Dear SimScalers,

in this weeks spotlight we will have a look at a heat transfer simulation of a **Laser Beam Welding process** by our Applications Engineer @ahmedhussain18.

**Introduction**

Laser beam welding (LBW) is a welding technique normally used to join pieces of metal by using laser beam. The welding process is performed by indenting a concentrated heat source provided by a laser beam over the area that needs to be welded. In this project, the **Thermal Analysis** module of SimScale was usedto demonstrate this process.

The main focus was on the use of surface heat flux boundary condition to produce the effect of a moving heat source. The geometry was a simple circular plate on which a small hump in a circular fashion was made to represent the welded area.

**Geometry**

Format: **STEP**

**Meshing**

Type: **Tet-Dominant Mesh**

The geometry was meshed using tetrahedralization with refinement on SimScale platform with much finer mesh over the welding area. The mesh is shown in figure below.

Mesh nodes: 55062

1D elements (edges): 2370

2D elements (faces): 61524

3D elements (volumes): 230208

**Simulation:**

Type: **Heat Transfer - Advanced**

Steel was selected as a plate material. All the surfaces of the plate except the bottom surface were considered exposed to air by giving the convective coefficient value of 5 \frac{W}{m^2*K} at room temperature i.e. 298.15 K (25Â° C). In order to have a moving heat source in circular fashion, the welding area was given a surface heat flux by using a Gaussian power distribution function represented as:

- P is the power of laser, 2 kW in our case.
- r_o is the radius of laser beam, 0.003 m (3 mm) in our case.
- r = \sqrt{(x-x_o)^2+(y-y_o)^2} is the radial distance of the beam from any point. Here, x and y are x and y direction of the coordinate system respectively. xo and yo are the terms used for defining the motion. In our case, x_o = a + R*cos(2 \pi v_\alpha t) and y_o = b + R sin(2\pi v_Î± t), where;
- a and b are the x and y coordinates of the circle center, in our case (a,b)=(0,0).
- R is the radius of the circle, 0.035 m (3.5 cm) in our case.
- v_\alpha is the angular velocity of the beam, 0.167 \frac{rad}{s} in our case. The actual velocity of the beam can be calculated by v = 2\pi R v_\alpha which gives v ~ 0.037 \frac{m}{s} (~2.22 \frac{m}{min}.)
- t is time step which is 6 s for a full revolution with timestep length of 0.06 s in our case i.e. cos(2\pi) and sin(2\pi) occurs when v_\alpha*t = 0.167 \frac{rad}{s} x 6 s = 1 rad

**Simulations Details**

**Solution**

Machine cores: 8

Run time [min]: 16

**Numerics**

Equation solver: **Multfront**

**Results**

The figures below show the contour plots of temperature and heat flux of a circulating laser beam respectively.

**Temperature**

**Heat Flux Magnitude**

**Animation**

**Interpretation**

Although the temperature of the laser beam was much higher than the highest temperature of the legend i.e. around 2500 K, the trimmed value of 1783.15 K is used since it represents the melting temperature of steel.

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**SimScale project**:

To look at the simulation setup, please have a look at the project from @ahmedhussain18 :

**Thermal Analysis - Laser Beam Welding**

To copy this project into your workspace, simply follow the instruction given in the picture below.