Types Of Fasteners Research Articles

The European Yield Model (EYM) for laterally loaded timber connections with smooth nails

ABSTRACT The European Yield Model (EYM) is a commonly accepted procedure to calculate the capacity of laterally loaded connections with dowel type fasteners. The standard procedure is specified in EC5 (EN 1995-1-1 2004) and uses characteristic values as input parameters for the calculation of characteristic values of the resistance of the connection. These characteristic values are the basis for an engineering design of structures. Nevertheless, there are situations, e.g. the design of a test set-up or a pushover analysis in earthquake engineering, when mean values of the resistance of a timber connection are needed. In this context, analytical equations and mechanical models were assessed on two levels by comparing theoretical values to experimental results. The first part of the research considered all the input parameters. The mechanical definition of the plastic moment proved to be more appropriate than the definition of a modified plastic moment according to EC5 for the determination of the yield moment of nails. On the other hand, it was confirmed that the embedment strength of Norway spruce softwood can be predicted reliably and slightly conservatively according to code regulations given by EC5. The definition for the withdrawal strength according to EC5 also seems to define a conservative lower boundary. The situation is not so clear for the embedment strength of oriented strand board (OSB). Test results are very scarce and do not account for the inhomogeneity regarding the thickness of the boards with higher density at the surfaces, which is the section where contact forces are transferred. In the second part, over 110 specimens considering eight different types of nailed connections were tested to assess different calculation procedures. The study focused on nailed connections with OSB and solid timber. This combination together with smooth nails as fasteners is very common in Europe for light-frame structures, especially in areas of low and medium seismicity because they exhibit large deformation capacity without losing strength. On the level of mean values, relationships are found between 1.00 and 1.47 for experimental results over calculated resistance, and it was found that the EYM is more conservative when the thickness of the sheathing is 10 mm instead of 18 mm, which means, that the expected failure mechanism changes from one to two plastic hinges. The findings are approximately the same if the relationship is studied on the level of characteristic values. Here, the relationship of values from experimental investigations over analytical calculation lays between 1.27 and 1.58 for a mechanism with one plastic hinge and between 0.90 and 1.12 for a mechanism with two plastic hinges. Based on these results, the question arises, if the EYM is the appropriate tool to predict the capacity of laterally loaded connections if comparatively large deformations occur between the connected parts. This question should be studied more detailed in the future.

Research into technology of fastening the mine workings in the conditions of unstable masses

Purpose.Determination of the rock stability along the strike of the mass, where the drift mining of the horizon -480 m is conducted, considering the possibility of using the improved types of supports in the conditions of the 10th Anniversary of Kazakhstan’s Independence mine at the Khromtau field with the substantiation of using the effective type of fastening that increases technical and technological, operational and economic indicators of the mine. Methods. Numerical modelling of the stress-strain state of the rock mass applied at the mine have been performed using the RS2 software in a two-dimensional formulation. The rock mass state, as well as the physical-mechanical properties of mine rocks are determined according to building codes and regulations (SNiP II-94-80), depending on the category of the rock stability. Findings. It has been revealed that the combined supports from rock bolts and shotcrete are the most rational type of fastening in the studied mine. The efficiency and prospects of using the combined supports have been determined, which ensure a decrease in their material consumption and cost while increasing the reliability of mine workings and the labor productivity of miners. The use of combined support allows to increase the economy of materials for support by 1.7 times, as well as to increase the drifting rate by 1.6 times in comparison with the metal support. Originality.The paper proposes a new approach to substantiation of an effective fastening method by comparing the costs when driving horizontal underground mine workings in the mining-and-geological conditions of the 10th Anniversary of Kazakhstan’s Independence mine. Practical implications.The research results can be used when planning mining operations, in particular, stable fastening methods at the 10th Anniversary of Kazakhstan’s Independence mine of the Khromtay deposit, as well as other mining enterprises with similar mining-and-geological conditions.

