Papers by Keyword: Self-Piercing Riveting (SPR)

Abstract: Self-piercing riveting (SPR) is a well-established joining technique in lightweight construction, as it enables the joining of different materials without requiring pre-drilling. However, the necessary adaptation of the rivet-die combination to the respective material and thickness combinations requires a large number of specific tool sets, which significantly limits the process's flexibility. To overcome these limitations, the versatile self-piercing riveting (V-SPR) was developed, which features enhanced punch actuation in combination with a multi-range-capable rivet . In this context, the concept of a movable die was introduced, which enables an extended process window and adaptable joint formation. Kappe et al. presented initial studies demonstrating the potential of this approach . However, a detailed numerical understanding of the underlying mechanisms remains lacking. This paper presents a numerical analysis of V-SPR with a movable die using a finite element (FE) model. The model includes deformable rivets, sheet metal materials and a kinematically controlled die with adjustable movement. A parameter study was conducted to analyse the influence of die movement on the material flow of the rivet and sheets, as well as joint formation. The simulations were validated using selected experimental data. The goal is to compare the joint geometries achieved with fixed and moving dies and expand the process windows of VSPR. The results demonstrate that the movable-die concept significantly enhances the material flow of both the sheets and the rivet, resulting in a noticeably larger and more reliable interlock than what is achievable with V-SPR using a fixed die. The numerical analyses support the observations reported by Kappe et al. and extend them by providing a quantitative description of how die displacement influences the resulting interlock size. Moreover, the ability to precisely control the die movement makes it possible to join challenging sheet-metal combinations that are difficult to process with conventional setups, particularly in cases involving thicker sheet materials.

Abstract: Conventional self-piercing riveting (SPR) produces rotationally symmetric joints with largely uniform mechanical behavior. While this provides robust performance in many applications, increasing demands for material-efficient lightweight design, complex load paths and hybrid material systems require more versatile joining strategies. Recent experiments have demonstrated that an adapted tumbling SPR (T-SPR) process can intentionally induce non-rotationally symmetric joint geometries and thereby extend process limits beyond those of conventional SPR. Such asymmetric joints offer the potential to tailor load-bearing capacity and energy absorption to specific load directions, which could be particularly advantageous in crash-relevant or multi-material applications. Building on these findings, the present study shifts the focus from geometry control to the systematic evaluation of the mechanical performance of asymmetric T-SPR joints. Specimens were produced using T-SPR with tailored combinations of tumbling angle and velocity. The joints are manufactured with a versatile tumbling self-piercing riveting tool. To assess the resulting mechanical properties, cross tensile and tensile shear tests are conducted. From the resulting force-displacement curves, typical mechanical properties such as ultimate load, load-bearing capacity, displacement at failure and absorbed energy are derived. The mechanical performance of asymmetric joints is evaluated in comparison with symmetric reference joints produced by tumbling self-piercing riveting. This enables both the demonstration of direction-dependent mechanical behavior of asymmetric joints compared to symmetric references and a systematic evaluation of how geometric anisotropy affects load-bearing capacity, absorbed energy and failure characteristics.

Abstract: Due to the drive from legislations, fuel efficiency, and CO₂ emission, the application of aluminium lightweight structures in automotive industry have been increased significantly. Self piercing riveting (SPR) has been one of the major joining technologies for aluminium structures due to its advantages to some traditional joining technologies. There are some standard parameters that will influence the joint quality and mechanical strengths of an SPR joint. However, even for the same parameters used, sometimes the joint quality and mechanical strengths of SPR joints could still be significantly different, which may cause joint failure or strength reduction. One reason found is the variation of rivet specifications between different batches. In this paper, the influence of rivet tip geometry on the joint quality and mechanical strengths was studied. The results showed that rivets with sharper tips flared more during riveting process, and joints with sharper rivets had higher lap shear strength; however, the influence of rivet geometry on T peel strength could be different for different rivets, and rivet tip geometry did not have an obvious influence on joint fatigue strengths.

