Pin–bushing bearings in heavy-duty construction machinery operating in severe industrial environments are susceptible to accelerated wear, grease degradation, and lubrication failure, yet application-specific guidance for lubricant selection and re-greasing intervals under such conditions remains limited. This study evaluates the combined effects of bushing material (hardened steel, cast bronze, and Cu–Sn alloy), grease type (three commercially used greases with viscosities of 120, 460, and 150 mm2/s at 40 °C), and lubrication interval (8, 12, and 24 h) on grease-condition indicators in a field-operating wheel loader used in slag handling, where surrounding slag temperatures may reach 700–800 °C. A Taguchi L9 orthogonal array was used to define nine experimental configurations, each applied for approximately one week under real operating conditions. Grease samples were characterised using the SKF grease analysis kit based on NLGI consistency grade, base oil release rate, and contamination particle count. All greases showed an increase in NLGI grade from 2 to 3–4 during service, indicating thickening and a possible risk of lubrication channel blockage. Oil release rates decreased by up to 60% in some configurations, indicating reduced base oil mobility during service. When the three grease-condition indicators were evaluated together by Grey Relational Analysis, the combination of steel bushing, type B grease (ISO VG 460, lithium complex with MoS2), and a 12 h lubrication interval showed the most balanced overall response. These findings provide field-based guidance for grease selection and maintenance scheduling in pin–bushing systems operating under demanding service conditions

There are many studies on improving the properties of aluminum alloys, but the addition of rare earth elements occupies a particularly important place among them. In this study, the effect of erbium (Er) addition on the microstructure and mechanical properties of A380 aluminum casting alloy was systematically investigated. A series of alloys with varying Er contents (0.03%, 0.05% and 0.1 wt.%) was fabricated using the conventional casting method. The addition of Er led to significant grain refinement, primarily due to the formation of Al₃Er intermetallic particles, which acted as potent nucleation sites during solidification. Optical microscopy and SEM analyses confirmed the morphological transformation of the eutectic silicon phase into a finer and more fibrous structure. Mechanical testing revealed that the alloy containing 0.1 wt.% Er exhibited the highest ultimate tensile strength (236 MPa), elongation (4.56%), and hardness (87.6 HB), indicating an optimal balance between strength and ductility. The improvement is attributed to both microstructural refinement and dispersion strengthening mechanisms. These results suggest that controlled Er addition can be an effective strategy for enhancing the performance of cast Al–Si alloys, making them promising candidates for demanding structural applications in the automotive and aerospace industries.

This finite element study compared the effects of prosthetic superstructure material and supporting implant number on stresses in implants, multiunit abutments, and restorations, and on peri-implant bone strains under bruxism-like loading. Two posterior mandibular models representing missing left FDI 34–36 were generated: a 2-implant configuration (implants at 34 and 36) and a 3-implant configuration (implants at 34, 35, and 36), each restored with a three-unit implant-supported fixed bridge. For each configuration, three superstructure materials were simulated: cobalt–chromium (Co–Cr), polyetheretherketone (PEEK), and monolithic zirconia (MZ). Static parafunctional loads were applied as a 500 N oblique load (30° to the implant long axis; 125 N to each buccal cusp) and a 1000 N vertical load applied to the central fossae. Cortical bone generally exhibited higher strain than trabecular bone, and the maximum cortical principal strain under vertical loading averaged approximately 5800 μɛ. The highest implant von Mises stress occurred in the first molar implant of the 2-implant MZ model under oblique loading, while the maximum under vertical loading was 236 MPa (also 2-implant MZ). Prosthetic peak stresses reached 184 MPa under vertical loading (3-implant PEEK composite–veneered model) and 233 MPa under oblique loading (2-implant MZ), with a minimum of 51 MPa in the 3-implant PEEK framework under vertical loading. Overall, increasing implant number reduced the stress/strain values, and MZ showed comparatively higher stress and strain levels

The sternum protects the intrathoracic organs and contributes to chest wall mechanics, which makes reconstruction after tumor resection, trauma, or infection a demanding biomechanical problem. This study presents an in silico workflow for preselecting materials for sternal implants before physical prototyping. After a virtual resection, an anatomically conformal implant was designed and candidate biomaterials were screened in CES Selector using density, elastic modulus, fatigue strength, fracture toughness, toxicity, medical grade suitability, and MRI safety. A representative subset of the screened candidates was then compared by finite element modeling in terms of stress transfer and deformation. Seventeen candidates met the screening criteria. Ti-13Nb-13Zr showed an elastic modulus of about 80 GPa, and the titanium-based candidates showed deformation values of about 0.96 to 1.03 mm, whereas GF PEEK reached about 1.74 mm. The stress shielding index also showed that titanium-based materials remained on the implant-dominant side, while polymer-based materials shifted stress transfer toward bone. Taken together, the findings suggest that Ti-13Nb-13Zr offers the best overall balance for load-bearing sternal reconstruction, whereas PEEK-based systems may be more suitable within the present model for hybrid or adjunct designs. The proposed workflow can support early implant planning and guide future experimental and clinical studies.