Determination of the strength performance of table frames

The objective of this study was to investigate relation of diameter of pilot hole and screw, and machining accuracy on withdrawal strengths of the screws and durability of the dining tables. For this purpose, fasteners and material types on the failure loads of dining table corner joints have been analyzed experimentally and statistically. Double ended thread bolts with different drilling regimes have been used as fastener types. Parallel investigation of rigidity and durability of tables, according to the current EN norms, and withdrawal capacities in accordance with the procedures described in ISO 9087 was performed. According to the results, it is concluded that the diameter of the drilled hole significantly influences the value of the withdrawal strengths of the screws. By analyzing the effect of drilling diameter on rigidity of tables, a statistically significant difference was determined. As the drilling diameter increases, the rigidity of the examined dining tables decreases

Contribution of OSB Sheathing to Racking Capacity of Cold‐Formed Steel Frames

AbstractIn recent years, new innovative systems to ensure high structural and environmental performance have emerged in constructional steel practice. Among others, modular construction using cold‐formed steel (CFS) frames which offer some advantages over conventional structural system counterparts, such as high strength‐to‐weight ratio, controlled material quality and sustainability. Wood‐sheathed shear wall is one of the lateral load resisting systems adopted in CFS modular construction. It is composed of CFS C‐shaped framing members (chord studs, studs and tracks) attached to wood sheathing using fasteners. The resistance capacity of these shear walls, when subjected to in‐plan lateral loads, is governed by the connections between the frame and the sheathing board. It is therefore crucial to quantify the shear capacity of sheathing‐to‐frame fasteners. In this context, a testing rig was developed consisting of two CFS lipped channels facing back‐to‐back connected on the flanges by oriented strand board (OSB) and loaded such that the 8 connecting fasteners experience shear. The prevailing role of sheathing thickness and fastener type is highlighted in the results. The experimental results are summarized for further use in the analysis of shear walls under lateral load.

Features of the influence of intermediate rail fastenings on the operational durability of rails

Heat-strengthened rails of the R65 type are the main type of rails used on the railway network of Russian Railways. Reducing the number of cropped and acutely defective rails is possible due to the rational use of the design features of intermediate rail fasteners and their current content.The article presents study results of the stiffness influence of intermediate fasteners on the operational durability of rails. The general statistics of the use of various types of intermediate rail fastenings on the network of Russian railways is considered. The main results of previously published studies on the effect of the stiffness of intermediate rail fasteners on the accumulation of contact fatigue damage in rails are briefly presented.Calculations of the accumulation of contact-fatigue damages in rails, carried out by the authors, are based on the data on the vertical and horizontal transverse stiffness of intermediate rail fastenings obtained from the results of bench tests. Calculations of the accumulation of contact-fatigue damage were carried out using the “Universal Mechanism” software package. In the process of modeling, four types of intermediate rail fasteners were considered: ARS-4, ZhBR-65Sh, ZhBR-65PShM and W-30. Calculation results were obtained for a curve with a radius of 650 m on a continuous welded track section.

Distribution of the friction coefficient in the tension connections by the HV set using the combined method

AbstractThe use of bolts in steel structures nowadays is one of the cheapest, fastest and easiest solutions for joining elements. HV high‐strength bolts used in tension connections are a special type of fasteners covered by supervision beginning with the selection of the material from which they will be made through the production process and quality confirmation, ending with clearly defined assembly requirements.The tests were focused on two assortments of M16 and M24 bolt assemblies made according to EN 14399. A test of the suitability of the connection was performed, expanding it with tests of the coefficient of friction on the bolt thread and between the nut head and washer according to EN ISO 16047. The dynamic joint load tests showed that the distribution of the coefficient of friction on the thread and between the nut and the washer affects the degree of tension through the preloading force.Tensile tests were carried out on the both aforementioned assortments. The determined yield point of the bolt was analyzed, which was referred to the stress causing plastic deformation in the test of connection suitability. Bolts in two systems of forces were compared with each other (simple ‐ stretching and complex ‐ stretching and torsion) and the difference between them was shown. Based on the correlation of results from both tests, the importance of the K‐factor on the mechanical properties of the HV set was emphasized. The dependence of the K‐factor on the coefficients of friction in a bolted joint has been demonstrated.HV high‐strength bolt sets consider assembly procedures using a combined method according EN 1090‐2. Cases of exceeding the yield point of the bolt during assembly and permanent deformation of the fastener have been shown. The scope of assembly was determined in the elastic range and the transition to the range of plastic deformations. Again, reference was made to the coefficient of friction and its effect on the difference in the obtained preloading force leading to risky assembly in the plastic range.

