Alleviation of Stress Concentration with Rivet-Like Joints Fabricated by Friction-Stir Forming

2020 ◽  
Vol 858 ◽  
pp. 33-38
Author(s):  
Takahiro Ohashi ◽  
Kenta Wakiyama ◽  
Hamed Mofidi Tabatabaei ◽  
Tadashi Nishihara
Keyword(s):  
Aluminum Alloy ◽  
Stress Concentration ◽  
Steel Plate ◽  
Substrate Material ◽  
Hole Array ◽  
Round Hole ◽  
Array Design ◽  
Alloy Plate ◽  
Friction Stir ◽  
Aluminum Alloy Plate

In this paper, the authors propose a design for the mechanical joining of dissimilar materials by employing rivet-like structures fabricated by friction-stir forming (FSF) considering the stress concentration on the joined material. The authors have utilized the FSF approach to generate rivet-like joints as follows. First, a substrate material (an aluminum alloy plate) was placed on a joined dissimilar-material plate containing prepared holes, i.e., a steel plate. Afterwards, these materials were placed on a die containing the cavity to fabricate the head of the rivet-like structure. FSF was then conducted to form the stems and heads of the rivet-like structure from the substrate material. Unlike conventional riveting, fastener was not considered necessary for the process; therefore, choosing different diameters of the prepared holes with multiple joints for the optimization of their structural design was easier. It is known that two auxiliary holes neighboring a main hole on either side reduce the stress concentration on the rim of the main hole. In this study, the authors applied the “round-hole-array design” on rivet-like joints fabricated by FSF. The authors examined the design of two smaller prepared holes with a commercial Finite element analysis (FEA) software for the rivet-like joint containing a 4 mm-diameter hole on a joined plate. To prove this, a 3 mm-thick A5083P-O aluminum alloy plate and a 0.7 mm-thick and 20 mm-wide SPCE steel plate was joined with the suggested design, and the strength and fracture of the joints were investigated using the tensile shear test. As a result, all joints were destroyed by the facture of the prepared holes, and it was confirmed that their strength was improved by the round-hole-array design.

Fastenerless-Riveting Utilizing Friction Stir Forming for Dissimilar Materials Joining

2017 ◽  
Vol 751 ◽  
pp. 186-191 ◽  
Author(s):  
Takahiro Ohashi ◽  
Hamed Mofidi Tabatabaei ◽  
Tadashi Nishihara
Keyword(s):  
Aluminum Alloy ◽  
Steel Plate ◽  
Dissimilar Materials ◽  
Substrate Material ◽  
Back Surface ◽  
Forming Limit ◽  
Alloy Plate ◽  
Friction Stir ◽  
Aluminum Alloy Plate ◽  
The Individual

This paper proposes a new joining approach for dissimilar materials, called ‘the fastenerless-riveting,’ employing the friction stir forming (FSF). The FSF is a friction stir process invented by Nishihara in 2002. In FSF, a substrate material was put on a die firstly. Next, friction stirring was conducted on the back surface of the material. The material then deformed and precisely filled the cavity of the die due to high pressure and heat caused by the friction stirring. The authors utilized the FSF approach to generate rivet like joints as followings. First, a substrate which is capable for friction stirring, i.e. an aluminum alloy plate, was put on a dissimilar material plate having holes, i.e. a steel plate. The authors call the former ‘the host member,’ the latter ‘a joined member.’ These members were put on a die having the cavity to fabricate the head of the rivet-like structure. Then FSF was conducted to form the stems and heads of the structure. Joint members are able to be stacked within the forming limit. In the study, the authors firstly conducted the proof of the concept (PoC) tests to generate rivet-like structure between steel and aluminum alloy plate and between CFRP and aluminum alloy plate, then investigated the forming conditions, i.e. tool feed rate, tool pass and the corresponding results, including the volume of the generated stem and head of the individual rivet-like structure. 3mm-thick A5083P-O aluminum alloy plates was utilized as the host member, and a 0.7mm-thick SPCE steel plate and a 0.8mm-thick CFRP plate as the joined members.

Effect of Residual Aluminum Thickness on Microstructure and Strength of Friction Stir Spot Welded Aluminum Alloy/Copper Lap Joint

2021 ◽  
Vol 1042 ◽  
pp. 3-8
Author(s):  
Mitsuhiro Watanabe ◽  
Shinpei Sasako
Keyword(s):  
Aluminum Alloy ◽  
Pure Copper ◽  
Optical Microscope ◽  
Copper Plate ◽  
Laminate Structure ◽  
Alloy Plate ◽  
Friction Stir ◽  
Residual Aluminum ◽  
Welding Interface ◽  
Aluminum Alloy Plate

