% infill density, which exhibited the lowest volumetric wear loss among all printing configurations. The best-performing heat treatment conditions varied by material and were determined to be 90 °C for 15 min for PLA and 90 °C for 45 min for PLA-Wood, reducing volumetric wear loss from 17.97 to 14.32 mm³ (approximately 20%) and 24.92 to 22.36 mm³ (approximately 10%), respectively. Moreover, water absorption largely eliminated the heat-treatment-induced improvement in PLA, with volumetric wear loss increasing to 17.93 mm³, whereas the improvement was substantially retained in PLA-Wood, which exhibited a wear loss of 22.67 mm³ after water absorption. Overall, the findings demonstrate that improvements in wear resistance achieved through processing may not be equally retained after subsequent environmental exposure and that this response depends on the material composition.

In recent years, the design and fabrication of lightweight structural systems have emerged as a significant area of interest within engineering applications. The multifunctional properties of sandwich structures—particularly their high bending strength, thermal insulation, and energy absorption capabilities—have facilitated their widespread adoption across various industries, including aerospace, marine, automotive, and construction. Additive manufacturing technologies offer considerable advantages over conventional manufacturing methods, particularly in enabling the fabrication of structures with complex core geometries. This study investigates the mechanical behavior of sandwich structures fabricated from polylactic acid (PLA) material using the fused filament fabrication (FFF) technique. The core sections of the sandwich structures were modeled in three different thicknesses using Autodesk Inventor Professional, and each configuration was manufactured at three distinct layer heights, resulting in a total of nine unique sandwich structure variants. To evaluate the influence of core thickness and layer height on mechanical performance, the specimens were subjected to three-point bending tests in accordance with ASTM D790 standards. Experimental results indicate that sandwich structures produced via FFF using PLA material exhibit high dimensional accuracy. Moreover, an increase in layer height led to enhanced bending strength, whereas increased core thickness relative to surface thickness was found to negatively impact the bending performance of the structures. Lastly, the highest flexural strength (73.5 MPa) was obtained with a 2 mm core and 0.3 mm layer thickness, while the lowest (25.8 MPa) occurred with a 4 mm core and 0.1 mm layer thickness.

Polymer composite laminates with different core and sheet combinations are extensively adopted in the automotive and aerospace industries due to their low density, superior vibration-damping and shock absorption characteristics. This study presents the experimental and numerical analysis of the vibration behavior of sandwich tapered beams consisting of 3D printed acrylonitrile styrene acrylate (ASA) layers and AZ31B grade Mg alloy first time in the literature. First, the vibration analysis of tapered sandwich beams was conducted using the finite element method by ANSYS software. In addition, the solution approach was checked through comparison of the natural frequency values calculated from ANSYS software with literature studies. Then, the calculated natural frequencies were compared with experimental results to ensure the correctness of the numerical models. It was observed that the numerical findings showed great correspondence. Finally, we investigated in great detail how tapering angle and infill rate affected the natural frequencies of sandwich conical beams. According to the output, natural frequencies of the samples dropped as ASA’s infill rate rose. Furthermore, it was found that the natural frequency dropped when the AZ31B layer was moved nearer the center.

Purpose: The real-time performance requirements of montage components and assembly features of structural parts are among the most critical factors for the utilization of polymer-matrix laminates in the aerospace industry. In this context, the present study provides a comprehensive perspective on the dry drilling optimization of nanographene-added basalt fiber-reinforced epoxy composite laminates, focusing on cutting force and surface delamination damage. Design/methodology/approach: The combined effects of feed rate (FR) (0.10, 0.15 and 0.20 mm/rev), tool diameter (3 and 5 mm) and nanographene ratio (0, 0.3 and 0.7 wt.%) were investigated as input parameters using a specially designed dagger tool for the first time in the literature. Additionally, Taguchi’s L18 design was employed to determine the optimal combination of input variables. Findings: The results indicate that lower feed rates, smaller tool diameters and higher nanoparticle concentrations result in the lowest cutting forces. As for the delamination factor, lower feed rates, larger tool diameters and higher nanoparticle concentrations were identified as the best combination to maintain the structural integrity of the machined surfaces. Only localized minor chips were seen at the best combination. Detected outcomes can be used for future projects that aim to explore the joining strength of mechanical assembly for aircraft laminate structures. Originality/value: Achieving high-performance composite assemblies in aerospace applications (particularly in wing, fuselage and interior components), with sufficient mechanical properties, requires precise optimization of drilling operations to ensure strong joints and high-quality surfaces without delamination defects. This study, specifically focusing on nanoparticle-modified basalt fiber-reinforced laminates for aerospace implementations, is the first to elucidate the combined effects of FR, tool diameter and nanoparticle ratio on thrust force and delamination factor.

