Fastening System Research Articles

Experimental and finite element assessments of the fastening system of fiber-reinforced foamed urethane (FFU) composite sleepers

This paper studies the structural integrity of fastening systems used in fiber-reinforced foamed urethane (FFU) composite sleepers. 24 FFU specimens are studied with screw pull-out tests and digital image correlation (DIC) to investigate the effects of parameters such as wet conditions, the sleeper drilled hole diameter and the screw active length inside the sleeper. The pull-out test results reveal that a moisture content of 0.3% in FFU specimens can reduce the pull-out strength between the dry and water-absorbed specimens with 18 mm FFU hole and 80 mm screw active length in dry and wet states (18-AD &18-AW), 18 mm FFU hole and 90 mm screw active length in dry and wet states (18-BD & 18-BW), 20 mm FFU hole and 110 mm screw active length in dry and wet states (20-CD & 20-CW), and 20 mm FFU hole and 90 mm screw active length in dry and wet states (20-BD & 20-BW) by approximately 18%, 19%, 6% and 13%, respectively. Specimens with 20 cm holes have the highest pull-out loads of 71.9 kN and 68 kN in dry and water-absorbed states, respectively. When the active length of the screw decreases from 110 mm to 90 mm, the pulling strength decreases by approximately 14% and 16% in dry and water-absorbed states, respectively. Therefore, the experimental and FEM results show that a 20 mm FFU hole with a 110 mm active length and a 24 mm thick screw is the best option for an FFU sleeper fastening system, especially in wet conditions.

FEM-Based Evaluation of the Point Thermal Transmittance of Various Types of Ventilated Façade Cladding Fastening Systems

The prevalence of ventilated façade systems is not only due to their aesthetic properties but also due to the fact they provide mechanical and acoustic protection for the façade and reduce the energy demand of the building. However, it is essential to mention that the point thermal bridges of the fastening system with brackets and anchors are often neglected during simplified energy performance calculations and practical design tasks. The reason practitioners do not consider the brackets in the calculation is the lack of standards for the simplified calculation of point thermal transmittances, or there being no comprehensive, manufacturer-independent thermal bridge catalogue available. This study aims to evaluate the point thermal transmittances created by the brackets and anchors of the ventilated façade claddings by using 3D numerical thermal modelling. A broad point thermal bridge catalogue was created, considering multiple factors of the ventilated facades. The FEM-based results show that thermal breaks/isolators could reduce the point thermal transmittances by only 2 to 28%, depending on the material of the brackets and the isolators. The brackets’ material and geometrical properties/parameters could cause up to 70% of difference between corrected and uncorrected thermal transmittance values, as well as significant differences between the results if the brackets were applied to different kinds of masonry walls or reinforced concrete walls.

Laboratory investigation on contribution of fastening system and sleeper in longitudinal resistance of ballasted railway tracks

Track longitudinal resistance is defined as the resistance generated by sleeper-ballast and rail-sleeper interactions against the imposing forces, which cause longitudinal displacement. This component is one of the important indicators of the continuously welded rail (CWR) track's stability and lateral resistance against buckling. In this paper, the track longitudinal resistance (TLR) and track longitudinal stiffness (TLS) have been investigated to determine the contribution of the fastening system and sleeper in TLR and TLS through laboratory tests and a numerical model. A track panel with one to eight sleepers fastened with 100, 80 and 60 Nm prestressed torqe-force applied to fastening screws was loaded. The average contribution of the sleepers in TLR in the case with a rail-pad for 100 and 60 Nm torque-forces is approximately 30% and 75%, respectively, and the average contribution of the fastening system in the same state is approximately 70% and 25%, respectively.

Quantification of longitudinal fastener stiffness and the effect on fastening system loading demand

Over the past 20 years, there have been at least 10 derailments due to spike fastener fatigue failures in North America. These fatigue failures have been considered a moderate to severe challenge that require manual walking inspections that are both time and labor intensive. These fatigue failures have been found to result from spike overloading due to lateral and longitudinal loads. To date, there has been limited quantification of the vertical, lateral, and longitudinal fastener forces in track. This paper quantifies the effect of fastener type on fastener load to account for various track types and locations. Laboratory experimentation was performed to quantify the stiffness of multiple fastening systems and this data was input into a previously validated analytical model to quantify the effect of stiffness on fastener loading. Additional laboratory experimentation was performed to quantify the relationships between both fastening system type and vertical loading and spike strain. While the laboratory data indicate a significant variance in stiffness between fastening systems, the model results indicate that the load transferred to the fastening system is less sensitive. However, spike strain data indicate the load path was affected by fastener type and vertical load. The characterization of longitudinal stiffness of multiple fastening systems and the relationship to spike load as presented can be used to advance track mechanistic-empirical design and improve rail neutral temperature prediction and track buckling models.

