Search Results (24)

Rod ends are critical structural components primarily designed to sustain axial loads in mechanical and aeronautical assemblies. However, operational conditions may involve transverse loading, which induces significant bending stresses concentrated in the threaded shank region. This research presents an experimental investigation aimed at characterizing the elastoplastic bending behavior of the threaded portion of rod ends subjected to such off-axis loads. Specimens manufactured from precipitation-hardened stainless steel 17-4 PH were tested under both displacement and force control strategies. Each specimen was subjected to incremental loading until failure to determine the elastic limit, yield point, ultimate bending strength and fracture mode. The experimental results enabled a preliminary assessment of the static resistance of the threaded region; furthermore, a comparison with analytical formulations and empirical estimation methods available in the literature revealed promising agreement. These findings highlight the importance of accounting for non-axial loading in the design of threaded joints for critical applications. This study establishes a baseline for broader experimental campaigns aimed at validating these results and exploring fatigue behavior under cyclic transverse loads. Full article

Threaded fasteners and tapping joints are essential for the structural integrity and leak-proof performance of subsea systems subjected to high external pressure, aggressive corrosion, and complex cyclic loading. This study presents a comprehensive, systematically structured review of experimental, analytical, and numerical investigations of nut–bolt and threaded connections used in deep- and ultra-deepwater applications. The literature is classified based on governing performance parameters, including thread engagement mechanics, preload retention, fracture behavior, corrosion–fatigue interaction, material evolution, and environmental effects such as hydrostatic pressure and thermal gradients. Experimental observations are critically synthesized with finite element modeling to interpret stress distributions, failure mode transitions, and sealing reliability. A comparative material selection framework is developed by linking conventional carbon steels with advanced alloys such as duplex stainless steels, titanium, and nickel-based materials for long-term subsea service. The novelty of this review lies in the development of an integrated, design-oriented framework that unifies engagement optimization, preload control, fracture modeling strategies, material selection, and environmental coupling into a single engineering interpretation for subsea fastening systems, which has not been collectively addressed in previous studies. The presented synthesis provides direct application guidelines for improving the design, analysis, and operational reliability of subsea bolted joints. Full article

Background/Objectives: Accessory mandibular foramina (AMaFs) are small osseous openings of the mandible that are clinically relevant anatomical variations. This study aimed to characterize the morphology and spatial distribution of AMaFs in dry mandibles and to integrate the existing anatomical evidence through a systematic review and meta-analysis, with the goal of clarifying their potential clinical relevance. Methods: A series of dry mandibles from human adults of unknown age and sex from our laboratory collection was examined to document AMaFs using direct osteological inspection. Stainless steel wire threads and digimatic caliper measurements were utilized by two separate raters. Cluster analysis was employed for the classification of foramina into distinct spatial groups. Furthermore, in accordance with the PRISMA guidelines, an unrestricted literature search was conducted across PubMed, Scopus, SciELO, and Google Scholar using appropriate database-specific combinations of the terms “accessory mandibular” and “foramen/foramina” to search for studies on the prevalence and morphology of AMaFs in dry mandibles or cadaveric material. Radiological studies were excluded. The search was completed on 13 July 2025. Study quality was evaluated using the appropriate AQUA tool. Data synthesis was carried out using STATA 19. No external funding was received. Results: A total of 96 dry mandibles (50 dentate and 46 edentulous) were analyzed. AMaFs were detected in 8/96 mandibles (8.3%). In these mandibles, a total of 25 accessory mandibular foramina, all superior to the mandibular foramen, were identified (mean: 3.13 foramina/mandible), with a mean diameter (SD) of 0.56 ± 0.10 mm and a mean distance from the mandibular foramen of 11.34 ± 1.29 mm (mean vertical distance: 10.32 ± 1.35 mm; mean absolute horizontal distance: 3.78 ± 0.49 mm). Of these foramina, 21/25 (84%) had a diameter ≥0.5 mm; the number, diameters, and distances from the mandibular foramen were comparable between left and right hemimandibles. Based on their positioning relative to the mandibular foramen, the AMaFs were classified into two distinct groups (clusters). In the meta-analysis, a total of 36 studies were included. In most of the mandibles (65.1%; 95% CI: 57.7–72.2%; I²: 94.9%), no AMaFs were detected. The unilateral presence of one or more AMaFs was observed in 20.9% of the mandibles (95% CI: 16.3–25.9%; I²: 91.3%), while bilateral occurrence was identified in 10.6% (95% CI: 6.9–15.0%; I²: 93.0%). Additionally, 2.4% of the mandibles (95% CI: 1.0–4.2%; I²: 86.3%) exhibited multiple AMaFs (≥2) on at least one side. On average, each hemimandible contained 0.253 AMaFs (95% CI: 0.198–0.312; I²: 96.9%). The overall mean diameter of AMaFs was estimated to be 0.65 ± 0.33 mm. The substantial heterogeneity observed was not explained by geographic origin, sample size, publication period, or publication bias. Conclusions: AMaFs were detected in approximately one-third of the mandibles in the studies included in the meta-analysis. AMaFs are typically located superior to the mandibular foramen and may represent additional anatomical pathways associated with inferior alveolar nerve branching. Awareness of these features could help clinicians to anticipate anatomical variability during mandibular surgery and when applying local anesthesia. In addition, it should be acknowledged that inferior alveolar nerve block failure is multifactorial and not solely determined by the presence of AMaFs. Full article

