Standard Fasteners Research Articles

Influence of impact-centrifugal hardener on microhardness of workpiece surface made of aluminium alloys

This article develops a tool for impact-centrifugal processing and establishes processing modes that increase the microhardness of the surface. An experimental study was carried out, where the tightening force, the number of working strokes, the rotation frequency of the hardener and the motion were proposed as technological parameters of impact-centrifugal processing. The experiments were carried out using flat machine-cut samples based on aluminium alloy D16T. A prototype of the rotary hardener with the standard fastening was designed and manufactured. During the experiment, it was revealed that, for the variation in average microhardness, the contribution of the rotation frequency is higher than that of the longitudinal motion. A significant influence of the tension on the surface microhardness is noted: following processing with a rotary hardener, it increases. It is shown that, to a greater extent, this increase depends on the technological tightening force and to a lesser extent on the rotation speed of the tool; it is recommended to increase these parameters. It was found that a 2-fold increase in tightening force resulted in an increase in microhardness by 70 HV 0.1, while increasing the tool rotation speed by 200 rpm led to an increase in microhardness by 42 HV 0.1. However, technological parameters must be selected taking into account the operability of the hardener. It was shown that the longitudinal motion has little influence on the increase in microhardness. The prototype of the designed tool can be used for processing at milling, boring, and grinding machines with computerised numerical control through a standardised fastening unit. This ensures sufficient technological flexibility and allows it to be used for reinforcing flat surfaces and fillet radii. The forecasted increase in the surface microhardness of the D16T sample using a rotary hardener amounts to 38.5% of the initial value in the experimental area with satisfactory productivity.

Improving seismic resistance using absorbing nodes

A flexible gusset is a device that improves the seismic resistance and energy dissipation capacity of a structure. To achieve these solo vibration characteristics, the flexible gusset is designed to remain elastic, resulting in reduced vibration to the structure. The designed energy-absorbing gusset is attached to the column with bolts, thereby connecting the ties to the column and putting them into operation while dissipating vibration. The proposed design was theoretically studied using modeling and calculation in the STARK-ES software package, which allows you to carry out calculations of buildings and structures for stability, as well as calculate natural vibrations in a relatively deformed state, taking into account the one-sided operation of the elements, create a calculation of constraints for forced vibrations with an arbitrary, power, kinematic and dynamic load. The results of the calculation of the bearing capacity assessment showed that the reliability of the system in places of critical stresses was increased. These results allow us to assume that the use of energy-absorbing gussets of frame ties increases the seismic resistance of the building and reduces the load on the foundations of the building than with standard fastening of columns and ties.

Дослідження фазоутворення після дифузійного зварювання у вакуумі з’єднання нікель-ніобій

Diffusion welding is the ideal solution for joining dissimilar materials. This method is particularly effective if you should get a strong monolithic joint without the formation of a rough weld or solder seam. It is used if it is impossible to use standard fasteners. The main scope of this type of welding is the area of high technologies - aviation, space and other types of heavy engineering. All the advantages make the process indispensable under certain conditions and classify it as a high-tech type. This paper considers compounds of dissimilar metals nickel-niobium. In connection with the formation of many intermetallic compounds between these metals, the technology of diffusion welding in a vacuum was chosen. This method allows you to connect materials without melting due to the mutual diffusion of the components. The welding parameters affect the phase formation of the diffusion zone. To study the phase composition, a method of microstructural, X-ray microanalysis, as well as a state diagram of nickel-niobium, is proposed. When studying the weldability of the nickel-niobium system, samples were made in the form of a cube with a side of 10 mm, which was clamped in a mandrel and filled with Wood's alloy. The samples were not subjected to digestion, since during the polishing process, due to the different hardness of the phases, the structure turned out to be thermal polishing. The proposed scheme made it possible to study in detail the phase composition of individual layers of the diffusion zone, their dimensions and dependence on welding parameters. According to the results of quantitative X-ray microanalysis, we did not obtain accurate data on the phase composition and extent of diffuse layers. Qualitative X-ray spectral microanalysis, which was carried out by continuous scanning with an electron probe through the diffuse zone, made it possible to fix the phase reflections on the concentration curves and to determine the extent of the diffusion layers. For a more visual representation of the arrangement of the phases, a combined nickel-niobium diagram with a concentration curve is considered. The studies carried out made it possible to obtain a high-quality joint with mechanical properties that ensure reliability under operating conditions.

