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Friction self-piercing riveting (F-SPR) process based on a pip die has been invented to solve the cracking problems in riveting high-strength and low-ductility light metals, such as magnesium alloys, cast aluminum, and 7 series aluminum alloys. In this paper, in order to solve quality issues caused by the misalignment between rivet and pip-die in F-SPR, a flat-die based F-SPR process was proposed and employed to join 1.27 mm-thick AA6061-T6 to 3 mm-thick AZ31B. The results indicate that a 1.0 mm die distance is effective to avoid rivet upset and insufficient flaring. As the feed rate increases, the heat input in the whole process decreases, resulting in a larger riveting force, which in turn increases both the bottom thickness and interlock amount. Besides, solid-state bonding, including Al-Mg intermetallic compounds (IMCs), Al-Mg mechanical mixture, and Al-Fe atom interdiffusion was observed at the joint interfaces. The upper Al layer was softened, but the lower Mg layer was hardened, and both sheets exhibited a narrowed affected region with the increase of feed rate, while the rivet hardness shows no obvious change. Three fracture modes appeared accompanying the variations in lap-shear strength and energy absorption as the feed rate increased from 2 mm/s to 8 mm/s. Finally, the F-SPR process using a flat die was compared to those using a pip die and a flat bottom die to show the advantage of flat die on coping with the misalignment problem.

The application of the step lap joint has been increased due to its good characteristics such as lightweight, high stiffness, and good fatigue durability. Moreover, it has a wide application in the aerospace, automotive and marine sector because of its efficient strength and less stress concentration. The present study is concentrated on the effect of the kind of joint used for lap joint like the adhesive joint, riveted joints, and bolted joints. In addition, the length of the steps has been changed to study the behavior of adhesive lap joint in detail. Also, the hybrid joint such as a bolted-adhesive and riveted-adhesive joint is examined in the current study. The variation in the number of bolts and rivets are made for detailed analysis. The main objective of this project is to analyze the step lap joint with different length, different material for adherend and adhesive and also compare it with different mechanical fasteners such as rivets and bolts considering hybridization of it with and without the adhesive, Finite Element Analysis (FEA) is carried out in ANSYS Workbench for analysis and SolidWorks software is used for 3-D modelling.

The study covers the analysis of the following elements namely AISI 4130, stainless steel and Aluminium alloy in the making of the rivetted joint and comparing the efficiency based on strength, availability, the factor of safety and cost. Static and dynamic forces are applied to the joint to obtain the analytical result from ANSYS. The model used in the study has been designed with the help of solid-works. ANSYS software's assistance helped lead to the assignment of different materials mentioned above to our model from engineering data. A comparative study considers these three materials for the riveted joint, and static and dynamic analysis is done considering the external forces. The study reviews a comparative assessment of metals based on affordability and suitability to design rivet for boilers, boxes, packaging and automotive industries, etc.

Many riveted joints bear the action of out-of-plane bending moments in steel truss bridges. The fatigue resistance of these joints isn’t stipulated in the current design criteria. Ensuring the safety of structures necessitates analysing the fatigue process of such riveted joints. This paper attempts to evaluate the fatigue life of riveted lap joints from the perspective of engineering applications. The study first found through fatigue tests with two types of fatigue details in riveted lap joints: plate surface cracking and rivet hole edge cracking. Then, the fatigue progression is divided into three stages: the microstructure short crack (MSC) stage, the physical short crack (PSC) stage and the long crack stage. The crack propagation model in the short crack stage is established by combining a scanning electron microscope test of the material and an empirical formula. The crack propagation model of the long crack stage is established by the crack propagation test and considering the crack closure effect. Results show that the fatigue life corresponding to the hole edge crack fatigue detail category is shorter than that to the plate surface crack. In each crack propagation stage, the crack propagation life decreases with increasing load and decreasing load ratio RL. For the two fatigue detail categories, the proportion of the long crack stage to the whole fatigue life is small, and the effect of the crack closure on the overall fatigue life is limited; therefore the effect of the load ratio RL on the fatigue life can be ignored.

This paper is focused on solving the problems of positioning and alignment of rivets in double-sided self-pierce riveting by means of flat-bottom holes that are previously machined in the overlapped sheets with greater mechanical strength. The work combines experimentation in joints made from dissimilar materials (aluminium AA5754-H111 and polyvinylchloride) with finite element modelling to investigate the influence of the flat-bottom hole geometry in the overall joining mechanisms. It is shown that the use of flat hole-bottom holes with rivets having identical chamfered angles in both ends is unable to create undercuts and to produce form-closed mechanical interlockings. Undercuts are created if different chamfered angles in the rivet ends are introduced to compensate the greater or lesser difficulty of the rivets to pierce through sheets with different mechanical strengths. Destructive shear and peel tests performed with different types of joints confirm the good performance of the joints produced by double-sided self-pierce riveting with flat-bottom holes.

Self-piercing riveting (SPR) is a mechanical joining process that has the potential to replace resistance spot welding (RSW) and is being adopted in the automotive industry.In this study, a dissimilar stack configuration widely used in the automotive industry was used. Joining was performed using self-piercing riveting and resistance spot welding processes. Welding parameters in spot welding were optimized to produce anugget with a diameter similar to the rivet shank. Tensile and fatigue attributes of these joints were assessed to evaluate the joint performance. Additionally, microstructure-property correlation was performed to evaluate the failuremode and susceptible region in the joint that can lead to crack initiation and failure.

