Effect of weld orientation on static strength and failure mode of friction stir stitch welds in lap-shear specimens of aluminium 6022-T4 sheets

2011 ◽  
Vol 34 (11) ◽  
pp. 908-920 ◽  
Author(s):  
H. BADARINARAYAN ◽  
Q. YANG ◽  
K. OKAMOTO
Keyword(s):  
Failure Mode ◽  
Static Strength ◽  
Friction Stir ◽  
Lap Shear

Effect of stirring time on the mechanical behavior of friction stir spot weld of Al 6061-T6 lap-shear configuration

2018 ◽  
Vol 233 (10) ◽  
pp. 3583-3591 ◽  
Author(s):  
Amirreza Shahani ◽  
Ali Farrahi
Keyword(s):  
Mechanical Behavior ◽  
Failure Modes ◽  
Static Strength ◽  
High Load ◽  
Welding Condition ◽  
Friction Stir ◽  
Al 6061 ◽  
Lap Shear ◽  
Low Load ◽  
Stirring Time

The effect of five different stirring times of friction stir spot welding on lap-shear specimens of Al 6061-T6 alloy has been experimentally analyzed. The welding condition with 2 s of stirring shows the optimum mechanical behavior in comparison to the others. The static strength and fatigue behavior of the joint are justified using the microhardness profiles. The static results prove that the increase of stirring time beyond the 2 s case has little effect on improving the static strength. The fatigue results reveal two different failure modes, which are shear fracture at high load levels and transverse crack growth at low load levels. At medium load levels, although the final failure is similar to high load levels, the transverse growth of the crack outside the welding zone, just like low load levels, is also observed.

Joint Formation and Mechanical Performance of Friction Self-Piercing Riveted Aluminum Alloy AA7075-T6 Joints

2019 ◽  
Author(s):  
YunWu Ma ◽  
YongBing Li ◽  
ZhongQin Lin
Keyword(s):  
Aluminum Alloy ◽  
Failure Mode ◽  
Feed Rate ◽  
High Speed ◽  
Shear Failure ◽  
Shear Fracture ◽  
Peak Load ◽  
Spindle Speed ◽  
Friction Stir ◽  
Lap Shear

Abstract AA7xxx series aluminum alloys have great potentials in mass saving of vehicle bodies due to pretty high specific strength. However, the use of these high strength materials poses significant challenges to traditional self-piercing riveting (SPR) process. To address this issue, friction self-piercing riveting (F-SPR) was applied to join aluminum alloy AA7075-T6 sheets. F-SPR is realized by feeding a high speed rotating steel rivet to aluminum alloy sheets to form a dissimilar material joint. The effects of spindle speed and rivet feed rate on F-SPR joint cross-section geometry evolution, riveting force and energy input were investigated systematically. It was found that the rivet shank deformation, especially the buckling of the shank tip before penetrating through the top sheet has significant influence on geometry and lap-shear failure mode of the final joint. A medium rivet feed rate combined with a high spindle speed was prone to produce a defect free joint with sound mechanical interlocking. F-SPR joints with the failure mode of rivet shear fracture was observed to have superior lap-shear peak load and energy absorption over the joints with mechanical interlock failure. The optimized F-SPR joint in this study exhibited 67.6% and 13.9% greater lap-shear peak load compared to, respectively, SPR and refill friction stir spot welding joints of the same sheets. This research provides a valuable reference for further understanding the F-SPR process.

Joint Formation and Mechanical Performance of Friction Self-Piercing Riveted Aluminum Alloy AA7075-T6 Joints

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Yun Wu Ma ◽  
Yong Bing Li ◽  
Zhong Qin Lin
Keyword(s):  
Aluminum Alloy ◽  
Failure Mode ◽  
Feed Rate ◽  
Shear Failure ◽  
Mechanical Performance ◽  
Shear Fracture ◽  
Peak Load ◽  
Spindle Speed ◽  
Friction Stir ◽  
Lap Shear

AA7xxx series aluminum alloys have great potentials in mass saving of vehicle bodies due to pretty high specific strength. However, the use of these high strength materials poses significant challenges to the traditional self-piercing riveting (SPR) process. To address this issue, a novel process, friction self-piercing riveting (F-SPR), was applied to join aluminum alloy AA7075-T6 sheets. The effects of the spindle speed and rivet feed rate on F-SPR joint cross section geometry evolution, riveting force, and energy input were investigated systematically. It was found that the rivet shank deformation, especially the buckling of the shank tip before penetrating through the top sheet, has significant influence on geometry and lap shear failure mode of the final joint. A medium rivet feed rate combined with a high spindle speed was prone to produce a defect-free joint with sound mechanical interlocking. F-SPR joints with the failure mode of rivet shear fracture were observed to have superior lap shear peak load and energy absorption over the joints with mechanical interlock failure. The optimized F-SPR joint in this study exhibited 67.6% and 13.9% greater lap shear peak load compared with SPR and refill friction stir spot welding joints, respectively, of the same sheets. This research provides a valuable reference for further understanding the F-SPR process.