Axial cracking in threaded joints of rotary steerable tools is a critical but under-investigated failure mode that can severely disrupt shale gas drilling operations. Understanding its root cause is essential for prevention. This study aims to determine the cause of an axial cracking failure in an S35150 austenitic stainless steel threaded joint from a field operation. A comprehensive analysis was conducted, integrating physicochemical characterization of the failed joint. The stress corrosion behavior of the threaded joint in a simulated corrosive environment was evaluated via four-point bend (FPB) and double cantilever beam (DCB) stress corrosion tests. The results showed that the material exhibited high susceptibility factors: a hardness of 38.5 HRC, a yield-to-tensile ratio near 1, and a P content exceeding the standard. Fracture surface analysis revealed an intergranular morphology with substantial chlorine (0.78%) and sulfur (0.93%) contents, indicative of stress corrosion cracking (SCC). The laboratory tests results demonstrated that the threaded joint had poor crack resistance: the fracture toughness value of the specimen measured by the DCB test was 24.14 MPa·m^0.5, and all specimens fractured during the FPB. Full article

Steel and prestressed concrete traction poles can be fixed to reinforced concrete pile foundations using typical bolted connections. The stainless steel fastening screw is connected to the ordinary steel foundation pile reinforcement by friction welding under specific friction welding process parameters. From the perspective of the structural strength of the connection between the traction pole and the foundation pile, regarding the transfer of tensile and shear forces through a single anchor bolt, the yield strength of stainless steel bolts should be R_e,min ≥ 345 MPa for M30 anchors, R_e,min ≥ 310 MPa for M36 anchors and R_e,min ≥ 300 MPa for M42 anchors. This requirement is reliably met by martensitic stainless steels, while other stainless steels have yield strengths below the required minimum. What truly determines the foundation pile’s load capacity is not the satisfactory mechanical strength of the stainless steel (here, the parameters are met), but the quality of the friction-welded end connection between the reinforcement and the threaded bars. Incorrect selection of the type of prestressing steel in the analyzed connection can have enormous consequences for foundation pile manufacturers. Annual production of foundation piles amounts to thousands of units, and an incorrect decision made by the pile designer at the design stage can result in significant financial losses and a high risk to human life. This article presents the results of studies on friction-welded connections of M30, M36, and M42 threaded bars made of austenitic 1.4301 (AISI 304) and martensitic 1.4021 (AISI 420) stainless steel with B500SP reinforcement bars. The tests yielded negative results for 1.4021 (AISI 420) steel, despite its yield strength exceeding R_e ≥ 360 MPa. Full article