The necessity of dissimilar joining between aluminum alloy and steel is increasing in order to meet the demand for weight reduction in automobiles. However, dissimilar joining between 7000 series aluminum alloy and steel is challenging with mechanical joining methods such as self-piercing rivet(SPR) and flow drill screw(FDS) without hole processing. In this study, mechanical performances of dissimilar joints between 3 mm thick Al7075-T6 and 1 mm thick SPFC590DP were evaluated for use in lightweight B-pillar assembly. Self-Piercing Rivet(SPR) and Flow Drill Screw(FDS) with one-hole processing, bolt/nut and blind rivet with two-hole processing and adhesive bonding were compared with respect to joint performance. In SPR joining, rivet did not penetrate and rivet buckling occurred in the rivet due to the thickness and high strength of the Al7075-T6. By processing pre-hole on Al7075-T6 and applying an additional Al5052-H32 sheet to induce mechanical interlock in SPR joint, it became possible to join Al7075-T6 to SPFC590DP with an SPR. The tensile shear load of the SPR joint was 9.8 kN. In FDS joining, it is also necessary to process pre-hole on Al7075-T6 since the fastener could not penetrate the Al7075-T6. The tensile shear load of the FDS joining was 8.1 kN. In bolt/nut and blind rivet joining, the tensile shear load were measured respectively 11.1 kN and 5.2 kN. In adhesive bonding with 1K glue, the tensile shear load was measured 18.5 kN when the interfacial surface was roughened with a sand paper.

Adhesives offer significant advantages when joining materials since they do not create discontinuities in the material, unlike bolting or riveting. Another interest of adhesive joints is the possibility of joining different materials and the lower weight. The analysis of the stress singularity in adhesive joints can provide a better understanding of joint behaviour, and it is mesh independent. The ISSF is based on a fracture mechanics concept, the Stress Intensity Factor (SIF). However, generally, the SIF is only applicable to cracks in a single material, while the ISSF is applicable to multi-material corners and does not require a crack. This work aims to study the stress singularity of aluminium adhesive joints bonded with a brittle adhesive with four different overlap lengths (LO) by determining the singularity’s exponents and its intensity. A method for joint strength prediction using the ISSF is also proposed. Additionally, the interface corner’s stress is studied, with the different singularity components presented separately to assess their influence on the overall stress. These predictions are also compared with the experimental strength to verify this strength prediction criterion’s accuracy when applied to brittle adhesives. In conclusion, the ISSF criterion provides accurate results and can be utilised for further studies in this area.

The purpose of this paper is to numerically investigate the fatigue life and the fatigue crack growth path of 2024 aluminum plate riveted joints. For this purpose, according to field observations, the parameters affecting fatigue life are obtained. Relevant geometric parameters such as rivet shank length, hole diameter and dimensional tolerances, as well as the location pattern of the rivets and the material of the rivet joints are studied. In this study, modeling is performed to calculate the equivalent plastic strain using the finite element method. For this purpose, a three-dimensional elastoplastic model is used for simulation. The information obtained from the finite element method in this study made it possible to place the rivets in this type of joint for use in high safety structures such as the aerospace industry. Given the importance of the problem of crack growth in 2024 aluminum plates, having the geometrical and physical parameters of the problem, the goal is to achieve the exact path of crack growth and fatigue life of riveted joints. Fatigue crack growth simulation is performed on the samples using the boundary element method. The stress intensity factor for different loading modes is determined using the boundary element method. The results showed that the geometric parameters and the rivet material have a significant effect on fatigue cracking in aluminum plates.

This paper presents a new hybrid joint aimed at improving the defects of simple self-piercing rivet (SPR) or self-drilling screw (SDS) in thin-walled steel structures. This hybrid SPR-SDS joints took advantage of mechanical performance and construction technology for both simple SPR and SDS joints. A total of 132 hybrid joints were tested to evaluate structural behavior and capacity in shear. The differences among simple SPR joint, simple SDS joint and hybrid SPR-SDS joints were compared and analyzed. The parameters of sheet thickness, thickness ratio and fastener arrangement were considered with regard to their influences on shear behavior and failure mechanism. The results showed that hybrid joints could fully combine and exploit the advantages of SPR and SDS. The hybrid SPR-SDS joint could effectively improve the shear strength, stiffness and ductility of the simple SDS joint by 10.5%, 539.1.3% and 381.9%, respectively. The hybrid joint also demonstrated that the deformation and energy dissipation were 107.4% and 25% higher than the simple SPR joint, respectively. In addition, this paper proposes a new design method of shear strength for the hybrid joint. The design method was not only more accurate, but also could consider more comprehensive failure modes in design than the existing methods.