Investigation of the structural reliability of technological solutions of suspended ceilings

The object of research is fasteners for suspended ceiling systems. The purpose of the study was to test the strength of non-standard solutions for fixing suspended ceilings. The relevance of this study is confirmed by the large number of accidents involving the collapse of suspended ceilings. Non-standard fasteners for creating a suspended ceiling frame were studied and tested. Technical solutions from KNAUF catalogues were chosen as standard fasteners. The actual strength characteristics of the applied products for fasteners were determined. The measured characteristics were compared with official data from the manufacturers. The destructive loads and conditions of application of non-standard methods of fixing suspended ceilings and the possibility of their safe operation were evaluated. The costs of installing ceilings with non-standard fasteners were estimated. Recommendations were developed on eliminating defects in fasteners and on the use of non-standard fasteners for suspended ceilings.

Based on the Influence of Standard parts Installation and Surface Quality on Aircraft Assembly

In the process of aircraft assembly, various parts have an important impact on the aircraft assembly, among which the fasteners play an important role in the aircraft assembly, affecting the stability of the aircraft assembly and the service life of the aircraft. Standardized fastener installation and surface quality affect the aircraft assembly quality. Proper fastener installation and guaranteed quality are conducive to reducing the risk of aircraft assembly. However, the characteristics of standard fasteners in aircraft assembly need to be studied urgently. This paper analyzes the assembly characteristics of aircraft standard parts, the information and constraints of standard parts, discusses the assembly information of standard parts, and explores the types and installation requirements of fasteners, hoping to improve the assembly effect of standard parts in aircraft assembly.

Detection of Pin Defects in Aerial Images Based on Cascaded Convolutional Neural Network

Pins are standard fasteners in power transmission lines, and the hidden dangers of pins falling off dramatically affects their safe operation. If a pin is missed, it is called pin defects in this paper. As the pin is a small target and has a complex background, traditional detection algorithms were used to identify pin defects from aerial images which suffer from poor accuracy and low efficiency. This paper proposed a target detection method based on cascaded convolutional neural networks. First, a small-scale shallow full convolutional neural network was used to obtain the region of interest; then, a deeper convolutional neural network conducted target classification and positioning on the obtained region of interest. Next, a nonlinear multilayer perceptron was introduced, the convolution kernel was decomposed, and the multi-scale feature maps were fused. At this point, an angle variable was added to the classification cross-entropy loss function. Multi-task learning and offline hard sample mining strategies were used in the training phase. The proposed method was tested on a self-built pin dataset and the remote sensing image RSOD dataset, and the experimental results proved its effectiveness. Our method can accurately identify pin defects in aerial images, thereby solving the engineering application problem of pin defect detection in transmission lines.

Print-A-Punch: A 3D printed device to cut dumbbell-shaped specimens from soft tissue for tensile testing

The failure behavior and mechanical properties of soft tissue can be characterized by conducting uniaxial tensile tests on small sectioned specimens, called test coupons. An ideal coupon geometry for tensile testing is a dumbbell shape (dog-bone), yet the cost and time required to fabricate custom steel punches to cut dumbbell-shaped coupons has hindered their universal application in biomechanics research. In this study, we developed an economical and reliable cutting device that can extract dumbbell-shaped coupons from soft biological tissue. The novel device, called Print-A-Punch, uses three-dimensional (3D) printed components in combination with standard fasteners and replaceable flexible razors. We identified design factors that influence the dimensional accuracy and symmetry of elastomer coupons extracted using this cutting device, and demonstrated its use on bovine meniscus. Advantages of this 3D printed device include a fast fabrication time, low material cost, good accuracy, replaceable blades, and an ability to scale coupon dimensions for specific tissues and experiments. By reducing the cost and time to cut accurate dumbbell-shaped coupons, this technology can facilitate the broad adoption of standard test methods that improve the quality and reproducibility of tensile tests in soft biological tissue. Researchers can freely download a set of STL files from this study to build their own Print-A-Punch device (https://boisestate.edu/coen-ntm/technology/print-a-punch).

