Joints Of Sheets Research Articles

The effect of pre-existing structures on the Moosfluh landslide and its lateral propagation (Great Aletsch Glacier, Switzerland)

The retreat of the Great Aletsch Glacier is accompanied by a series of slope failures in solid bedrock, which are heavily influenced by the presence of pre-existing deformation structures. Since the 1880's, the Great Aletsch Glacier has shortened by more than 3 km and decreased about 400 m in thickness. As a reaction to the loss of the stabilizing effect of the ice, one of the largest active deep-seated landslides in the European Alps with an affected surface area of about 1.5 km2, called Moosfluh landslide, is evolving. In this study, a multimethod approach combining field work, remote sensing techniques and microseismic monitoring is used to assess the effect of pre-existing structures on the landslide deformation processes.The landslide evolution from 2008 to 2018 could be reconstructed with high spatial resolution. Surface deformation analysis reveals the concentration of high deformation in narrow zones, allowing to directly link pre-existing tectonic and exhumation structures with landslide deformation processes. Toppling as the main gravity-driven process is enabled by reactivation of NE-SW striking, steeply SE dipping Alpine Handegg phase shear zones. Differences in the lateral detachment processes are attributed to shear zone bridges in the NE as well as fractures and shear zones similarly oriented to Alpine Oberaarb phase shear zones in the SW. At the landslide toe, a transition from toppling to sliding mechanism due to the formation of a continuous basal detachment surface can be observed, which is favored by the presence of exfoliation joints. The dramatic acceleration of the Moosfluh landslide in autumn 2016 is directly related to an increase in glacier height loss rate, which implies that glacier retreat is the main trigger of the landslide. A temporal stabilization of the landslide is recorded after 2017, most probably caused by the self-stabilizing properties of flexural toppling. However, microseismic data records a lateral propagation of the landslide, following the retreating Great Aletsch Glacier.

The influence of the shoulder depth on the properties of the thin sheet joint made by FSW technology

PurposeThis paper aims to experimentally determine the influence of the tool shoulder depth value on the structural and strength properties of the single lap joints made of 7075-T6 aluminium alloy made with friction stir welding (FSW) technology. The aim of the preliminary tests is to optimize the parameters of joining process of thin-walled structures such as the skin-stringer joint or skin-frame joint of the aircraft fuselage. The tests were carried out for materials commonly used in such structures, i.e. 1.6 mm thick sheet 7075–T6 aluminium alloy with cladding on both sides (cladding thickness 4% per each side). The layer of clad protects plates from corrosion.Design/methodology/approachThis study shows the results of the investigation for the joining of 7075–T6 ALCLAD aluminium alloy sheets. The welding process was carried out on a computer numerical control milling machine SOLARUCE TA–20A. Linear FSW welding was performed using a commercial tool from RSS SCHILLING with the symbol 10–K–4–Z–M–O, which is fabricated of hot work tool steel. Constant parameters of the technological process were applied. The welding process was executed for different values of the shoulder depth ZS.FindingsThis paper investigated the dependence between the thinning of the welded material and the depth value of the tool shoulder during the FSW process. The influence of the depth value of tool shoulder on joint strength in the static tensile/shear test was also performed. With the increase of the depth of the tool, the size of flash and structures of the face of the joint changes as well (its annular surface resulting from the tool’s work and the accompanying process of material flow on the run-off side). Such conditions in the process require a proper tool depression to reduce the occurrence of flash and minimize material thinning to achieve high joint strength and maintain the conditions for plasticizing the material.Practical implicationsBased on the experimental tests carried out, a number of guidelines for the correct conduct of the welding process can be outlined.Originality/valueTaking into account the various aspects of the process, the optimal range of the tool depth into the material is a value of approximately 0.06 mm. At this value, the face of the weld is not porous; the flash is easily removed; and the strength of the joint and the deformation of contact line are at an acceptable quality level.

