Classification of Failure Modes in Friction Stir Blind Riveted Lap-Shear Joints With Dissimilar Materials

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Wei-Ming Wang ◽  
Haris Ali Khan ◽  
Jingjing Li ◽  
Scott F. Miller ◽  
A Zachary Trimble
Keyword(s):  
Failure Modes ◽  
Dissimilar Materials ◽  
Polymeric Composite ◽  
Tensile Tests ◽  
Great Promise ◽  
Lightweight Structures ◽  
Friction Stir ◽  
Lap Shear ◽  
Transportation Sector ◽  
Static Tensile

In transportation sector, there is an increasing need for joining dissimilar materials for lightweight structures; however, substantial barriers to the joining of dissimilar materials have led to an investigation and development of new joining techniques. Friction stir blind riveting (FSBR), a newly invented method, has shown great promise in joining complex structures with dissimilar materials. The process can be utilized more effectively if knowledge regarding the failure mechanisms of the FSBR joints becomes available. This research focuses on investigating the different mechanisms that lead to a failure in FSBR joints under lap-shear tensile tests. An in situ, nondestructive, acoustic emission (AE) testing method was applied during quasi-static tensile tests to monitor the initiation and evolution of damage in FSBR joints with different combinations of dissimilar materials (including aluminum, magnesium, and a carbon-fiber reinforced polymeric composite). In addition, a fractographic analysis was conducted to characterize the failure modes. Finally, based on the analysis, the distinct failure modes and damage accumulation processes for the joints were identified. An AE accumulative hit history curve was found to be efficient to discriminate the deformation characteristics, such as the deformation zone and failure mode, which cannot be observed through a traditional extensometer measurement method. In addition, the AE accumulative hit history curve can be applied to predict the failure extension or moment of FSBR joints through an identification of the changes in curve slope. Such slope changes usually occur around the middle of Zone II, which is defined in this study.

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.

Joining sheets made from dissimilar materials by hole hemming

2022 ◽  
pp. 146442072110726
Author(s):  
Mohammad Mehdi Kasaei ◽  
Lucas FM da Silva
Keyword(s):  
Mechanical Properties ◽  
Research Work ◽  
Dissimilar Materials ◽  
Element Analysis ◽  
Lightweight Structures ◽  
Lap Shear ◽  
Gradual Failure ◽  
Peel Tests ◽  
Dp780 Steel ◽  
Joining Process

This research work presents a new joining process based on the hemming process for attaching sheets made from dissimilar materials with very different mechanical properties. The process is termed ‘hole hemming’ and consists in producing a mechanical interlock between pre-drilled holes which can be made anywhere on the sheets. The process is carried out in a two-stage operation including flanging the hole of an outer sheet and bending the flange over the hole of an inner sheet. First, the joining stages and the required tools are designed. Then, the joining of DP780 steel and AA6061-T6 aluminium alloy sheets, which are applied to manufacture lightweight structures in the automotive industries, is investigated using finite element analysis. Results show that the hole hemming process is able to successfully join these materials without fracture. The hole-hemmed joint withstood the maximum forces of 2.5 and 0.5 kN in single-lap shear and peel tests, respectively, and failed with hole bearing mode which is known as a gradual failure mode. The results demonstrate the applicability of the hole hemming process for joining dissimilar materials.

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.

scholarly journals Dynamic Behavior of Self-Piercing Riveted and Mechanical Clinched Joints of Dissimilar Materials: An Experimental Comparative Investigation

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Yulong Ge ◽  
Yong Xia
Keyword(s):  
Mechanical Behavior ◽  
Failure Modes ◽  
Dissimilar Materials ◽  
Dynamic Effect ◽  
Comparative Investigation ◽  
Rate Dependent ◽  
Lap Shear ◽  
Baking Process ◽  
Before And After ◽  
Peel Tests

The present work compares the dynamic effect of a self-piercing riveted (SPR) joint with that of a mechanical clinched joint having the dissimilar materials combination. The substrates used in this investigation are aluminum alloy AA5182-O and deep drawing steel DX51D+Z. The static and dynamic behaviors and the failure modes of the SPR and clinching joints are characterized by lap-shear, cross-tension, and coach-peel tests. The influence of the strain-rate-dependent mechanical behavior of the substrates on the joints is examined; this can help improve prediction of the energy absorption of the joints under impact loading. Considering the realistic baking process in a painting shop, the deforming and hardening effects on the SPR and the clinched joints induced by baking are also studied. The specimens are heated to 180°C for 30 min in an oven and then cooled down in air. The SPR and the clinched joints before and after the baking process are compared in terms of the mechanical behavior.

