Metal Fasteners Research Articles

STUDY OF CONDITIONING EFFECT OF BALL VALVES

Two or more configurations are combined to provide common use of ball valves. The use of metal fasteners in ball valves is used to ensure tightness under conditions of high temperature and pressure. Studies conducted on connecting structures show that 70% of them fail due to problems of fixation. With the application of a magnetic device, the position of the connectors is different in the open and closed state of the faucet. In the open state of the faucet, the magnetic force does not affect the connectors. This, in turn, minimizes the friction that may arise in the coupling elements in the ball-coupling pair. The correct design of fastening systems is an important factor for efficient and reliable operation. Methodologies range from simple computation-based procedures to detailed mathematical models. An appropriate mathematical model for the design and analysis of a crane provides a logical equivalent determined by the characteristics of the system. The design methodology offers a number of innovations for the identification of all possible system configurations capable of meeting a specific requirement according to the required levels of reliability. Keywords: ball valve, metal fitting, magnetic device.

SYSTEM OF MONITORING THE DEGREE OF DESTRUCTION FROM ELECTROCHEMICAL CORROSION OF UNDERGROUND METAL ELEMENTS OF OVERHEAD POWER LINE SUPPORTS

In this article, the studies were carried out and the block diagram was developed for a system of monitoring the degree of destruction from electrochemical corrosion of underground metal fastening elements for overhead power line supports. The analysis of the causes of emergency shutdowns of overhead power lines in the CIS and the methods of assessing the consequences used in foreign countries are carried out. The studies were aimed at modernizing the unified power system of Kazakhstan, reducing emergency situations and increasing reliability of power supply to consumers. The article presents a diagram of the design solutions of the proposed monitoring system for the portal-type support mounting unit. One of the aspects was direct controlling the degree of destruction of the support fastening points located underground. The proposed system allows collecting and transmitting to the control center the information of the degree of destruction from electrochemical corrosion of metal fastening elements of portal-type supports. Key words: portal type supports, overhead power lines, power system safety, power system reliability, galvanic corrosion, U-bolt, monitoring system.

Measurement of air permeance in mass timber elements assembled through the dovetail technique

Adhesives and metal fasteners are important components in engineered wood products (EWPs), but the petroleum-based nature of adhesives raises environmental concerns and metal fasteners lead to challenges with end-of-life disposal and reusability. However, there is a promising solution in the form of ‘mass timber elements assembled through the dovetail technique (MTADT)’, also called ‘dovetailed massive wood board elements’, which is entirely composed of wood and devoid of adhesive or metal connections. However, existing literature on MTADT has focused on insufficient structural analysis and model testing of connection details rather than assessing the performance of a structural component. In this study, air permeance measurement in MTADT was conducted in accordance with the Finnish building code as part of the DoMWoB project (Dovetailed Massive Wood Board Elements for Multi-Story Buildings). The research aimed to explore the impact of storage conditions and moisture content on the air permeance values of three massive wood elements with varying dimensions. The smallest element had dimensions of 1160 mm × 1160 mm x 200 mm, while the other two were approximately 1300 mm × 1300 mm x 200 mm in size. The results from the air permeance tests indicated significant variability among the three test pieces, with q50 values of 1.4 m³/(m2h) for sample O, 2.9 m³/(m2h) for sample K, and 9.9 m³/(m2h) for sample Y. This data suggested that test piece Y demonstrates substantially higher air permeability compared to the other samples because it was the driest of these test elements.

Failure analysis of thermoplastic composites subject to galvanic corrosion in hybrid metal–composite joints

The damage sustained by carbon fibre reinforced polymers due to the effect of galvanic corrosion induced by coupling between carbon fibres and a metallic material in a hybrid joint is investigated. Composite laminates with two fibre architectures and two thermoplastic matrices (polycarbonate and polyamide 6) are coupled to a metallic fastener and exposed to salted fog conditions. Both the effects of the salted fog environment and the coupled effect of the environmental and the galvanic corrosion are analysed. The analysis is centred in, firstly, characterising the functional properties of the hybrid joint, secondly characterising the laminate properties and finally characterising the chemical degradation of the matrix. The results show a degradation of properties for the polycarbonate material, in terms of bearing performance and interlaminar shear strength as well as presenting obvious changes in the thermal characterisation. The polyamide composites remain largely unaffected and only minor changes in the surface appearance are noteworthy.

