Types Of Fasteners Research Articles

Comparative Study on the Wear Characteristic and Control Method of Rail Corrugation in Typical Fastener Sections

This paper conducts a comparative study on the severity, development trends of rail corrugation, and the suppression effects of rail vibration absorbers on small-radius curved track sections supported by two types of typical fasteners. Firstly, a finite element model (FEM) of the wheel-rail system for small-radius curved track sections is established based on field investigation data. Then, a comparative analysis is conducted on the frictional coupling vibration characteristics and wear characteristics of the rail surface for wheel-rail systems in the two typical fastener sections. Additionally, the suppression effect of installing rail vibration absorbers on rail corrugation is analyzed. The results indicate that the frictional coupling vibration in the wheel-rail system is the primary cause of rail corrugation on small-radius curved track sections, and the vibration response of the wheel-rail system in the Cologne egg fastener section is significantly greater than that in the DTVI2 fastener section. Furthermore, rail corrugation in the Cologne egg fastener section is more severe and develops faster compared to the DTVI2 fastener section. Finally, the installation of vibration absorbers suppresses rail corrugation in both fastener sections, with a more pronounced suppression effect observed in the Cologne egg fastener section.

Cyclic loading test for brick masonry veneer anchored to reinforced concrete walls

Despite the importance of seismic design for brick masonry veneer anchored to reinforced concrete (RC) backup walls, the effects of several design parameters on the seismic capacity of such nonstructural component remain unexplored. In this study, material tests and cyclic loading tests were performed to investigate the seismic performance of connection for the brick masonry veneer wall anchored to a RC back-up wall under excitation. To this end, tensile tests were first carried out for each element comprising the unit connection to investigate the basic material strengths. A cyclic loading test was then performed on brick-tie-concrete subassembly to investigate the seismic capacity of the unit connection subjected to seismic loads. The major test parameters included the type and embedded depth of veneer anchor, type of mechanical fastener, compressive strength of concrete, and use of insulation. Based on the material strengths and unit specimen strength, the failure mode and seismic capacity of the unit connection for brick veneer anchored to concrete block were evaluated. The test results showed that the presence of the insulation significantly affected the seismic capacity. Based on the test results, design recommendations were proposed to improve the prescriptive design or general design in current practice for brick masonry veneer walls.

APPROACHES TO ASSESSING THE STABILITY OF BANK PROTECTION STRUCTURES OF WATERBODIES: ANALYSIS OF CONSTRUCTIONS AND MODELS FOR THEIR CALCULATION

The article analyzes the theoretical foundations for determining the stress state in a soil mass and the design of fastening the bank slope of reservoirs. Scientific research and theoretical principles on determining the forces that act on a bank protection structure have been systematized. Methodological approaches to the static calculation of bank protection for indirectly vertical structures are proposed, taking into account the relationship between the load on the structure and its deformation. The purpose of the research is to ensure the stability and reliability of bank protection structures and to substantiate directions for improving technical solutions in modern conditions. The work analyzes the use of various types of slope fastenings for bank protection structures in accordance with the requirements of State construction standards. It is proposed to focus research on sheet piling shore fastenings, as a modern and progressive technology for bank protection. The "soil massif - fastening structure" system is considered as a calculation model in the form of a one-sided type, which is an elastic element, which makes it possible to apply the modern apparatus of the theory of elasticity in considering this problem. This makes it possible to accept a linear relationship between stress and strain and obtain sufficient accuracy, which is confirmed by the available results of domestic and foreign research. For calculations of deformations, and assessment of the strength and stability of soil massifs and foundations, it is proposed to pay direct attention to the characteristics of the mechanical properties of soils, while three stages of foundation deformation are considered. The formulated differential equations of the equilibrium of the soil massif make it possible to solve a wide range of issues related to the limit equilibrium and to obtain the calculated parameters of the pressure of earth masses on the retaining walls of shore fortifications of the oblique-vertical type. The results of the research analysis are recommended for use in determining the main loads on hydraulic structures, substantiating technical solutions for the development and improvement of slope and slope-vertical types of bank protection of reservoirs.