Lateral loading performance of end narrow panel reinforced light wood frame shear walls

PurposeThe sheathing panels of traditional light wood frame shear walls mainly use oriented strand board (OSB) panels, and the damage of the traditional walls is mainly caused by the tear failure at the bottom corner of the OSB panel. In order to improve the lateral performance of the traditional light wood frame shear wall, a new type of end narrow panels reinforced light wood frame shear wall is proposed.Design/methodology/approachThe monotonic loading tests and finite element analysis of nine groups of walls, with different types of end narrow panel, types of fasteners used on the end narrow panels and the end narrow panels edge fastener spacing, are carried out. The effects of different characters on lateral performance of light wood frame shear walls are reported and discussed.FindingsThe failure modes of the wall reinforced by parallel strand bamboo narrow panels with 150 mm edge nails spacing are similar to the traditional wall. Conversely, the failure modes of other groups of walls reinforced by end narrow panels are the tears of the bottom narrow panel or the bottom beam. The end narrow panel reinforced light wood frame shear wall can make full use of the material property of sheathing panels. Compared with the lateral performance of traditional walls, the new-type end narrow panels reinforced walls have better lateral performance.Originality/valueA new type of end narrow panels reinforced light wood frame shear wall is proposed, which can enhance the lateral performance of the traditional light wood frame shear wall. The new-type walls have advantages of convenient operation, manufacture cost saving and important value of engineering application.

The Disassembly Map: A new method to enhance design for product repairability

Designers and engineers need better tools and methods to create highly repairable products. Design for disassembly and reassembly is an important product related design feature that can enhance repair. In a highly repairable product, the components that fail most often should be easily accessible for repair or replacement. This paper describes the development of a method to visually map the disassembly of a product, showing different routes towards target components. These components can be those with a high potential failure rate (important for repair), embodied environmental impact (important for recycling) and economic value (relevant for component harvesting), depending on the circular strategy under consideration. The ‘Disassembly Map’ method is set up to guide product design and is aligned with the most recent research and standards on product repairability. The ease of disassembly is assessed on Four main design parameters are considered in this method to assess the ease of disassembly of: disassembly sequence/depth, type of tools, fastener reusability/reversibility, and disassembly time. In contrast to most of the related literature found, the Disassembly Map method is not based on the use of an algorithm for the automatic calculation of optimised disassembly sequences. It asks designers and engineers to analyse each disassembly step using standardized visual elements based on the ease of Disassembly Metric (eDiM) and the Maynard Operation Sequence Technique (MOST). Insights gathered from this analysis and the resulting visualisation can be used in an iterative product development process. The method was developed by analysing seven vacuum cleaners. Its effectiveness was then tested by redesigning one of them, enhancing its repairability.

Cyclic experiments on isolated steel sheet connections for CFS framed steel sheet sheathed shear walls with new configurations

The main objective of this research is to experimentally characterize the performance of isolated single sheathing-to-framing fastener connections under cyclic load as utilized in emerging classes of cold-formed steel (CFS) framed steel sheet sheathed shear walls used for seismic lateral resistance. New shear wall variations include the use of steel sheet sheathing sandwiched between framing members (i.e., mid-ply) and the use of heavy hollow structural sections (HSS) chord members with the thin steel sheet sheathing attached by power actuated fasteners (PAF) to the HSS. The cyclic nonlinear response of the framing to steel sheet fastener connection is fundamental for simulating the seismic performance of steel sheet sheathed shear walls. Minimal cyclic fastener-level test data under shear exists for these new configurations. A unique lap shear test following AISI S905 was designed to study and characterize the cyclic fastener connection behavior. The specimens were loaded with an asymmetric cyclic loading protocol which intentionally buckles the thin sheet in the compression direction, and progressively increases in the tension direction. Sixty-three tests covering a wide range of framing thickness, sheet thickness, fastener type and size were completed. Each connection configuration is characterized with a multi-linear backbone curve ready for use in numerical shear wall models. The tested fastener configurations exhibit excellent performance as fastener tilting is largely or completely eliminated in these configurations, and connection degradation from buckling of the steel sheet is minimized. It is also shown that AISI S100 connection strength provisions are applicable to the tested connections.