The Continuous Monitoring of Selected Railway Structures using the Autonomous Data Logger

This contribution focuses on issue of the autonomous monitoring of selected dynamic parameters of the railway lines test sections under conditions in the Czech Republic. Description of the possibilities of such data collection, including the designed hardware and software, is a part of this contribution. At the same time, the contribution describes application of such a measuring system, comparing the selected dynamic parameters of the two types of switches, the first one was a switch with a standard fastening node, the other one with an elasticized fastening node. Recommendations and conclusions of railway infrastructure manufacturers and railway line managers are parts of this contribution, as well.

Содержание сайта сопровождения региональной студенческой олимпиады по инженерной и компьютерной графике

At the beginning of this paper has been pointed a large number of works, in which organizational, methodological and informational questions related to student competitions of different levels on graphic cycle’s courses are considered. In Saint Petersburg Electrotechnical University "LETI" in 2000-2012 were hold 13 city (regional) student competitions on engineering and computer graphics (ECG) among St. Petersburg high educational institutions. In 2013-2016 regional student competitions were hold in Saint Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO University). In this paper has been presented the main page of the site for supporting of regional student competitions on engineering and computer graphics preparation and holding in the St. Petersburg region. Has been demonstrated an example for representation of original data for one of the task options (2016) where it was necessary to create solid models of two parts, assemblies of these parts with standard fasteners, associative drawings of one part and assembly, and the assembly specification. Have been presented tables with criteria for assessments the development correctness of four documents: the part drawing, the assembly drawing, the specification, and a document with the assembly’s axonometric view and a localized section of two parts connection by fasteners. Has been considered a compilation of reference data from the Russian State Standards for student competition task fulfillment. This compilation usage excludes the need for reference books with a large amount of excess information not related to competition tasks. Has been presented information about the procedure for evaluation of performed competition tasks. The efficiency of preparation for participation in the competition based on the analysis of competition tasks performed in previous years has been marked. The experience in preparing students for participation in competitions shows the effectiveness of posting informational and methodical materials on the relevant thematic sites.

Prediction of conditions of flange joints depressurization during the assembly of pipelines using technological and standard fastening elements

This article shows the prediction method of conditions of flange joints depressurization during the assembly of pipelines using technological and standard fasteners.

Quality assured tightening of screw joints

Assembly of critical threaded connections such as safety belt and steering wheel screw joints must be quality assured to 100%. Not only the screw needs to be in position but the strength of the joint must also be guaranteed. To accomplish this, classical process surveillance is combined with angle monitoring and screws with special features. A plant system that keeps track on cars of various variants sends information to a screw joint controller that in turn sends a unique parameter set to the screw joint equipment. Together with so-called socket trays and balancing rules, the process arrangement can be made in such a way that the wrong screw can never be assembled without detection. To provide sufficient strength of joints, different kinds of angle monitoring are used. For example, entering/down running angle monitoring that are used to secure sufficient thread engagement with static high strength joints. Angle monitoring is also used to control that all parts are in position before the joint is tightened. For clamp load critical joints, final angle monitoring is used. Together with standard torques and standard assembly friction given by standard fasteners, sufficient clamping force can be guaranteed. With clamp load critical chassis joints, gradient-controlled yield point tightening has shown to be a successful assembly technique with the all new Volvo XC90. Furthermore, screws with special thread geometries are used to avoid cross threading, and in many cases hand entering can be taken away. Altogether, it can be concluded that the Volvo Cars assembly technology not only is very safe but also at a relatively low cost.