Modern titanium alloys and innovative polymer composites are envisaged as promising contributors in developing composite multi-material aerospace structures in near future by aerospace industries. The structural complexity demands multiple parts, which are to be assembled by joining technique in order to accomplish the targeted lightweight structure. Conventional riveting techniques cause severe bearing damages while riveting composites due to the inference with non-uniformity and leads to restrict the application of conventional riveting in composites. Bolted joints are alternative solutions for composite structures. They however lead to increase in the weight and cost of the structures. Hence, electromagnetic riveting has emerged out as a promising candidate in the recent years, since it provides positive solutions with uniform interference and lightweight structures. The current work exhibits a comprehensive understanding on joining mechanism and nature of electromagnetic riveting toward the development of composite hybrid lightweight aerospace structures. Overcoming challenges such as inadequate degree of deformation and formability issues, electromagnetic riveting offers three times superior fatigue properties, uniformity in interference, minimal impact damage, homogeneous expansion, etc., that make it a lucrative choice for aerospace manufacturers.

The present transportation industry has been challenged by cost-saving requirements, ever-stronger environmental protection regulations and the significant growth of transport volume. One approach for tackling these challenges is the development of new improved transportation vehicles using new materials and innovative joining technologies. In the recent decade, the use of fiber-reinforced plastics-metal structures has increased significantly in bridge, automotive and aircraft structures, and friction riveting has evolved as a new and promising candidate for joining fiber-reinforced plastics to metals. Friction riveting bridges the gap between mechanical fastening and welding, and offers advantages such as short joining cycle times and a minimum of surface pre-treatment of the joining partners. The present work provides a comprehensive understanding of joining mechanism and behavior of friction riveted multi-material joint structures. Friction riveting has full potential to grow as an ecofriendly, economical and reliable joining method for developing polymer-metal multi-material structures.

The assembling process includes various techniques, out of which riveting has been employed most successfully in fields like construction of enormous structures, auto-motives, and most notably in the aerospace industry. This process includes marking, drilling followed by riveting. Furthermore, being a successful process, most of the aircraft structure is assembled using rivets. However, various factors contribute to the result. Therefore, the effect of riveting process parameters such as Sheet Thickness, Rivet Diameter, Rivet Type, and Riveting Sequence have been studied on responses, i.e., Deformation and Joint Load Capacity of lap joint composed of Aluminum Alloy sheets (LY-12) at T0 condition by sandwiching aerospace-grade sealant (XM-22B). Each of these parameters is studied on three levels and the experimental setup is designed using Response Surface Methodology (RSM). The main objective of this work is to demonstrate the effect of riveting parameters on lap joints with sealant and analyze the effect through careful measurement of deformation and joint load capacity of the test specimen. Finally, a variance analysis (ANOVA) is performed to identify significant factors influencing response parameters using Design Expert Software V-12.

Heavy duty riveted gratings are a good alternative for applications that often employ other deck systems, if they are carefully analyzed under static and fatigue loads. Understanding the static behavior of a riveted steel deck under tire patch loads will aid in establishing a design model based on an effective beam width. In addition, use of a riveted system avoids welded details that may lead to fatigue cracking, thereby improving design life. In this study, analysis of a typical riveted steel deck under a standard AASHTO fatigue truck with a 15% impact factor was conducted. Hand calculations were compared with the results of a finite element model using SAP2000 v19.2.1. Bending moments and stresses were evaluated and compared. Stresses at the rivet hole for the most highly loaded bearing bar were evaluated. A model for fatigue cracking around a rivet hole is discussed.

The predictive quality of numerical simulations for mechanical joining processes depends on the implemented material model, especially regarding the plasticity of the joining parts. Therefore, experimental material characterization processes are conducted to determine the material properties of sheet metal and generate flow curves. In this regard, there are a number of procedures which are accompanied by varying experimental efforts. This paper presents various methods of determining flow curves for HCT590X as well as EN AW-6014, including varying specimen geometries and diverse hardening laws for extrapolation procedures. The flow curves thus generated are compared considering the variety of plastic strains occurring in mechanical joining processes. The material data generated are implemented in simulation models for the joining technologies, clinching and self-piercing riveting. The influence of the varied methods on the predictive accuracy of the simulation model is analysed. The evaluation of the differing flow curves is achieved by comparing the geometric formation of the joints and the required joining forces of the processes with experimentally investigated joints.

The objective of this work was to investigate how different joining techniques affect the level of damping in structures. Beams were constructed from four different joining techniques, bolting, riveting, adhesive bonding, and brazing by joining two lengths of steel each with a ‘U’-shaped cross-section. They were joined such that the edges of the ‘U’ overlapped to form a tube. The damping of each beam was determined by flexural vibration. The bolted beam had a series of bolts along its length. The effect of removing bolts was investigated. It was found that removing bolts increased damping. When bolts were removed successively from holes at the end of the beam, the damping increased more than when bolts were removed from holes in the middle of the beam. A further objective of this project was to investigate the effect of introducing penetrant between two surfaces. WD-40 was introduced between the contacting surfaces for the beams joined by mechanical fastening. The penetrant had the effect of increasing damping. This may be because the penetrant has the effect of increasing the relative displacement between the two beams, leading to greater energy dissipation. Introducing penetrant also changed the order of which beam had the greatest damping, with the bolted beam now having greater damping than the riveted beam. The effect of increasing bolt tension on the bolted beam was also investigated. When the beams were dry, increasing bolt tension reduced the damping, but when penetrant was introduced increasing the bolt tension increased the damping. A comparison between the damping properties from different joining techniques was made. The conclusions could be applied in industry by engineers constructing beams of a similar fashion.

