Journal articles on the topic 'Joints with mechanical fasteners'
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1
Zhuang, Fujian, and Puhui Chen. "Effects of missing fasteners on the mechanical behavior of double-lap, multi-row composite bolted joints." Journal of Composite Materials 52, no. 28 (May 2, 2018): 3919–33. http://dx.doi.org/10.1177/0021998318771464.
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This paper presents a numerical investigation into the effects of missing fasteners on the mechanical characteristics of double-lap, multi-row composite bolted joints. A highly efficient explicit finite element model, which was validated effective and accurate by experiments, was developed and employed to conduct the virtual tests. Single-column and multi-column joints with various positions of missing fastener were considered. It is shown that the removal of fasteners can reduce the joint stiffness significantly, especially in joints with fewer columns or missing fasteners in the outside rows. The removal of fasteners can also cause considerable reductions in both the initial significant failure loads and ultimate loads of multi-column joints, while in single-column joints only the initial significant failure loads are influenced. Considering the load distribution, it is suggested that bolts in the same column as or in the adjacent column to the missing fastener experience a notable growth in load. Meanwhile, if a bolt bears more loads in the pristine joint, the larger changes in stiffness, ultimate strength, and load distribution may be obtained when it is lost.
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Godzimirski, Jan, Marek Rośkowicz, Michał Jasztal, and Iga Barca. "Static and Fatigue Strength and Failure Mechanisms of Riveted Lap Joints of CFRP Composites." Materials 16, no. 5 (February 21, 2023): 1768. http://dx.doi.org/10.3390/ma16051768.
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The background of this work is the search for the most effective ways of joining composites, inter alia in aeronautical applications. The purpose of this study was to analyze the impact of mechanical fastener types on the static strength of lap joints of composite elements and the impact of fasteners on the mechanism of failure of such joints under fatigue load. The second objective was to check to what extent the hybridization of such joints, consisting of supplementing them with an adhesive joint, affects their strength and the mechanism of failure of such joints loaded with fatigue. Damage to composite joints was observed using computed tomography technology. The fasteners used in this study (aluminum rivets, Hi-lok and Jo-Bolt) differed not only in terms of the materials they were made of, but also in terms of the pressure forces they exerted on the joined parts. Finally, in order to check how a partially cracked adhesive joint affects the load on the fasteners, numerical calculations were carried out. Analyzing the results of the research, it was found that partial damage to the adhesive joint of the hybrid joint does not increase the load on the rivets and does not impair the fatigue life of the joint. An important advantage of hybrid joint is the two-stage destruction of the connection, which significantly increases the safety of aircraft structures and facilitates the process of supervising their technical condition.
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Chowdhury, Nabil, Wing Kong Chiu, and John Wang. "Review on the Fatigue of Composite Hybrid Joints Used in Aircraft Structures." Advanced Materials Research 891-892 (March 2014): 1591–96. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1591.
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The use of composite materials as a replacement for commonly used metals such as aluminium and steel are increasing in the engineering industry, particularly in the aerospace sector. The move towards light weight and high stiffness structures that have good fatigue durability and corrosion resistance has led to the rapid move from metal to composites. This change allows for further flexibility in design and fabrication of various components and joints. There are three main categories of joints used in composite materials – mechanically fastened joints, adhesively bonded joints and the combination of the two called hybrid joints. In order to adequately understand the effectiveness of these joints, substantial testing and validation is required, particularly in the use of hybrid joints for real life applications. Static testing, load distribution and parametric studies of hybrid joints have been investigated by various researchers; however further work is still required in understanding the durability and fatigue of hybrid joints and ensuring that both the adhesive and mechanical fasteners can work together effectively in producing an optimum joint. Mechanical fastening alone in composite laminates is not a preferred joining method as they create high stress concentrations around the fastener holes. Adhesive bonding although has numerous benefits it is difficult to detect the bond defect particularly in cases where weak bonds can occur during applications and it is sensitive towards the environmental conditions. Thus hybrid joints are seen arguably as being more effective in joining composite components together and offer greater residual strength. Hence the performance, strength and long-term durability of these joints need to be further investigated and be applied to practical situations whilst assisting in repair certification.
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Erki, M. A. "Modelling the load–slip behaviour of timber joints with mechanical fasteners." Canadian Journal of Civil Engineering 18, no. 4 (August 1, 1991): 607–16. http://dx.doi.org/10.1139/l91-074.
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An analytical model of behaviour is presented, which uses one-dimensional finite element approximations to predict the short-term load – slip response of a single fastener joint. The model treats the elastoplastic behaviour of the fastener as well as the nonlinear, nonelastic properties of the wood. It accounts for some of the distinctive behaviour of timber joints such as fastener withdrawal, rotational restraint at the fastener ends, joint interface characteristics, and combined fastener bending and axial tension. Good agreement is obtained between model predictions and test behaviour for single fastener glulam rivet, nail, and bolt joints. The model can be adapted to include the variability in wood and fastener properties, and can be incorporated into a large number of computer simulations in order to predict the fifth fractiles of the populations of joint resistances, which can be used in a limit states design approach. Key words: timber structures, glulam rivet connections, nailed connections, bolted connections, mathematical model, finite element, nonlinear analysis.
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Nečasová, Barbora, Liška Pavel, and Michal Novotný. "Stress/Strain Behaviour of Mechanical and Adhesive Joints in Timber Façade Applications." Key Engineering Materials 868 (October 2020): 142–49. http://dx.doi.org/10.4028/www.scientific.net/kem.868.142.
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This paper compares the stress and strain behaviour of mechanical fasteners and elastic adhesive connections in timber façade applications. Two common designs with timber cladding are introduced. The traditional façade planks and multilayer large-format solid wood panels were selected. The resistance of a reference façade section with mechanical fasteners or adhesive bond to wind suction is determined according to the recommendations of European guideline ETAG 034. The pressure/suction chamber allowing hermetic closure was used. The sample deformation was measured at 15 locations, this also allowed to determine the elongation of the adhesive layer at break. The failure loads reached with the adhesive joint exceeded 20 kN/m2 in both combinations of façade cladding. On the other hand, the sample with a large-format panel and mechanical fasteners showed the lowest failure load at 12 kN/m2. The results confirmed that bonded joints are a suitable solution for large-format cladding, whereas an increase in the number of mechanical fasteners will be a more convenient solution for façade plank applications.
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Menzemer, C. C., L. Fei, and T. S. Srivatsan. "Design Criteria for Bolted Connection Elements in Aluminum Alloy 6061." Journal of Mechanical Design 121, no. 3 (September 1, 1999): 348–58. http://dx.doi.org/10.1115/1.2829467.
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Plates frequently find use as connecting elements in structures built from aluminum alloys. Many structural elements employ mechanical fasteners. Design of connections necessitates that due consideration be given to: (a) bolt or rivet failure, (b) progressive bearing distress of material adjacent to the fastener(s), (c) net-section tensile failure, and (d) tear out of the fastener group(s). Current design provisions for block shear failures of bolted and riveted joints in aluminum-based alloys make use of models initially developed for structural steels or, alternatively, fail to address an estimation of joint capacity. Shear failure of aluminum connecting elements is the focus of this paper. An experimental and analytical program was undertaken with the objective of studying block shear failure of aluminum connecting elements. Twenty aluminum alloy 6061-T6 gusset plates, representing four different bolt patterns, were mechanically deformed. Models to estimate the capacity of the joints are examined and compared with experimental results. Strain distribution around the periphery of the connections were measured and compared to finite element predictions. The correlations between the design models and experimental observations are highlighted.
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Cope, Dale A., and Thomas E. Lacy. "Modeling Mechanical Fasteners in Single-Shear Lap Joints." Journal of Aircraft 41, no. 6 (November 2004): 1491–97. http://dx.doi.org/10.2514/1.14435.