Investigation of fatigue durability and influencing factors of coil springs: A case study for metro vehicles

This study investigates the fatigue failure behavior of coil compression springs and various influencing factors. The intrinsic and induced causes of fatigue failure in metro steel springs were revealed by systematic tests. Macroscopic observation and metallographic analysis of the fracture indicate that decarburization, which leads to a reduction in the fatigue limit of the material, was the essential cause of the failure. The resonance of the steel spring caused by rail corrugation leads to an increase in dynamic stress, which is the induced cause of the failure. The combined effect of the two factors promoted the failure of the springs. In addition, decarburization led to a decrease in the microhardness of the spring surface from 462 HV to 151 HV and a decrease in fatigue life from over 3.6 million kilometers to 521,000 km (with the decarburization depth of 0.3 mm). The effects of different stress ratios and decarburization depths on the equivalent shear stress (ESS) were comprehensively investigated. The ESS of steel springs with decarburization and different stress ratios were calculated according to the FKM Guideline and the EN 17149 standard. The ESS decreases from 188 MPa to 77 MPa at a stress ratio of R = 0, and from 168 MPa to 76 MPa at a stress ratio of R = 0.5. If the effects of rail corrugation are not taken into account, the ESS meets the design life requirements. Furthermore, the effects of different rail fastener types and track structures on the dynamic stress were compared. It was found that the double-layer nonlinear vibration damping fasteners can significantly improve steel spring vibration. Finally, improvement measures and recommendations are proposed based on the root causes of failure and the influencing factors.

Leveraging transformers architectures and augmentation for efficient classification of fasteners and natural language searches

A primary concern in the realm of mechanical engineering is to ensure the efficient and effective data entry of hardware devices. Fasteners are mechanical tools that rigidly connect or affix two surfaces or objects together. They are small and often different fasteners might look similar; it is therefore a long and prone-to-risk procedure to manually analyze them to classify and store their related information. With the widespread diffusion of AI frameworks in several domains, equipment manufacturers started to rely on AI technologies for these heavy tasks. Automatically classifying fasteners by type and extracting metadata from natural language questions are important tasks that fastener manufacturers and suppliers encounter. In this paper, we address these challenges. To address the first task, we introduce an augmentation methodology that starts with a small set of 3D models representing each of the 21 types of fasteners we aim to classify. This methodology efficiently generates multiple 2D images from these models. Next, we train a vision transformer using the collected data to address a single-label multi-class classification task. For the second task, we introduce a prompt-engineering technique designed for conversational agents. This technique leverages in-context knowledge to extract (metadata field, value) pairs from natural language questions. Subsequently, we tackle a question-answering task to the description fields of the extracted fasteners. Our evaluation demonstrates the effectiveness of both approaches, surpassing the baselines we tested.

Experimental study on structural performance of 7A04-T6 high-strength aluminium alloy shear connections in and after fire

The present study addresses the structural behaviour and design of 7A04-T6 high-strength aluminium alloy double shear connections under elevated temperatures and post-fire conditions with air cooling. A total of thirty-three connection specimens, featuring different fastener types and geometric characteristics, including end distances and edge distances, were tested under varying temperature histories, ranging from 20 to 400 ℃. An electric furnace was employed to heat the connection specimens, while digital image correlation (DIC) technology was employed to record displacements of the specimens during testing. Three distinct failure modes were observed in the tested specimens, namely the bearing, shear-out, and net section tension failures. The experimental results obtained from this study were compared to the predictions generated by the current design methods outlined in the American specification (AA), European standard EN 1999–1-1 (EC9) and Chinese code GB 50429 (GB). The comparisons revealed that the design rules often exhibit conservatism in predicting the ultimate resistances of 7A04-T6 high-strength aluminium alloy shear connections under elevated temperatures and post-fire conditions. Notably, EC9 emerged as providing the most accurate predictions for both resistances and failure modes of the investigated shear connections.