Dissimilar Material Joint Strength and Structure for Friction Stir Forming Process

2014 ◽  
Author(s):  
Kenneth A. Ogata ◽  
Sladjan Lazarevic ◽  
Scott F. Miller
Keyword(s):  
Failure Modes ◽  
Dissimilar Materials ◽  
High Strength Steels ◽  
High Strength ◽  
Forming Process ◽  
Experimental Conditions ◽  
Friction Stir ◽  
Automotive Body ◽  
Neck Fracture ◽  
Ultra High Strength Steels

Mass reduction of automotive body structures is a critical part of achieving reduced CO2 emissions in the automotive industry. There has been significant work on the application of ultra high strength steels and aluminum alloys. However, the next paradigm is the integrated use of both materials, which creates the need to join them together. Friction stir forming is a new environmentally benign manufacturing process for joining dissimilar materials. The concept of this process is stir heating one material and forming it into a mechanical interlocking joint with the second material. In this research the process was experimentally analyzed in a computer numerical controlled machining center between aluminum and steel work pieces. The significant process parameters were identified and their optimized settings for the current experimental conditions defined using a design of experiments methodology. Three failure modes were identified (neck fracture, aluminum sheet peeling, and bonding delamination i.e. braze fracture). The overall joint structure and grain microstructure were mapped along different stages of the friction stir forming process. Two layers were formed within the aluminum, the thermo-mechanical affected zone that had been deformed due to the contact pressure and angular momentum of the tool, and the heat affected deformation zone that deformed into the cavity.

Experimental Investigation on Joining Dissimilar Aluminum Alloy 6061 to TRIP 780/800 Steel Through Friction Stir Welding

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Xun Liu ◽  
Shuhuai Lan ◽  
Jun Ni
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Cross Sections ◽  
Failure Modes ◽  
High Strength ◽  
Tensile Tests ◽  
Weld Strength ◽  
Friction Stir ◽  
Aluminum Alloy 6061 ◽  
Alloy 6061

Friction stir welding (FSW) technique has been successfully applied to butt joining of aluminum alloy 6061-T6 to one type of advanced high strength steel (AHSS), transformation induced plasticity (TRIP) 780/800 with the highest weld strength reaching 85% of the base aluminum alloy. Mechanical welding forces and temperature were measured under various sets of process parameters and their relationships were investigated, which also helped explain the observed macrostructure of the weld cross section. Compared with FSW of similar aluminum alloys, only one peak of axial force occurred during the plunge stage. Three failure modes were identified during tensile tests of weld specimens, which were further analyzed based on the microstructure of joint cross sections. Intermetallic compound (IMC) layer with appropriate thickness and morphology was shown to be beneficial for enhancing the strength of Al–Fe interface.

Fabrication of Tailor-Made Metallic Structures for Lightweight Applications and Mechanical Behaviour

2022 ◽  
pp. 216-261
Author(s):  
R. Ganesh Narayanan ◽  
Perumalla Janaki Ramulu ◽  
Satheeshkumar V. ◽  
Arvind K. Agrawal ◽  
Sumitesh Das ◽  
...  
Keyword(s):  
Adhesive Bonding ◽  
Mechanical Performance ◽  
Dissimilar Materials ◽  
Metallic Structures ◽  
Mechanical Joining ◽  
Lightweight Structures ◽  
Friction Stir ◽  
Tailor Welded Blanks ◽  
Critical Issues ◽  
Novel Methods

Tailor-made metallic structures are fabricated by welding, adhesive bonding, and mechanical joining methods. Here the aim is not only to fabricate lightweight structures, but also to develop novel methods of joining. Lightweight structures are advantageous in several ways including reduction of fuel consumption and vehicle emissions. Developing novel methods of joining is advantageous due to the possibility of joining of dissimilar materials, improved mechanical performance, and microstructures. In the chapter, initially, tailor-welded blanks (TWB) are introduced, and after that, fabrication of TWBs by laser welding, friction stir welding, and friction stir additive manufacturing are elaborately discussed. Some critical issues in modeling the deformation during fabrication of TWBs is also discussed. A brief account of mechanical behavior of adhesive bonded sheets and mechanical joining are presented in the later part.