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Sampaio, Rui F. V., João P. M. Pragana, Ricardo G. Clara, Ivo M. F. Bragança, Carlos M. A. Silva, and Paulo A. F. Martins. "New Self-Clinching Fasteners for Electric Conductive Connections." Journal of Manufacturing and Materials Processing 6, no. 6 (December 12, 2022): 159. http://dx.doi.org/10.3390/jmmp6060159.
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This paper presents new rotational and longitudinal symmetric self-clinching fasteners to fabricate reliable connections in busbars with low electrical resistance for energy distribution systems. Connections consist of form-closed joints that are hidden inside regions where two busbars overlap. The investigation into the fabrication and performance of the new self-clinched joints involved finite element modelling and experimentation to determine the required forces and to evaluate the electric current flow and the electrical resistance at different service temperatures. The original design of the joints that was proposed in a previous work was modified to account for busbar strips of copper and/or aluminum with similar or dissimilar thicknesses, connected by means of self-clinching fasteners made from the same materials of the busbars, instead of steel. The effectiveness of the new self-clinched joints was compared to that of conventional bolted joints that are included in the paper for reference purposes. The results show that rotational symmetric self-clinching fasteners yield lighter fabrication and more compact joints with a similar electrical resistance to that of bolted joints. They also show that longitudinal symmetric self-clinching fasteners aimed at replicating the resistance-seam-welding contact conditions yield a reduction in electrical resistance to values close to that of ideal joints, consisting of two strips in perfect contact and without contaminant or oxide films along their overlapped surfaces.
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Kenchappa, Bharath, Lokamanya Chikmath, and Bhagavatula Dattaguru. "A study on prognostic analysis of attachment lugs under off-axis loading." International Journal of Structural Integrity 10, no. 6 (December 2, 2019): 809–24. http://dx.doi.org/10.1108/ijsi-10-2018-0075.
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Purpose Lug joints with fasteners play a crucial role in connecting many major components of the aircraft. Most of the failures in the past were credited to the damages initiating and progressing from these types of joints. Ensuring the structural integrity of these fastener joints is a major issue in many engineering structures, especially in aerospace components, which would otherwise lead to fatal failure. The purpose of this paper is to adopting the prognostic approach for analysing these lug joints with fasteners subjected to off-axis loading by estimating the crack initiation and crack growth life of these joints. This data will be useful to estimate the remaining life of these joints at any given stage of operations, which is mandatory in structural health monitoring (SHM). Design/methodology/approach Straight and tapered lug joints are modelled using the finite element method in MSC PATRAN and analysed in MSC NASTRAN. These lug joints are analysed with a push fit fastener. The contact/separation regions at the pin–lug interface are carefully monitored throughout the analysis for various loading conditions. Critical locations in these lug joints are identified through stress analysis. Fatigue crack initiation and fatigue crack growth analysed is carried out at these locations for different load ratios. A computational method is proposed to estimate the cycles to reach crack initiation and cycles at which the crack in the lug joint become critical by integrating several known techniques. Findings Analysis carried out in this paper describes the importance of tapered lug joints, particularly when subjected to non-conventional way of loading, i.e. off-axis loading. There is a partial loss of contact between pin and lug upon pin loading, and this does not change further with monotonically increasing pin load. But during load reversals, there is a change in contact/separation regions which is effectively handled by inequality constraints in the boundary conditions. Crack growth in these lug joints pertains to mixed-mode cracking and is computed through the MVCCI technique. Originality/value Most of the earlier works were carried out on in-plane pin loading along the axis of symmetry of the lug. The current work considers the off-axis pin loading by loading the lug joints with transverse and oblique pin load. The significance of taper angle under such loading condition is brought in this paper. The results obtained in this paper through prognostic approach are of direct relevance to the SHM and damage tolerance design approach where the safety of the structural components is of foremost priority.
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Eraliev, Oybek Maripjon Ugli, Yi-He Zhang, Kwang-Hee Lee, and Chul-Hee Lee. "Experimental investigation on self-loosening of a bolted joint under cyclical temperature changes." Advances in Mechanical Engineering 13, no. 8 (August 2021): 168781402110394. http://dx.doi.org/10.1177/16878140211039428.
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The most commonly used part in engineering fields is threaded fasteners. There are a lot of advantages of fasteners. One of them is that they can be easily disassembled and reused, but a bolted joint can loosen easily when a transversal load is applied. The clamp load of a bolted joint can also loosen slowly when subjected to repeated temperature changes. This paper presents an experimental investigation of the self-loosening of bolted joints under cyclical temperature variation. Experiments are carried out under several cyclical temperature changes with different bolt preloads. Rectangular threaded bolted joints with M12 × 1.75 bolts and nuts are tested in a specially designed testing apparatus. Material of bolt, nut, and plates is a stainless steel. The experimental results show that the high initial bolt preload may prevent the joint from self-loosening and the bolted joint has loosened significantly in the first cycle of temperature changes. From this investigation, the loosening of the bolted joint can be considered as a first stage self-loosening.
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P. Racher and J.F. Bocquet. "Non-linear analysis of dowelled timber connections: a new approach for embedding modelling." Electronic Journal of Structural Engineering 5 (January 1, 2005): 1–9. http://dx.doi.org/10.56748/ejse.546.
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A finite element modelling is developed to analyse the behaviour of timber connections taking into account the plastic behaviour of the timber beneath the fasteners. The local non linearities control the stiffness and the load-carrying capacity of the timber joints. It results in interaction effects on the stress states in the timber and the load distribution among the fasteners that can lead to brittle failure modes such as the block shear failure.This paper presents a new approach based on the development of a pseudo three-dimensional model for the timber in the vicinity of the fasteners. According to the observed behaviour, this finite element model was developed to describe the geometrical and mechanical non-linear behaviours at the micro-scale of the wood beneath the fasteners. Considering the orthotropic behaviour of the timber, the timber around the fasteners is modelled as a structure made up of elementary finite elements. The model accounts also for the friction, the contact and the various irreversible deformations which appear within the timber. An analysis of the embedding behaviour is carried out for three species: spruce, hem-fir and iroko. The comparison of experimental and simulated results shows that this new approach provides a good approximation. An additional sensibility analysis calibrates the model efficiency for coupling the fastener deformation and the timber stresses in the analysis of timber connections.
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Zhang, Xizhi, Jiashu Hao, Dongchao Duan, Shengbo Xu, Shaohua Zhang, and Houxin Yu. "Experimental study on bolted and anchored beam-to-column joints of prefabricated concrete frames." Advances in Structural Engineering 23, no. 2 (August 29, 2019): 374–87. http://dx.doi.org/10.1177/1369433219872432.
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A new type of beam-to-column joint used in prefabricated concrete frames was proposed in this study. In this joint, the longitudinal bars at the top of the beam are anchored to the column using straight thread sleeves, and the bars at the bottom are welded to the steel fastener that is bolted to the column. Cyclic loading tests of three specimens, namely, two beam–column joints of this type and a cast-in-place beam–column joint, were conducted to study the seismic behavior and feasibility of this type of joint. The difference between the two prefabricated joints is the shape of the holes on the end plate. Failure modes of the specimens were observed and analyzed. The hysteretic curves, bearing capacities, stiffness degeneration, ductility, and energy-dissipating capacities of the specimens were compared and studied. Test results indicated that all beam–column joints exhibited beam hinge failure. No slippage was observed between the concrete and horizontal plates of the steel fasteners used in the new type of joint. The bearing capacity and initial stiffness of both prefabricated specimens compared with the cast-in-place ones were increased. The steel fastener could increase the distance between the plastic hinge and the side surface of the column while enlarging the length of the plastic hinge. The trend of energy dissipation and stiffness degeneration of the specimens were similar, and the ductility coefficient ranged from 2.7 to 4.91. The displacement angles of the joints exceeded 1/50 before the failure of the specimens. The mechanical behavior of both prefabricated joints was similar, but the joint with U-shaped holes on the end plate was convenient to create.