Experimental and Numerical Analyses of Timber–Steel Footbridges

In addition to traditional building materials, such as steel and concrete, wood has been gaining increasing prominence in recent years. In the past, the use of wood was limited due to its susceptibility to damage by fungi, insects, and temperature. These shortcomings were gradually eliminated as the quality of wood processing increased and thanks to modern high-quality insulating and protective materials. The return to the utilisation of this natural building material was also supported by the development of new wood-based materials, such as glued laminated wood, and new types of mechanical fasteners, as well as by the introduction of new design methods provided in the Eurocodes. Within this context, this paper focuses on using wood in transport infrastructure, especially as the basic material for footbridges and small road bridges. Combined timber–steel bridges emerge as a very effective type of superstructure in contemporary road bridges and footbridges, especially in areas with natural exposure. Usually, wood is used for the main bridge girders, while steel is preferred for bridge deck elements—stringers and cross-girders. The results of this parametric study offer optimal structural solutions for footbridges with spans of 12.0–24.0 m, reflecting satisfactory static and dynamic footbridge behaviour. Particular attention is paid to a problematic structural detail—the connection between the steel cross-girder and the timber main girder. Firstly, this connection’s characteristics were measured experimentally using nine laboratory samples made of two glued laminated timber blocks, simulating main girders connected with a hot-rolled steel cross-girder. The connection was prepared in three variants, with different heights of the end plates and different numbers of bolts. Subsequently, these characteristics were computed using two numerical FEM models. The first model was created using SCIA Engineer software with a combination of shell and beam finite elements. The second, more sophisticated model was created in the ANSYS software environment using 3D finite elements, allowing us to better take into account the plasticity and orthotropic properties of wood and the points of contact between the individual members. Finally, the experimental results produced by sample testing in the laboratory were compared to the outputs of FEM numerical studies.

Exploring the electrical robustness of conductive textile fasteners for wearable devices in different human motion conditions

Conventional snap fasteners used in clothing are often used as electrical connectors in e-textile and wearable applications for signal transmission due to their wide availability and ease of use. Nonetheless, limited research exists on the validation of these fasteners, regarding the impact of contact-induced high-amplitude artefacts, especially under motion conditions. In this work, three types of fasteners were used as electromechanical connectors, establishing the interface between a regular sock and an acquisition device. The tested fasteners have different shapes and sizes, as well as have different mechanisms of attachment between the plug and receptacle counterparts. Experimental evaluation was performed under static conditions, slow walking, and rope jumping at a high cadence. The tests were also performed with a test mass of 140 g. Magnetic fasteners presented excellent electromechanical robustness under highly dynamic human movement with and without the additional mass. On the other hand, it was demonstrated that the Spring snap buttons (with a spring-based engaging mechanism) presented a sub-optimal performance under high motion and load conditions, followed by the Prong snap fasteners (without spring), which revealed a high susceptibility to artefacts. Overall, this work provides further evidence on the importance and reliability of clothing fasteners as electrical connectors in wearable systems.

Study of Innovative Connector for Steel–Concrete Composite Structures

The paper presents an analysis of the innovative connector for manufacturing a steel–concrete composite beam. The connector consists of a corrugated metal sheet in the shape of a dovetail and shot nails. The nails are shot through the sheet fold into the flange of the steel I-section. Experimental studies of push-out tests were carried out. The conducted tests proved that the proposed solution can be applied as the fastener for steel–concrete composite beams for the construction of ceilings in utility public buildings with small beam’s span. Considering the criteria presented in the Eurocode 4 standard and the results of the experiments, it was proven that all analyzed types of fasteners are ductile. The connector made of sheet with a thickness of 1.00 mm and 2 nails is characterized by a breaking load of 30.83 kN. The load-bearing capacity of the fastener can be adjusted by changing the corrugated sheet thickness and changing the number of nails shot in the single fold of the sheet.