A material–structure–process–performance integration multi-objective optimization design of a magnesium/aluminum alloy punch-forming solid rivet joint based on Taguchi, grey relational analysis (GRA), and fuzzy rough set theory (FRST) weighting method was proposed. First, the material constitutive models of the rivet and riveted sheets were established through experiments. Second, simulation models of the rivet forming process and the pull-out and shear tests of the riveted joint were established, and corresponding experiments verified accuracy. Finally, the FRST weighting method was proposed. The integration multi-objective optimization of a rivet joint was conducted based on Taguchi, GRA, and FRST methods with optimization objectives (the rivet forming head’s dimensions and the riveted joint’s maximum pull-out and shear forces) and design variables (the material, structure, and riveting process parameters of the rivet joint). The optimal combination of design variable levels was obtained. Optimization results show that the rivet forming head’s dimensions were quite close to the recommended values after optimization, and the pull-out and shear mechanical strengths of the riveted joint were increased by 10.7% and 12.8%, respectively. Furthermore, a comparison was presented among FRST, principal component analysis, and entropy weighting methods. The FRST weighting method was concluded to be highly effective.

Purpose: To analyze and estimate the strength of duralium rivets which had been treated by using multistage artificial aging compared with duralium that had not been treated. This processwas necessary to be conducted in riveting process effectively. Duralium has been widely used in aerospace industry, one of duralium usage in aerospace industry is aircraft fittings such as rivet. Riveting is one of method that used for joining airframe structural components. During riveting process, the load transfer causing stress that led to the fatigue. Riveting process also causes deformation on the rivet and sheet metal. Deformation that occurs on the rivet will affect the performance of rivet structure. Thus, duralium rivet was analyzed its total deformation, shear stress, and its equivalent stress Von Misses. Design/methodology/approach: that used in this study was finite element analysis. Geometry of rivet that used in this study was drawn by using Autodesk Inventor Professional 2018. While total deformation, shear stress and equivalent stress Von Mises on duralium rivets were found out by using ANSYS Workbench 18.1. Findings: Comparison result was obtained between duralium rivet with and without treatment of multistage artificial aging. The result shown that total deformation, shear stress and equivalent stress Von Mises which obtained by duralium rivet with multistage artificial aging had the lower value than duralium rivet without multistage artificial aging. Duralium rivet with multistage artificial aging could be used as aircraft fitting which had the higher strength. Research limitations/implications: Direct experiment on duralium rivet had not been done yet, this study only did simulation based on data that obtained form previous research that had been conducted by the researcher. Practical implications: Duralium rivet with multistage artificial aging had lower value on total deformation, shear stress, and equivalent stress Von Misses, thus duralium rivet with multistage aritificial aging had a higher strength. Originality/value: Application of duralium as a rivet with treatment of multistage artificial aging.

This paper is focused on innovative self-pierce riveting concepts to produce invisible joints in sheet-sheet and tube-sheet connections. The common element to these two different types of joints is the use of tubular rivets with chamfered ends, which are accessories in the case of sheet-sheet joints and constitutive (structural) elements in the case of tube-sheet joints. The presentation draws from the deformation mechanics of double-sided self-pierce riveting for producing lap joints in overlapped sheets to the development of self-pierce riveting of tubes to sheets, which is a new joining by forming process capable of attaching a sheet to the end of a tube, at room temperature. Aluminum sheets, carbon and stainless-steel tubes are utilized to demonstrate the effectiveness of the new self-pierce riveting concepts and finite element modelling using an in-house computer program gives support to the overall presentation. Destructive tests are carried out to evaluate the destructive strength that the joints are capable to withstand without failure.

The research presented in this manuscript focuses on the development of an LS-DYNA finite element model to predict the dynamic shear strength of short riveted lap-spliced specimens. Using data collected from experimental testing at the U.S. Army Engineer Research and Development Center (ERDC), a finite element model was developed to replicate the behavior of A502 Grade short riveted connections under quasi-static loading. Subsequent analyses used published Cowper-Symonds constitutive model coefficients to replicate the behavior of these connections under dynamic loading. Computed results were then compared with available test data from ERDC. Given the challenges involved in creating physical models with riveted connections and the abundance of historical bridges constructed with rivets, the developed finite element analysis engineering solution can serve as a critical tool for researchers interested in predicting the response of short riveted connections to dynamic loading and those interested in developing strategies to mitigate against this loading.

The riveting process involves numerous parameters and complex problems, such as contact phenomena and material nonlinearity; therefore, it is challenging to accurately control the deformation of riveted parts by adjusting the riveting parameters. Therefore, this paper proposes a global sensitivity analysis method to determine the effects of riveting parameters on the maximum deformation of aeronautical thin-wall structures (ATWS). Considering the correlation among variables, the riveting parameters are used as input variables and the maximum deformations of ATWS are used as the output response to establish a high-precision second-order random sampling-high dimensional model representation response function. The structure and correlative sensitivity analysis method is then used to analyze the response function, and an importance ranking of the input variables is obtained to provide guidance for designs that reduce the riveting deformation of thin-walled plates.