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Rośkowicz, Marek, Jan Godzimirski, Andrzej Komorek, Jarosław Gąsior, and Michał Jasztal. "Influence of the Arrangement of Mechanical Fasteners on the Static Strength and Fatigue Life of Hybrid Joints." Materials 13, no. 23 (November 24, 2020): 5308. http://dx.doi.org/10.3390/ma13235308.
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This paper presents the results of experimental research and numerical calculations regarding the static strength and fatigue life of hybrid joints. In the experiments, specimens built as single-lap adhesive–mechanical joints (hybrid joints) were tested. In a two-stage process of the failure of the hybrid joints, the adhesive joint was damaged first. Therefore, it was assumed that the assembly of fasteners closer to the edge of the overlap (beyond the ranges recommended for mechanical joints) limits the negative impact of the peeling phenomenon on the strength and performance properties of hybrid joints. The specimens used in the experiments were prepared from composite elements (i.e., carbon fiber-reinforced polymer (CFRP)), as well as from the aluminum alloy 2024T4. Because the detection of fatigue damage in composite materials is a complex problem, computed tomography was used to evaluate the degradation of the composite material. Experimental and numerical comparative analyses of the static strength and fatigue life of hybrid joints with adhesive and mechanical joints confirmed the assumptions made.
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Nassar, Sayed A., Payam H. Matin, and Gary C. Barber. "Thread Friction Torque in Bolted Joints." Journal of Pressure Vessel Technology 127, no. 4 (February 23, 2005): 387–93. http://dx.doi.org/10.1115/1.2042474.
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In this paper, formulas are developed for the calculation of the effective thread friction radius in fasteners, in order to determine the thread friction torque component. Due to the lack of exact formulas in the literature, current practice uses the average value of the minor and major thread radii, as an approximation, for determining the thread friction torque component. Results provided by these formulas are compared with those given by the current practice that uses the average value of the minor and major thread radii, instead of the exact value. It is well known that the torque-tension relationship in threaded fastener applications is highly sensitive to the friction torque components: between threads, and under the turning fastener head or nut. Even moderate variations or inaccuracies in determining the friction torque components would significantly impact the fastener tension and the joint clamp load. High accuracy in the estimation of the friction torque components is critical, as it directly affects the reliability, safety, and the quality of bolted assemblies. This analysis focuses on the thread friction torque component. The new formulas for the thread friction radius are developed for a mathematical model of a bolted joint using five assumed scenarios of the contact pressure between male and female threads. Because of the fact that the variation in the sliding speed of various points on a thread surface is insignificant, a uniform thread friction coefficient is used in the analysis. However, a contact area weighted average value is used for the thread friction coefficient. Numerical results and error analysis are presented in terms of a single nondimensional variable, namely, the ratio between the major and minor thread radii.
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Nečasová, B., P. Liška, J. Šlanhof, P. Sedlák, and V. Motyčka. "Long adhesive joints in façade applications exposed to wind suction." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 234, no. 5 (July 22, 2020): 488–98. http://dx.doi.org/10.1177/0954408920945065.
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This paper provides an insight into the investigation of long thick-layer adhesive façade joint resistance to negative pressure loads, i.e. wind suction. The real structural response to wind actions was simulated with reference to ETAG 034. Each specimen represented a reference façade section. The experiment focused on four different adhesive systems with flexible high strength 1-K polyurethanes and 1-K modified silyl polymers. Several variants of the test assemblies were tested: 1) a test assembly with an adhesive joint when a) the manufacturers’ application instructions for the system were followed and b) the instructions were violated; 2) a test assembly with a mechanical joint. These variants made it possible to compare the properties of both fastening methods, and moreover, to assess the impact of the mounting tape on the properties of the adhesive joint. The comparison of adhesive joints and a mechanical joint proved the greater structural stiffness and stress resistance of bonded assemblies. Monitoring showed that a local failure of the fastening element between the load-bearing frame and supporting structure caused the failure of the bonded assemblies, whereas the specimen with mechanically attached cladding failed due to pull-through of the fasteners. The average failure load of the bonded assembly was 10.88 kPa. In contrast, the failure load of the segment with mechanical fasteners was 10.12 kPa. Even though the difference in maximum pressure loads was only around 7%, the recorded values clearly demonstrate that the weakest part of the whole façade system is the mechanical joint, not the bonded one. Furthermore, the comparison of the results for segments with and without mounting tape showed that tape can have a major impact on the bond strength, since in case of the test specimens without mounting tape, the recorded failure load was a maximum of 30% higher.
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Nassar, Sayed A., and Aditya B. Veeram. "Ultrasonic Control of Fastener Tightening Using Varying Wave Speed." Journal of Pressure Vessel Technology 128, no. 3 (August 4, 2005): 427–32. http://dx.doi.org/10.1115/1.2218347.
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A high precision ultrasonic technique and a test apparatus are developed for the real time control of the fastener elongation during the tightening process of bolted joints. This is accomplished by monitoring the propagation of longitudinal ultrasonic waves through the fastener material and the reflection of these waves at the end of the fastener. The round trip time of the longitudinal waves is continuously measured and monitored in real time. Using the wave speed in the fastener material, the change in the round trip time determines the fastener elongation, which creates fastener tension and joint clamp load. The wave speed through the bolt material is stress dependent; hence, it continuously changes as the fastener is being elongated during the tightening process. A varying wave speed algorithm is developed and utilized in order to compensate for wave speed variations. Because the torque-tension relationship in threaded fasteners is highly sensitive to friction variations, the scatter in such relationship is often unacceptable, especially in critical applications. By contrast, the automatic control of the fastener elongation during the tightening process would eliminate the dependence on the torque value as a predictor for the bolt tension. Hence, the new ultrasonic technique for the real-control of the fastener tension, by monitoring its elongation, would significantly enhance the reliability of bolted assemblies.
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Pitta, Roure, Crespo, and Rojas. "An Experimental and Numerical Study of Repairs on Composite Substrates with Composite and Aluminum Doublers Using Riveted, Bonded, and Hybrid Joints." Materials 12, no. 18 (September 14, 2019): 2978. http://dx.doi.org/10.3390/ma12182978.
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In this work, experimental and numerical analyses of repairs on carbon fiber reinforced epoxy (CFRE) substrates, with CFRE and aluminum alloy doublers typical of aircraft structures, are presented. The substrates have a bridge gap of 12.7 mm (simulated crack), repaired with twin doublers joined with riveted, adhesive bonded, and hybrid joints. The performance of the repairs using different doubler materials and joining techniques are compared under static loading. The experimental results show that riveted joints have the lowest strength, while adhesive bonded joints have the highest strength, irrespective of the doubler material. Finite element analysis (FEA) of the studied joints is also performed using commercial FEA tool Abaqus. In the FEA model, point-based fasteners are used for the rivets, and a cohesive zone contact model is used to simulate the adhesive bond. The FEA results indicate that the riveted joints have higher tensile stresses on the metal doublers compared to the composite doublers. As per the failure modes, interestingly, for hybrid joints using composite doublers, the doublers fail due to net-section failure, while, for hybrid joints using metal doublers, it is the composite substrate that fails due to net-section failure. This suggests vulnerability of the composite structures to mechanical fastener holes. Lastly, the Autodesk Helius composite tool is used for prediction of first-ply failure and ply load distribution, and for progressive failure analysis of the composite substrate.