Dissimilar metal lap joining of A5052 aluminum alloy plate and C1100 pure copper plate was performed by using friction stir spot welding. The rotating welding tool, which was composed of a probe part and a shoulder part, was plunged from the aluminum alloy plate which was overlapped on the copper plate, and residual aluminum alloy thickness under the probe part of the welding tool after plunging of the welding tool was controlled in the range from 0 mm to 0.4 mm. The strength of the welding interface was evaluated by using tensile-shear test. Microstructure of the welding interface was examined by using an optical microscope and a field emission scanning electron microscope. The welding was achieved at the residual aluminum alloy thickness under the probe part of the welding tool below 0.3 mm. The welded area was formed at aluminum alloy/copper interface located under the probe part of the welding tool, and its width increased with decreasing the residual aluminum alloy thickness. A characteristic laminate structure was produced in the copper matrix near the welding interface. In the joint fabricated at the residual aluminum alloy thickness below 0.1 mm, hook of Cu was formed at edge of the welded area. The fracture did not occur at the welding interface. A remarkable improvement in strength was observed in the joint fabricated at the residual aluminum alloy thickness below 0.1 mm. The formation of laminate structure and hook is considered to result in joint strength improvement.

Surface Smoothing of A5083 Aluminum Alloy Plate by Friction Stir Forming

2019 ◽  
Vol 803 ◽  
pp. 50-54
Author(s):  
Takahiro Ohashi ◽  
Kento Okuda ◽  
Hamed Mofidi Tabatabaei ◽  
Tadashi Nishihara
Keyword(s):  
Aluminum Alloy ◽  
Feed Rate ◽  
Metal Plate ◽  
Spindle Speed ◽  
Back Surface ◽  
Alloy Plate ◽  
Friction Stir ◽  
Shoulder Diameter ◽  
Aluminum Alloy Plate ◽  
Aluminum Plates

This paper provides a framework for the transcription of the surface of a mirror-finished die onto a metal plate by friction stir forming (FSF). In FSF, a material is put on a die, then friction stirring was conducted on its back surface for the transcription of the profile of the die onto the material. In this paper, a mirror-polished die of JIS SUS304 stainless steel with surface roughness Sz 0.014 mm and a probe-less friction-stirring tool in 18 mm shoulder diameter were employed for the experiment. A5083P-O aluminum plates, 3 mm thick, were utilized as base metals for the transcription. The authors varied tool spindle speed and tool feed rate to evaluate the forming results. Consequently, a mirror-finished surface under the friction-stirring tool was successfully transferred from the die to the aluminum alloy plate. The roughness of the base metal before processing was Sz 0.022 mm and that of the processed metal was Sz 0.012–0.016 mm. Higher spindle speed and faster feed rate resulted in a smoother surface; it is thought that high spindle speed and faster feed rate should be effective for higher contact pressure between a die and a material.

Research on Joint Strength of Aluminum Alloy Welded by FSW

2014 ◽  
Vol 590 ◽  
pp. 249-253 ◽  
Author(s):  
Chuan Hong Luo ◽  
Ting Chen ◽  
Wei Ping Peng
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Joint Strength ◽  
Nugget Zone ◽  
Alloy Plate ◽  
Friction Stir ◽  
Transverse Tensile ◽  
Plastic Damage ◽  
Aluminum Alloy Plate ◽  
Transverse Tensile Strength

The joint of 2219-T6 aluminum alloy plate was obtained by friction stir welding, and the microstructures and mechanical properties of the joint were investigated. The causes of the weakened joint strength in friction stir welding were analyzed and summarized correspondingly. The tensile properties show that the transverse tensile strength of the joint can reach about 70% of the base metal and the elongation can reach about 7%. The main reason of the weakened strength is due to the plastic damage of metal, followed by the defects generated in the nugget zone and the growth of θ phase in the heat affected zone.

Texture Evolution of Friction-Stir-Welded 5A30 Aluminum Alloy Plate

2014 ◽  
Vol 599-601 ◽  
pp. 136-139
Author(s):  
Wen Ying Gan ◽  
Zheng Zhou ◽  
Li Xin Wang ◽  
Yong Gang Wu
Keyword(s):  
Aluminum Alloy ◽  
Simple Shear ◽  
Texture Evolution ◽  
Shear Texture ◽  
Alloy Plate ◽  
Friction Stir ◽  
Complete Recrystallization ◽  
Aluminum Alloy Plate

In the present study, the texture of friction-stir-weled 5A30 aluminum alloy was investigated by EBSD technology. Cubic texture {100}<100> is obtained in the shoulder-affected region of NZ due to the complete recrystallization. The dominate texture in the pin-affected region of NZ is the {112}<110> B/ simple shear texture induced by the rotation pin.

Joining of CFRP and Aluminum Alloy Plate Employing Friction Stir Forming (FSF)

2016 ◽  
Vol 2016.24 (0) ◽  
pp. 228
Author(s):  
Takahiro OHASHI ◽  
Hamed MOFIDI TABATABAEI ◽  
Tadashi NISHIHARA
Keyword(s):  
Aluminum Alloy ◽  
Alloy Plate ◽  
Friction Stir ◽  
Aluminum Alloy Plate
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