During automatic electromagnetic riveting, the positioning deviation between punch and rivet is easy to occur. This leads to the asymmetric deformation of rivet tail and affects the performance of riveted joint. In this paper, the riveted specimens under various angle deflections (0°, 2°, 4°, 6°) were prepared to investigate the effect of angle deflection on deformation characteristic and mechanical property of electromagnetic riveted joint. The microstructure observation, interference analysis, hardness measurement, and shear and pull-out test were performed to evaluate the performance of riveted joints. Results showed that the angle deflection had significant effects on the deformation characteristics and mechanical properties of riveted joints. Compared to the riveted joint with 0° angle deflection, the rivet shaft of riveted joints with 2°, 4°, and 6° angle deflection would tilt. The tilt of the rivet shaft caused relative displacement between riveted sheets and generated a clearance between the rivet shaft and riveted sheets, affecting the interference of riveted joints. The mechanical property of riveted joint decreased with the increase of angle deflection. For shear tests, the failure modes were all rivet failure, and the rupture positions were all in the middle portion of the rivet shaft. For the pull-out test, there were three failure modes. In addition, the reliability of automatic electromagnetic riveted joint could be preliminarily judged by this work, which provided scientific guidance for the engineering application of automatic electromagnetic riveting technology.

An overview of the principal schemes and designs of testing tools for handheld impact machines, such as riveting hammers, is given. The formation of a bench test method for riveting hammers is considered, which most objectively reproduces the real work of a manual machine when processing an object with a riveting hammer, including with the help of support. Keywords: hand-held machine, riveting hammer, support, test bench, test procedure, processed package, rivet, characteristics of hand-held machine. vvanaev@mail.ru

In the aircraft manufacturing industry, rivet inspection is a vital task for the aircraft structure stability and aerodynamic performance. In this article, we propose a novel framework for fully automated rivet flush measurement, which is the key step in rivet inspection task. To efficiently perform rivet flush measurement, we first develop a mobile 3-D scanning system to automatically capture the 3-D point cloud of the aircraft skin surface. Subsequently, rivet regions are extracted through point cloud processing techniques. Instead of relying on handcrafted features, we propose a novel data-driven approach for rivet point extraction via a deep-learning-based technique. Our algorithm takes a scanned point cloud of the aircraft skin surface as input and produces a dense point cloud label result for each point, distinguishing as rivet point or not. To achieve this, we propose a rivet region classification network (RRCNet) that can input the 2-D representations of a point and output a binary label indicating that the point is rivet or nonrivet point. Moreover, we design a field attention unit (FAU) to assign adaptive weights to different forms of 2-D representations via the attention mechanism in convolutional neural networks. The extracted rivet regions can then be used to perform rivet flush measurement. The abovementioned components result in a fully automatic contactless measurement framework of aircraft skin rivet flush. Several experiments are performed to demonstrate the priority of the proposed RRCNet and the effectiveness of the presented rivet flush measurement framework.

Riveted steel bridges, which were built in the early 20th century, require their regular structural integrity assessment to avoid any catastrophic failure. This article presents continuous strain monitoring of a single riveted lap joint, which is a representative critical element of riveted steel bridges through an optical frequency domain reflectometry (OFDR)-based distributed fiber optic sensor (DFOS). The aim of this study was to instrument a DFOS on a single riveted lap joint for monitoring the surface and critical strains experienced by the rivet joint under two fatigue loading conditions and also to compare the strain transfer between the two commonly used adhesives for bonding the DFOS. Initially, through finite element analysis (FEA), a location for installing the DFOS was identified, and also a strategy was developed for monitoring the critical location of the joint during fatigue loading. Subsequently, the DFOS was instrumented on the riveted joint at the identified location in two segments, where similar strain levels were expected with the aid of two types of adhesives: cyanoacrylate and epoxy. The strains on the rivet joint were monitored under high cycle fatigue (HCF) for up to $2\times {10}^{6}$ loading cycles with constant stress amplitude and followed by low cycle fatigue (LCF) loading with increasing stress amplitude until the failure of the specimen. The results showed that the DFOS could continuously sense the cyclic peak strain of $- 223\,\,\mu \varepsilon $ under HCF conditions and a peak maximum strain of $- 1244\,\,\mu \varepsilon $ under LCF conditions. Furthermore, the internal critical strain on the rivet joint during loading could be monitored with the application of the developed damage monitoring strategy and DFOS strain data. Finally, the DFOS segment bonded using cyanoacrylate measured marginally high strains than epoxy adhesive during the HCF test.

Deep-learning architectures were employed to simulate the self-piercing riveting process of steel and aluminum sheets and predict the cross-sectional joint shape with a zero head height. Four steels (SPRC440, SPFC590DP, GI780DP, SGAFC980Y) and three aluminum alloys (Al5052, Al5754, Al5083) were considered as the materials for the top and bottom sheets, respectively. The key objective was to consider the material properties of these metal sheets (Young’s modulus, Poisson’s ratio, and ultimate tensile strength) in a deep-learning framework. Two deep-learning models were considered: In the first model, the properties of the top and bottom sheets were adopted as the scalar inputs, and in the second model, the three properties were graphically assigned to the three channels of the input image. Both the models generated a segmentation image of the cross-section. To assess the accuracy of the predictions, the generated images were compared with ground truth images, and three key geometrical factors (interlock, bottom thickness, and effective length) were measured. The first and second models achieved prediction accuracies of 91.95% and 92.22%, respectively.