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Pegado, Helio de Assis, Rafael Felipe De Souza, and Rodrigo de Sa´ Martins. "Allowable Load Assessment in Metal-Composite Double-Lap Joint / Avaliação de Carga Permitida em Junta de Dupla Folga Metal-Composto." Brazilian Journal of Development 7, no. 8 (August 18, 2021): 82563–75. http://dx.doi.org/10.34117/bjdv7n8-456.
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This work consists of evaluating the tensile and compression static allowable stress of a hybrid (metal-composite) riveted joint. The analyzed joint is composed by two sheets of 2014 – T6 aluminium alloy and a T300/5208 Graphite/Epoxy quasi-isotropic laminate, which were joined by twelve Lockbolt Swaged Collar rivets titanium alloy Ti–6Al–4V annealed. The joint was analyzed through a computational model developed using the Finite Element Method (FEM), with the fasteners modelled through the Multi - Springs technique. This method was widely used to simulate the mechanical behaviour metal-metal and composite-composite parts of the joint. It is validated comparing its results with analytical results of metallic joints available in the literature. Through this model, both the allowable load and its distribution in the fasteners of the joint were determined. Since the evaluated joint is subjected to double shear and, therefore, has no eccentricities, the presence of secondary bending was not observed, the bearing and bypass loads were the most relevant in evaluating the allowable loads of the joint. The load distribution in the joint and its components’ safety margin was determined, with the laminate being the limiting component of the allowable load.
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Martin Charles, M., A. Gnanavelbabu, and K. Rajkumar. "Evaluation of Mechanical Property of Friction Welded EN24 Steel Joints." Applied Mechanics and Materials 591 (July 2014): 108–11. http://dx.doi.org/10.4028/www.scientific.net/amm.591.108.
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EN24 steel is widely used in many engineering applications such as shaft, axle and fasteners due to high tensile strength and low cost. Friction welding is generally used to join the similar and dissimilar materials. The present work investigates on the mechanical properties of friction welded EN 24 steel joints. The effects of the four main parameters: friction duration, forging time, friction pressure and forging pressure on the mechanical properties of the weld such as hardness and axial shortening are studied experimentally and analyzed using ANOVA statistics.
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Kavaliauskas, Saulius, Audronis Kazimieras Kvedaras, and Balys Valiūnas. "MECHANICAL BEHAVIOUR OF TIMBER‐TO‐CONCRETE CONNECTIONS WITH INCLINED SCREWS." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 13, no. 3 (September 30, 2007): 201–7. http://dx.doi.org/10.3846/13923730.2007.9636437.
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The purpose of this paper is to adopt the Johansen's yielding theory as a possibility to predict the ultimate load for timber‐to‐concrete joints using self‐tapping threaded connectors screwed at an angle into the wood. The ultimate load‐bearing capacity of a single connector is predicted to be when either the stresses in the wood reach the plastic failure stress level or when a combination of plastic failure in wood and dowel is attained. K. W. Johansen assumed that no axial tension occurred in the dowel and, thus no frictional contribution affected the lateral load‐bearing capacity. However, the joints with inclined fasteners are first affected by tension load, so the withdrawal capacity of the screws has to be taken into account. In order to determine the load bearing capacity for specific connector geometry, the kinematical possible failure modes are determined. The screw in the concrete part of connection was taken as rigidly embedded and thus no deformations appeared. The study showed that the load‐bearing capacity for connections with inclined high tensile strength screws can be predicted using the yielding theory, but this theory was unable to predict precisely the failure mode. Possible reasons for that include limited fastener ductility and influence of the screw inclination on the strength properties of timber.
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PIKINA, ANNA M. "IMPROVING THE CORROSION RESISTANCE OF THREADED JOINTS BY USING LUBRICANTS." Agricultural engineering, no. 3 (2022): 64–67. http://dx.doi.org/10.26897/2687-1149-2022-3-64-67.
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Modern industry places a number of stringent requirements to the performance properties of fasteners. All fastening elements made of metal are subject to corrosion-mechanical wear. Their disassembling is a time-consuming process which is often accompanied by destruction of the part. Damage to threaded connections can be prevented by applying a special thread lubricant to the part. Based on theoretical and experimental research, the authors have developed a formulation of high-temperature thread compound “Udar”, which contains the following components: molybdenum disulphide (70 wt.%), titanium dioxide (3 wt.%), colloidal graphite compound (70 wt.%), aluminium (powder) (5 wt.%), OMIK “TELAZ” (10 wt.%), thickener (petrolatum), and industrial oil I-40A. The lubricant efficiency in protecting fasteners against atmospheric corrosion and corrosion setting was tested on six specimens representing a pair of “bolt-nut”. The results of comparative laboratory tests of the developed composition with foreign-made greases have shown that the developed thread lubricant is able to protect threaded joints from thermal-oxidative setting occurring at up to 9000C. Application of this composition will considerably reduce the equipment disassembling time due to reduction of the absolute value of torque when disassembling fasteners, and prevent thermochemical and corrosion “seizure” of threaded joints.
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Ufferman, B., T. Abke, M. Barker, A. Vivek, and Glenn S. Daehn. "Mechanical properties of joints in 5052 aluminum made with adhesive bonding and mechanical fasteners." International Journal of Adhesion and Adhesives 83 (June 2018): 96–102. http://dx.doi.org/10.1016/j.ijadhadh.2018.02.030.
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Coelho, Mário, Pedro Fernandes, José Melo, José Sena-Cruz, Humberto Varum, Joaquim Barros, and Aníbal Costa. "Seismic Retrofit of RC Beam-Column Joints Using the MF-EBR Strengthening Technique." Advanced Materials Research 452-453 (January 2012): 1099–104. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.1099.
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The strengthening technique based on the application of multi-directional laminates of CFRP (MDL-CFRP) simultaneously glued and anchored to the surface of the elements to be strengthened has been recently proposed. This technique was designated Mechanically Fastened and Externally Bonded Reinforcement (MF-EBR) and combines the fasteners from the MF-FRP technique with the externally glued properties from the EBR. With the aim of assessing the potentialities of this technique for seismic retrofitting, three interior RC beam-column joints were strengthened according to the MF-EBR technique and tested. This work presents the entire test program executed, including test configuration, results and corresponding analysis.
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Yang, Haoran, Luling An, Xu Chen, and Liyang Zou. "Preload loss of CFRP bolted joint without rotation under transverse and axial loading." Advances in Mechanical Engineering 15, no. 1 (January 2023): 168781322211453. http://dx.doi.org/10.1177/16878132221145342.
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There are a large number of CFRP-steel bolted joints with jet nuts subjected to transverse and axial load in aircraft structures, which have passed standard testing of locking characteristics of fasteners under transverse loading conditions. This fastener has a great preload loss and no rotation loosening occurs. Based on the observation, we designed a biaxial loading experiment for CFRP bolted joint, and measured the preload and loosening angle under different initial preload. The biaxial research suggests that compared with the uniaxial loading condition, the preload loss is larger, the rotation is minimal and only appears in the early stage of test, and there are obvious indentations on the surface of CFRP panel. Embedment as an important factor leads to the preload loss due to the weak ability of CFRP panel suffering out of plane load. In order to study the effect of embedment, the relationship between stress S22 and indentation depth under different preload, the relationship between biaxial load amplitude and embedding depth, and the ratio of the preload loss caused by embedding to the total preload loss are revealed by finite element analysis.
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Sadowski, T., and P. Golewski. "Numerical Study of the Prestressed Connectors and Their Distribution on the Strength of a Single Lap, a Double Lap and Hybrid Joints Subjected to Uniaxial Tensile Test." Archives of Metallurgy and Materials 58, no. 2 (June 1, 2013): 579–85. http://dx.doi.org/10.2478/amm-2013-0041.