Approaching the re-design of reusable packaging from an environmental perspective: a case study in the railway sector

The production of railway vehicles determines the handling of a large amount of materials which are transferred from suppliers to production site using industrial packaging. The activity here described is part of the MORIMB project, which dealt with the reduction of waste related to railway sector; wood, plastic, cardboard and metal fasteners are the typical materials which are adopted for such packaging.The study is motivated from the evidence that, due to the peculiarities of the transported components, most of the packaging units were different from standardized formats therefore they were frequently used for a single transport and subsequently scrapped. An applicative methodology for the analysis, redesign, and evaluation of environmental and economic impacts was defined, with particular attention to packaging reusability. An adaptation of the DMAIC approach was used to analyze the various components and find solutions reusability and performance improvement, especially in terms of volume efficiency and component protection. Depending on the item to be transported, specific crates have been designed and structurally verified according to existing technical regulation, and their sustainability has been analyzed considering environmental and economic impact during production, transport and storage phase; appropriate scenarios regarding distance travelled and volume occupancy were defined. The case study presented in detail in this work concerns the concept of special crates for the transport of passenger seats – a key component for train production - for which an increase in packaging density and a reduction of transportation costs was achieved. Other case studies were also considered.

Augmenting bamboo strength and thermal stability for sustainable construction

In modern timber structures, the prevalent use of metal fasteners for structural connections introduces concerns related to their high thermal conductivity, which can induce excessive charring of adjacent wood and compromise joints fire resistance. To address this, the exploration of high-strength bio-materials presents a promising alternative. In this study, an eco-friendly methodology was employed to augment the densification of bamboo, resulting in the creation of composite-modified bamboo without the use of organic thermosetting resin. Comprehensive investigations were conducted to evaluate its mechanical properties and high-temperature performance. Microscopic alterations were unveiled through Fourier Transform Infrared spectroscopy (FT-IR) and scanning electron microscopy, complementing each other in revealing substantial changes. The results of chemical constituents and FT-IR analyses corroborated the observed alterations. A noteworthy observation is that the modification of composite materials significantly increased modulus of elasticity, bending, and tensile strengths of bamboo, with a slight improvement in compressive strength. Additionally, it concurrently enhanced ductility. The thermal stability of composite-modified bamboo exhibited an initial increase followed by a subsequent decline over duration. The increased density induced by hot pressing facilitated the formation of a denser charring layer, effectively serving as a protective shield against external heat and oxygen. Consequently, this limited the degradation of bamboo constituents under high-temperature conditions. The optimal alkaline treatment duration for 9 mm thick bamboo was determined as 7 h based on the methodology established in this investigation.

Shape-Changing Wood Joints in Crafts and Industry and Their Potential for Building Construction and Wood Culture

Abstract Timber has regained popularity in construction in recent years due to its ecological benefits. The connection methods used in this study play a vital role in the sustainability of structures and materials. Monomaterial timber connections are sustainable alternatives to metal fasteners and adhesives commonly used in construction. Wood is an anisotropic material with dimensional changes resulting from changes in atmospheric conditions. Understanding and accounting for this property are crucial for the longevity and functionality of wooden structures. The cumulative knowledge of wood´s material characteristics and its use in design, construction, and human culture can be defined as wood culture developed through artists’ and craftsmen’s experiences, science, and industry. The development of various techniques by artisans to leverage the dimensional change in wood to join timber elements is a major contribution to wood culture. In contrast, until now, the timber industry has mainly focused on limiting or controlling these changes in standardized production and has neglected their use for joining timber elements. However, technological advances have changed dramatically. The digital manufacturing and analysis of wood structures have the potential to guide machine tools and may allow the integration of dimensional changes, especially in the design and construction of timber joints. This study explores the state-of-the-art utilization of dimensional changes in timber to join elements in craft, material science, and industrial production. The potential of techniques utilizing this behavior for innovation in modern design and construction and their implications for wood culture were examined. Research gaps and avenues for further research are identified.

Micro-Scale Abrasive Wear Resistance of a Nanoceramic Sealant Applied on Galvanized Low Carbon Steel

The idea for this work came from a market need to obtain coatings or sealants that would extend the useful life of metallic materials in applications that involve exposure to corrosive environments. The main objective of the nanoceramic sealant studied in this work is to extend the life of metallic fasteners. To evaluate the performance of the sealant from other perspectives, microstructural analysis, adhesion test, micro-scale abrasive wear tests and corrosion test were carried out. These tests were performed on samples coated only with white zinc, which is commonly used in the fastener industry, and on samples coated with white zinc followed by application of the nanoceramic sealant. The application of the nanoceramic sealant contributed to the improvement of corrosion resistance and reduction of the corrosion rate. The corrosion rate of the sample coated with the sealant reduced by 62.2% when compared to the sample that only went through the white zinc coating process. The coating showed low adhesion to the substrate with the presence of severe delamination and microcracks. This feature contributed to the low wear resistance presented by the coating under the conditions studied in this work. Less attention, compared to studies involving corrosion resistance, has been given to wear resistance in the fastener industry. The results obtained in this paper show that the study of tribological behavior is an important factor in increasing the efficiency of fasteners applied in harsh environments.