Razvoj novih i poboljšanje postojećih elastičnih pritiskalica za pričvršćenje tračnica

One of the problems of railway fastening systems (fastening system) that occurs due to the development of railways is the damage of the elastic clips, which leads to the loss of structural integrity between the rail and the base. Therefore, there is a need to develop new clips or improve existing ones. The paper describes the contribution and role of each component of the fastening system in different loading cases. As a tool whose parameters can affect the efficiency of the fastening system, special attention is given to the clips. Finally, an example is briefly described for creating numerical models that can be used to perform parametric analyses in order to develop new clips or improve existing ones.

УПРАВЛЕНИЕ ГРУППОЙ БПЛА ПРИ ОТРАБОТКЕ КРИЗИСНЫХ ПОЛЕТНЫХ СИТУАЦИЙ В РЕШЕНИИ ТРАНСПОРТНЫХ ЗАДАЧ

The relevance of the development of algorithms for managing a group of UAVs in the event ofcrisis situations that affect the performance of the task is substantiated. An algorithm for autonomouscollective (decentralized) control of a group of UAVs is described when performing the target task oftransporting goods, as well as combined control in the event of crisis situations when the autonomouscontrol mode cannot be fully implemented. The algorithm for working out a crisis situation in case of alack of energy resources on board the UAV and the return of group agents to the starting position isdescribed in detail. The results of modeling the movement of a group of UAVs of multirotor and aircrafttypes and working out a crisis situation for managing a group of UAVs based on information about thereserves of energy or fuel resources are presented. During the experiment, iteratively calculated theremaining fuel when the UAV moved to the landing point, as well as the amount of fuel available to theUAV at a given time. As a result of the experiments, it was found that the time for calculating the balanceof the energy resource does not exceed 6.792 ms. If the leader runs out of fuel, the cargo transportationmission ends ahead of schedule, since it cannot be completed without the participation of theleader. If several slaves fail, the mission can be continued if their number does not exceed a predeterminedvalue, which is critical for the continuation of the cargo delivery mission. The results of experimentalstudies on modeling the flight of an UAV with a load are presented, during which a flight routewas built that simulates a curvilinear trajectory of movement in urban conditions from the starting pointto the end point, where the UAV is landing and transferring the cargo. In the experiments, the developedUAV and the onboard fastening system of the thermal container were used. During flight tests, the averagehorizontal speed of the UAV was set to 10 m/s. The length of the flight was 5350 m. The flight timewas 13 minutes. 51 seconds.

Failure Analysis of Front Axle Wheel Studs in Small Commercial Vehicles

Irrespective of specific applications, the Small Commercial Vehicles (SCV) are always subjected to severe working conditions, especially the front wheels experience higher loads than design intended due to higher overloading by customers, driver abuse and frequent brake applications. The front axle wheels fasten system plays a key role for safety of the vehicle and pedestrian. The wheel separation can lead to serious injuries to passengers of the vehicle and pedestrian or from another vehicle maneuvering including fatalities. In this project investigation, the causes that promote failure of front axle wheels fasten system and subsequent wheels separation of SCV is analyzed carefully. Metallurgical analysis of the failed fasten system shows that it is characterized by a series of synergetic steps that include plastic deformation of nuts and studs caused due to disproportionate torque tightening practices. Also, the effect of other external factors that lead to deterioration of stud fatigue life such as road camber and driver abuse are analyzed. Based on this promise, the present investigation deals with detailed analysis of the root causes contributing such failures are analyzed and discussed in this paper. This study would help the fellow designers to select optimized fastening system considering all the parameters influencing wheel separation due to stud failures for SCV, passenger vehicles and heavy duty trucks.