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Prestressed joints are widely used in construction using connectors in the form of screws, whose task is to strong clamping of joined parts, thereby the internal forces in joint are transferred by surface friction contact of the elements. In the automotive and aerospace industries hybrid joints are more widely applied. Mechanical connectors are added to the adhesive joint in form of rivets, screws or clinch increasing its strength properties. The aim of this study was to determine how the prestressed connectors influence the mechanical response of hybrid, single and double lap joints. The influence of different distribution of the connectors was also investigated. Numerical study was conducted in ABAQUS program. Mechanical connectors were modeled by using fasteners, that allowed for a considerable simplification of the numerical model. In their application, there is no need for an additional submodels for connectors in the form of the rivet or the bolt. Prestressing is activated by direct application of the force to the connector. In the numerical examples the authors assumed that the diameter of the mechanical connectors was equal to 6mm and shear strength was equal 1kN. Adhesive layers were modeled by using cohesive elements for which maximum shear stresses and fracture energy were specified. The layer thickness was assumed to be equal 0.1mm and it was initially removed from the areas where mechanical connectors were placed. Two types of joints were analysed in the study: the single lap joint with lap dimensions 40x40mm as well as the double lap joint with lap dimensions 40x20mm, from which it results that theoretical strength of both connections should be the same. The prestressing of connectors was introduced by the force 1.5kN. For all pure - mechanical joints and for single lap joints positive effects were obtained. For double lap joints additional prestressing did not significantly affect for their strength. The influence of distribution of mechanical connectors was additionally analyzed by consideration of three configurations, where the rows of rivets were located at distances of 5, 10 and 15mm from the lap edge. The maximum increase of the load capacity by 24% was achieved for single lap joint as well as 35.7% for double lap joint. The obtained numerical results indicate the positive effects of additional pressure and allows for practical suggestions how to correct and optimize spacing distance of mechanical connectors in hybrid joints to get better mechanical response.
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Saitou, Kazuhiro. "Built to be Reclaimed." Mechanical Engineering 133, no. 09 (September 1, 2011): 52–54. http://dx.doi.org/10.1115/1.2011-sep-5.
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This article elaborates a new design approach that aims at designing products with built-in disassembly means to be activated at the end of a product’s life. Two projects explored in this area are the design of a new class of joints that can be detached by the application of localized heat, and the design of assemblies that can disintegrate via a domino-like process triggered by the removal of one or only a few fasteners. The detachable joints (heat-reversible locator-snap systems) allow easy, non-destructive, and clean detaching of product enclosures. They consist of locators and snaps molded on the internal surfaces of thin-walled product enclosures. During disassembly, thermal expansion of the enclosure walls constrained by locators and the temperature gradient along the wall thickness are exploited to realize the deformation required to release the snaps. In self-disintegrating assemblies, the relative motions of components are constrained by the locators integral to the components, in such a way that the removal of one or few fasteners would cause the self-disintegration of the assembly in a desired sequence.
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Domínguez, Manuel, Jose G. Fueyo, Alberto Villarino, and Natividad Anton. "Structural Timber Connections with Dowel-Type Fasteners and Nut-Washer Fixings: Mechanical Characterization and Contribution to the Rope Effect." Materials 15, no. 1 (December 29, 2021): 242. http://dx.doi.org/10.3390/ma15010242.
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Dowel-type fasteners are one of the most used type of connections in timber joints. Its design follows the equations included in the Eurocode 5. The problem with these equations is that they do not adequately contemplate the resistive capacity increase of these joints, when using configurations which provoke the so-called rope effect. This effect appears when using threaded surface dowels instead of flat surface dowels, expansion kits or nut-washer fixings at the end of the dowel. The standards consider this increase through a constant value, which is a poor approximation, because it is clearly variable, depending on the joint displacement and because is much bigger, especially when using nut-washer fixings. It is also very important because of the rope effect trigger interesting mechanisms that avoids fragile failures without warning of the joints. For these reasons, it is essential to know how these configurations work, how they help the joint to resist the external loads and how much is the increase resistance capacity in relationship with the joint displacement. The methods used to address these issues consisted of a campaign of experimental tests using actual size specimens with flat surface dowels, threaded surface dowels and dowels with washer-nut fixings at their ends. The resistance capacity results obtained in all the cases has been compared with the values that will come using the equations in the standards. After the tests the specimens were cut to analyze the timber crushings, their widths, the positions and level of plasticizations suffer in the steel dowels and in the washer-nut fixings and the angle formed in the dowel plastic hinges. With all this information the failure mode suffered by the joints has been identified and compared with the ones that the standards predict. The results for the size materials and types of joints studied shows that the crush width average values go from 20 mm with flat surface dowels, to 24 mm in threaded to 32 mm in threaded with washer-nut fixings. The rope effect force/displacement goes from 100 N/m in threaded surface dowels to 500 N/m in threaded with washer-nut fixings. Finally, the load capacities are on average 290% higher those indicated in the standard. The main conclusion is that the rope effect force should be considered in the standards in more detail as a function of multiple variables, especially the displacement of the joint.
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Ibrahim, R. A., and C. L. Pettit. "Uncertainties and dynamic problems of bolted joints and other fasteners." Journal of Sound and Vibration 279, no. 3-5 (January 2005): 857–936. http://dx.doi.org/10.1016/j.jsv.2003.11.064.
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Hermansson, Thomas O. "Quality assured tightening of screw joints." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 15 (August 9, 2016): 2588–94. http://dx.doi.org/10.1177/0954406215602038.
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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.
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Hu, Junshan, Kaifu Zhang, Hui Cheng, and Zhenchao Qi. "Mechanism of bolt pretightening and preload relaxation in composite interference-fit joints under thermal effects." Journal of Composite Materials 54, no. 30 (July 13, 2020): 4929–46. http://dx.doi.org/10.1177/0021998320941218.
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The present research investigates the mechanism of bolt pretightening and preload relaxation in composite interference-fit joint structures under thermal effects. In view of the dissimilar material properties and the interfacial friction in such joints, the mechanical behavior of bolt and composites during assembly can be regarded as immediate preload response which is described by a linear elastic model, whereas the long-term behavior of composites during preload relaxation in service is considered as delayed response which is characterized by a viscoelastic model. The clamping forces on both sides of joints were captured to evaluate the preload balanced by the frictional behavior. The preload relaxation of joints with various interference-fit sizes and tightening torques under thermal effects were monitored for 240 hours to calibrate and validate the proposed model. The research revealed that the interference-fit size determined the level of frictional force which resulted in a difference between clamping forces at two sides of the fasteners. The preload first increases slowly with the growth of temperature, then decreases sharply when it approaches to glass transition temperature of matrix. The interference-fit joint behaves better in terms of maintaining the stability of preload than clearance-fit joints.
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Akhtar, Muhammad Maaz, Øyvind Karlsen, and Hirpa G. Lemu. "Study of Bondura® Expanding PIN System – Combined Axial and Radial Locking System." Strojniški vestnik – Journal of Mechanical Engineering 67, no. 12 (December 15, 2021): 625–34. http://dx.doi.org/10.5545/sv-jme.2021.7306.
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Bolted connections are widely used in parallel plates and flanged joints to axially lock using the preload generated by the tightening torque and to constrain radial movements of the flanges by the surface friction between mating surfaces. The surface friction depends on the micro-asperities of mating surfaces; under the influence of vibrations and other external radial loads, these asperities tend to deform over time, resulting in the failure of the connection. The Bondura expanding pin system presented in this article is an innovative axial and radial locking system, in which the failure of bolted connections due to radial movements is eliminated by relying on the mechanical strength of the pin system along with the surface friction. The present study describes an experimental design to verify the maximum possible preload on the axial-radial pin at different levels of applied torque. The article also provides a realistic comparison of the pin system with standard bolts in terms of handling axial and radial loads. With some alterations in the axial-radial pin system’s design, the joint’s capability to resist failure improved appreciably compared with the original design and standard bolts with higher preload. As a result, the estimated capability improvement of the joint against the connection failure due to the external radial load by the axial-radial pin is observed to be more than 200 % compared to standard bolts. Considering the pros and cons of both fasteners, i.e., axial-radial pin and standard bolts, a practical solution can be chosen in which both fasteners are used in a connection, and an optimized situation can be developed based on the working conditions.