Analysis and optimization of rivet load distribution in multi-rivet connections of thermoplastic composite rivets

GF/PP thermoplastic composite components predominantly employ metallic fasteners, leading to corrosion and weight issues. This study utilized an extrusion process to fabricate GF/PP thermoplastic composite rivets with properties akin to laminated panel materials. Through the controlled application of heat and pressure to the rivet ends, a novel connection structure was established. The article fabricated thermoplastic composite joints with varying end configurations and compared them with metallic rivet joints. Emphasizing the convex form, diverse multi-rivet links were crafted for single-lap tensile samples. Integrating tensile tests and strain gauge measurements, this research explored load distribution patterns across diverse rivet quantities and assessed the impact of size on distribution. Furthermore, finite element software was used to dissect the load distribution patterns and failure mechanisms in the multi-riveted connection structure. Drawing from experimental findings, convex GF/PP rivets exhibited an 18% higher tensile load than metallic ones, with a simultaneous 32% weight reduction. In multi-rivet connections, end rivets demonstrated higher load-bearing capacity. Enhanced spacing and plate width improved load distribution, elevating joint load capacity by 7% (spacing 25 mm to 55 mm) and 6% (width 30 mm to 55 mm). The simulation results indicate that increasing the spacing reduces the stress concentration at the first nail location.

Tempered Martensite Embrittlement of the Metallic Fastener After Austempering Heat Treatment and Coating Process Due to the Existence of Inclusion

Tempered Martensite Embrittlement of the Metallic Fastener After Austempering Heat Treatment and Coating Process Due to the Existence of Inclusion

Feasibility of using Uruguayan Eucalyptus for sustainable timber connections

Uruguayan fast-growing Eucalyptus grandis has emerged as a promising sustainable material for structural building components. However, traditional methods for joining timber components, such as beams and columns, typically rely on metallic fasteners, and mass timber products like glued laminated timber often use adhesives. In response to growing environmental concerns over the past five years, researchers have explored the substitution of petroleum-based adhesives and metallic fasteners with wooden pegs or dowels. To create effective connections, these dowels must be fashioned from denser wood than the lamellae. The embedment strength of both woods with varying densities is a critical factor in the design of timber connections using fasteners. This paper presents the results of a structural performance analysis of fully eucalyptus dowelled connections, constructed by combining Eucalyptus grandis (? = 473.2 kg|m3, COV = 13.2 %) for the lamellae and Eucalyptus tereticornis (? = 1042.4 kg|m^3, COV = 3.2 %) for the dowel. The bending strength of dowels was determined for specimens with 15- and 18-mm diameters, yielding 173.0 MPa (COV = 10.7 %) and 184.0 MPa (COV = 8.3 %), respectively. Four series of connections were tested, varying the fiber orientation of the lamellae (longitudinal L, transversal T) and dowel diameter (15, 18), following the half-hole method described in ASTM D 5764 standard. The embedment strength values obtained for the connections are as follows: L-15 = 31.3 MPa (COV = 9.3 %), T-15 = 11.2 MPa (COV = 28.7 %), L-18 = 29.6 MPa (COV = 10.1 %), T-18 = 16.7 MPa (COV = 25.7 %). These results reveal that the longitudinal application of the load, aligned with the fiber orientation, exhibits approximately twice the strength of the transversal orientation, with less variability in the outcomes. Furthermore, a strong correlation with the lamellae density was observed, while no significant dependency on the dowel diameter was found. These findings represent a crucial initial step in characterizing and designing glue-free wood-wood connections. The utilization of different eucalyptus species presents a promising path for the development of connections that promote more sustainable timber construction systems.