Study into the Use of Alternative Technologies in the Manufacture of Rolled and Welded Tube-to-Tube Sheet Joints

An alternative technology for the manufacture of rolled and welded tube-to-tube sheet joints using friction welding without heat treatment is proposed. The aim of the study was to evaluate the operational characteristics of samples simulating rolled and welded tube-to-tube sheet joints using alternative technology, as well as their comparison with samples made using the basic technology involving heat treatment. The test results confirmed the conformity of samples made using the alternative technology in terms of density and strength, as well as in the predicted reliable operation resource for samples made according to the basic technology.

A self-piercing riveting method for joining of continuous carbon fiber reinforced composite and aluminum alloy sheets

During the self-piercing riveting process of carbon fiber reinforced polymer (CFRP) and aluminum sheets, the CFRP is penetrated by the rivet, which weaken the mechanical properties of the joint of CFRP and aluminum alloy sheets to a certain extent. To improve quality of the joint, this study proposes a post-curing self-piercing riveting (PC-SPR) method to join CFRP with aluminum alloy sheets. The mechanical properties and failure modes of the joints were studied through tensile shear tests and the effects of joint structure and CFRP thickness on joint quality were examined. The failure mode of the joint was analyzed by observing the microscopic appearance, and the damage mechanism of the joint was systematically discussed. Results showed that compared with regular self-piercing riveting (R-SPR) joints, PC-SPR joints had better strength.

КОНСТРУКТИВНА ТА ЕКОНОМІЧНА ЕФЕКТИВНІСТЬ ЗОВНІШНЬОГО УТЕПЛЕННЯ СТІН БУДИНКІВ

The article considers several different options for materials for external wall insulation and their advantages from an economic and structural point of view, taking into account the characteristics of some of the most popular insulation and the feasibility of use in a given case. Currently, energy saving and reducing the use of fuel resources is one of the most pressing issues, both in the construction of new buildings and in the case of reconstruction of the existing building stock and means the need to have structures that will minimize heat loss. It is understood why high-quality thermal insulation is an investment for many years in the conditions of unstable energy prices and the economic advantages of reliable insulation from different directions are described. The comparative technical characteristics of the most popular materials of polyfoam and mineral wool in thermal insulation of walls are given, features of their use in different conditions are analyzed, the average prices for the device for the city of Kiev are compared. For a cheaper option, the calculation of the economic effect for the city of Kyiv is performed. It is determined that one of the most important factors of comfortable life is maintaining a comfortable microclimate in the building for many years, regardless of the weather outside, where you can feel as safe and comfortable as possible, and its direct dependence on quality protection of structures outside. Emphasis is placed on the fact that reliable protection of structures is also an investment in the peace of mind of the building owner and the confidence that the structures will not require repair in a short period of time. Whatever new forms of buildings and structures are invented today by developers, high-quality and modern insulation is an integral part of modern and comfortable housing, a part that should not be neglected and first of all perform all work qualitatively and pay special attention to joints of sheets of insulation material, to have as little chance as possible of external influences on warming which action can reduce service life not only of a design of warming, but also of the building as a whole.

Strength of Bolted Lap Joints in Steel Sheets with Small End Distance

AbstractThe objective of this work is to investigate the shear capacity of small end distance lap joints in sheet steel fastened with a single bolt. For bolted connections in shear, the current Ame...

Quality assessment of pressed joints of heat-exchanger tube-tube sheets

The specific features of the procedures for heat-exchanging tubes assembly and fixation in the tube sheets of the power equipment heat-exchanging sections are set out, disadvantages of the existing procedure and the problems of joint quality control due to contact welding are noted. The approaches to assess the pressed joint quality are proposed. The calculation dependences to determine the joint tension considering the fixation procedure features.

Особливості отримання біметалевих тонколистових з’єднань Al-Ti методом дифузійного зварювання у вакуумі

Особливості отримання біметалевих тонколистових з’єднань Al-Ti методом дифузійного зварювання у вакуумі

Peculiarities of producing Al–Ti bimetal sheet joints by the method of vacuum diffusion welding

The Paton Welding Journal, 2020, №08. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

High cycle fatigue behaviour of thin sheet joints of aluminium-lithium alloys under constant and variable amplitude loading