Effect of cast-in-place concrete application on moisture distribution in timber-concrete composite floors with notched connections, investigated via finite element simulations

Timber-concrete composite (TCC) structures are an efficient way to combine the advantages of cross-laminated timber (CLT) and concrete plates. By cutting notches into the timber part and applying the concrete on top, efficient shear connections can be formed, eliminating the need for additional use of any type of fasteners. However, fresh concrete releases moisture after application, which is absorbed by the highly hygroscopic wood and can lead to a critical reduction in mechanical properties or to problematic situations due to a difference in expansion behavior. Therefore, a separating foil is usually applied between the two materials, which represents an additional time and cost effort and can also negatively influence the connection properties or make the use of notch-only connections impossible. Thus, we investigate numerically what effects the exclusion of such a foil has on the moisture distribution in the CLT plate. Further, the moisture propagation after a fictitious installation on site is analyzed by applying realistic indoor climates to the open wood surface on the bottom of the CLT plate for a period of two years. In addition, the numerical model allows us to study the effect of local sealings of the most critical wooden part, the end-grain surfaces in the notch region. We were able to confirm that, especially in the unsealed case, locally high moisture contents can occur in the critical region next to the notch, where the highest shear stresses are also to be expected. However, by fully sealing the end-grain surfaces in these regions, the moisture levels and thus the risk of failure could be reduced efficiently. The use of such detailed moisture simulations, where moisture uptake due to bleeding of fresh concrete has been calibrated based on experiments, allows the long-term moisture behavior of such critical situations to be studied and effective solutions to be developed.

Identification of multi-bolt head corrosion using linear and nonlinear shapelet-based acousto-ultrasonic methods

Among different types of fasteners used in multiple industries, the bolted connection attracts the most attention due to its low costs and ease of operation. However, bolt failures may induce severe catastrophes if not timely detected. One of the most common bolt failures is bolt corrosion (especially at the bolt head), and bolt head corrosion can significantly affect the mechanical performance of the bolted connection and even the entire structure. So far, no relevant investigations have been conducted to detect multi-bolt head corrosion, and thus the author applies the linear and nonlinear acousto-ultrasonic methods to attempt to solve this problem for the first time. Notably, this paper’s main contribution is that two new shapelet-based acousto-ultrasonic methods, i.e. shapelet-based active sensing and shapelet-based vibro-acoustic modulation (VAM), are developed by utilizing the concept of time-series shapelets. Compared to existing approaches such as entropy-enhanced acousto-ultrasonic methods, the proposed shapelet-based active sensing and shapelet-based VAM can achieve better detection performance. Finally, by conducting a multi-bolt head corrosion test, the effectiveness of the proposed methods is verified. Overall, the proposed methods can provide a new direction for researching bolt corrosion identification, and they can also contribute to the development of structural health monitoring, e.g. the detection of other structural damages in future work.

Experimental evaluation of angle bracket connections in CLT structures under in- and out-of-plane lateral loading

In cross laminated timber (CLT) structures, angle brackets are commonly used in wall-to-floor connections to transfer the shear in seismic and wind loads. In reality, these connections could experience multi-directional forces under in- and out-of-plane lateral loads. A two-phase experimental program consisting of 12 monotonic tests in the first phase, and 24 monotonic and 24 cyclic tests in the second phase was conducted to investigate the behaviour of CLT wall-to-floor connections, connected with two different sizes of steel angle brackets and four types of fasteners, under uplift, in-plane shear, and out-of-plane shear loads. The performance of the connections was evaluated in terms of strength, stiffness, ductility, energy dissipation capacity, and failure modes. Results show that small diameter fasteners are more desirable for wood-to-wood angle bracket connections in terms of failure modes, load-bearing capacity and stiffness. Specimens exhibited considerable ductile performance under both uplift and in-plane shear loads due to combinations of yielding of brackets and yielding or pull-out of screws. Connections loaded under out-of-plane tension may fail in splitting of CLT panels. Fully-threaded screws led to higher strength, stiffness and energy dissipation capacity but less ductility compared to partially-threaded screws in angle bracket connections.

