scholarly journals Effect of Loading Methods on the Fatigue Properties of Dissimilar Al/Steel Keyhole-Free FSSW Joints

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4247
Author(s):  
Zhongke Zhang ◽  
Yang Yu ◽  
Huaxia Zhao ◽  
Hui Tong
Keyword(s):  
Fatigue Limit ◽  
Fatigue Fracture ◽  
Fracture Mechanism ◽  
Fatigue Loading ◽  
Fatigue Properties ◽  
Loading Frequency ◽  
Fatigue Load ◽  
Friction Stir ◽  
Absorption Energy ◽  
Spot Welded

The energy evolution, fatigue life and failure behaviour of dissimilar Al/steel keyhole-free Friction stir spot welding (FSSW) joints were studied under different fatigue loads. The absorption energy of fatigue fracture, the fracture mechanism and the sensitivity of the fatigue limits to the fatigue load parameters were analysed. It was found that the stress ratio R determines the fatigue limit Ff, while the fatigue limit Ff is not sensitive to the loading frequency. The high-frequency fatigue load will increase the displacement deformation μ and fatigue fracture absorption energy Ea of the spot-welded joint, which are larger under asymmetric fatigue loading than those under symmetrical fatigue loading. At the same time, the symmetrical fatigue load can form the steady-state hysteresis loop, while asymmetric fatigue loading cannot, but asymmetric fatigue loading exhibits the displacement increment of fatigue softening. The fracture failure of spot-welded joints is a multiple crack source and the mixed-mode of ductile and brittle fracture mechanism, which exhibits typical fatigue striations in the fatigue fractures.

Fracture mechanism of refill friction stir spot-welded 2024-T4 aluminum alloy

2016 ◽  
Vol 86 (5-8) ◽  
pp. 1925-1932 ◽  
Author(s):  
Zhengwei Li ◽  
Shude Ji ◽  
Yinan Ma ◽  
Peng Chai ◽  
Yumei Yue ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Fracture Mechanism ◽  
Friction Stir ◽  
Spot Welded

Elucidation of fatigue characteristics and fracture mechanism of friction stir spot‐welded tension–shear joint steels

2020 ◽  
Vol 44 (1) ◽  
pp. 74-84
Author(s):  
Thomasprabhu Selvaraj ◽  
Shogo Ishida ◽  
Jinta Arakawa ◽  
Hiroyuki Akebono ◽  
Atsushi Sugeta ◽  
...  
Keyword(s):  
Fracture Mechanism ◽  
Friction Stir ◽  
Shear Joint ◽  
Fatigue Characteristics ◽  
Spot Welded

S0301-6-1 Fatigue properties and 3dimensional observation about fatigue fracture morphology of spot welded joints

2009 ◽  
Vol 2009.1 (0) ◽  
pp. 115-116
Author(s):  
Ryota Tanegashima ◽  
Hiroyuki Akebono ◽  
Masahiko Kato ◽  
Aki Miyagaki ◽  
Atsushi Sugeta
Keyword(s):  
Fatigue Fracture ◽  
Welded Joints ◽  
Fracture Morphology ◽  
Fatigue Properties ◽  
Spot Welded

scholarly journals Corrosion Fatigue Fracture Characteristics of FSW 7075 Aluminum Alloy Joints

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4196
Author(s):  
Qingna Ma ◽  
Fei Shao ◽  
Linyue Bai ◽  
Qian Xu ◽  
Xingkun Xie ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Aluminum Alloys ◽  
Fatigue Fracture ◽  
Corrosion Fatigue ◽  
Weld Nugget ◽  
Fatigue Properties ◽  
Nugget Zone ◽  
Fracture Characteristics ◽  
Friction Stir ◽  
Secondary Cracks

The corrosion fatigue properties and fracture characteristics of friction stir welding joints of 7075 aluminum alloys were studied via corrosion fatigue tests, electrochemical measurements, and corrosion fatigue morphology and microstructure observations. The results show that the corrosion fatigue crack of the friction stir welding (FSW) joint of 7075 aluminum alloys originated in the junction zone between the thermomechanically affected zone and the weld nugget zone. The corrosion fatigue life of the joint decreased with increasing stress amplitude, with an S–N curve equation of lgN = 5.845 − 0.014S. Multiple crack sources were observed in the corrosion fatigue fracture. The main crack source originated from the corrosion pits at the interface between the thermomechanically affected zone and the weld nugget zone due to the influence of the coarse microstructure and the large potential difference between both zones. Corrosion morphologies of a rock candy block and an ant nest appeared in the crack propagation zone and the grain boundary of the weld nugget zone. In addition, fatigue speckles and intergranular fractures were observed, as well as brittle fracture characterized by cleavage steps and secondary cracks in the final fracture zone.

scholarly journals Influence of Strength Level of Steels on Fatigue Strength and Fatigue Fracture Mechanism of Spot Welded Joints

2006 ◽  
Vol 55 (12) ◽  
pp. 1095-1101 ◽  
Author(s):  
Keiichiro TOHGO ◽  
Ryo ADOMI ◽  
Hiroyasu ARAKI ◽  
Kazuhiro SYOKO ◽  
Hidetaka TANAKA ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Fatigue Fracture ◽  
Welded Joints ◽  
Fracture Mechanism ◽  
Strength Level ◽  
Spot Welded ◽  
Fatigue Fracture Mechanism

scholarly journals Experimental Investigation of the Three-point Bending Fatigue Properties of Carbon Fiber Composite Laminates

2016 ◽  
Vol 1 (1) ◽  
pp. 1 ◽  
Author(s):  
Meihong He ◽  
Tao Yang ◽  
Xuejuan Niu ◽  
Yu Du
Keyword(s):  
Fatigue Life ◽  
Carbon Fiber ◽  
Stress Level ◽  
Fiber Composite ◽  
Fatigue Loading ◽  
Fatigue Properties ◽  
Loading Frequency ◽  
Carbon Fiber Composite ◽  
Bending Fatigue ◽  
Three Point Bending

The three point bending fatigue properties of carbon fiber epoxy matrix composite laminates were compared for fatigue loading stress levels of 75, 80 and 85%, and fatigue loading frequencies of 10, 15 and 20Hz, respectively. The experimental results showed that: the bending fatigue life of the composites obviously decreased with the increase of the fatigue loading stress level or the loading frequency. The fatigue damage accumulation process could be divided into three distinct stages according to the accumulation rate: fast, slow and then fast. When the loading stress level was increased from 75 to 85%, the duration of the third stage decreased from 40 to 10% of the overall fatigue life. When the loading frequency was increased from 10 to 20Hz, the duration of the third stage increased from 20 to 40% of the overall fatigue life. Matrix cracking, fiber breaking, interface debonding and delamination were identified as the main three-point bending fatigue damage modes of the carbon fiber composite material, and the stress level and the loading frequency were found to significantly influence the fatigue failure properties of the composites.

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