Abstract: In this study a numerical simulation model was designed for representing the joining process of carbon fiber-reinforced plastics (CFRP) and aluminum alloy with semi-tubular self-piercing rivet. The first step towards this goal is to analyze the piercing process of CFRP numerical and experimental. Thereby the essential process parameters, tool geometries and material characteristics are determined and in finite element model represented. Subsequently the finite element model will be verified and calibrated by experimental studies. The next step is the integration of the calibrated model parameters from the piercing process in the extensive simulation model of self-piercing rivet process. The comparison between the measured and computed values, e.g. process parameters and the geometrical connection characteristics, shows the reached quality of the process model. The presented method provides an experimental reliable characterization of the damage of the composite material and an evaluation of the connection performances, regarding the anisotropic property of CFRP.

Abstract: Self-Piercing Riveting (SPR) is receiving more recognition as a possible and effective solution to join body panels and structures. For example self-piercing riveting is still the first choice for the most well-known automotive car industries when considering the intensive use of aluminum alloy. To combine the advantages of the two joints techniques, in the last years hybrid joints combining a classical mechanical fastening (riveting) and a classical adhesive bonding, or a co-cured joint, have attracted great interest.In the present paper the static behavior of single-lap hybrid joints (SPR-bonded) between GFRP and aluminum through experimental tests. In particular, tensile strength, energy absorption and failure modes of studied joints were investigated through tensile tests.

Abstract: Self-pierce riveting (SPR) is a new high-speed mechanical fastening technique which is suitable for point joining dissimilar materials, as well as coated and pre-painted materials. In this study, an experimental measurement technique was provided for the prediction of the free vibration behavior of single-lap cantilevered SPR beams. The dynamic test software and the data acquisition hardware were used in the experimental measurement of the dynamic response of the single-lap cantilevered SPR Beams. The frequency response functions of the SPR beams of different rivet number were measured and compared. The main goal of the paper is to provide a basis for further research on vibration based non-destructive damage detection in single-lap cantilevered SPR beams.

Abstract: As one of the most important technology of Lightweight of Automobile, Self-pierce riveting (SPR) is suitable for joining similar or dissimilar sheet materials. In this paper, the process of the SPR was introduced, the test specimen was prepared by using electrolysis and anodized coated, and the microstructure of the joint is observed by the differential interference contrast method (DIC). According to the distribution of the grain size, the section of the joint could be divided into five areas, un-deformed matrix, upper plate self-locking area, lower plate self-locking area, upper plate transition area, and lower plate transition area. From transition area to matrix the grain deformation and hardness decreases gradually, and the maximum hardness of the joint was founded in the upper plate self-locking area.

Abstract: With increasing application of self-piercing riveting (SPR) in different industrial fields, the demand for a better understanding of the knowledge of strength and energy absorption characteristics of the SPR joints is required. It is also important for SPR to benefit from the advantages of adhesively bonding. It is commonly understood that the addition of adhesive in SPR joints is beneficial but it is not clear if there are negative effects on mechanical properties of SPR joints. In present study, deformation and failure of homogeneous joints under monotonic tensile loading were studied for validating the strength and energy absorption of SPR and SPR-bonded hybrid joints.

Abstract: The need to create lighter vehicles to aid in reducing emissions and increase fuel efficiency has become increasingly important in recent years. Self-pierce riveting (SPR) has drawn more attention as it can join some advanced materials that are dissimilar and hard to weld. In present study, the SPR process has been numerically simulated using the commercial finite element (FE) software LS-Dyna. For validating the numerical simulation of the SPR process, experimental tests on specimens made of aluminium alloy have been carried out. The online window monitoring technique was used in the tests for evaluating the quality of SPR joints. Good agreements between the simulations and the tests have been found, both with respect to the force-travel curves as well as the deformed shape on the cross-section of SPR joint.

Abstract: In this study, a numerical model was built to simulate the self-piercing riveting (SPR) process using commercial LS-DYNA finite element code. The difficulties in numerical simulation of the SPR process, such as large deformation and fracture, were resolved by the use of an explicit solution process combined with the r-adaptive meshing method. The model was applied to joining two sheets of 6061 aluminium alloy. The effects of die geometry, rivet material properties and the adaptive step size in numerical calculation were studied, using 6061 aluminum sheets as a model system. The simulation agrees well with the experimental results in terms of geometric characterisitcs of the cross-sections of the joints formed.