Multimaterial joining has become necessary to continue to reduce vehicle mass in order to further improve fuel economy. Novel processes continue to be developed which are capable of joining various materials. Friction element welding (FEW) is one such process used to join aluminum and steel sheets. This process is well known for its rapid process times, typically less than two seconds, and its extraordinary robustness. FEW is also capable of joining aluminum sheets to the strongest steels used in automotive bodies. A derivative of the FEW process was explored, termed friction element riveting (FER). This process is used to perform aluminum to aluminum joining and shares many of the same benefits as FEW. For example, there remains no need for pre-hole drilling, a distinct advantage of the FEW process. Several strength metrics and the influence of process parameters are defined herein. It was determined that FER is a viable process for use in industrial applications. Through parameter optimization of the welding step, the joint resulted in a cross tension strength and transverse shear strength of 7.37±0.31 kN and 21.4±1.21 kN, respectively, which makes it a competitive technology for similar joining methods.

This work introduces a cost modelling architecture in order to determine the cost-effectiveness of the latest joining technology developments. Riveting is the conventional joining method in the aerospace industry, but is a time-consuming, expensive process that adds excessive weight to a structure. As part of the JTI Clean Sky 2 Joint Technology Initiative, the OASIS project (“Optimization of Friction Stir Welding (FSW) and Laser Beam Welding (LBW) for assembly of structural aircraft parts”) aims to demonstrate the feasibility and cost-effectiveness of novel joining technologies. The technologies being investigated are LBW, FSW and Friction Stir Spot Welding (FSSW). Physical demonstrators, simulation studies and access to industry leading technical expertise from OASIS project partners have helped develop detailed production process maps and input accurate process metrics to determine manufacturing costs. To this end, an activity-based cost modelling architecture has been developed to predict the cost-effectiveness of the joining technologies and assess them against both manual and automatic riveted solutions. The model has been designed in a manner that enables integration into current manufacturing eco-systems, has scalability for large aerospace companies and the ability to perform multi-fidelity process cost models that can be integrated with one another as required.

The statement of the problem of defects detection and recognition in aviation riveted joints is given. The solution is proposed to be implemented using a deep neural network with a recurrent LSTM layer. An example of solving the problem of detecting and recognizing a defect in rivets is considered. The accuracy of the result obtained in the simulation was 100% for two-class and 96.25% for four-class recognition by echo signals of an ultrasonic flaw detector. It is shown that it is possible to use the fractal properties of the non-destructive testing echo signal when detecting defects.

The riveted and bolted joints are more commonly used for joining mild steel body structures for boilers, bridges and automobile industry, etc. These two main joining technologies is investigated and a comparison of mechanical behaviour is documented for joints under loading conditions. Joint efficiency increases as thickness increases. This research also deals with collaborative study using ANSYS software version 17.2. The finite element technique was used in present work study. Joint analysis was conducted through analytical and experimental approaches. IS 2062 were selected for bolted joints and IS 513 D were selected for rivets. By applying appropriate boundary conditions, stress analysis and tension test were conducted for both approaches and is compared with single-lap riveted and bolted joints. For different pitch dimensions of 27 mm, 37 mm and 47 mm for the applied boundary conditions, riveted joints have more endurance than bolted joints.

Developments in the field of joining technologies have given researchers increased opportunities for joining dissimilar materials in so many areas such as automotive, aerospace, marine and structural fields. The fields said here require fuel efficiency and at the same time improved mechanical and thermal properties. To achieve these, it is not sufficient for us to use olden day mono-material structures such as aluminium for the entire structures. Nowadays, improvements in polymers and composites have led to a very good foundation stone for using dissimilar materials as per requirements in the above-said fields. These polymers and composites are having very less weight and at the same time good strength as compared to some of the high strength metals. One of the significant properties of these materials is that they could be tailor-made as per requirements. Even though with these improvements in these polymers and composites, the methodology used for joining them with the metallic structures still becomes a challenging task. This present work details an account of the new technique namely Low-Speed Friction Riveting which is used for joining polymers and metals as a promising methodology. Here, the effect of temperature distribution on the point of contact of the two surfaces namely, the polymer and metal has been discussed. In the present work, the formulation of modelling approaches as well as the very fundamental pure thermal models are presented and discussed together with selected modelling results including prediction of heat generation with the thermo-mechanical model. Measurements by the IR sensor at the joint interface shows and reveal a reasonable agreement between the experimental results and the numerical calculations.

The experience of testing of joints on pop rivets, which formed the basis of design standards, is considered. Experience of testing joints on pop rivets of sheets having bulge, carried out at the Metal and Wood Structures Chair of the Samara State Technical University is given. According to the test results, the maximum load on the joints was obtained, which turned out to be 20% higher than the value determined by the design standards for similar joints, but without bulge

PurposeThe purpose of this paper is to investigate the strain concentration factor in a central countersunk hole riveted in rectangular plates under uniaxial tension using finite element and response surface methods.Design/methodology/approachIn this work, ANSYS software was elected to create the finite element model of the present structure, execute the analysis and generate strain concentration factor (,) data. Response surface method was implemented to formulate a second order equation to precisely compute (,) based on the geometric and material parameters of the present problem.FindingsThe computations of this formula are accurate and in a great agreement with finite element analysis (FEA) data. This equation was further used for obtaining optimum hole and plate designs.Originality/valueAn optimum design of the countersunk hole and the plate that minimizes the (,) value was achieved and hence validated with FEA findings.