An Experimental Comparison of Airborne Sound Insulation between Dovetail Massive Wooden Board and Cross-Laminated Timber Elements

Adhesives and metallic fasteners play a pivotal role in the domain of engineered wood products (EWPs). Nevertheless, owing to their origins in petroleum, adhesives can pose environmental hazards, whereas metal fasteners can complicate end-of-life disposal and reusability. Nonetheless, a resolution emerges in the form of dovetail massive wooden board elements (DMWBEs), characterized by their pure wood composition and absence of adhesive metal connections. The existing literature pertaining to DMWBEs has predominantly focused on inadequate structural analysis and model testing of connection specifics rather than appraising the efficacy of a structural member, such as a floor slab. This article presents a comparative analysis between a DMWBE and a correspondingly sized cross-laminated timber (CLT) panel, focusing on their respective airborne sound insulation capabilities. Experimental samples of model scale with dimensions of 200 mm thickness, 1160 mm width, and 1190 mm length were employed for both CLT and DMWBE. The evaluation of airborne sound insulation performance was conducted in accordance with ISO 10140-2 standards. The findings underscored the superior performance of DMWBE (Rw = 43 dB) in contrast to CLT (Rw = 40 dB) concerning airborne sound insulation efficacy. Additionally, the damping of the panel increased due to the different composition of the DMWBE, as evidenced by a higher measured total loss factor (TLF) compared with CLT.

Influence of repeated wetting and drying on withdrawal capacity of wooden nails and metal nails

Metal nails pose inherent safety risks to wood structures due to their susceptibility to moisture-induced rusting. Currently, densified wooden nails create an opportunity to replace metal fasteners with renewable materials, so the durability of wooden nail joints is crucial for the stability of wood structures. This study investigated the withdrawal resistance and corrosion resistance of densified wooden nails (gun-driven and manual-driven) and low-carbon steel nails (smooth shank and helical shank) when inserted on Chinese fir(Cunninghamia lanceolata (Lamb.) Hook.) specimens following repeated wet-dry cycles, aiming to provide scientific evidence for the engineering application of densified wooden nails. The results demonstrated that among the untreated samples, gun-driven wooden nails exhibited the highest withdrawal strength, surpassing manual-driven nails by factors of 4.16 (wooden nails), 3.19 (smooth nails), and 1.24 (helical nails). However, following the wet-dry cycles, the withdrawal strength and withdrawal energy of gun-driven wooden nails experienced significant reductions, but no obvious corrosion traces were found on the nail surfaces. Although the mechanical properties of smooth nails were obviously increased, the degree of corrosion was the most serious. In contrast, the mechanical properties of manual-driven wooden nails and helical nails remained relatively stable. Except for cycle-0, all types of nails displayed small stiffness fluctuations throughout the wet-dry cycles.

Thermal and mechanical damage to carbon fibre reinforced composites with metallic fasteners under lightning strike

In this study, lightning strike (LS) damage to carbon fibre reinforced composites (CFRCs) with metallic fasteners was investigated by simulated LS tests and finite element (FE) model. First, the LS damage mode and mechanism of a single-lap composite joint and a CFRC laminate with a metallic rivet were studied. Resin pyrolysis was found on the surface but severe delamination was evident inside the composites due to a gas explosion caused by the sudden burn-off of polymer matrices and thermal expansion inside the laminate. Then, the effect of rivet spacing on the LS damage to CFRCs was examined. The results showed that the damaged area was significantly reduced because the surrounding rivets effectively suppressed impact-induced delamination and consumed more electrical energy. The results also showed that large-area delamination across the rivets was achieved due to high potential at the surrounding rivets when the spacing was short but dynamic deflection was confined by the surrounding rivets. In contrast, delamination was only concentrated at the central rivet when the spacing was large, which can be ascribed to fewer currents flowing into the surrounding rivets, and the confinement of the adjacent rivets was less significant.

Electrolyte migration through electrochemical membranes: Potential source of error in batch electrochemical cells

AbstractElectrochemical membranes (ECMs) and porous electrodes have gained much attention in a broad range of applications including water and wastewater treatment, energy production and storage, and carbon dioxide capture. Lab scale batch experiments (electrochemical stirred cells) are the baseline for developing ECMs and porous electrodes. We observed electrochemical dissolution of metal fasteners (alligator clips), used to hold porous conductive and non‐conductive membranes in batch electrochemical cells, despite being kept outside the electrolyte. The electrolyte migrated through the porous membranes by the action of capillary forces, forming a closed electrochemical circuit with the metal fasteners. This unexpected leaching can lead to misleading results for electrochemical experiments on porous electrodes and ECMs. In this study, we compared (1) porous membranes versus non‐porous electrodes, (2) hydrophilic versus hydrophobic membranes, and (3) conductive versus non‐conductive membranes in their ability to cause capillary wetting‐induced corrosion of metal fasteners. We proposed a simple solution for the problem: separating the metal fasteners from the porous membrane electrode with a non‐porous conductive graphite foil, which keeps the electrochemical circuit open. We have validated this solution and propose it as a standard method for experiments using porous electrodes and electrically conductive membranes.