Analysis of Static Strength and Failure Mode of FSSW Joint in Aluminum Alloy

2014 ◽  
Author(s):  
Francesco Vivio ◽  
Vincenzo Vullo ◽  
Pierluigi Fanelli
Keyword(s):  
Aluminum Alloy ◽  
Failure Mode ◽  
Mechanical Characteristics ◽  
Experimental Tests ◽  
Static Strength ◽  
Structural Behavior ◽  
Fe Model ◽  
Lap Joint ◽  
Actual Distribution ◽  
Friction Stir

In this paper an analysis of Friction Stir Spot Welds (FSSW), applied to lap joint aluminum alloy is presented. The analyses regards the structural behavior of FSSW joints in order to assess the failure mode and its dependence on mechanical properties distribution of the sheets material and, consequently, on process parameters. FSSW joint is analyzed by means of a complex 3D FE model, which allows to evaluate, in a parametric manner, the multifaceted internal geometry of the joint and the actual distribution of material mechanical characteristics after welding. Experimental tests allowed to verify the results and to calibrate the material characteristics in the FE model.

Dissimilar Friction Stir Lap Welding of AA2198 and AA7075 Sheets: Forces, Microstructure and Mechanical Properties

2021 ◽  
Author(s):  
Antonello Astarita ◽  
Fausto Tucci ◽  
Alessia Teresa Silvestri ◽  
Michele Perrella ◽  
Luca Boccarusso ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Welding Process ◽  
Processing Parameters ◽  
Processing Parameter ◽  
Friction Stir Lap Welding ◽  
Friction Stir ◽  
Lap Shear ◽  
Microstructure And Mechanical Properties ◽  
Lap Welding ◽  
Factorial Design Of Experiments

Abstract This paper deals with the dissimilar friction stir lap welding of AA2198 and AA7075 sheets. The influence of processing parameters, namely welding speed and tool rotational speed on joint features, microstructure, and mechanical properties were investigated implementing a full factorial design of experiments. During the welding process, axial and transversal forces were continuously measured using a dedicated sensed fixture aiming at the correlation of this processing parameter with the quality of the achieved joints. The reported outcomes showed a very narrow processing window in which it was possible to avoid the formation of defects while the formation of an hook was observed for all the joints welded. The influence of the weld bead morphology on the lap shear strength was elucidated proving that the strength is ruled by the hook morphology. A correlation between the process parameters and the forces arising was also attempted. The final microstructure of the joints was studied and explained and also compared with the microhardness results.

Sensor Fusion and On-Line Monitoring of Friction Stir Blind Riveting for Lightweight Materials Manufacturing

2021 ◽  
pp. 1-36
Author(s):  
Zhe Gao ◽  
Haris Khan ◽  
Jingjing Li ◽  
Weihong Guo
Keyword(s):  
Sensor Fusion ◽  
Failure Modes ◽  
Processing Parameters ◽  
Data Driven ◽  
Structure Property ◽  
Cross Sectional ◽  
Friction Stir ◽  
In Situ Data ◽  
Lap Shear

Abstract This research focused on developing a hybrid quality monitoring model through combining the data driven and key engineering parameters to predict the friction stir blind riveting (FSBR) joint quality. The hybrid model was formulated through utilizing the in-situ processing and joint property data. The in-situ data involved sensor fusion (force and torque signals) and key processing parameters (spindle speed, feed rate and stacking sequence) for data-driven modeling. The quality of the FSBR joints was defined by the tensile strength. Further, the joint cross-sectional analysis and failure modes in lap-shear tests were employed to confirm the efficacy of the proposed model and development of the process-structure-property relationship.

scholarly journals Preliminary study on the mechanical behavior of friction spot welds

2009 ◽  
Vol 14 (3) ◽  
pp. 238-247 ◽  
Author(s):  
José Antônio Esmerio Mazzaferro ◽  
Tonilson de Souza Rosendo ◽  
Cíntia Cristiane Petry Mazzaferro ◽  
Fabiano Dornelles Ramos ◽  
Marco Antônio Durlo Tier ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Spot Welding ◽  
Mechanical Response ◽  
Analysis Procedure ◽  
Research Centre ◽  
Friction Stir ◽  
Lap Shear ◽  
State Process ◽  
Welding Processes

The Friction Spot Welding - FSpW is a solid-state process that allows joining two or more metal sheets in lap configuration with no residual keyhole as occurs in the Friction Stir Welding - FSW process. The present work reports part of the efforts made at GKSS Research Centre to better understand the complex phenomena that take place during FSpW of aluminum alloys and establish the mechanical response of the resulting joints. Over the recent years the research on modeling friction based welding processes has increased considerably. Most of the works related to this subject deal with the process mechanics. On the other hand, some investigations have shown how the process variables affect the mechanical properties of the joints, but it is very difficult to find quantitative results that can be readily used for mechanical design purposes. The aim of this work is to develop an analysis procedure based on the process characteristics that allows evaluating how the resulting geometry and microstructure affect the joint mechanical behavior. For this, the results of the mechanical tests obtained on AA2024-T3 aluminum alloy were used to calibrate and validate a numerical model that was used to predict the joint failure mode. The model reproduced the specimen geometry and load conditions adopted in the lap-shear and cross-tensile tests. The joint was considered as formed by three main regions (SZ - stir zone, TMAZ - thermo mechanically affected zone and HAZ - heat affected zone) whose properties and dimensions were based in microhardness evaluation and macrographic analysis of welded specimens. It was observed a good agreement between the simulation results and experimental data. The numerical modeling of the joints allows the prediction of the joint mechanical properties, as well as to understand how a change in geometry and property of each region affects the final mechanical behavior. Based in the obtained results, the analysis procedure can be easily extended to the related friction based spot processes as Friction Stir Spot Welding - FSSW.

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