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Ellegaard, Peter. "Finite-Element Modeling of Timber Joints with Punched Metal Plate Fasteners." Journal of Structural Engineering 132, no. 3 (March 2006): 409–17. http://dx.doi.org/10.1061/(asce)0733-9445(2006)132:3(409).
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Dias, A. M. P. G., S. M. R. Lopes, J. W. G. Van de Kuilen, and H. M. P. Cruz. "Load-Carrying Capacity of Timber–Concrete Joints with Dowel-Type Fasteners." Journal of Structural Engineering 133, no. 5 (May 2007): 720–27. http://dx.doi.org/10.1061/(asce)0733-9445(2007)133:5(720).
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Xu, Chang, Wenjing Wang, Zhiming Liu, and Chen Fu. "Prediction model and parametric study on CFRP flat-joggle-flat hybrid (bonded/bolted) joints." Journal of Composite Materials 54, no. 26 (May 14, 2020): 4025–34. http://dx.doi.org/10.1177/0021998320925542.
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As the weakness zone of composite structures, joints are of great concern. Adding fasteners in the bonded joint is another type of jointing, technology used in engineering. In this research, considering a new type of flat-joggle-flat carbon fibre reinforced plastic (CFRP) joint, a prediction model based on the commercial software ABAQUS was proposed to predict the joint load carrying capacity and analyse the joint failure modes. Tensile tests were performed to verify the validity of the model. Furthermore, the orthogonal design was applied to explore the effects of four kinds of factors on the hybrid joints. The results showed that the load-carrying capacity of the hybrid joint improved by 40.5% and 31.9% on average, compared with that of the adhesively bonded joint and the bolted joint, respectively. The carrying capacity for the bonded joint, bolted joint and hybrid joint predicted by the model has error values of 3.5%, 2.7% and 3.1%, respectively, which illustrates good accuracy with the test results. The width-to-diameter ratio appears to have the most substantial effect on the first drop load and the maximum load of the hybrid joint. The failure modes are influenced by the width-to-diameter ratio, edge-to-diameter ratio and stacking sequence.
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Kinloch, A. J. "Adhesives in engineering." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 211, no. 5 (May 1, 1997): 307–35. http://dx.doi.org/10.1243/0954410971532703.
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When considering methods for joining materials, there are many advantages that engineering adhesives can offer, compared to the more traditional methods of joining such as bolting, brazing, welding, mechanical fasteners, etc. The advantages and disadvantages of using engineering adhesives are discussed and it is shown that it is possible to identify three distinct stages in the formation of an adhesive joint. Firstly, the adhesive initially has to be in a ‘liquid’ form so that it can readily spread over and make intimate molecular contact with the substrates. Secondly, in order for the joint to bear the loads that will be applied to it during its service life, the ‘liquid’ adhesive must now harden. In the case of adhesives used in engineering applications, the adhesive is often initially in the form of a ‘liquid’ monomer which polymerizes to give a high molecular weight polymeric adhesive. Thirdly, it must be appreciated that the load-carrying ability of the joint, and how long it will actually last, are affected by: (a) the design of the joint, (b) the manner in which loads are applied to it and (c) the environment that the joint encounters during its service life. Thus, to understand the science involved and to succeed in further developing the technology, the skills and knowledge from many different disciplines are required. Indeed, the input from surface chemists, polymer chemists and physicists, materials engineers and mechanical engineers are needed. Hence, the science and technology of adhesion and adhesives is a truly multidisciplined subject. These different disciplines have been brought together by developing a fracture mechanics approach to the failure of adhesive joints. The advances that have been made in applying the concepts of fracture mechanics to adhesive joints have enabled a better understanding of the fundamental aspects of adhesion and the more rapid extension of adhesives technology into advanced engineering applications.
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Mahar, Akshay Mangal, and S. Arul Jayachandran. "A Computational Study on Buckling Behavior of Cold-Formed Steel Built-Up Columns Using Compound Spline Finite Strip Method." International Journal of Structural Stability and Dynamics 21, no. 05 (February 16, 2021): 2150064. http://dx.doi.org/10.1142/s0219455421500644.
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This paper presents a computational methodology to compute the critical buckling stress of built-up cold-formed steel columns joined with discrete fasteners. The fasteners are modeled as three-dimensional beam elements, and their effect is integrated into the spline finite strip framework, evolving the compound strip methodology. Although this technique has been presented in the literature, this paper presents yet another robust framework for the buckling load evaluation of compound cold-formed steel columns with arbitrarily located fasteners. The proposed framework is applied to study the effect of fasteners on the formation of local, distortional, and global buckling modes of built-up section and a comparison is drawn with the buckling behavior of a single section. In this study, the proposed formulations are also used to get insights into the stability behavior of single-span and multi-span compound cold-formed steel columns in the presence of (i) fasteners with varied spacings with respect to span and (ii) the presence of the additional restraining system such as wall panels. For different buckling modes, a significant increment in buckling stress for a built-up section from a single section is observed when the fastener spacing is kept less than the critical buckling half-wavelength of the respective buckling modes. The study on the effect of wall panels shows that in comparison to unsheathed wall studs, the sheathed wall studs that produce additional constraints lead to the elimination of the global buckling deformations. The proposed formulations are simple, yet rigorous and have been validated using finite element-based numerical results.
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Hehl, Simon, Till Vallée, Thomas Tannert, and Yu Bai. "A Probabilistic Strength Prediction Method for Adhesively Bonded Joints Composed of Wooden Adherends." Key Engineering Materials 417-418 (October 2009): 533–36. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.533.
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Joining timber structural elements using mechanical fasteners goes against the anisotropic and fibrous nature of the material. Adhesive bonding is by far better adapted, since it permits a smoother load transfer. However, the strength prediction of adhesively bonded wooden joints is difficult brittle nature of the adherends, the complex stress distribution as well as the uncertainties regarding the associated material resistance. As a contribution to help close this research gap, the authors have carried out experimental and analytical investigations on adhesively bonded double lap joints composed of timber. This paper describes the experimental and numerical results and suggests a probabilistic method for the strength prediction of joints composed of brittle adherends and adhesives. The method considers the scale sensitivity of material strength modelled using a Weibull statistical function, and considers both the statistical variation and the size effect in the strength of the material. The probabilistic method presents a mechanical explanation for the increased resistance of local zones subjected to high strain or stress peaks.
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Máchová, Eliška, Nadežda Langová, Roman Réh, Pavol Joščák, Ľuboš Krišťák, Zdeněk Holouš, Rastislav Igaz, and Miloš Hitka. "Effect of moisture content on the load carrying capacity and stiffness of corner wood-based and plastic joints." BioResources 14, no. 4 (September 17, 2019): 8640–55. http://dx.doi.org/10.15376/biores.14.4.8640-8655.