Evaluating the Effect of Rail Fastener Failure on Dynamic Responses of Train-Ballasted Track-Subgrade Coupling System for Smart Track Condition Assessment.

Rail fasteners are among the key components of ballasted track of high-speed railway due to their functionality of fixing rails to sleepers. The failure of rail fastening system hinders the transmission of train loads to underlying track substructure and therefore endangers the operation safety and longevity of ballasted track. This paper first established a three-dimensional (3D) numerical model of the train-ballasted track-subgrade coupling system by integrating multibody dynamics (MBD) and finite element method (FEM). Numerical simulations were then performed to investigate the effects of different patterns of rail fastener failure (i.e., consecutive single-side, alternate single-side, and consecutive double-side) on critical dynamic responses of track structures, train running stability, and operation safety. The results show that the resulting influences of different patterns of rail fastener failure descend in the order of consecutive double-side failure, consecutive single-side failure, and alternate single-side failure. As the number of failed fasteners increases, the range where dynamic responses of track structures are influenced extends, and the failure of two consecutive single-side fasteners exerts a similar influence as that of four alternate single-side fasteners. The failure of single-side fasteners affects dynamic responses of the intact side of track structures relatively insignificantly. The influence of rail fastener failure on track structures exhibits hysteresis, thus indicating that special attention needs to be paid to locations behind failed fasteners during track inspection and maintenance. The occurrence of the failure of two or more consecutive fasteners demands timely maintenance work in order to prevent aggravated deterioration of track structures. The findings of this study could provide useful reference and guidance to smart track condition assessment and condition-based track maintenance.

Analytical Nonlinear Modeling of Rail and Fastener Longitudinal Response

Comparatively little attention has been given to the quantification of fastener demands, especially in the longitudinal direction. Research quantifying fastener demands is justified by the more than 250 FRA reportable derailments on mainlines and sidings in the United States caused by “defective or missing spikes or rail fasteners” over the last 20 years. Failed fasteners are rarely caused by loads acting from a single direction (vertical, lateral, or longitudinal); they occur from a combination of these loads. A literature review identified that though multiple models have been developed for analyzing track, they were not designed to quantify fastener demands, especially those in the longitudinal direction, and some make assumptions that could be improved on based on more recent research into the mechanics of fastening system behavior. This paper advances the mechanistic–empirical (M-E) track analysis and design approach through the development, validation, and application of a 3D nonlinear parametric track model that quantifies longitudinal fastener demands. Key research findings include: bilinear approximations, in combination with considering the interaction between vertical loads and slip, were necessary to accurately quantify fastener forces; ballast and fastener stiffness had a direct logarithmic relationship on fastener load; and for well-supported sleepers, changes in component resistance to slip produced minimal changes in fastener demands because the vertical applied load increased the required load to produce slip. Going forward, this validated model could be used to quantify fastener and track demands for additional loading and operational scenarios to further optimize component design for improved track safety and reliability.

Unsupervised Machine Learning for Missing Clamp Detection from an In-Service Train Using Differential Eddy Current Sensor

The rail fastening system plays a crucial role in railway tracks as it ensures operational safety by fixing the rail on to the sleeper. Early detection of rail fastener system defects is crucial to ensure track safety and to enable maintenance optimization. Fastener inspections are normally conducted either manually by trained maintenance personnel or by using automated 2-D visual inspection methods. Such methods have drawbacks when visibility is limited, and they are also found to be expensive in terms of system maintenance cost and track possession time. In a previous study, the authors proposed a train-based differential eddy current sensor system based on the principle of electromagnetic induction for fastener inspection that could overcome the challenges mentioned above. The detection in the previous study was carried out with the aid of a supervised machine learning algorithm. This study reports the finding of a case study, along a heavy haul line in the north of Sweden, using the same eddy current sensor system mounted on an in-service freight train. In this study, unsupervised machine learning models for detecting and analyzing missing clamps in a fastener system were developed. The differential eddy current measurement system was set to use a driving field frequency of 27 kHz. An anomaly detection model combining isolation forest (IF) and connectivity-based outlier factor (COF) was implemented to detect anomalies from fastener inspection measurements. To group the anomalies into meaningful clusters and to detect missing clamps within the fastening system, an unsupervised clustering based on the DBSCAN algorithm was also implemented. The models were verified by measuring a section of the track for which the track conditions were known. The proposed anomaly detection model had a detection accuracy of 96.79% and also exhibited a high score of sensitivity and specificity. The DBSCAN model was successful in clustering missing clamps, both one and two missing clamps, from a fastening system separately.