Seismic behavior assessment of fasteners based on a shaking table test of a museum building model with a display case and artifacts

Fasteners are widely used in museums as an attachment method to secure objects. However, due to the lack of research on the seismic behaviour of fasteners under seismic loads, the implementation of fasteners in museums usually lacks scientific guidance, resulting in their ineffectiveness in improving the seismic safety of museum artifacts. In addition, few studies have experimentally investigated the adverse effects of structural dynamic amplification on the seismic safety of museum artifacts. Therefore, this study aimed to assess the seismic behavior of fasteners used in museums and provide valuable insights for protecting museum artifacts. Shaking table tests were conducted on a full-scale model of a museum building, display case, and artifacts to simulate seismic loads and investigate the seismic response of two typical artifacts secured with fasteners. A numerical study was also performed to evaluate different types of fasteners and their effectiveness in enhancing the seismic safety of artifacts. The adverse effects of dynamic amplification on artifact safety were discussed, and recommendations were provided for improving the seismic behavior of fasteners. Furthermore, the impact of multidirectional seismic excitation on the safety of the artifacts and the seismic performance of the fasteners were analyzed. The research findings contribute to the selection of appropriate fasteners for preserving valuable artifacts in museums.

Fatigue of 1.5 Single-Shear Lap Joints with Sealant and Corrosion-Inhibiting Compounds

Corrosion-inhibiting compounds (CICs) are a secondary protection method used with aircraft that can reduce the rate of corrosion development. However, CICs can also affect the fatigue life of fastened lap joints. This study uses a 1.5 single-shear lap joint design to investigate fatigue life changes with CIC application. Hi-Lok and rivet fastener types are compared, along with the inclusion of faying surface sealant. It was found that without sealant, the application of CICs increased the fatigue life due to prolonging the crack initiation process. The presence of faying surface sealant led to a reduction in fatigue life for the rivet samples. The Hi-Lok samples saw no change in life due to the squeeze-out of the sealant around the fastener holes. This study provides a foundational understanding of the mechanisms and significance of the change in fatigue life with the presence of CICs and faying surface sealant in a fastened lap joint.

Pull-out capacities of screw connections in thin steel battens exposed to bushfire conditions

External building envelopes made of cold-formed steel (CFS) claddings are commonly used in bushfire prone areas due to their non-combustible properties. However, their designs should ensure safety under the combined action of enhanced wind suction loading and elevated temperatures experienced during bushfires. Although numerous studies have investigated the critical pull-out failures in CFS batten screw connections under wind suction loading at ambient temperature, the pull-out failure behaviour of batten screw connections under bushfire conditions has not been investigated. The main objective of this study is to examine the pull-out failure mechanisms and capacities of screw connections in CFS battens under wind suction loading at elevated temperatures. Two hundred and sixteen small-scale tests were conducted on CFS battens made of three commonly used thicknesses and both high (G550) and low (G300) strength steels. Tests were conducted at six different temperatures using three types of screw fasteners to investigate the critical localised pull-out failures of batten screw connections. The results of these tests were utilised to develop applicable design equations and capacity reduction factors for the pull-out capacities of batten screw connections under the combined action of wind suction loading and elevated temperatures. The findings of this study will help design and build structures safely in bushfire-prone regions.

A BRIEF COMPARATIVE OVERVIEW OF THE TYPES OF RAIL LINES AND METRO TRACKS

The article presents a brief and comparative overview of the technical and operational rail lines used in the Baku Metro. The principles of schemes and rules for fixing rail lines on wooden sleepers and on concrete foundations, as well as their advantages and disadvantages, are described. It is established that relative to the construction with "metro" type fasteners, the path on the concrete structure is characterized by a low intensity of deviations. It is also shown that the main defects of the it stops alow structure can be associated, firstly, with the lack of restriction of the vertical degree of freedom of the rail (terminals), as a result of which the contact points of the fastening elements experience increased wear, and secondly, with rotting, shrinkage and deformation of wooden sleepers. All the described defects are massive in nature and lead to a large number of deviations in the current content of the GRK, including deviations that require limiting the speed of trains.

