In this paper, residual stresses due to indentation and rolling of a rigid cylinder on a finite plate at a very high rolling load with a relative peak pressure of 22 are examined by two-dimensional plane strain finite element analyses using abaqus for the first time. In the finite element analyses, the roller is modeled as rigid and has frictionless contact with the finite plate. The geometry of the finite plate and its boundary conditions are assigned to correspond to those of fillet rolling of...
Last. Yongbing Li(SJTU: Shanghai Jiao Tong University)H-Index: 18
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Conventional magnesium alloys, due to their low ductility, have a poor self-piercing rivetability. Cracks always occur when the magnesium sheet is placed at the bottom layer, which brings great challenge to the use of the magnesium alloys. In this paper, friction self-piercing riveting (F-SPR) process was adopted to join 1 mm thick aluminum alloy AA6061-T6 to 2.2 mm thick magnesium alloy AZ31B, and the effect of rivet hardness and key geometrical features on joint formation were studied systemat...
An increase in fuel economy standards has affected automakers' decision toward designing lightweight vehicles and therefore transitioning from steel-based bodies to ones predominantly composed of aluminum. An introduction to lightweight materials couples that of lightweight joining with a thermomechanical process, flow drill screwdriving (FDS). This process is favored in terms of robustness, short installation time, and only requiring access to one side. The current limitation with FDS occurs wi...
#1Junying Min(U.H.: University of Hawaii at Manoa)H-Index: 19
#2Jingjing Li(U.H.: University of Hawaii at Manoa)H-Index: 19
Last. Weiming Wang(U.H.: University of Hawaii at Manoa)H-Index: 6
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A new one-sided joining method, friction stirring blind riveting (FSBR) was successfully implemented to form lap-shear joints for dissimilar metals from pairs of 3.05 mm thick cast Mg AM60, rolled 1.5 mm thick Al AA6022, and extruded 3.15 mm thick Al AA6082 specimens. The concept of this process is riveting the two workpieces with reduced force under frictional heat and fastening the workpieces through blind riveting once the rivet is fully inserted. In this research, the process was experimenta...
Conventional fusion joining methods such as resistance spot welding have been demonstrated to not be effective for magnesium alloys. Therefore, self-pierce riveting (SPR) has been presented as an attractive joining technique for these lightweight metals. However, SPR must be performed at elevated temperatures because of the low ductility of magnesium alloys at room temperature. Even though the SPR joining process has been established on magnesium alloys, this joining process is not optimized. As...
The continued advancement of implantable medical devices has resulted in the need to join a variety of dissimilar, biocompatible metal pairs to enable selective use of their unique properties. Typical materials used in implantable medical devices include stainless steel (SS), titanium, platinum (Pt), as well as shape memory materials such as NiTi. Joining these dissimilar metal pairs, however, often results in excessive formation of brittle intermetallics, which significantly reduce the strength...
In collaboration with Airbus-UK, the dimensional growth of aircraft panels while being riveted with stiffeners is investigated. Small panels are used in this investigation. The stiffeners have been fastened to the panels with rivets and it has been observed that during this operation the panels expand in the longitudinal and transverse directions. It has been observed that the growth is variable and the challenge is to control the riveting process to minimize this variability. In this investigat...
Residual stress can play a significant role in the processing and performance of an engineered metallic component. The stress state within a polycrystalline part can vary significantly between its surface and its interior. To measure three-dimensional (3D) residual stress fields, a synchrotron x-ray diffraction-based experimental technique capable of non-destructively measuring a set of lattice strain pole figures (SPFs) at various surface and internal points within a component was developed. Th...
Last. Myoung-Gyu Lee(SNU: Seoul National University)H-Index: 44
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Abstract Analytical strength estimators for self-piercing riveted (SPR) metal sheets under the lap-shear and the cross-tension modes are developed. The modeling is based on the local mechanical responses of rivet and sheet metals during the riveting process and joint strength tests, which are investigated using finite element (FE) simulations as virtual experiments. The FE simulations consist of the riveting process model and lap shear test model, and the plastic strain hardening and damage of s...
#1N. Karathanasopoulos(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 1
Last. Dirk Mohr(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 4
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Abstract Developing robust numerical simulation tools to investigate the self-piercing riveting process is critical, since the feasibility, quality and strength of riveted connections relies on the successful formation of mechanical interlocks between the rivet and sheet materials. In the present study, we investigate the riveting of aluminum alloy and dual-phase steel sheets (AA7075-F/DP600 and AA6016-T4/DP600) over a wide range of sheet thicknesses, as a function of the rivet and die geometrie...
Last. Xianping Liu(Warw.: University of Warwick)H-Index: 20
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Abstract This study systematically investigated the influences of cutting positions on the measurement accuracy of the self-piercing riveted joint quality indicators. Evaluation and correction methods were proposed for the first time to estimate and compensate the interlock error caused by improper cutting positions. It was found that the measurement accuracy of the rivet head height was not influenced, but the accuracy of the interlock and the remaining bottom sheet thickness were affected by t...
Abstract 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 load...
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 effic...
Last. Gerson Meschut(University of Paderborn)H-Index: 11
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Abstract In this study, the damage model GISSMO (Generalized Incremental Stress State dependent damage MOdel) is used to describe the evolution of ductile damage and predict the onset of fracture during the self-pierce riveting of thin aluminum (EN AW-5182) sheets. By accurate prediction of the pre-damage and material separation in the simulation of joining process, the accuracy of crashworthiness simulations can be improved. Besides, over dimensioning will be reduced and more precise components...
Last. Lars Lindkvist(Chalmers University of Technology)H-Index: 19
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Spot welding is the predominant joining process for sheet metal assemblies. The assemblies, during this process, are mainly bent and deformed. These deformations along with single part variations are the main sources of aesthetic and functional geometrical problems in an assembly. The sequence of welding has a considerable effect on the geometrical variation of the final assembly. Finding the optimal weld sequence for geometrical quality can be categorized as a Hamiltonian graph search problem w...
Abstract The role of the process deformation history on the mechanical performance of self-pierce riveted (SPR) joints is examined in detail. The SPR process was simulated using a non-linear finite element model coupled with a damage criterion sensitive to the stress state. Results of the FE simulation compared closely to cross-sectional images of experimental SPR joints. The FE simulation results suggest that the strain hardening due to the piercing process is the main mechanism for joint stren...
Abstract In this paper, the mechanical properties of electromagnetic self-piercing riveted (E-SPR) joints with carbon fiber reinforced plastics (CFRP)/aluminum alloy (Al) 5052 were comprehensively investigated. Microtopography observations, hardness measurements and tensile-shear strength tests were performed by comparing with regular pressure self-piercing riveted (P-SPR) joints. Results showed that the undercut value of E-SPR joints was higher than that of P-SPR joints. The hardness values on ...
Last. Yvonne Durandet(Swinburne University of Technology)H-Index: 16
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Abstract Manufacturing industries throughout the world are constantly facing the pressure to reduce carbon emissions. The automobile industries strategy for reducing carbon emissions are targeted at reducing the overall weight of the car body. Efforts to accomplish this haven been based on clever materials selection that suggests using materials like aluminium and magnesium with high strength to weight ratio in place of the traditional steel. However, these lightweight alloys are difficult or so...