# Numerical Simulation for FSW Process at Welding Aluminium Alloy AA6082-T6

^{*}

## Abstract

**:**

^{o}, a diameter of the pin d mm, diameter of the shoulder D mm. During the performing of the FSW process, forces were measured in three normal directions: Axial force F

_{z}, longitudinal force F

_{x}and side force F

_{y}, as well as the temperature in the adopted measuring positions of the workpiece. The experimental results obtained in this way were compared with the numerical experiment in the same adopted measuring positions, i.e., in the paper an analysis and comparison of the obtained experimental and numerical data of the measured forces and the generated temperature field were made.

## 1. Introduction

## 2. Experimental Research

_{0}= 4. The total number of experimental points is determined by the expression:

^{0}—the angle of pin slope,

#### 2.1. Measurement of Forces

_{z}, the longitudinal force F

_{x}, and the side force F

_{y}(Figure 4).

#### 2.2. Temperature Measurement

_{1}, T

_{2}, T

_{3}, T

_{4}, T

_{5,}and T

_{6}in the function of time are shown [22].

## 3. Numerical Simulation

_{u}= 200 mm/min, v

_{l}= 80 mm/min and v

_{b}= 125 mm/min.

_{z}, F

_{x}, and F

_{y}which occur during the first phase of the numerical simulations for the 34th point of the experimental plan are presented in Figure 9.

_{z}, F

_{x}, and F

_{y}of the second phase of simulation for the 34th point of the experimental plan are given in Figure 10. Data for welding force components obtained in DEFORM 3D, for all points of the experimental plan, are processed in the MATLAB (vR2015a, MathWorks, Natick, MA, USA) software, and for the points 1 and 20 of the experimental plan, shown in Figure 11.

## 4. Results and Discussion

_{z}and F

_{y}reach their highest values. Since in this stage the tool is plunged into the material, variable values of the force are obtained. As F

_{z}is an axial force that presses material, it always has positive values. Due to the consequence of heat generation when plunging the tool, the F

_{x}force material may also have negative values ranging from −0.12 to −0.48 kN for all points of the experimental plan. As the direction of rotation of the tool corresponds to the direction of rotation of the hands on the clock, the values of force F

_{y}are obtained positively, because, during rotation, the tool tends to turn the workpieces in the same direction. At this stage, the maximum values of the force F

_{z}for all points of the experimental plan range from 5.3620 to 9.7300 kN, while the values of force F

_{y}range from 0.3877 to 1.1375 kN.

_{x}, F

_{y}and F

_{z}retain constant values. For the process of welding by FSW, from the point of view of energy consumption, the most important is the vertical component of the force F

_{z}, which is often called the welding force. For each point of the experimental plan, the component F

_{z}compared to the other two components of the force F

_{x}and F

_{y}has a higher value. The force F

_{z}ranges from 2.4099 to 5.4799 kN, and the force F

_{x}from 1.0118 to 1.7561 kN, while the force F

_{y}is from 0.0987 to 0.2316 kN.

_{x}force, the welding speed has the greatest influence. The higher the welding speed, the greater the resistance of the material to the tool, and the higher values of the longitudinal force F

_{x}are obtained. Another significant factor that influences the value of force F

_{x}is the angular rotation speed of the tool, and the third surface of the tool in contact with the material. If the rotation speed of tool is larger and the surface of the tool is larger, more heat is generated, so the tool moves easily through the material so that the resistance is smaller and the lower value of the F

_{x}force is obtained. If the rotation speed of tool is smaller, and the surface of the tool will generate less heat, so the resistance to the movement of the tool will be higher, and therefore the longitudinal force F

_{x}will be higher.

_{y}force acting in the side direction has relatively low values compared to other forces, so its influence on the welding process is relatively small.

_{z}and F

_{y}reach their highest values. Analogously to the experimental values in this stage, variable values of the force are obtained. For numerical simulations, the force F

_{z}always has positive values, while the forces F

_{x}and F

_{y}have negative values in this stage of plunging the tool into the material. Force F

_{x}and F

_{y}at this stage have approximate values that range within ± 1.2 kN. At this stage, the maximum values of the force F

_{z}for all numerical simulations range from 7.1982 to 11.5214 kN.