Fire hazard presents a critical challenge to the structural reliability of underground modular infrastructure. This study examines the fire resistance performance of prefabricated monolithic utility tunnels featuring longitudinal threaded connections. A series of fire exposure tests was conducted on assembled utility tunnel specimens using different bolt materials and thermal conditions, enabling evaluation of fire behavior, deformation behavior, and residual capacity. The observed thermal properties revealed significant temperature gradients across tunnel sections, with the peak internal–external differential reaching 536.8 °C. Post-fire mechanical degradation was evident in reduced stiffness and ductility, and the residual load-bearing capacity declined by up to 12.28% compared to unexposed specimens. Specimens using high-strength threaded bolts demonstrated superior performance compared to stainless steel bolt specimens, exhibiting a 4.67% higher residual capacity and 13.87% less residual deformation. A sequential thermal–mechanical finite element model was developed and calibrated based on experimental results, offering a reliable simulation framework for investigating fire-induced damage and residual strength in modular utility tunnel systems. These findings provide a quantitative basis for fire safety assessment. Full article

This study presents a novel design method for determining the tensile load-bearing capacity of a rivet nut connection with an aluminium alloy profile. The method, developed based on the requirements of standards LVS EN 1993-1-8:2025, LVS EN 1999-1-1:2023, and LVS EN 1999-1-4:2023, incorporates checks on the aluminium profile web’s shear strength, rivet and rivet nut capacities, thread strength, and profile web buckling. Twenty-five laboratory specimens across five groups—with web thicknesses ranging from 2 mm to 5 mm and utilising rivet nuts made of AISI 303 1.4305 stainless steel and AW 5052 H32 aluminium alloy—were tested. The aluminium profiles were grade AW 6060 T66. Results show that using stainless steel rivet nuts increased the elastic-stage load-carrying capacity (Fp_0.2) by 18.33% and the ultimate load capacity (Fm) by 15.89% compared to aluminium alloy nuts. The proposed design algorithm, validated by experimental tests and finite element method (FEM) analyses using Dlubal RFEM 6 (v. 4), predicts tensile resistance within a 10% accuracy. The study identifies pull-out of the aluminium profile wall as a critical failure mechanism, emphasising its inclusion to avoid overestimating connection capacity. This method provides a practical and reliable design tool for tensile load-bearing rivet nut connections in aluminium structural systems. Full article

Objectives: This study aimed to compare the biomechanical effects of Ballista Spring and Elastic Thread systems on impacted maxillary canines using three-dimensional finite element analysis (FEA). Materials and Methods: Finite element models were constructed from CBCT images of a human maxilla, incorporating cortical bone, spongy bone, teeth, and periodontal ligament. Two orthodontic force application methods were simulated: Ballista Spring (0.016-inch stainless steel) and Elastic Thread (0.25 mm medical-grade latex). Both systems delivered a force of 150 g to the impacted canine. Stress distribution and initial displacement patterns were analyzed using ANSYS Workbench. Results: The Ballista Spring generated a more uniform stress distribution across the periodontal ligament and cortical bone, with a maximum von Mises stress of 0.0042 MPa. The impacted canine exhibited an initial displacement of 0.015 μm, primarily in the vertical and distal directions, indicating a controlled movement path. In contrast, the Elastic Thread showed a more concentrated stress pattern with a maximum von Mises stress of 0.0035 MPa, and the impacted canine experienced 0.013 μm of displacement, accompanied by greater lateral deviation and buccal tipping of the adjacent teeth. The Ballista Spring induced higher stress levels on anchorage teeth—particularly the first molars and premolars—while the Elastic Thread exerted more localized stress around the impacted canine and adjacent structures. All observed stress values remained within physiological thresholds, indicating no immediate risk of tissue damage. Conclusions: Both systems were effective in facilitating the eruption of the impacted canines. However, the Ballista Spring provided more favorable stress distribution and controlled displacement, making it suitable for complex cases requiring anchorage preservation. The Elastic Thread, while less biomechanically efficient, remained a practical and cost-effective alternative in patients with adequate periodontal support. Full article