Evaluating Fire Performance: An Experimental Comparison of Dovetail Massive Wooden Board Elements and Cross-Laminated Timber

The use of adhesives and metal connectors is vital in engineered wood product (EWP) composition. However, the utilization of adhesives poses sustainability and recyclability challenges due to the emission of toxic gases. Similarly, metal fasteners negatively impact the disposal, reusability, and recyclability of EWPs. An alternative solution that exclusively employs pure wood, known as dovetail massive wooden board elements (DMWBEs), eliminates the need for adhesives and metal fasteners. This paper presents an experimental comparative assessment of the fire/charring performance of DMWBEs and cross-laminated timber (CLT). Model-scale test specimens measuring 200 mm in thickness, 950 mm in width, and 950 mm in length were vertically tested according to EN 1363-1. The charring behavior of DMWBEs closely resembled that of solid timber, with only a slight increase in the charring rate. Charring primarily occurred in the third lamella layer out of five, with no observable flames or hot gases on the unexposed side. The dovetail detail effectively prevented char fall-off with the tested lamella thickness. CLT specimens exhibited a notable rise in the charring rate due to the fall-off of the first lamellae layer.

Nano-coated composite fastener: Structure health monitoring based on magneto-mechanical effect

The heavy metallic fasteners and undetectable defects in the joining area have long posed challenges for composite structures. In this study, we propose a composite fastener that incorporates a nano-coating on the thread and embeds magnet in the shank. Based on magneto-mechanical effect, a physics-guided neural network (PGNN) is proposed to establish a correlation between magnetic density and bearing stress. For the strengthening effect of nano-coating, the bearing strength of composite joint reinforced by nano-coated composite fastener reaches 196, representing a 26.5% increase compared to the composite joint reinforced by an un-coated fastener. When all-composite joint fails, the nano-coated fastener shears off at the shank, whereas the un-coated fastener shears off at the thread. The predicted bearing stress from PGNN can reasonably quantify the real stress situation of testing joints. The maximum prediction error of the PGNN is merely 18.9 MPa, which is 51.7% lower than that of a neural network (NN) without physical guidance. Compared with the NN, the PGNN shows the abilities of reducing prediction randomness, better convergence, and higher prediction accuracy. This research presents a possible substitute for metallic fasteners to reduce the composite structure weight and monitor structure health.

The use of isothermal calorimetry to measure corrosion rates of metals in contact with preservative-treated wood

The purpose of this paper is to examine whether isothermal microcalorimetry can be used to determine the corrosion rates of metals embedded in wood. Metal fasteners were driven into dowels of wood treated with alkaline copper quaternary, a common wood preservative that increases the corrosiveness of wood. The dowels were stored in a nearly 100% relative humidity environment at 27°C for one year; throughout the exposure period, dowels were removed and the thermal power generated by the sample was measured in an isothermal calorimeter. Measurements over the 1-year exposure showed that the thermal power depended upon the wood moisture content and ranged from 0 to 200 µW. The heat, determined by integrating thermal power over time, was higher than expected compared with the total amount of mass lost due to corrosion at the end of the experiment. Despite this, the technique shows promise as a method to determine how changes in wood moisture content affect the corrosion rates of metals in contact with preservative treated wood.

Experimental Investigation on the Effect of the Electrochemical Corrosion on Destruction of Metal Fastening Elements of Portal Type Supports

Experimental Investigation on the Effect of the Electrochemical Corrosion on Destruction of Metal Fastening Elements of Portal Type Supports

Corrosion behavior of embedded pad hook in glass fiber reinforced concrete

AbstractGlass fiber reinforced concrete (GFRC) comprises of hydration products of cement or cement plus sand, and glass fibers which take part in the concrete as reinforcement characteristics. GFRC has been used for over 50 years in several construction elements, such as facade panels, decorative no recoverable formwork, and other products. However, various anchor elements and pad hooks are needed to attach large or small parts made of GFRC panels to the main structure of the buildings. The corrosion rate of embedded metal fasteners over time is related to the water impermeability properties of the GFRC elements. In this study, corrosion of an electro galvanized pad hook embedded in 10–20 mm of the GFRC panel was investigated as a result of the salt spray test performed in accordance with ASTM B 117 standards. At the end of the experiment, the embedded pad hook was taken from the GFRC and analyzed by scanning electron microscopy, energy‐dispersive spectroscopy methods. The results showed that the embedded pad hook in the GFRC, which was examined in the test procedures comply with the TS EN 12467 standards, was not corroded by 120‐h test carried out in accordance with ASTM B 117 standards.