Organizational-legal aspects of realization of publicity’s principle in the President of Ukraine activity’s

Article is devoted to research of a role of the constitutional principle of publicity in activity of the President of Ukraine, organizational-legal aspects of its realisation. The analysis of features of standard fastening in the operating constitutional legislation of Ukraine of a principle of publicity and the organizational mechanism of its realisation in activity of the President of Ukraine is carried out. Offers on improvement of legal regulation of organizational bases of publicity in activity of the head of the Ukrainian state are given

Structural Analysis of Steel Pipe Scaffolding Based on the Tightening Strength of Clamps

In this study, the authors' plan to investigate the status of steel pipe scaffolding assembled on domestic construction sites, to use specific tests to determine whether the torque of the clamps surveyed satisfies the test criteria specified in the functional examination standard of the provisional facility, to compare and analyze the marginal load of buckling using main variables (by size, construction work type) by applying the spring coefficient of the clamps as calculated using the MIDAS structural analysis program and, with all these results, to propose improvements and direction for the future. Ultimately, the goal is to establish measures to prevent accidental falls due to the collapse of improperly assembled scaffolding.The result of functional certification standard tests for clamps showed that the fastening strength of clamps on the main members (poles, wales, and joists) reached only 63.3% (13.03 average maximum load/35Nm Standard fastening strength × 100) of the standard fastening strength (35Nm), indicating that certified clamps were not used. Accordingly, there is a necessity for thorough public relations, education, guidance, and examination to allow workers to engage in safety management and understand the importance of clamp fastening strengths on outdoor steel pipe scaffolding.

Research on Force Feedback-Based Tool Operation in Virtual Assembly

To verify the accessibility and workspace of tool operation in virtual assembly system, this paper presented a tool-part operation method based on force feedback. According to characters of common tool-part operations, standard fastening tools and parts were modeled using features and parameters at initial stage. Then operator was enabled to conduct different kinds of fastening and unfastening operations in virtual assembly system by three steps namely identification, interactive positioning and operation. With feedback force, the operator can feel corresponding motion constraints of tool during virtual fastening and unfastening operation, so the immersion of virtual assembly operation is promoted.

A review of research towards computer integrated demanufacturing for materials recovery

The recovery of both toxic and non-toxic materials from billions of end-of-life electronics calls for efficient processes and exploration of opportunities for computer integrated demanufacturing for materials recovery. To date, recycling automation for selective disassembly has been limited by the proliferation of product designs, the difficulty of acquiring product feature and material content information, and the lack of integration of collection and demanufacturing processing. Product designs with standard modules and standard fasteners would improve the options for more automated disassembly. Making product structure and material composition information from a product design profile available will support planning models, Petri net algorithms and control models for demanufacturing, as well as integrated manufacturing and demanufacturing. Advances in imaging and materials identification techniques as well as more flexible technologies to separate materials may provide new opportunities for expert Petri net approaches for selective robotic disassembly. Linking end-of-life product service demand information will enhance scheduling for demand-driven demanufacturing. Nonetheless, the random arrival of so many different product sizes and design structures will require new approaches to designing reverse logistics networks and linking their activities. The present paper reviews the research to automate materials recovery planning and control, identifies challenges, and discusses directions for future research.

The Tightening of Bolts to Yield and Their Performance Under Load

The mechanism of tightening bolted joints and the stress distribution in the bolt are analyzed. Measurements were made of static and dynamic strength of joints. It is shown that all bolts behave elastically when external loads are applied to the joint even when the fastener was tightened to its torque-tension yield point. It is shown that joints generally fail when the external loads are sufficient to overcome the bolt preload. Fatigue reesults show that joint fatigue strength increases with preload, and that high fatigue bolts gave an improvement over standard fasteners at all preloads.