Comparison of polymethyl methacrylate skull implant fixation by three types of titanium fasteners

To evaluate mechanical strength of three methods of polymethyl methacrylate skull implant fixation in two experimental models. The first experiment was performed on a plastic model that was as close as possible to bone in structural characteristics. The second experiment was performed on a biological specimen (a ram's head). We assessed the quality of implant fixation to bone window edges by craniofixes, ties and microscrews and lateral intercortical screws. Craniofixes are feasible for small flat flaps, but not advisable for wide highly curved implants. They are also the most expensive method of fixation. Implant fixation by ties and microscrews is a universal method comparable in price to craniofix. Lateral intercortical fixation is effective both for small flat implants and wide implants with large curvature. However, this method is not always applicable. Combined fixation by lateral intercortical screws and ties allows for the most effective fixation while reducing the overall price of consumables.

Load-Bearing Capacity Assessment of Traffic Superstructures for Roads and Tramways

The load-bearing capacity of traffic superstructures is usually assessed based on deformation measurements. The bearing capacity is defined as the superstructure’s resistance to short-term deformations. However, different measurement concepts and evaluation methods are required for different superstructures to assess the bearing capacity. Therefore, this paper will present various methods for road and tramway superstructures and illustrate them with practical examples.The bearing capacity of road pavements is typically assessed by deflection measurements using the falling weight deflectometer (FWD). This dynamic measurement method applies a falling weight to the road surface, and the resulting deflection basin is recorded briefly. This can then be evaluated. Evaluations of various measurements in Germany are presented.The assessment of load-bearing capacity in the tramway sector is not currently established in German regulations. An individual measurement concept was developed and applied to assess the load-bearing capacity in urban transportation. The measurements aimed to determine the in-situ deformations of the grooved rail with a selected type of fastening during the passing of trams. In addition, the serviceability during operation was checked. The measurements were carried out on an open construction (grass track) and a closed construction (asphalt), as well as in tight curves and on straight track sections. Based on the deformations determined, conclusions can also be drawn about the service life.

Dynamic analysis of functional gradient porous sigmoidal sandwich plates

Analysis of free vibrations of functionally graded (FG) porous sigmoid sandwich plates, is considered in this paper. The plate can have a complex geometric shape and various types of fastening. To solve the problem, we used the variational-structural method (RFM), which combines the theory of R-functions and variational method of Rayleigh-Ritz. The mathematical statement of the problem is carried out within the framework of the deformation theory of plates of the first order (FSDT). Plates are considered, the outer layers of which are made of functionally graded materials (FGM), and the core is isotropic. For different models of porosity distribution (sigmoid uniform and nonuniform), analytical expressions were obtained to calculate the effective properties of FGM. For rectangular plates, a comparison of the obtained results with known results obtained using other approaches is shown. Calculations for plates with a complex shape are presented in the form of tables and graphs. The influence of the volume fraction of ceramics, the different types Of FGM and the coefficient of porosity on the natural frequencies of the plate is analyzed.

Experimental study on the mechanical properties of stainless steel high strength short tail swage-locking pins

As a type of fastener, swage-locking pins have demonstrated remarkable performance and widespread utilisation across aviation, aerospace, and railway industries. As the variety of swage-locking pin products continues to expand, the production of larger-sized pins with different materials has become feasible. Consequently, these pins can be effectively employed in stainless steel structures in civil engineering construction as an alternative to high-strength bolts, effectively mitigating the challenges associated with stainless steel high-strength bolts. In this study, stainless steel short tail swage-locking pins were fabricated and tested to assess their applicability in stainless steel structures as a viable substitute for M20 high-strength bolts. Specifically, the mechanical properties of the raw material of the stainless steel swage-locking pins were tested. The preload level of the swage-locking pins was measured, and negligible relaxation in preload over time was observed. The average preload value achieved met the requirements for M20 high-strength bolts. The bearing capacity of the swage-locking pins under tension and shear was measured, and a bearing capacity design equation was proposed. Furthermore, a principle for the pin group installation sequence was proposed and the relaxation of the preload under this principle was measured. In conclusion, this study offers valuable insights and references for the seamless integration of stainless steel high-strength short tail swage-locking pins within stainless steel structures.