In this study, electromagnetic riveting (EMR) was proposed to connect CFRP/Al structures due to its little damage on composite. The joining process and failure behaviors of CFRP/Al joints were stud...

El artículo es un análisis por elemento finito (CAD-CAE) para validar un proceso mecánico real de una prueba destructiva en materiales compuestos de fibra de vidrio, remaches y pegamentos. La validación por elementos finitos simuló probetas utilizadas en procesos para la fabricación de autobuses, dichas probetas están sujetas a cumplir las normas ASTM D3039 y ASTM D5766. Por lo tanto, el objetivo del análisis CAD-CAE fue simular, con el menor error posible, la prueba destructiva y cumplir con los requerimientos de las normas ASTM. Los ensayos experimentales mostraron que las propiedades en la unión mixta cumplen los requerimientos de las propiedades mecánicas y de deformación. Las pruebas mecánicas mostraron que las probetas no fallan en los materiales, pero sí fallan por el concentrador de esfuerzos del remache. Finalmente, se elaboraron los modelos por el método de elementos finitos analizando la zona de falla y manteniendo las características de las uniones probadas. Los resultados de los análisis CAD-CAE reprodujeron las condiciones del modelo experimental satisfactoriamente que, en contraste, logró un error máximo del 3%.

Due to continuously increasing requirements on lightweight sheet metal constructions, new processes and technologies are necessary to face current and future challenges. A trend in lightweight construction is the multi-material mix with sheets of different geometric and mechanical properties. To manufacture these so-called composite structures, new joining technologies and methods are required. One possibility is the further development of the self-pierce riveting joining process. For the simulation and evaluation of new and adapted processes of self-pierce riveting, numerical models are used to investigate process parameters and constraints. Besides precise material models for the numerical simulation of this joining process, the identification of friction parameters between the individual sheets and rivet elements is necessary to achieve exact results. Thus, a method is necessary to identify the friction coefficients between rivet elements and sheets. Such a method is presented and evaluated in this work. Different process parameters like the relative speed are varied for the experimental investigations and an analysis of the respective influence on the resulting friction coefficients is conducted. For the use of the test set-up, coefficients of friction are determined for rivet elements “RIVSET® C 5.3x5.5” (Böllhoff GmbH) coated with Almac® in combination with two different sheet materials HCT590X+Z and EN‑AW 6014.

Self-piercing riveting (SPR) is one of the advanced mechanical joining techniques used intensively in modern automobiles. SPR is a cold forming process involving a semi-tubular rivet as fastener to join two or three similar or dissimilar materials. The present study deals with the development of a five-step simulation process chain capable of numerically predicting the SPR joint geometry and the joint strength under different loading conditions such as Shear, Cross-tension and Peel loading. The complete process chain considers a 2D axisymmetric model for the process simulation and a 3D simulation model with solid-shell interaction for the joint failure simulation. The calibration of damage models and their application in the joint strength analysis are integral parts of the present study. The comparison of joint strength analysis results with experiments under the criteria: mode of joint failure, maximum force (indicating joint failure) and displacement at maximum force provides basis for validation of the simulation process chain. Additionally, a comparison of joint geometry with joint cross-section images and force-displacement curves from experiments provides an opportunity for an intermediate verification of the numerical process flow. The study also presents an accuracy comparison of different damage models and the impact of rivet setting depth on the joint strength and mode of joint failure.

Vehicle weight reduction has been discussed by automotive industry for decades. The current solution for weight reduction purpose is the use of aluminum stamping and casting parts to replace the steel parts. However, joining aluminum with aluminum or aluminum with steel parts would be difficult to select a proper joining technology to ensure a qualified joint. Self-pierce riveting (SPR) as a mechanical joining technique has been used by automotive industry owing to its simplicity, versatility, and environment friendly nature. Although SPR can avoid the joining quality problems caused by welding to join aluminum with steel parts, the other joining problems from SPR still hinder the industry to widely use this joining technology. This article analyzed the cause of cracks on joint button from the understanding of joined material. The modified heat treatments were used to investigate the relationship between eutectic silicon morphology and cracking condition on joint button. In addition, the lap-shear strength according to the samples with various heat treatments was also tested and analyzed. Eventually, the results indicated that silicon content and its morphology take main responsibility on crack initiation and propagation on SPR joint button. But the influence of cracks on joining strength still needs to be investigated and studied in the future work.

Resistance Rivet Spot Welding (RRSW) is a joining technique with high flexibility and cost efficiency for connecting steel and aluminum sheet metal parts in an automotive body in white (BIW). Using...

The paper presents experimental studies of the use of blind rivets (one side connection/blind connection) in sandwich panels with polyisocyanurate foam core. The laboratory pull-out tests of the rivets from the panel facing involved two types of blind rivets (with three and four clamping arms), two types of the sandwich panel facing material (steel and laminate) and an occurrence or lack of a primer layer, which is applied between the external facing and the polyisocyanurate foam during its emerging. As a result of the laboratory tests the mechanical characteristics of the varied types of the blind connections (the equilibrium load paths, the initial and the elastic stiffnesses, the elastic and the ultimate capacity, and the ductility) as well as the failure mechanisms were obtained. The provided research data was used to verify the finite element 3D model created in the Abaqus\CAE environment. This numerical model correctly predicts the results of laboratory tests in the elastic range of the mechanical response of the blind connection with steel facing.