The main purpose of this work is to establish high cyclic fatigue behaviour of sound welds of aluminium alloys of Al-Mg-Li and Al-Cu-Li doping system under constant and variable amplitude loading. Sound welds of thin sheet (1.8 and 2.0 mm) aluminium-lithium alloys 1420 and 1460 were produced by tungsten inert gas (TIG) and friction stir welding (FSW) technologies. Microstructure investigations, hardness and residual stress measurements, tensile and fatigue tests of welds were performed. It is shown that FSW joints have fine grain microstructure in weld nugget with homogeneous disoriented structure and elongation and deviation of grains in a direction of plasticized metal movement, taken place in adjacent areas. Hardness on joints face was measured, showing areas of softening near the weld. Lower temperature of welded edges heating reduces the maximum level of longitudinal residual tensile stresses in FSW joints in comparison with TIG welds. Tensile strengths of TIG and FSW joints were obtained. The high cycle fatigue tests of FSW and TIG joints under constant and variable amplitude loading were performed. It is shown that fatigue behaviour of FSW joints exceeds the characteristics of the joints obtained by TIG welding.

Numerical and Experimental Modeling of Spot Welding Defects by Ultrasonic Testing on Similar Sheets and Dissimilar Sheets

This paper investigates the impact of defects on similar sheets and dissimilar sheets used in the automotive industry. Spot welding is one of the types of resistance welding used in this experiment for sheet welding. The thickness of sheets welded by the spot welding method can be between 0.5 and 3 mm. In this paper, the simulation is performed by finite element method for non-destructive tests on spot welding. This study investigated the propagation of ultrasonic waves in two similar layers of stainless steel and galvanized stainless steel sheets and two dissimilar layers of stainless steel sheets and galvanized stainless steel sheets in different thicknesses. This test was performed by ultrasonic immersion method and the intensity and amplitude of the reaction of the resulting defect waves and its effect on the results were also investigated. Due to the performance of finite element method softwares, Comsol Multiphysics software because of its high accuracy used. It has been studied various factors and conditions including excitation frequency, boundary conditions, the most suitable position for the probr Fto stimulate the waves, focused or unfocused waves in the simulation, sensitivity analysis of mesh size and appropriate mesh size for simulation. In this paper, the joint of similar sheets and dissimilar sheets is investigated. For this performance, the average relative error that can meet the industrial requirement is mentioned. The results of the simulation with the results of the experimental test They were compared and investigated And with the amount of error tests, have acceptable results and it can be used with the error specified and can meet the needs of the automotive industry.

Process analysis and regression modelling of resistance spot welded joints of austenitic stainless steel 304L and low carbon steel sheets by using surface response methodology

Evaluating the strength performance of spot-welded joints of dissimilar material is critical for their continued integration into the automobile and aerospace industries. The effect of weld joint strength is an important consideration in the design of weld structures. The objective of the present work undertaken to investigate the effect of the input process parameters on the strength of the welded joint of dissimilar material. Full factorial design (FFD) has used for designing the experiment matrix. Further, experimental results have used to develop a mathematical model to predict the strength of the spot weld joint. Analysis of Variance (ANOVA) has been applied to establish the correlation between the process parameters and their interaction on the output. The confirmation test case experiments have conducted for validating the developed mathematical model and observed that the developed model is capable of evaluating weld joint strength within the process parameters.

Friction stir welding of ultra high-purity aluminium thin sheets never to lower high conductivity at ultra-low temperature

ABSTRACT Ultrahigh-purity aluminium sheets with excellent electrical and thermal conductivity at ultra-low temperature have uses in heat dissipation components in, for example, superconducting equipment. Recently, here has been a requirement for the development of methods of welding these sheets without degrading their excellent conductivity. This study focused on friction stir welding (FSW), which was conducted for 99.999 wt.% (5 N) Al thin sheets with thickness of 0.8 mm. The FSW tool rotation speed was set to 3000 rpm, and both the welding speed and tool insertion depth were varied. Decreasing welding speed suppressed the occurrence of a kissing bond on an FSW back side and increased the area of the stir zone that had ultrafine grains, although residual strain in all the joints was greater than in tungsten inert gas (TIG)-welded joints which consisted of coarse grains similar to the base metal. Fracture occurred in the base metal in tensile tests of the FSW joints except for those made at the maximum welding speed, in contrast to rupture near the fusion line of the TIG-welded joint due to blowholes. On the other hand, the residual resistivity ratio (RRR) of FSW and TIG-welded joints decreased to almost half of that of the base metal. The heat treatment at 500°C for 3 h increased the RRR of the FSW joints to almost the same value as that of the base metal. This is attributed to a significant reduction of residual strain as well as grain coarsening. In TIG-welded joint, there is an evident decrease in the RRR associated with a decrease in purity. Therefore, FSW in conjunction with post-weld heat treatment would be a better choice to achieve high conductivity at ultra-low temperatures in 5 N-Al thin sheet joints, while maintaining a high joining strength.

