This research focuses on the computational modelling and comparative analysis of friction stir we... more This research focuses on the computational modelling and comparative analysis of friction stir welding (FSW) and stationary shoulder friction stir welding (SSFSW) applied to AA6061-T6 aluminium alloy. SSFSW, an FSW variant, employs a stationary shoulder and a rotating pin. This study introduces a numerical model for both processes, using the innovative Smoothed Particle Hydrodynamics (SPH) technique to capture their distinct thermo-mechanical characteristics. The aim is to unravel its mechanics and multi-physics in SSFSW and compare it with conventional FSW. The temperatures predicted by the model exhibited a close agreement between the advancing side (AS) and retreating side (RS). Plastic strain patterns show that regular FSW is different from SSFSW. In SSFSW, the strain is less, and the plastic area is comparatively slightly narrower. The distinct “ironing effect” resulting from the stationary shoulder in SSFSW reduces the heat-affected zone (HAZ). Yet, it maintains efficient plas...
A thermo-mechanical model of friction stir processing (FSP) using the Altair based on meshless Sm... more A thermo-mechanical model of friction stir processing (FSP) using the Altair based on meshless Smoothed-Particle Hydrodynamics (SPH) was developed and verified experimentally. Process parameters adopted for both experimentation and simulation during the FSP of AZ91 were 1000 rpm tool stirring speed, 40 mm/min tool advancing speed, and 0° tool tilt angle. The numerical analysis predicted the temperature distribution and material movement in the three phases: plunging, dwelling, and traversing. Simulated temperatures during the traversal phase were found to be greater than experimental temperatures using the Ti32 thermal camera as the heat was only transported by friction and plastic deformation. Peak temperatures for all three phases were observed to be in the range of 47% to 87% of the material’s melting point and are in accordance with the findings of the experiments. The SPH mesh-free model was proven to be capable of predicting the in-process thermal-mechanical state variables du...
Plunge depth is one of the most important process parameters that affect the joint strength in re... more Plunge depth is one of the most important process parameters that affect the joint strength in refill friction stir spot welding (refill FSSW). In this study, a three-dimensional numerical model is developed using the Lagrangian incremental formulation in DEFORM-3D to simulate the refill FSSW process of thin AA7075-T6 sheets. The numerical model is verified by comparing the obtained temperatures at specific locations with the temperatures from the previous experimental studies. Material flow and temperature behaviors at three different plunge depths are analyzed using the numerical model. The temperatures and effective strains in the weld zone increased with an increase in plunge depth. The movement of the material in the stir zone is enhanced and a larger extent of material from the bottom sheet is involved in the stirring with the increase in plunge depth. The width and thickness of the stir zone are identified from the numerical model and are consistent with the experimental stud...
The refill friction stir spot welding (refill FSSW) process is a solid-state joining process to p... more The refill friction stir spot welding (refill FSSW) process is a solid-state joining process to produce welds without a keyhole in spot joint configuration. This study presents a thermo-mechanical model of refill FSSW, validated on experimental thermal cycles for thin aluminium sheets of AA7075-T6. The temperatures in the weld centre and outside the welding zone at selected points were recorded using K-type thermocouples for more accurate validation of the thermo-mechanical model. A thermo-mechanical three-dimensional refill FSSW model was built using DEFORM-3D. The temperature results from the refill FSSW numerical model are in good agreement with the experimental results. Three-dimensional material flow during plunging and refilling stages is analysed in detail and compared to experimental microstructure and hardness results. The simulation results obtained from the refill FSSW model correspond well with the experimental results. The developed 3D numerical model is able to predict...
Plunge depth is one of the most important process parameters that affect the joint strength in re... more Plunge depth is one of the most important process parameters that affect the joint strength in refill friction stir spot welding (refill FSSW). In this study, a three-dimensional numerical model is developed using the Lagrangian incremental formulation in DEFORM-3D to simulate the refill FSSW process of thin AA7075-T6 sheets. The numerical model is verified by comparing the obtained temperatures at specific locations with the temperatures from the previous experimental studies. Material flow and temperature behaviors at three different plunge depths are analyzed using the numerical model. The temperatures and effective strains in the weld zone increased with an increase in plunge depth. The movement of the material in the stir zone is enhanced and a larger extent of material from the bottom sheet is involved in the stirring with the increase in plunge depth. The width and thickness of the stir zone are identified from the numerical model and are consistent with the experimental study from the literature. The increase and decrease in joint strength with the increase in plunge depth reported in the literature are correlated to the material flow behavior in the numerical models.
The refill friction stir spot welding (refill FSSW) process is a solid-state joining process to p... more The refill friction stir spot welding (refill FSSW) process is a solid-state joining process to produce welds without a keyhole in spot joint configuration. This study presents a thermo-mechanical model of refill FSSW, validated on experimental thermal cycles for thin aluminium sheets of AA7075-T6. The temperatures in the weld centre and outside the welding zone at selected points were recorded using K-type thermocouples for more accurate validation of the thermo-mechanical model. A thermo-mechanical three-dimensional refill FSSW model was built using DEFORM-3D. The temperature results from the refill FSSW numerical model are in good agreement with the experimental results. Three-dimensional material flow during plunging and refilling stages is analysed in detail and compared to experimental microstructure and hardness results. The simulation results obtained from the refill FSSW model correspond well with the experimental results. The developed 3D numerical model is able to predict the thermal cycles, material flow, strain, and strain rates which are key factors for the identification and characterization of zones as well for determining joint quality.