Self-piercing riveting (SPR) is a mechanical joining process which is applied for joining similar and dissimilar lightweight materials in modern car body manufacturing. For qualifying SPR joints, cross sections must be investigated with respect to predefined quality features. Thus, numerous tests must be carried out in order to determine the maximum load capacity of SPR joints for different load angles. The growing number of materials used for the body-in-white requires a reliable and time efficient routine for predicting the joining behavior and the load capacity of SPR joints. In this study, the load capacity of three SPR joints was investigated numerically and experimentally using so-called KS2 samples. The results of axisymmetric two-dimensional finite element simulations (Hönsch et al in J Phys Conf Ser 1063:1-6, 2018) are the basis for three-dimensional simulations of the destructive testing procedure. The experimental setup of destructive testing was modeled using the FE software Simufact Forming 15. The numerically determined load capacity was validated with experimental data. Comparing the failure modes and the force–displacement curves revealed good agreement of simulations and experiments. Therefore, the presented simulation is a powerful tool for predicting the behavior of SPR joints under different load cases.

Eddy current (EC) method is considered as most applicable for in-service detection of fatigue subsurface cracks initiated in aircraft multilayer structures near the rivet holes. At the same time, the successful solution of this problem is obstructed by additional noise created by defect-free rivets. All EC inspection techniques for the detection of subsurface cracks around the rivets can be classified into three main groups: 1) static mode – carried out by placing the EC probe concentrically on the rivet head; 2) rotational mode – when the EC probe is rotated around the rivet axle and 2) sliding mode – performed by the movement of EC probe along the rivet line or near it. All these approaches have some advantages and limitations. In this study, known EC techniques for the detection of cracks in multilayer aircraft structures are analyzed. New advanced EC techniques for the detection of fatigue cracks in internal layers of the riveted structures based on different types (ring, sliding, and rotational) probes are presented. The static EC method with developed low-height ring-type probe creates the possibility to detect cracks in the difficult of access areas. The possibility to estimate the length of detected cracks by a ring-type probe is shown. The proposed rotational remote field EC probe can detect as small as 1.0 mm long cracks under the button-head rivet and 2 mm thick upper skin with a high signal-to-noise ratio. Therefore, in many aircraft structures, fatigue cracks will be detected before a critical threshold achieved. New EC sliding techniques based on remote field and double differential probes were proposed for the rapid detection of cracks in internal layers of riveted aircraft structures. Remote-field EC probe for reliable detection of fatigue cracks in third and fourth layers of five-layer units was proposed. Another sliding technique based on a double differential EC probe gives the possibility to detect transverse cracks in the second layer without the rivet row area access. The main advantage of developed techniques is high inspection reliability due to the possibility to discriminate the signals created by cracks and defect-free rivets. Presented inspection procedures include the selective signal analysis in the complex plane diagram. Proposed EC inspection techniques were successfully implemented into the aircraft maintenance practice.

This paper addresses the problem of stabilizing the machine at a pose specified by a reference image and four laser sensor readings. The system configuration combining monocular vision and laser pointers is applied for pose estimation of the end-effector as well as providing the control objective. Specific features are selected to reflect the pose of the end-effector in Cartesian space, and an adaptive controller is designed to implement the alignment between the end-effector and a stationary object for further assembly. The complete control scheme is assessed through simulations and experiments conducted on an automatic drilling and riveting system, the results demonstrate that the assembly task can be accomplished accurately and efficiently even with coarsely calibrated camera and laser pointers. Furthermore, decoupled results can be gained thanks to the selected features.

The thin-walled component with I-type longitudinal ribs is widely used in aerospace and defense equipment due to its advantage of high-performance and lightweight, yet this complex structure is difficult to manufacture. One method is to form a simple thin-walled tube and I-type longitudinal ribs respectively and then connect them together by welding or riveting. Another method is to form a simple thick-walled tube firstly and then cut out the I-type longitudinal ribs. However, welding or riveting will weaken the component performance and cutting will waste lots of material. In this paper, the extrusion forming process is tried to manufacture the seamless thin-walled components with I-type longitudinal ribs. By FE simulation and experiment of the initial extrusion forming process scheme, it can be found that the metal flow velocities in the thin wall and longitudinal ribs areas are different, which lead to the deformation instability, even producing cracking. To solve the deformation instability, the effects of die structure including the porthole, the baffle-block, and the secondary welding chamber on the metal flow in extrusion process are studied. It reveals that increasing the area of the porthole will increase the metal flow velocity, increasing the height of the baffle-lock will decrease the metal flow velocity, and decreasing the height of the secondary welding chamber will improve the metal flow uniformity. Thus, the velocity uniformity of the metal flow at different position can be controlled in a better level to guarantee stable deformation by selecting appropriate die structure parameters. Finally, an optimized die structure is designed and the extrusion experiment is carried out, which obtain a good forming quality. The research work can provide an important guidance for improving the manufacturing level of thin-walled component with I-type longitudinal ribs.