Use of non-destructive eddy current technique to detect simulated corrosion of aircraft structures

Abstract The article deals with the issue of non-destructive testing of riveted joints. In the article, the authors used a non-destructive eddy current array technique, which was applied to detect simulated corrosion in the field of aircraft riveted joints of aluminum sheets. In aircraft maintenance, the eddy current method is used to control the outer surface of the aircraft skin, especially the areas around the riveted joints. This method makes it possible to detect hidden cracks and corrosion that may occur during aircraft operation. Especially hidden are hidden cracks and corrosion of aircraft structures, which cannot be detected during a visual inspection of the aircraft. The aim of the experimental measurements was to reveal simulated corrosion in the area of riveted joints formed on the experimental sample. Corrosion was simulated by gluing aluminum powder to the surface of the aluminum sheets from which the sample was made. The simulated corrosion in the second and third layers of the riveted sample was reliably detected. The settings, the method of control and the results of measurements are given in the article in the experimental part and the results of measurements. Measurements were performed using a defectoscope with an ECA measurement module, with appropriate measuring probes suitable for this type of inspection.

Impact of Assembly Method on the Strength of Single-Lap Joints of Aircraft Aluminum Alloy Sheets

Impact of Assembly Method on the Strength of Single-Lap Joints of Aircraft Aluminum Alloy Sheets

Mechanical properties and interfacial microstructures of magnetic pulse welding joints with aluminum to zinc-coated steel

In this study, the relations between interfacial microstructure and mechanical behavior of aluminum alloy sheets and zinc-coated steel sheets magnetic pulse welding (MPW) joints were characterized systematically. MPW joints of aluminum alloy and ungalvanized steel sheets were prepared for comparative analysis. Results showed that some of zinc layer on the galvanized steel was washed away to form metal jet under the high-speed collision. The change of failure mode from interfacial failure to base material fracture due to interfacial microstructure evolution was the fundamental reason for different mechanical behavior of two MPW joints. Because of the difference in element content and the severe plastic shear at the interface, the crystalline grain morphologies and sizes of aluminum and zinc in the transition zone changed. Amorphous structure was also found in the transition zone. The existence of the zinc layer would form brittle and hard phases on the interface, resulting in the generation of welding defects, thereby reducing mechanical properties of the joint.

Magnetic field edge-effect affecting joint macro-morphology in sheet electromagnetic pulse welding

ABSTRACT Electromagnetic pulse welding (EMPW) is an environmentally friendly and advanced manufacturing technology. Researches find the macro-morphology of EMPW joint of sheets presents a multilayer ellipse. The EMPW experiments of Al-Cu sheets and Al-Mg sheets were carried out, both the macro-morphology and the micro-morphology showed there were collision zone, bonding zone and bonding affecting zone in the joint, presenting multilayer elliptical morphology, which was independent of material. The welded seam was in the bonding zone. The 3D multiphysics simulation results also showed that the distribution of the plastic deformation of Al sheet, Lorentz force, induced eddy current and magnetic flux density at the welded joint were all elliptical, and they presented a multilayer elliptical continuous equivalent distribution surface due to the difference of amplitude. The magnetic field edge-effect affects the distribution of the magnetic flux density, and the non-uniform distribution produces the multilayer elliptical macro-morphology, which causes the induced eddy current, Lorentz force and the deformed area of the aluminum alloy plate to be the elliptical shape. Therefore, the macro-morphology of EMPW joint of sheets is a multilayer ellipse. This work may provide theoretical support for the performance improvement of the EMPW technology.