Improvement of the high pressure cylinder fastening system

Improvement of the high pressure cylinder fastening system

Research on the Influence of Loading Frequency, Material Elasticity, and Geometric Parameters on Mechanical Characteristics of the Mthdrp for Rail Transit Fastening System

Research on the Influence of Loading Frequency, Material Elasticity, and Geometric Parameters on Mechanical Characteristics of the Mthdrp for Rail Transit Fastening System

FEM models for jointed railway tracks and a loading test method on test tracks composed of a single rail fastening system at rail joints

FEM models for jointed railway tracks and a loading test method on test tracks composed of a single rail fastening system at rail joints

Evaluation of Structural Behavior and Fatigue Performance of a KR-Type Rail Clip

Rail clips are essential components of rail fastening systems that clamp the rails to sleepers. Fatigue damage of rail clips has been recently reported in railway lines. However, there has been a lack of research investigating this fatigue issue. The KR-type rail fastening system has been recently developed and used in some domestic railways. This study aimed at evaluating the structural behavior and fatigue performance of the KR-type rail clip. The assembly test performed in the laboratory showed that the stresses induced in the rail clips after tightening, particularly at the stress concentration locations, exceeded the yield stress, indicating that the rail clip could be vulnerable to fatigue cracking when combined with the stress range during repeated trainloads. The finite element analysis results, which revealed a good correlation with the experiments, were used to evaluate the fatigue performance of the rail clip by adopting the modified Goodman fatigue criteria. The fatigue evaluation results indicated that when the vertical rail displacement during train operation exceeded 2 mm, the rail clips could potentially suffer from fatigue failure.

A new fastening system for temporary pacing with active-fixation leads: effectiveness and safety.

Temporary cardiac pacing with active-fixation leads (TPAFL) using a reusable permanent pacemaker generator has been shown to be safer than lead systems without fixation. However, TPAFL requires the off-label use of pacemaker leads and generators. We designed a fastening system to ensure the safety and efficacy of the procedure: the KronoSafe System®. To demonstrate the safety and effectiveness of the KronoSafe System® for temporary pacing in a series of patients receiving TPAFL. A prospective cohort of 20 patients undergoing TPAFL between August 2019 and June 2020 was recruited in a Spanish region. The temporary pacemaker was implanted through jugular access and secured with the KronoSafe System®. R-wave detection, lead impedance, and capture threshold were assessed every 48 h. Complications associated with the procedure or occurring during TPAFL were recorded. There were no complications associated with temporary pacing, and the therapy was effective in all cases. TPAFL was used for a mean of 7.6 days (maximum 25 days), and 84.56% of the time in a cardiology ward. TPAFL secured using the KronoSafe system® provides safe and stable cardiac stimulation for patients requiring temporary cardiac pacing.

Problems and Timeline of Creating the Automatic Fastening and Deployment System of the Onboard Manipulator of the Orbital Spaceship Buran

Problems and Timeline of Creating the Automatic Fastening and Deployment System of the Onboard Manipulator of the Orbital Spaceship Buran

Mathematical model of harmonic movement of a fixed cargo on the deck of a ship

The research is aimed at creating a mathematical model that allows describing the movement of cargo fixed on the deck of a ship, depending on a number of physical parameters acting on the cargo. The study is relevant in connection with the need to minimize the harmonic movement of a fixed cargo on the deck and prevent its resonating with the vibration of the vessel. During the development of the model, a number of assumptions were made: the case was considered when the load moves along the deck in one plane, and the fastening system presses it to the surface of the deck with a given coefficient of resistance. Under the given constraints, a mathematical model was created that allows determining the trajectory of the cargo fixed on the deck. The cases are considered: the friction force of the load on the surface is zero, the friction force on the surface is proportional to the square of the speed of movement in accordance with the analytical equations of motion of the object fixed on the deck of the vessel. The analysis of the resulting model will allow us to develop measures to optimize the fastening of cargo on the deck.