Evaluation of dowel bearing strength of fungal-decayed cross-laminated timber

ABSTRACT Dowel bearing strength of three cross-laminated timber (CLT) species (Douglas-fir, Norway spruce, spruce pine fir) were periodically assessed through 40 weeks of exposure to two brown rot fungi species (Gloeophyllum trabeum and Rhodonia placenta). Time-dependent regression models were developed to describe the relationship between level of fungal exposure and dowel bearing strength of CLT. Obtained dowel bearing strength values were used to predict the capacity of floor-to-wall CLT connection systems. Predicted strength values were compared with capacity of actual connection systems which were subjected to similar biodeterioration treatments. Significant reductions in the dowel bearing strength of CLT were observed 30 weeks after fungal inoculation. Similar patterns of degradation were observed for both fungi in all three CLT species, but R. placenta was slightly more aggressive than G. trabeum, causing a 16.2 MPa reduction in dowel bearing strength of Douglas-fir after 40 weeks of exposure. Connection capacities estimated using National Design Specification yield models for dowel type fasteners and the dowel bearing strength of fungal-damaged CLT were consistent with observed properties and were within 85% of actual capacity of connections tested, especially in early stages of decay.

Effect of Critical Factors Influencing Longitudinal Track Resistance Leveraging Field Experimentation

As extreme temperatures increase, there is an increased need to ensure that continuous welded rail (CWR) stresses are more accurately set and better maintained. Therefore, to improve the management of CWR rail stresses and to increase safety through the reduction of buckled track derailments this paper documents the results from a field experimentation program of controlled single rail breaks (SRBs). SRBs were conducted at multiple field site locations to quantify the longitudinal resistance on both timber and concrete sleeper track. Accurate longitudinal resistance values are critical, because if the wrong value is selected, the rail neutral temperature could easily be set to a low value, increasing the probability of a track buckle or rail pull-apart, further compounding the impact of extreme temperatures. The results presented quantify the effect of sleeper and fastener type as well as ballast consolidation, and compare them with relevant results from the literature. From this, it was found that well-maintained concrete sleeper track exhibited a longitudinal resistance greater than the currently recommended value. Further, well-maintained timber sleeper track with anchors on every other sleeper exhibited a longitudinal resistance 44% lower than concrete sleeper track and 30% lower than timber track with anchors installed on every sleeper. Additionally, disturbing the ballast reduced the longitudinal resistance by 15%. Finally, the results indicated that slip was primarily occurring at the rail–sleeper interface for unanchored timber sleepers and at the sleeper–ballast interface for anchored timber sleepers and concrete sleepers.

Многовариантное моделирование параметров конструкции упругих клемм современных рельсовых скреплений с анализом их напряженно-деформированного состояния

Purpose: To determine the influence of geometric parameters on the most common elastic rod clip used in modern intermediate rail fastenings — the B-shaped clip (such as reinforced concrete rail (RCR) clip and anchor rail fastening (ARF)) — on changes in its stress-strain state. To propose a further direction of improving the design of elastic rod clips of rail fasteners to increase the reliability of the structure. Methods: The article presents the results of multivariate modeling of the geometric parameters of the clips (RCR — 20 pcs., ARF — 13 pcs.) with the analysis of their stress-strain state, using the methods of software and computer systems SolidWorks and Ansys Workbench. Results: Analysis of the design of modern fasteners has shown that the intervals for varying the geometric parameters of the clips (rod diameter, vertical radius, horizontal radius) have small limits and significant limitations associated with the requirements for ensuring the strength, elasticity and operability of the entire fastening. The necessity of considering options with vertical radii less than 60 mm has been revealed, which entails the need for a radical change in the shape of the clips themselves. Practical significance: As a result of the analysis of the calculations of multivariant models, the degrees of influence of the intervals of variation of the geometric parameters of rod clips (rod diameter, vertical radius, horizontal radius) on the stress-strain state have been determined. It is established that in order to further increase the elasticity of the clips, it is necessary to develop a new type of rail fastening with a fundamentally different shape (different from the modern B-shaped) elastic clip that does not have modern design limitations in geometric parameters.