Background/Objectives: The lingual foramina of the mandible serve as passageways for arterial branches that are susceptible to injury during surgical procedures, potentially leading to varying degrees of hemorrhage. The objective of the present study was to contribute to the quantification and classification of lingual foramina using cadaveric dry mandibles in relation to surgical safety and, especially, to the risk of perioperative bleeding. Methods: This study examined the number, diameter, and spatial relationship of lingual foramina to the genial tubercle, alveolar process, and alveolar crest in dry mandibles. Stainless steel wire threads and Digimatic caliper measurements were utilized. Cluster analysis was employed for the classification of foramina into distinct spatial groups. One-way analysis of variance (ANOVA) was used to compare mean values among ≥3 groups. Results: A total of 100 dry mandibles were initially analyzed for the presence of lingual foramina with a diameter of ≥2 mm. In 96 of them (50 dentate and 46 edentulous), 387 lingual foramina (mean: 4.03 per mandible) were recognized; the remaining 4 had smaller lingual foramina (diameter <2 mm). Only 4 mandibles (4.2%) exhibited a single lingual foramen, whereas the remaining 92 (95.8%) displayed multiple foramina (up to nine). The observed lingual foramina had a diameter of 0.44 ± 0.02 mm and were located at distances of 8.74 ± 0.54 mm from the genial tubercle, 14.19 ± 0.87 mm from the alveolar crest, and 14.53 ± 0.84 mm from the inferior border of the mandible. Based on their relationship to the genial tubercle, the foramina were classified into four distinct groups: (i) right (27/387—7%), (ii) proximal (254/387—66%), (iii) superior (81/387—21%), and (iv) left (25/387—6%). The superior group exhibited the largest mean diameter (0.52 ± 0.22 mm, ANOVA p < 0.001). The probability of detecting a lingual foramen was minimized at a distance of 13.00 ± 0.50 mm from the genial tubercle, delineating a relatively safe zone with a lower risk of hemorrhage. Conclusions: This study provides anatomical insights that contribute to appropriate preoperative planning and the minimization of complications during surgical interventions on the mandible. Full article

Toxic materials are a threat in workplaces and the environment, as well as households. In them, gaseous substances are included, especially ones without any colour or fragrance, due to their non-detectability with the human senses. In this article, an attempt was made to find a solution for its detection in various conditions with the use of intelligent textiles. The approach was to perform modification on fifteen materials by screen printing using carbon nanotubes paste with expanded graphite and embroidery with stainless steel thread and then investigate their reaction with risky gases such as acetone, methanol and toluene. Four combinations of samples were tested: before tests, after the washing test and after the alkaline and acidic sweat contact test. Three materials can be highlighted. Para-aramid knitwear which reacted well to all tested gases. The biggest value of sensory percentage response was 144%. Screen-printed linen knitwear showed properly detecting skills after washing test for toluene. The biggest value of sensory percentage response was noted at 186%. The third most promising material was low surface mass cotton knitwear with embroidery which had a visible response at every stage of testing for acetone. The biggest value of sensory percentage response was 94% and the smallest one was 27%. For these three materials, repeated contact with harmful gases was tested. Simulations showed also repeated responses expressed in changes in surface resistance under changed conditions. After analysis, there is a possibility to create textile sensors for the detection of hazardous substances. Full article

Ternary carbonate salts (Li₂CO₃-Na₂CO₃-K₂CO₃) are promising heat transfer fluids to increase the efficiency of the electric power in concentrated solar power (CSP) technology. However, the corrosion produced at high operating temperatures is a key challenge to tackle for employing cost-effective steels as construction materials in CSP. In this work, the use of stainless steels with amorphous carbon was investigated, for the first time, as a surface modification method to mitigate the corrosion of structural CSP materials by molten salts. In doing so, an amorphous carbon (a-C) film of 100 nm in thickness was deposited on the 301LN stainless steel’s surface by the carbon thread evaporation technique. The corrosion behavior of the 301LN was assessed in carbonate salt at 600 °C for 1000 h. This film decomposed forming carbide layers, contributing to corrosion mitigation due to the generation of denser oxide layers, decreasing the Li⁺ diffusion through the stainless steel. Full article