This study examines the combination of overhang constraints and Reliability-Based Topology Optimization (RBTO) in additive manufacturing (AM). AM offers intricate component production but faces challenges due to support structures. Incorporating overhang constraints in topology optimization enables self-supporting structures. RBTO addresses uncertainties in design variables to enhance reliability. This research investigates build direction parameter solutions using deterministic and RBTO algorithms. Topological properties, compliance, sensitivity, and density filters are assessed, alongside optimization techniques like Method of Moving Asymptotes (MMA) criterion and Optimality Criteria (OC). In numerical experiments on the MBB beam, the AM-RBTO algorithm reduced 3D printing time by approximately 18.3% and improved structural performance by lowering the objective function value by 1.85% compared to conventional RBTO. Results contribute to merging overhang constraints and RBTO in AM topology optimization, improving design by considering uncertainties. The study enhances computational efficiency and stability in optimizing build direction parameters, offering valuable insights for future AM applications.

This study presents a predictive biomechanical modeling approach for optimizing distal implant placement in the All-on-4 treatment concept, with a focus on implant angulation and occlusal load direction. Finite Element Analysis (FEA) was integrated with Response Surface Methodology (RSM) to develop 15 simulation models based on a Central Composite Design, incorporating distal implant angulations of 15°, 30°, and 45°, and occlusal load directions in both sagittal and frontal planes (45°, 67.5°, and 90°). The maximum von Mises stress in cortical bone was selected as the response variable. Regression analysis revealed that the frontal load angle had the most significant effect on stress distribution, followed by implant angulation. The resulting second-order predictive model demonstrated a strong statistical fit (R² = 93.39%, adjusted R² = 81.49%). The lowest cortical stress (95.75 MPa) occurred at 15° implant angulation with 45° occlusal loading in both planes, whereas the highest stress (265.72 MPa) was recorded at 45° angulation with 90° frontal loading. Although reducing implant tilt generally decreases peri-implant stress, no universally optimal angle can be defined due to variability in biomechanical responses under different occlusal loading conditions. Clinically, optimizing cusp inclination and load direction in conjunction with implant positioning may enhance the biomechanical performance and long-term success of full-arch implant-supported prostheses.

This study presents a comprehensive analysis of the earing and thinning ratios in the deep drawing process of DD13-grade sheet metal. The variable parameters investigated include press descent speed (x1), blank holder pressure (x2) and punch pressure (x3). These parameters have been carefully selected based on production experience and preliminary experiments, and appropriate ranges of values have been established. A distinctive feature of this research is its focus on specimens with a deep drawing ratio greater than 2. The relationships between the input parameters and the response parameters were determined using the Box–Behnken design (BBD). Analysis of variance (ANOVA) for the regression models developed for earing and thinning ratios gave R2 values of 0.98 and 0.97, respectively, indicating robust predictive ability of the models. For the earing ratio, the optimal values of x1, x2 and x3 were found to be 27.38, 10 and 22, respectively. When evaluated using the same algorithm for uniform wall thickness, the optimum values were found to be 26.55, 10 and 22, respectively. The final earing and thinning ratios for all experimental runs were 3.79 and 21.19, respectively. The results of this study show that by optimizing certain parameters in the deep drawing process, the disadvantages associated with this manufacturing method can be significantly reduced.

This study aims to evaluate the biomechanical behavior of titanium and carbon fiber-reinforced polyetheretherketone (CF-PEEK) dental implants under varying bone densities and loading conditions using finite element analysis (FEA). A single-tooth mandibular molar implant system was modeled, comprising titanium or CF-PEEK abutment and fixture, and surrounding bone structures with four configurations: (I) fully cortical bone, (II) 2 mm cortical layer with trabecular bone, (III) 1 mm cortical with high-density trabecular bone, and (IV) 1 mm cortical with low-density trabecular bone. Vertical and oblique static loads of 100 N were applied to simulate masticatory forces. FEA results revealed that titanium implants exhibited higher von Mises stress values in the implant and abutment under oblique loading, exceeding 400 MPa, while CF-PEEK components showed reduced stress but significantly higher strain levels. Cortical and trabecular bone surrounding CF-PEEK implants received more uniform stress distribution, potentially minimizing stress shielding effects. However, fatigue life analyses indicated that CF-PEEK abutment and screw components were more susceptible to mechanical failure under oblique loads, particularly in low-density bone models. In conclusion, CF-PEEK implants offer a more physiological load transfer to bone and reduced stress shielding compared to titanium. However, their structural reliability under complex loading, especially in low-quality bone conditions, requires careful consideration. These findings support the potential use of CF-PEEK in select clinical scenarios but highlight the need for further material and design optimization.

This study evaluates the biomechanical effects of different implant configurations in various mandibular arch types using finite element analysis (FEA). Stress distribution and deformation patterns were analyzed under different loading conditions in square, U-shaped, and V-shaped arches. The results indicate that increasing the number of implants generally reduces cortical bone stress, particularly in U and V arches, while implant-level stress tends to increase. Under molar loading, cortical bone stress in the square arch decreased by 16.9% (from 90.61 MPa to 75.27 MPa) with the All-on-5 system, while implant stress in the V arch dropped by 46.26% (from 142.35 MPa to 76.5 MPa). Additionally, the cantilever effect in All-on-4 configurations resulted in higher stress on the prosthesis and implants, particularly in V arches. While the All-on-5 system provided better load distribution, the study highlights the importance of optimizing implant positioning based on mandibular anatomy. Despite limitations such as the use of static forces and standardized arch types, these findings offer valuable insights into the biomechanical performance of full-arch implant rehabilitations, supporting future clinical applications and research.