_{x}, F

_{y}and F

_{z}also retain constant values until the simulation is complete, after 166 mm of travel. In each numerical simulation, the component F

_{z}has higher values than the components F

_{x}and F

_{y}. Force F

_{z}in this stage for all numerical simulations ranges from 3.3429 to 6.3681 kN, and force F

_{x}from 1.2968 to 2.2801 kN, while force F

_{y}is from 0.1420 to 0.3103 kN. For numerical simulations of the FSW process, the force F

_{y}, which acts in the side direction, also has relatively small values, so its effect on the friction welding process is small.

_{z}, that is, the welding forces obtained by experimental and numerical simulations, are given.

_{1}, T

_{2}, T

_{3}, T

_{4}, T

_{5,}and T

_{6}for all points of the experimental plan are shown.

_{4}. This thermocouple is at a distance from the joint line of 7 mm, so at this measuring point, the highest values of the measured temperature are obtained. The smallest measured value in the thermocouple number T

_{4}is at the 17th point of the experimental plan and is 254.5 °C. Otherwise, in the 17th point of the experimental plan, the least measured values for all other thermocouple positions were obtained, and the smallest was 135.1 °C, at a distance of 27 mm from the joint line in the upper zone. The reason for this low value of the temperature obtained is the consequence of the unfavorable relationship of the varied factors, which resulted in poor quality seams.

_{4}is closest to the joint line, at this point we have the highest values of the numerically generated temperature. The lowest value of the temperature at point P

_{4}is in the 21st simulation and is 310.14 °C. At point P

_{1}located in the lower zone and 12 mm from the joint line, the highest temperature value was obtained also in the 16th simulation, which is 405.04 °C. In the 17th simulation for the points P

_{1}, P

_{2}, P

_{3}, P

_{5,}and P

_{6}, the lowest temperature values were obtained, and the smallest is at the point P

_{3}of the upper zone, at a distance of 27 mm from the joint line and is 112.30 °C. Point P

_{5}is located in the upper zone at a distance of 17 mm from the joint line, and the highest temperature was measured in the 12th numerical simulation and is 354.15 °C. In the 12th simulation at point P

_{2}, located in the lower zone at a distance of 22 mm from the joint line, the highest temperature value was obtained, which is 310.26 °C. In the 10th simulation, at points P

_{3}and P

_{6}, the highest temperature was obtained. For point P

_{3}it is 233.26 °C, and for P

_{6,}227.70 °C.

## 5. Conclusions

_{x}, F

_{y}and F

_{z}were determined, as well as the distribution of the welded sample temperature from the aluminum alloy obtained by the FSW method. The influence of tool geometry (diameter of the shoulder, pin diameter, and angle of pin slope) and the welding speed and rotation speed on the change of force and temperature were investigated. The experiments were performed experimentally using special tools and accessories, as well as numerically, using the DEFORM 3D software package. By analyzing the obtained dependencies, we conclude that the FSW technology can be successfully applied to the welding of the investigated alumina alloy AA6082-T6.

_{z}, which is often called the welding force. It can be concluded that the geometric parameters of the tool, especially the size of the shoulder of the tool, have the largest influence on the F

_{z}value. All obtained values of the F

_{z}force can be divided into three areas. The first 16 points of the experimental plan belong to the first area. This is the area where the diameter of the shoulder of the tool is 28 mm. Here the values of the force F

_{z}are obtained from the limits of 3.4614 to 5.4799 kN. The other area belongs to the points of the experimental plan from 17 to 32, where the diameter of the shoulder of the tool is 25 mm, and the force ranges from 2.4099 to 4.0428 kN. The third area belongs to the central points of the plan, where the diameter of the shoulder of the tool is 26.46 mm, and the mean value of the force F

_{z}at these points is 3.6008 kN.