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The effect of moisture content on mechanical properties of corner furniture joints was evaluated for when different joining methods and materials were used. Results included statistical processing of the measured and calculated data and evaluation of the effect of selected factors on mechanical properties of joints caused by using mechanical fasteners and glue. The load-carrying capacity and stiffness of corner joints were investigated in two environments, humid and dry, with standard conditions for temperature and pressure, i.e., dry environment had a temperature of 23 °C ± 2 °C and relative humidity of 45% ± 5%, and the humid environment had a temperature of 23 °C ± 2 °C and relative humidity of 90% ± 5%. The two types of materials used were particleboard (PB) with a thickness of 12 mm and artificial stone (plastic) with a thickness of 12 mm. Both materials were tested individually as well as their combination. Epoxy and polyurethane (PUR) adhesives were used for the glued dowel joints. When the same materials were bonded, maximum load carrying capacity was achieved with PUR adhesive, material combination of plastic-plastic, and moisture content of 90%. The epoxy adhesive was most suitable for bonding materials with different properties.
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Wiesenmayer, Sebastian, and Marion Merklein. "Influence of Tool Wear on the Load-Bearing Capacity of Shear-Clinched Joints." Defect and Diffusion Forum 404 (October 2020): 3–10. http://dx.doi.org/10.4028/www.scientific.net/ddf.404.3.
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Shear-clinching allows the joining by forming of dissimilar materials with high differences between their mechanical properties without additional fasteners. Since the lower joining partner is indirectly shear cut during the process, even ultra-high strength materials can be joined. However, the cutting of the high-strength materials as well as the extrusion of the upper joining partner leads to high process forces and therefore to high tool loads. This applies in particular for the die, which is highly stressed during the cutting phase and therefore plastically deformed. Within the scope of this work, the influence of the occurring wear on the formation of the joint and its load-bearing capacity is analyzed for a scope of 500 strokes. For this purpose, press hardened 22MnB5 is used as lower joining partner. Its high strength leads to the plastic deformation of the cutting edge, which increases within the first 200 strokes. Afterwards only minor changes occur. Yet, no effect of the occurring wear on the joint formation and the joint strength, which was tested under shear and tensile load, could be determined. Functioning joints could still be produced for more than 500 strokes as the load-bearing capacity remained on a comparable level.
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Wi, Jun-Hee, Kwang-Hee Lee, and Chul-Hee Lee. "Self-loosening of 3D printed bolted joints for engineering applications." MATEC Web of Conferences 185 (2018): 00029. http://dx.doi.org/10.1051/matecconf/201818500029.
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A bolt joint is a simple element that joins mechanical components. Self-loosening of bolted joints occurs due to the vibrations caused by motors and engines, resulting in the breakage of machines, and potentially serious safety problems. Recently, developments in 3D printing technologies have enabled the fabrication of detailed components. These technologies can be used for producing fasteners using 3D printed bolts. Many researchers have proposed a theoretical model for self-loosening of the bolt, and experimental studies on the self-loosening phenomenon have been advanced. However, studies on the self-loosening of 3D printed bolts have not been conducted. Therefore, it aims to confirm the self-loosening phenomenon and the safety of 3D printed bolts through experiments and finite element simulation. A lateral vibration test system is constructed and self-loosening of the bolt is evaluated by observing the axial force according to the vibration cycle by using a strain gauge. This study compared the self-loosening of 3D printed bolts and steel bolts by changing the preload and amplitude. In addition, the experimental results are verified through finite element simulation. Through this study, it is expected that 3D printed bolts will be used more frequently in situations where specially shaped bolts are needed.
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Liu, Kang. "Experimental Study on Bond Characterization of Hybrid-Bonded FRP to Concrete Interfaces." Advanced Materials Research 790 (September 2013): 375–80. http://dx.doi.org/10.4028/www.scientific.net/amr.790.375.
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Pure adhesive bond of FRP to concrete is not only weak but also unreliable in a long term. This problem can be effectively overcome by a newly developed bond enhancement system the hybrid bonded FRP system (HB-FRP) in which small mechanical fasteners are used to augment the bond. In this paper, the bond behaviors of EB-FRP and HB-FRP joints were experimentally investigated by employing the single shear pull-off test on three EB-FRP and seven HB-FRP specimens with different bond lengths. Experimental testing is reported for characterization of the interfacial bond of the HB-FRP system.
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Fortier, Vincent, Jean-E. Brunel, and Louis L Lebel. "Fastening composite structures using braided thermoplastic composite rivets." Journal of Composite Materials 54, no. 6 (August 14, 2019): 801–12. http://dx.doi.org/10.1177/0021998319867375.
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Aerospace composite material components are currently joined using heavy titanium bolts. This joining method is not ideal when considering its weight, thermal expansion, electrical conductivity, and risk of unbalanced load distribution. We propose here an innovative fastening technology using thermoplastic composite rivets. A rivet blank is heated above its melting temperature using Joule heating and is formed directly in the composite laminates by an automated process. Carbon fiber and polyamide blanks were used with two fiber architecture: 2D braid and unidirectional. The braided architecture showed superior manufacturing performance and repeatability. Joints were riveted in less than 40 s per rivet. The temperature measured in the riveted composite laminate in the vicinity of formed rivet reached only 136℃ during riveting. Double fastener lap shear testing showed breaking load of 6146 N per fastener. This joint strength is higher than comparable aluminum-riveted joints, and the specific joint strength is higher than titanium-bolted joints. With these advantages, the technology could be developed and used in the next generations of lighter, cleaner, and safer aircraft.
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Afonso, Rafael M., and Luís M. Alves. "Tube Joining by a Sheet Flange Connection." Journal of Manufacturing and Materials Processing 7, no. 1 (December 29, 2022): 12. http://dx.doi.org/10.3390/jmmp7010012.
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Joining of tubes to tubes by means of plastic deformation at ambient temperature allows one to solve the main limitations produced by the necessity of joining thin-walled tubes of low-to-medium diameter size made from materials that are not suitable to be welded and/or have reduced contact interfaces. The new joining solution allows one to obtain permanent mechanical joints of tubes or pipes by means of an accessory lightweight sheet metal flange subjected to annular indentation and subsequent injection of its material towards the tube walls to produce a mechanical interlock between the different elements. The sheet-flange connection can then be utilized to affix the joined tube assembly to walls or other different structures and equipment, by means of fasteners or other joining accessories attached to the sheet flange. Similar or dissimilar material combinations can be easily and safely produced while guaranteeing levels of leak-tightness within the maximum internal operating pressure of the individual tubes. A combined numerical–experimental approach is employed to identify the operative parameters as well as to explain the deformation conditions. Pull-out loads and internal fluid pressure are applied to the manufactured joint to evaluate its behavior under typical operating conditions that it may be subjected to during its service life depending on the application.
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Mucha, Jacek, and Waldemar Witkowski. "The Structure of the Strength of Riveted Joints Determined in the Lap Joint Tensile Shear Test." Acta Mechanica et Automatica 9, no. 1 (March 1, 2015): 44–49. http://dx.doi.org/10.1515/ama-2015-0009.
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Abstract The article presents the analysis of the structure of the load capacity of riveted joints. For the four joining systems the lap joint specimens were made and tested in the shearing test. The joints were prepared for the three combinations of the DC01 steel and EN AW- 5754 aluminium alloy sheets with the thickness of 2mm. On the basis of the obtained load-elongation diagram tensile shear test curves, the basic parameters defined in the ISO/DIS 12996 standard were determined. In the case of the conventional riveted joints the maximum load capacity of the joint is determined by the strength of the fastener. For the joints with aluminium-steel blind rivet , the load capacity of the joint was on the strength limit of the rivet tubular part and on the strength limit of the sheet material. The strength of the SSPR joint is determined by the mechanical properties of the material of the joined sheets. From all sheets and rivet specimens arrangements the highest load capacity of the joint was obtained for the DC01 sheet material joints, and the lowest load capacity of the joint was obtained for the EN AW-5754 sheet material joints.
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Di, Jing, and Hongliang Zuo. "Experimental and Reliability-Based Investigation on Sheathing-to-Framing Joints under Monotonic and Cyclic Loads." Forests 12, no. 8 (July 27, 2021): 995. http://dx.doi.org/10.3390/f12080995.
