Fatigue Failure of Laser Welds in Lap-Shear Specimens of High Strength Low Alloy (HSLA) Steels under Cyclic Loading Conditions

2011 ◽  
Vol 4 (1) ◽  
pp. 571-580 ◽  
Author(s):  
Kamran Asim ◽  
Kulthida Sripichai ◽  
Jwo Pan
Keyword(s):  
Cyclic Loading ◽  
Fatigue Failure ◽  
High Strength ◽  
Loading Conditions ◽  
Lap Shear ◽  
Hsla Steels ◽  
Laser Welds

Fatigue Behavior of Laser Welds in Lap-Shear Specimens of High Strength Low Alloy (HSLA) Steels

2009 ◽  
Vol 2 (1) ◽  
pp. 40-46 ◽  
Author(s):  
K. Sripichai ◽  
Kamran Asim ◽  
W. H. Jo ◽  
Jwo Pan ◽  
Meng-Yen Li
Keyword(s):  
Fatigue Behavior ◽  
High Strength ◽  
Lap Shear ◽  
Hsla Steels ◽  
Laser Welds

Failure Mechanism of Laser Welds in Lap-Shear Specimens of a High Strength Low Alloy Steel

2010 ◽  
Author(s):  
Kamran Asim ◽  
Jaewon Lee ◽  
Jwo Pan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Failure Mechanism ◽  
Shear Failure ◽  
High Strength ◽  
Yield Function ◽  
Element Analysis ◽  
Lap Shear ◽  
Laser Welds ◽  
The Finite Element Analysis

In this study, the failure mechanism of laser welds in lap-shear specimens of a high strength low alloy (HSLA) steel under quasi-static loading conditions is examined based on the experimental results. Optical micrographs of the welds in specimens before tests were examined to understand the microstructure near the weld. A micrographic analysis of the failed welds in lap-shear specimens indicates a ductile necking/shear failure mechanism near the heat affected zone. Micro-hardness tests were conducted to provide an assessment of the mechanical properties of the joint area which has varying microstructure due to the welding process. A finite element analysis was also carried out to identify the effects of the weld geometry and different mechanical properties of the weld and heat affected zones on the failure mechanism. The computational results of the finite element analysis indicate that the material inhomogeneity and geometry of the weld bead play an important role in the ductile necking/shear failure mechanism. The computational results match well with the experimental observations of the necking/shear failure and its location. A finite element analysis with consideration of void nucleation and growth based on the Gurson yield function was also carried out. The results of the finite element analysis based on the Gurson yield function are in good agreement with the experimental observations of the initiation of ductile fracture and its location.

scholarly journals Fatigue Life Assessment of Refill Friction Stir Spot Welded Alclad 7075-T6 Aluminium Alloy Joints

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 633
Author(s):  
Andrzej Kubit ◽  
Mateusz Drabczyk ◽  
Tomasz Trzepiecinski ◽  
Wojciech Bochnowski ◽  
Ľuboš Kaščák ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Aluminium Alloy ◽  
Crack Growth ◽  
Fatigue Failure ◽  
Spot Welding ◽  
Lap Joints ◽  
Life Assessment ◽  
Loading Conditions ◽  
Friction Stir ◽  
Lap Shear

Refill Friction Stir Spot Welding (RFSSW) shows great potential to be a replacement for single-lap joining techniques such as riveting or resistance spot welding used in the aircraft industry. In this paper, the fatigue behaviour of RFSSW single-lap joints is analysed experimentally in lap-shear specimens of Alclad 7075-T6 aluminium alloy with different thicknesses, i.e., 0.8 mm and 1.6 mm. The joints were tested under low-cycle and high-cycle fatigue tests. Detailed observations of the fatigue fracture characteristics were conducted using a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS). The locations of fatigue failure across the weld, fatigue crack initiation, and propagation behaviour are discussed on the basis of the SEM analysis. The possibility of predicting the propagation of fatigue cracks in RFSSW joints is verified based on Paris’s law. Two fatigue failure modes are observed at different load levels, including shear fracture mode transverse crack growth at high stress-loading conditions and at low load levels, and destruction of the lower sheet due to stretching as a result of low stress-loading conditions. The analysis of SEM micrographs revealed that the presence of aluminium oxides aggravates the inhomogeneity of the material in the weld nugget around its periphery and is a source of crack nucleation. The results of the fatigue crack growth rate predicted by Paris’s law were in good agreement with the experimental results.

Failure Mechanism of Laser Welds in Lap-Shear Specimens of a High Strength Low Alloy Steel

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Jaewon Lee ◽  
Kamran Asim ◽  
Jwo Pan
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Failure Mechanism ◽  
Shear Failure ◽  
High Strength ◽  
Element Analysis ◽  
Lap Shear ◽  
Laser Welds ◽  
The Finite Element Analysis

In this study, the failure mechanism of laser welds in lap-shear specimens of a high strength low alloy (HSLA) steel under quasi-static loading conditions is examined based on the experimental and computational results. Optical micrographs of the welds in the specimens before tests were examined to understand the microstructure near the weld. A micrographic analysis of the failed welds in lap-shear specimens indicates a ductile necking/shear failure mechanism near the heat affected zone. Micro-hardness tests were conducted to provide an assessment of the mechanical properties of the joint area which has varying microstructure due to the welding process. A finite element analysis was also carried out to identify the effects of the weld geometry and different mechanical properties of the weld and heat affected zones on the failure mechanism. The results of the finite element analysis show that the geometry of the weld protrusion and the higher effective stress–plastic strain curves of the heat affected and weld zones result in the necking/shear failure of the load carrying sheet. The deformed shape of the finite element model near the weld matches well with that near a failed weld. A finite element analysis based on the Gurson yield function with consideration of void nucleation and growth was also carried out. The results of the finite element analysis indicate that the location of the material elements with the maximum void volume fraction matches well with that of the initiation of ductile fracture as observed in the experiments.

Structural response of high strength S690 welded sections under cyclic loading conditions

2021 ◽  
Vol 182 ◽  
pp. 106696
Author(s):  
H.C. Ho ◽  
Y.B. Guo ◽  
M. Xiao ◽  
T.Y. Xiao ◽  
H. Jin ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Structural Response ◽  
High Strength ◽  
Loading Conditions
Sign in / Sign up

Export Citation Format

Share Document