The Impact of Material Positioning Towards the Friction Stir Welded Dissimilar Aluminium Alloy Joints

2020 ◽  
Vol 13 ◽  
Author(s):  
Velaphi Msomi ◽  
Sipokazi Mabuwa
Keyword(s):  
Microstructural Analysis ◽  
Ductile Failure ◽  
Dissimilar Materials ◽  
Traverse Speed ◽  
Tensile Tests ◽  
Dissimilar Joints ◽  
Friction Stir ◽  
Strength Alloy ◽  
Materials Used ◽  
The Impact

Background: Friction stir welding is at an advanced state such that it could be used to joint dissimilar materials and alloys. However, there are some areas which require some further analysis. This involves the impact of the material positioning of various dissimilar joints. Objective: The purpose of this paper is to investigate the influence of material positioning towards the microstructure and the mechanical properties of AA8011/AA6082 and AA6082/AA8011 dissimilar joints. Methods: The materials used in this study were the 6mm thick AA8011 and AA6082-T6 plates. The welding conditions include a tool rotational speed of 1100 rpm, traverse speed of 60 mm/min. Microstructural analysis, Vickers hardness and tensile tests were conducted in order to be able to draw a comparison between the respective joints. Results: The joints (AA8011/AA6082 and AA6082/AA8011) both experienced dynamic recrystallization. The positioning of the stronger strength alloy on the advancing side resulted in finer microstructural grains compared to when the lower strength alloy was positioned on the advancing side. The maximum stir zone hardness of 75 HV was obtained on the AA8011/AA6082 dissimilar joint, while the AA6082/AA8011 had a minimum hardness of 68 HV. Both hardness values were lower than the AA6082 hardness but greater than that of the AA8011. The positioning of AA6082 on the advancing side resulted in higher ultimate tensile strength than when AA8011 was on the advancing side. The AA6082/AA8011 joint was found to be more ductile in comparison to the AA8011/AA6082 joint. The fracture surface morphology of the post tensile specimens also revealed a ductile failure morphology. Conclusion: Placing the stronger strength alloy on the advancing side resulted in sound overall results of the tests conducted.

Performance Prediction for Ultrasonically Welded Dissimilar Materials Joints

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Liang Xi ◽  
Mihaela Banu ◽  
S. Jack Hu ◽  
Wayne Cai ◽  
Jeffrey Abell
Keyword(s):  
Failure Modes ◽  
Mechanical Performance ◽  
Welding Process ◽  
Dissimilar Materials ◽  
Lithium Ion ◽  
Microscopic Analysis ◽  
Lap Shear ◽  
Physical Attributes ◽  
Assembly Operations ◽  
Metal Welding

Ultrasonic metal welding has been used to join multiple layers of battery tabs with the bus bar in lithium-ion battery assembly operations. This paper describes joint performance models for ultrasonic metal welds of multiple layers of dissimilar battery tab materials, i.e., aluminum and copper. Finite element (FE) models are developed to predict the mechanical performance of the ultrasonically welded joints. The models predict peak shear load, energy absorption capability, and failure modes, which are necessary for modeling product performance and defining process requirements for the welds. The models can be adjusted to represent different quality of welds created in conditions of underweld (UW), normal-weld (NW), or overweld (OW) using physical attributes observed through microscopic analysis. The models are validated through lap shear tests, which demonstrate excellent agreement for the maximum force in the NW condition and good agreement for the UW and OW conditions. The models provide in-depth understanding of the relationship among welding process parameters, physical weld attributes, and the weld performance. The models also provide significant insight for further development of ultrasonic welding process for battery tabs and help optimize welding process for more than four-layered joints.

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