ANALYSIS OF MECHANICAL STRENGTH OF CONNECTION BETWEEN COMPOSITE AND ALUMINUM SHEET METAL USING HOLE CLINCHING PROCESS

Aluminum and composite materials are the types of materials that are used to construct structures on aircraft airframes. It is not uncommon for both types of materials to be used together with the joining method. In the process of connecting between two types of material in the aircraft structure, it is mostly carried out by the riveting method. This process is carried out by making a hole in the two materials according to the rivet diameter and then the hole diameter is then filled with rivets and the riveting process is carried out. The process uses rivets so that it will relatively increase the weight of the structure because there is additional rivet material. In this study, the objectives are to determine the mechanical strength of the joint between the composite and aluminum sheet metal using the mechanical clinching and riveting processes. The method used is an experimental method, namely by making test specimens with composite and aluminum, solid rivet type fasteners and punches to determine the connection of the riveting, the drilling process is carried out with a hole diameter of 3.5 mm, for the clinching method with variations in the diameter of the punch 3.5 mm, 4.0 mm. , and 4.5 mm. Then the tensile test, macro photo test were carried out. The results obtained from this research are that the maximum load increase in the specimen tested by clinching is because the damage length (gap) value is obtained at the joint boundary between the rivet and the test material.

Application of Deep Learning Networks to Segmentation of Surface of Railway Tracks.

The article presents a vision system for detecting elements of railway track. Four types of fasteners, wooden and concrete sleepers, rails, and turnouts can be recognized by our system. In addition, it is possible to determine the degree of sleeper ballast coverage. Our system is also able to work when the track is moderately covered by snow. We used a Fully Convolutional Neural Network with 8 times upsampling (FCN-8) to detect railway track elements. In order to speed up training and improve performance of the model, a pre-trained deep convolutional neural network developed by Oxford’s Visual Geometry Group (VGG16) was used as a framework for our system. We also verified the invariance of our system to changes in brightness. To do this, we artificially varied the brightness of images. We performed two types of tests. In the first test, we changed the brightness by a constant value for the whole analyzed image. In the second test, we changed the brightness according to a predefined distribution corresponding to Gaussian function.

CLAMPING FORCE OF INTERMEDIATE FASTENERS AND THEIR DETERMINATION

The article considers the main type of intermediate rail fastening used on the railways of Uzbekistan. The elastic characteristics of various types of terminals are presented, as well as a developed measuring device that allows you to evaluate the force of pressing the terminals on the sole of the rail under operating conditions.

Pull-out performance and optimization of a novel Interference-fit rivet for composite joints

Since high-performance composite materials were widely used in various fields, composite fasteners’ connection technology has been a research hotspot. In this paper, a new type of interference-fit fastener was proposed and manufactured. Pull-through resistance tests were conducted to explore the pull-out performance of the fastener. The installation and pull-out process were analyzed by a finite element method. The simulated pull-out force well matched the results of the tests. The main failure modes of the composite plate are matrix damage and delamination. The simulation results showed that the extended length of the expansion sleeve, the length of the reducer segment, the extension length of the nut, and the interference size greatly influence the joint’s performance. Based on the response surface method (RSM), the structural parameters that affect the fastener’s pre-tightening and pull-out performance were optimized. The optimal parameter combination of the interference-fit fastener was obtained.