Failure analysis of fatigue damage for fastening clips in the ballastless track of high-speed railway considering random track irregularities

In order to study the influence of wheel-rail random dynamic interaction on the fatigue damage for fastening clips, a three-dimensional (3-D) high-speed railway vehicle-track coupling random dynamics model is established based on the random theory of the probability density evolution method (PDEM). The number theoretic method (NTM) and stochastic harmonic functions (SHF) are employed to generate the representative random track irregularities. Furthermore, a refined finite element model of WJ-8 fastening system is established, and the stress time history results of the clips are obtained based on the co-simulation analysis. Eventually, the rain-flow counting is introduced to study the influence of random track irregularities on fatigue damage of fastening clips combined with cumulative damage theory and the S-N curve of the clips. The results show that, the dynamic characteristics and stochastic probability evolution mechanism of the vehicle-track random system considering random track irregularities, as well as the evolution characteristics of the fatigue failure probability of clips with service time are accurately reproduced based on PDEM. Significantly, the fatigue damage of fastening clips caused by one vehicle passing by follows the lognormal distribution with a mathematical expectation of 2.35 × 10-8 and a variance of 1.48 × 10-12. The 95% confidence interval of mathematical expectation is [7.05 × 10-9, 5.89 × 10-7] and the 95% confidence interval of variance is [1.37 × 10-13, 1.59 × 10-11]. Additionally, the longer the service time of the fastening system, the more serious the fatigue damage of the clips and the greater the fatigue failure probability.

A STATIC ANALYSIS OF E-TYPE CLIPS BASED ON INSTALLATION PROCESS OF DT-III FASTENING SYSTEMS

The installation state of fastening systems directly affects the fatigue lives of rail clips. Most existing researches on the failure and fatigue lives of e-type clips simulated the installation process of fastening systems based on the simplified loading mode (inserting the rail clip into the jack and then lifting the toe end to move), ignoring those effects on the static behavior of the rail clip, viz., the constraint of the spanner on the middle leg of the rail clip, the gradual lifting of the heel end and back arch for the rail clip, and the friction between the heel end of the rail clip and the base plate of the iron bottom plate. Taking the DT-Ⅲ fastening system as an example, based on the loading mode which is to pull the middle limb of e-type clip in the actual installation process, a fine element model is proposed and the calculation results are compared with those for simplified loading cases. Besides, field and simplified installation experimental verifications are carried out. The results show that: the measured maximum principal strain of field installation case is close to that of a simplified loading case, but the orientation angle differs by about 5° from the latter. In the case of the field installation process, the global maximum position of the maximum principal strain changes significantly with the increased insertion depth of the rail clip. When the rail clip is in an over-installation state, the global maximum position jumps to the place where the middle leg of the rail clip and the jack of the iron base is squeezed, resulting in a step increase. To accurately evaluate and predict the fatigue life of an e-type clip, the fatigue analysis can only be carried out under the actual installation state. A simplified loading condition can be used for approximate simulation when merely analyzing the strength of the clip.

An Investigation of Railway Fastener Detection Using Image Processing and Augmented Deep Learning

The rail fastening system forms an indispensable part of the rail tracks and needs to be periodically inspected to ensure safe, reliable and sustainable rail operations. Automated visual inspection has gained significant importance for fastener inspection in recent years. Position accuracy, robustness, and practical limitations due to the complex environment are some of the major concerns associated with this method. This study investigates the combined use of image processing and deep learning algorithms for detecting missing clamps within a rail fastening system. The images used for this study was acquired during field inspections carried out along the Borlänge-Avesta line in Sweden. The image processing techniques proposed in this study enabled the improvement of the fastener position and removal of redundant information from the fastener images. In addition, image augmentation was carried out to enhance the data set, ensure experimental reliability and replicate practical challenges associated with such visual inspection. Convolutional neural network and ResNet-50 algorithms are used for classification purposes, and both the algorithms achieved over 98% accuracy during training and validation and over 94% accuracy during the test stage. Both the algorithms also maintained a good balance between the precision and recall scores during the test stage. CNN and ResNet-50 algorithms were also tested to analyse their performances when the clamp areas were covered. CNN was able to accurately predict the fastener state up to 70% of clamp area occlusion, and ResNet-50 was able to achieve accurate predictions up to 75% of clamp area occlusion.