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The seismic performance of a light wood frame structure is determined by sheathing-to-framing joints. In order to encourage the use of more sustainable materials in structures, the spruce-pine-fir (SPF) panel and the bamboo scrimber (BS) panel were considered as sheathing materials. Monotonic and cyclic tests were conducted on the joints with different parameters to obtain their mechanical properties. Moreover, the design value of the bearing capacity of sheathing-to-framing joints was calculated and compared in accordance with Chinese code (GB50005) and European code (Eurocode 5). Based on the test results and the design codes, the reliability index of the design value of the bearing capacity of joints was calculated using the first-order reliability method (FORM). Results demonstrate that the joints have high bearing capacity and stiffness at initial loading stage when the loading direction is perpendicular to the framing grain. BS panels make better use of the bending strength of fasteners than SPF panels. The screwed joints have lower strength and stiffness degradation than nailed joints, but the nailed joints show better ductile and dissipation than screwed joints. In addition, the reliability indexes of design bearing capacity calculated by the Chinese code of joints under monotonic load are conservative, but those of joints under cyclic load are unconservative. Therefore, in order to ensure the safety and economy of design, a modification factor for the GB50005 design method of joints is proposed to meet the target reliability index.
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N.A.Z. Abdullah, M.N.A.M. Asri, and Mohd Shahrir Mohd Sani. "Strategies of Finite Element Modeling for Spot Welded Joints and its Modal Correlation with Experimental Data." International Journal of Automotive and Mechanical Engineering 19, no. 1 (March 24, 2022): 9543–50. http://dx.doi.org/10.15282/ijame.19.1.2022.17.0736.
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In building many complex engineering structures, there are many types of joining methods such as welding and fasteners that can be implemented. Modeling for joints in finite elements can be challenging as it sometimes has limiting factors that cause the prediction of the dynamic behaviour of the actual joints to be less accurate. This study aims to demonstrated several approaches of finite element modeling for spot-welded joints ad to analyse its accuracy through the correlation of modal data from experimental modal analysis. These modeling approaches are created by creating and manipulating the elements at the associated location of the spot weld joint on a top-hat beam structure. Four different approaches of spot weld modeling that uses the modeling strategies performed in other studies were created. The spot weld models are validated by comparing the modal properties of the tested structure which are obtained through finite element analysis and experiments. Model updating was performed on all models in order to observe the ability of model improvement in those different modelling approaches. The findings show that the model that uses solid elements has the lowest error compared to the model that uses beam elements. The model that uses multiple-beam elements shows the ability to be improved the most. The model that uses the simplest modeling approach using a single beam has the highest error and shows the lowest improvement after model updating. It was found that solid element is more suitable to model spot weld and the application of solid element for spot weld joints should be investigated in more types of analyses.
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Liu, Kang. "Analytical Study on Bond Characterization of Hybrid-Bonded FRP to Concrete Interfaces." Applied Mechanics and Materials 405-408 (September 2013): 2528–33. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.2528.
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Pure adhesive bond of FRP to concrete is not only weak but also unreliable in a long term. This problem can be effectively overcome by a newly developed bond enhancement system the hybrid bonded FRP system (HB-FRP) in which small mechanical fasteners are used to augment the bond. In this paper, theoretical modeling is reported for characterization of the interfacial bond of the HB-FRP system. Local bond-slip model involving adhesive and mechanical mechanisms is proposed. Based on the basic bond-slip model, load-slip response, ultimate bond strength, and effective bond length of the HB-FRP bond interface are obtained by analytical or numerical solution. Good agreement between the analytical and experimental results indicates that the proposed bond-slip model can well predict bond behaviors of HB-FRP joints.
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Johanides, Marek, Lenka Kubíncová, David Mikolášek, Antonín Lokaj, Oldřich Sucharda, and Petr Mynarčík. "Analysis of Rotational Stiffness of the Timber Frame Connection." Sustainability 13, no. 1 (December 25, 2020): 156. http://dx.doi.org/10.3390/su13010156.
Full textAbstract:
Initially, timber was considered only as an easily accessible and processable material in nature; however, its excellent properties have since become better understood. During the discovery of new building materials and thanks to new technological development processes, industrial processing technologies and gradually drastically decreasing forest areas, wood has become an increasingly neglected material. Load-bearing structures are made mostly of reinforced concrete or steel elements. However, ecological changes, the obvious problems associated with environmental pollution and climate change, are drawing increasing attention to the importance of environmental awareness. These factors are attracting increased attention to wood as a building material. The increased demand for timber as a building material offers the possibility of improving its mechanical and physical properties, and so new wood-based composite materials or new joints of timber structures are being developed to ensure a better load capacity and stiffness of the structure. Therefore, this article deals with the improvement of the frame connection of the timber frame column and a diaphragm beam using mechanical fasteners. In common practice, bolts or a combination of bolts and pins are used for this type of connection. The subject of the research and its motivation was to replace these commonly used fasteners with more modern ones to shorten and simplify the assembly time and to improve the load capacity and rigidity of this type of frame connection.
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Lv, Jiaxin, Yi Xiao, and Yuande Xue. "Time–temperature-dependent response and analysis of preload relaxation in bolted composite joints." Journal of Reinforced Plastics and Composites 37, no. 7 (January 11, 2018): 460–74. http://dx.doi.org/10.1177/0731684417752082.
Full textAbstract:
Although mechanically fastened joints are generally considered a mature technology, significant problems still exist with their use, among which the preload loss in pretensioned bolts is a major one. This paper has investigated two key issues in structural durability design for mechanically fastened composite joints, i.e. temperature–time-dependent behavior for viscoelastic preload relaxation and prediction method for its long-term performance. Towards this purpose, a two-phase experimental program was conducted consisting of short- and long-term joint relaxation tests. Phase I monitored the short-term fastener preload relaxation (up to 36 h), with a special self-made bolt strain sensor. Phase II utilized the time–temperature superposition principle to establish a method of using short-term relaxation curves to construct the long-term master curve (accelerated test). It was found that there was a significant loss of bolt preload when temperature and initial preload increased, and the relaxation rate of composited joint was much larger than that of the metallic joint. Based on the strong temperature dependence of bolt relaxation, accelerated characterization was conducted for long-term behavior. Furthermore, to quantitatively relate the relaxation data to a model equation, a new preload prediction model was developed based on the creep total-strain theory. Comparisons of the prediction model and accelerated test results indicated that the improved model provided better accuracy than existing models such as Shivakumar–Crews’s and Hook-Norton’s models for describing the long-term preload behavior.
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Ganne-Chédeville, Christelle, Milena Properzi, Antonio Pizzi, Jean-Michel Leban, and Frédéric Pichelin. "Parameters of wood welding: A study with infrared thermography." Holzforschung 60, no. 4 (July 1, 2006): 434–38. http://dx.doi.org/10.1515/hf.2006.068.
Full textAbstract:
Abstract Welding of wood is a well-known joining procedure that offers several advantages over traditional mechanical fasteners or gluing. During welding, extensive solid-state transformation phases occur in the so-called melting zone and the heat-affected zone. The nature and the extension of such transformations are correlated to the energy input and thus to the heat generated during the process at the wood joint interface. In the present work the influence of the welding parameters and wood grain orientation on the temperature profile and distribution and final strength of welded connections was investigated. For this purpose, the characteristics of the joints were evaluated with both destructive and non-destructive techniques. Non-destructive evaluation was performed with infrared thermography, which allowed measurement of the maximal and average peak temperature, temperature profile and distribution, and rate of temperature increase. Thus, this technique can also be used to detect welding defects and to provide information on material modification during welding.