A low-cost electronic yarn (e-yarn) fabricated with conductive yarns and light-emitting diodes (LEDs) for wearables is presented. As part of ongoing research to develop smart interactive pedestrian clothing, this work demonstrates the design and performance qualities of braided e-yarns to produce red lighting effects. The design process adopted a simple encapsulation process with adhesive tape and a heat contraction tube to secure stainless steel conductive threads to solder pads of the LEDs. These were arranged in series against two stainless steel conductive threads to provide single positive and negative terminals at both ends. The success of these low-cost, flexible, and strong (wash durability) braided e-yarns proved to be a major achievement for integration into woven fabrics for smart pedestrian safety clothing. These braided e-yarns producing the necessary lighting effects are a key safety feature for improving pedestrian visibility and driver recognition at night-time. Full article

This article focuses on the technologies used by a manufacturing company to produce threads in chrome–nickel steel 1.4301 at specific sheet thicknesses. To enhance production quality, two specific technologies were chosen for hole formation, considering the requirements of the company. Both conventional drilling and nonconventional laser cutting methods were evaluated as potential techniques for hole production. Conventional thread-cutting technology and progressive forming technology were employed to create metric internal threads. The aim of integrating these diverse technologies is to identify the optimal solution for a specific sheet thickness in order to prevent the occurrence of defective threads that could not fulfil the intended purpose. The evaluation of the threads and holes relies on the examination of surface characteristics, such as the quality of the surface, as well as the lack of any signs of damage, cracks, or burrs. Furthermore, residual stresses in the surface layer were monitored because these stresses have the potential to cause cracking. Additionally, extensive monitoring was performed to guarantee that the form and size of the manufactured threads were correct to ensure smooth assembly and optimal functionality. Full article

This paper utilized a hot-rolling process to produce composite rods and subsequently manufactured 304/45 composite bolts through the process of drawing and thread rolling. The study focused on examining the microstructure, fatigue performance, and corrosion resistance of these composite bolts. Additionally, the impacts of quenching and tempering on the fatigue performance of the composite bolts were explored and compared to the performance of 304 stainless steel (SS) bolts and Grade 6.8 35K carbon steel (CS) bolts. The results indicate that the SS cladding of the cold-worked 304/45 composite (304/45-CW) bolts was primarily strengthened by the cold deformation mechanism, which resulted in high microhardness, averaging 474 HV. At a maximum surface bending stress of 300 MPa, the fatigue cycles of the 304/45-CW reached 342,600 cycles at a 63.2% failure probability, which was significantly higher than that of commercial 35K CS bolts. The S-N fatigue curves showed that the fatigue strength of the 304/45-CW bolts was approximately 240 MPa, but the fatigue strength of the quenched and tempered 304/45 composite (304/45-QT) bolts decreased significantly to 85 MPa, due to the loss of the cold deformation strengthening effect. The corrosion resistance of the SS cladding of the 304/45-CW bolts was impressive and remained largely unaffected by carbon element diffusion. Full article

This paper presents the results of an analysis of carbon (in the form of graphene oxide) deposited on the surface of threads made from stainless steel 316 and titanium alloy Ti6Al4V used in orthopedics using Laser Induced Breakdown Spectroscopy (LIBS). The aim of the article is to indicate the possibility of using the LIBS spectra for the study of thin layers, including graphene derivatives and other elements. Stratigraphic measurements allowed the detection of differences in the spectra peaks of individual elements, not only in the surface layer itself and in the native material, but also in the intermediate layer connecting the two layers. Due to the clear difference in the outline of the spectrum of graphene oxide and the spectrum of the native material of the samples analyzed, a clear incorporation of carbon atoms into the surface layer was observed. A factor analysis was performed, which confirmed the incorporation of graphene oxide into the surface layer of the native material of the elements examined. Full article