Quasi-static and fatigue characteristics of self-piercing riveted joints in dissimilar aluminium-lithium alloy and titanium sheets

The dissimilar self-piercing riveted (SPR) joints between aluminium-lithium alloy (AL1420) and titanium (TA1) sheets were investigated. The effects of the overlap form and rivet hardness on the forming structures, quasi-static and fatigue characteristics of the considered dissimilar joints were analysed systematically. A new curve-fitting method was adopted to fit the fatigue data of SPR joints. The results show that the potential weak areas in the forming structures could be changed using different overlap forms or rivet hardness. The overlap form for the dissimilar joints plays a more important role on the joint strength compared to the rivet hardness, but has little influence on the energy absorption. The fatigue property of the dissimilar joints is improved with the rivet hardness increased and the joints taken TA1 as the locked sheet possess a better fatigue life. The rivet hardness presents an obvious influence on the fatigue fracture path. The forming structures of the dissimilar joints are significantly affected by the overlap forms, which finally results in the fatigue fracture originated in different initiation sites.

Sheet metal joining process selector

Selecting the most suited manufacturing process for a specific product, as well as optimizing the design regarding manufacture and assembly, is actions that will directly impact on cost and quality, aiming at finding the best match between the product’s functional requirements and the attributes of the processes, and it should be carried out in the first stages of product development. In this context, the literature presents some sheet metal joining process selection methods, which can be classified as: mechanical (forming), metallurgical (welding) and chemical (adhesive) processes. However, such methods are complex and not specific for thin sheet metal. Therefore, our goal is to propose a joining process selector for overlapping sheet metal, which can correlate the product’s functional requirements with the technical characteristics of the processes (clinching, rivets and welding) in early stages of product development. Unlike what is found in the literature, this selector is subdivided into five different types of clinching processes. The selector design was based on the Quality Function Deployment (QFD) principle, which easily converts a product’s functional requirements into an ordered joining process list. The joining process data collection was carried out from two approaches: quantitative (joining sheet thickness, joint dimensions, production batch and joining strength) and qualitative (type of material, surface finish and accessibility to perform the joining). Three products were chosen to validate the selector. The results were compared against the literature and commonly commercially employed processes. The application of the selector in commercial products showed compatibility with the literature as well as the commercially used processes. However, depending on the product, other requirements might be considered, such as availability of equipment and production costs.

Microstructure, mechanical properties and corrosion behavior of austenitic stainless steel sheet joints welded by gas tungsten arc (GTA) and ultrasonic–wave–assisted gas tungsten pulsed arc (U–GTPA)

Here, ultrasonic–wave–assisted gas tungsten pulsed arc (U–GTPA) welding is proposed as a new alternative welding process to gas tungsten arc (GTA) welding. To better understand the advantages of this new process, in this paper, the microstructure, mechanical properties and corrosion behavior of GTA- and U–GTPA-welded joints of 316L stainless steel are systematically compared. These results show that the weld zone (WZ) depth-to-width ratio of the U–GTPA-welded joint increased, and the area of the equiaxed grain zone was larger than that of the GTA-welded joint. This results in finally increasing the strength and hardness for U–GTPA-welded joints, and the ultimate tensile strength and elongation of the U–GTPA-welded joints were 7.1% and 26.2% greater than those of the GTA-welded joint, respectively. For the U–GTPA-welded joint, under the action of the pulsed arc, the grain distribution with high-angle boundaries (HABs) was different from that of the GTA-welded joint. The minimum of the HAB fraction corresponded to the fracture position for both joints in tensile tests. It shows that a large number of HABs were beneficial in improving joint tensile properties. However, for electrochemical corrosion experiments of two WZs in 3.5% NaCl solution, despite this GTA WZ having a higher HAB fraction, the corrosion current density and corrosion potential of U–GTA WZ were lower and higher than those of the GTA WZ, respectively. The corrosion rate and corrosion sensitivity of U–GTPA WZ indicated good corrosion resistance.