Evenki Reindeer Riding Saddle: Certain Principles of Mobility in the Taiga

On the basis of museum collections, field records, photographic and video recordings made in the 20th to early 21st centuries, a reindeer riding saddle with flaps, typical of the eastern Evenki, is analyzed. Its construction and types of fastening are described in detail. Manufacturing technologies are discussed in the context of modern theories of material culture as adaptations to changing natural and social environments under a mobile lifestyle. The key principles underlying mobility in the taiga include the use of a wide range of materials and techniques, modularity (assembled construction with mutually complementary and interchangeable parts), a technological cycle adapted to natural rhythms, adherence to traditional knowledge, the use of artificial materials along with products of nature (since the mid-1900s), etc. In the nomadic culture, the esthetics of an artifact are intrinsically related to function, harmony, and social significance. The manufacture of reindeer riding saddles has been affected by changes in the social structure of nomadic groups.

Design And Analysis Of Formula Sae Vehicle Rear Upright Andcomparision Of Analytical And Software Analysis Solutions Ofprincipelstressesat Differentpoints

Upright is used in vehicles which connects frame or chassis and tires. Chassis is connected toupright with A-arms at the top and bottom using different types of fasteners through which theload is transmitted to it. I choose to design a FSAE(formula society of automobile engineers) caruprightbasedonthedatacollectedfromarealtimehybridformulavehicle.Uprightismodeledin Solidworks 2015 and all principle stresses and strains are found through simulation analysissoftware ANSYS 19.2. Now these solutions are compared with the analytical solutions which issolved using MATLAB software, So that we can be able to predict which one is more accurateandhowthese simulationsoftwareare beingableto solveproblemsbased ontheseconcepts.

Strength comparative analysis of furniture joints made of various materials

The strength comparative analysis of furniture joints made of various materials. The influence of the load on the angular deformation of the furniture joint samples made of various materials was studied. The tests were carried out for six types of furniture materials: chipboard, MDF, hardwood plywood, glued pine wood, glued oak wood and HPL and for three types of fasteners with different ways of fixing in connected elements: shape-thread, expansion-expansion and expansion-thread way of anchoring in material of boards. The joint samples were loaded with a bending moment only (without inducing transverse loadings). The maximum load capacity and load capacity at the 3° (0.052 rad) sample rotation was measured and then the stiffness coefficients were calculated. Considerable differences were found between HPL and others lignocellulosic materials. Expansion fasteners offer incredibly low joint rigidity. This was observed for all tested furniture materials, from soft (chipboard) to very hard (HPL). Expansion connectors work better in soft lignocellulosic materials than in hard materials. The main advantage of expansion fasteners, in comparison to shape-thread fasteners, is its low visibility in the joint and the technological ease of assembly. On the other hand, thread-shaped connectors offer much greater strength and stiffness of joints.

Computer-aided design system for vibration-frequency density meters

The article is devoted to the description of the developed automated design system for vibration-frequency density meters with a demonstration of the wide functionality of the program and interface settings. The development solves the problem of designing vibration-frequency density meters, calculating the quality factor and sensitivity of resonators, which provide the dependence of the frequency of self-oscillations on the controlled density. The lack of clear methodological recommendations for calibration, correction techniques for different methods of mounting the resonator significantly limits the use of vibration-frequency density meters, since the tasks set require special skills, competencies of both developers and personnel during operation.
 The algorithm of the developed software package is based on the calculation of the amplitude-frequency characteristics of a tubular resonator using a differential equation to determine the frequencies and forms of bending vibrations of a tubular resonator. The software implementation of the developed calculation model makes it possible not only to visualize the shapes, frequency, antinodes and vibration nodes of a tubular resonator of any design and a wide range of materials, but also takes into account the type of fastening, the numerical value of the support stiffness, makes it possible to adjust the placement of supports that meets the operating conditions while visualizing the shapes oscillations, simulate the distribution of sensitivity along the entire measurement range. The developed computer-aided design system has a simple and clear interface, and the absence of the necessary software installation and settings makes the product more accessible in the industrial environment of small enterprises.
 When using a subroutine for the numerical solution of the equation of free vibrations of a string, the software complex can be used to design string mechanical resonators of vibration-frequency sensors.
 
 Keywords: vibration-frequency density meter; resonator; amplitude and frequency of oscillations; fixing conditions; antinode; sensitivity