In the contemporary era of additive manufacturing technologies, the production of components with intricate geometries from a diverse array of materials, including polymers, ceramics, metals and composites, has become a reality. In particular, polymer materials, which are easily and inexpensively available, as well as meeting the desired strength values by optimizing the production parameters, can often be produced by material extrusion based fused deposition modelling. Polylactic acid, a polymer of choice in numerous fields, including biomedical and automotive applications, is of particular interest in this study. The objective of this study is to investigate the effect of infill pattern and number of contours, which are production parameters, and deformation rate, which is a test parameter, on the tensile strength values of the related products in additive manufacturing products produced from the frequently used polylactic acid material. To this end, tensile test specimens were fabricated using three distinct infill patterns (zigzag, triangle and cubic) and three different contour numbers (2, 3 and 4). These specimens were then subjected to tensile testing at three different deformation rates (1, 5 and 25 mm/min). The resultant tensile strengths were obtained and the fracture surfaces were examined. The findings indicated that tensile strength values increased with an increase in the number of contours, that the effects of infill patterns varied depending on the deformation rate, and finally, that tensile strength values increased with increasing deformation rate.

Additive manufacturing (AM) technology is a game-changer that allows one to produce parts with intricate geometry that have high specific strength despite having low weight. In this study, the wear behavior of parts produced with powder bed fusion at different building directions (horizontal, inclined, and vertical) was examined under different test forces (1, 5, and 10 N). Additionally, the mechanical properties of these parts were determined using tensile tests and hardness evaluations. To explore the deformation mechanism, macroscopic and microscopic observations were carried out. The results showed that the horizontal samples exhibited the highest tensile strength, elongation at break, and toughness values. However, these samples also reflected the highest wear when subjected to a 10 N force. The friction coefficient values dropped depending on the rising test forces for all printing angles. Groove-like damage marks stemming from the ploughing style deformation were more remarkable on the sample surfaces as the test force levels went up. Regional severe wear tracks, debris fragments having an abrasive role, and discrete delamination states were ascertained as probable reasons for the lowest wear endurance of the horizontally built samples under the highest test load.

The objective of this study is to investigate the mechanical performance of Ti6Al4V cellular structures, including different unit cell forms such as honeycomb, re-entrant, hybrid (honeycomb + re-entrant), and chiral structures manufactured with selective laser melting. The study examines the influence of rib thickness and unit cell orientation on compressive strength, elasticity modulus, Poisson's ratio, energy absorption, and specific energy absorption. Increasing the rib thickness of the unit cells improved not only the compressive strength and elasticity modulus of the samples but also their energy absorption capacities. The mechanical properties of the cellular structures varied with changes in unit cell orientation, and no direct relationship was found. The highest values for compressive strength, energy absorption, and specific energy absorption were observed in re-entrant structures, while hybrid structures had the highest elasticity modulus values. It was also found that chiral structures had the lowest compressive strength, modulus of elasticity and energy absorption capacity of all the parameters investigated. In addition, re-entrant structures with negative Poisson's ratio tend to perform positive Poisson’s ratio when they are subjected to deformation under compression. The elasticity modulus of the biocompatible Ti6Al4V cellular structures is similar to that of femoral bone values. These structures meet the requirements for use in the core of implants. The results obtained from this experimental study may guide researchers in the field of biomechanics.

Wind turbines are subjected to extreme weather and load conditions; hence, high strength and impact resistance are required. Furthermore, wind turbine blades can be subjected to impact loads such as bird strikes, resulting in the formation of microcracks. Self‐healing capsules can be used to mend turbine blades for microscale damage. The incorporation of self‐healing capsules may cause a decrease in the mechanical characteristics of the composites prior to impact resistance, which can be compensated for with efficient fillers such as silicon carbide whiskers (SiC_w). Thus, a novel hybrid composite structure is examined with the advantage of using a self‐healing mechanism and SiC_w reinforcement. Tensile, tribological, and Charpy impact tests were performed to characterize the mechanical and tribological properties, which were supported with microscopic observations. Multiple experimental characterizations were performed to investigate the impact, and the ultimate tensile strength (UTS) and energy absorption capacity of the structure were shown to increase by 32% and 45%, respectively, with the addition of SiC_w. The presence of self‐healing agents provides a 5% rise in UTS after enough time for healing following the collision. The structure's tribological performance is improved by 10% in wear resistance and 20% in friction coefficient.Highlights: Hybrid laminated composite structure with silicon carbide whisker and self‐healing capsules. Tensile and Charpy impact tests conducted with microscopic observations Increased ultimate tensile strength and energy absorption capacity by 32% and 45%. Tribological improvement by 10% in wear resistance and 20% in friction coefficient.