This research focuses on the computational modelling and comparative analysis of friction stir we... more This research focuses on the computational modelling and comparative analysis of friction stir welding (FSW) and stationary shoulder friction stir welding (SSFSW) applied to AA6061-T6 aluminium alloy. SSFSW, an FSW variant, employs a stationary shoulder and a rotating pin. This study introduces a numerical model for both processes, using the innovative Smoothed Particle Hydrodynamics (SPH) technique to capture their distinct thermo-mechanical characteristics. The aim is to unravel its mechanics and multi-physics in SSFSW and compare it with conventional FSW. The temperatures predicted by the model exhibited a close agreement between the advancing side (AS) and retreating side (RS). Plastic strain patterns show that regular FSW is different from SSFSW. In SSFSW, the strain is less, and the plastic area is comparatively slightly narrower. The distinct “ironing effect” resulting from the stationary shoulder in SSFSW reduces the heat-affected zone (HAZ). Yet, it maintains efficient plas...
A thermo-mechanical model of friction stir processing (FSP) using the Altair based on meshless Sm... more A thermo-mechanical model of friction stir processing (FSP) using the Altair based on meshless Smoothed-Particle Hydrodynamics (SPH) was developed and verified experimentally. Process parameters adopted for both experimentation and simulation during the FSP of AZ91 were 1000 rpm tool stirring speed, 40 mm/min tool advancing speed, and 0° tool tilt angle. The numerical analysis predicted the temperature distribution and material movement in the three phases: plunging, dwelling, and traversing. Simulated temperatures during the traversal phase were found to be greater than experimental temperatures using the Ti32 thermal camera as the heat was only transported by friction and plastic deformation. Peak temperatures for all three phases were observed to be in the range of 47% to 87% of the material’s melting point and are in accordance with the findings of the experiments. The SPH mesh-free model was proven to be capable of predicting the in-process thermal-mechanical state variables du...
Plunge depth is one of the most important process parameters that affect the joint strength in re... more Plunge depth is one of the most important process parameters that affect the joint strength in refill friction stir spot welding (refill FSSW). In this study, a three-dimensional numerical model is developed using the Lagrangian incremental formulation in DEFORM-3D to simulate the refill FSSW process of thin AA7075-T6 sheets. The numerical model is verified by comparing the obtained temperatures at specific locations with the temperatures from the previous experimental studies. Material flow and temperature behaviors at three different plunge depths are analyzed using the numerical model. The temperatures and effective strains in the weld zone increased with an increase in plunge depth. The movement of the material in the stir zone is enhanced and a larger extent of material from the bottom sheet is involved in the stirring with the increase in plunge depth. The width and thickness of the stir zone are identified from the numerical model and are consistent with the experimental stud...
The refill friction stir spot welding (refill FSSW) process is a solid-state joining process to p... more The refill friction stir spot welding (refill FSSW) process is a solid-state joining process to produce welds without a keyhole in spot joint configuration. This study presents a thermo-mechanical model of refill FSSW, validated on experimental thermal cycles for thin aluminium sheets of AA7075-T6. The temperatures in the weld centre and outside the welding zone at selected points were recorded using K-type thermocouples for more accurate validation of the thermo-mechanical model. A thermo-mechanical three-dimensional refill FSSW model was built using DEFORM-3D. The temperature results from the refill FSSW numerical model are in good agreement with the experimental results. Three-dimensional material flow during plunging and refilling stages is analysed in detail and compared to experimental microstructure and hardness results. The simulation results obtained from the refill FSSW model correspond well with the experimental results. The developed 3D numerical model is able to predict...
Plunge depth is one of the most important process parameters that affect the joint strength in re... more Plunge depth is one of the most important process parameters that affect the joint strength in refill friction stir spot welding (refill FSSW). In this study, a three-dimensional numerical model is developed using the Lagrangian incremental formulation in DEFORM-3D to simulate the refill FSSW process of thin AA7075-T6 sheets. The numerical model is verified by comparing the obtained temperatures at specific locations with the temperatures from the previous experimental studies. Material flow and temperature behaviors at three different plunge depths are analyzed using the numerical model. The temperatures and effective strains in the weld zone increased with an increase in plunge depth. The movement of the material in the stir zone is enhanced and a larger extent of material from the bottom sheet is involved in the stirring with the increase in plunge depth. The width and thickness of the stir zone are identified from the numerical model and are consistent with the experimental study from the literature. The increase and decrease in joint strength with the increase in plunge depth reported in the literature are correlated to the material flow behavior in the numerical models.
The refill friction stir spot welding (refill FSSW) process is a solid-state joining process to p... more The refill friction stir spot welding (refill FSSW) process is a solid-state joining process to produce welds without a keyhole in spot joint configuration. This study presents a thermo-mechanical model of refill FSSW, validated on experimental thermal cycles for thin aluminium sheets of AA7075-T6. The temperatures in the weld centre and outside the welding zone at selected points were recorded using K-type thermocouples for more accurate validation of the thermo-mechanical model. A thermo-mechanical three-dimensional refill FSSW model was built using DEFORM-3D. The temperature results from the refill FSSW numerical model are in good agreement with the experimental results. Three-dimensional material flow during plunging and refilling stages is analysed in detail and compared to experimental microstructure and hardness results. The simulation results obtained from the refill FSSW model correspond well with the experimental results. The developed 3D numerical model is able to predict the thermal cycles, material flow, strain, and strain rates which are key factors for the identification and characterization of zones as well for determining joint quality.
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