_{z}can also be divided into three areas: The area of the larger diameter of the shoulder of the tool of 28 mm, the area of the smaller diameter of the shoulder of the tool of 25 mm and the area of 26.46 mm (center point of the plan).

## Author Contributions

## Conflicts of Interest

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**Figure 3.**The welded joint in the 1st point of the experimental plan. (

**a**) a view from the top; (

**b**) a bottom view.

**Figure 4.**Diagram of forces F

_{z}, F

_{x}, and F

_{y}at the points of the experimental plan: (

**a**) number 1; (

**b**) number 20; (

**c**) number 34.

**Figure 5.**Scheme of measuring temperature positions in the workpiece to be welded [22].

**Figure 6.**Diagram of temperature at the points of the experimental plan number: 1, 20, and 34 [22].

**Figure 9.**The forces obtained by numerical simulation in the first stage of the process for the 34th point of the experimental plan: (

**a**) Axial force F

_{z}; (

**b**) longitudinal force F

_{x}; (

**c**) side force F

_{y}.

**Figure 10.**The forces obtained by numerical simulation in the second stage of the process for the 34th point of the experimental plan: (

**a**) Axial force F

_{z}; (

**b**) longitudinal force F

_{x}; (

**c**) side force F

_{y}.

**Figure 11.**Forces obtained by numerical simulation (

**a**) for the 1st point of the experimental plan; (

**b**) for the 20th point of the experimental plan.

**Figure 12.**Distribution of temperature fields: (

**a**) At the end of the first phase of the FSW process; (

**b**) at the end of the second phase of the FSW process.

**Figure 13.**The resulting temperature diagram numerical simulations at the six selected points for 33rd, 34th, 35

^{th}, and 36th point of the experimental plan [22].

**Figure 15.**The obtained values of the welding temperature in the adopted measuring positions, for all points of the experimental plan.

No. | Welding speed mm/min | Rotation speed of tool rpm | The angle of pin slope ° | Tool pin diameter mm | Tool shoulder diameter mm | Output vectors Y |
---|---|---|---|---|---|---|

${X}_{1}=v$ | ${X}_{2}=\omega $ | ${X}_{3}=\alpha $ | ${X}_{4}=d$ | ${X}_{5}=D$ 28 25 26.46 | F_{x}, F_{y}, F_{z},T _{1}, T_{2}, T_{3}, T_{4}, T_{5}, T_{6} | |

${x}_{ui}$ ${x}_{li}$ ${x}_{bi}$ | 200 80 125 | 1000 630 800 | 5 3 3.87 | 7 5 5.92 |

Parameters | Tools9 - - Workpiece | Basic Plate - - Workpiece |
---|---|---|

Contact relation CNTACT | Master-Slave Shear 0.4 5 | Master-Slave Shear 0.4 5 |

Friction model FRCFAC Friction Heat Transfer Coefficient |

No. | 1 | 2 | 3 | 4 | 5 | 6 |
---|---|---|---|---|---|---|

1. | 305.92 | 219.31 | 170.23 | 371.82 | 263.51 281.47 328.03 | 161.90 187.19 187.62 |

20. 34. | 313.46 383.25 | 243.85 278.42 | 193.96 193.17 | 358.62 445.10 |

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

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**MDPI and ACS Style**

Sibalic, N.; Vukcevic, M. Numerical Simulation for FSW Process at Welding Aluminium Alloy AA6082-T6. *Metals* **2019**, *9*, 747.
https://doi.org/10.3390/met9070747

**AMA Style**

Sibalic N, Vukcevic M. Numerical Simulation for FSW Process at Welding Aluminium Alloy AA6082-T6. *Metals*. 2019; 9(7):747.
https://doi.org/10.3390/met9070747

**Chicago/Turabian Style**

Sibalic, Nikola, and Milan Vukcevic. 2019. "Numerical Simulation for FSW Process at Welding Aluminium Alloy AA6082-T6" *Metals* 9, no. 7: 747.
https://doi.org/10.3390/met9070747