The cracks have very little effect on the optical performance of the LiDAR sensor. Figure 4 shows a single measurement taken on a crack surface after laser treatment, as well as a measurement taken without cracks immediately after laser treatment and one taken with cracks 4. and with a powder feed flow of 9 g / min, using Ar as the carrier gas.
CRACK Carrier Block Load v4.16
The cracks have very little effect on the optical performance of the LiDAR sensor. Figure 4 shows a single measurement taken on a crack surface after laser treatment, as well as a measurement taken without cracks immediately after laser treatment and one taken with cracks 4. and with a powder feed flow of 9 g / min, using Ar as the carrier gas.
CRACK Carrier Block Load v4.17
The cracks have very little effect on the optical performance of the LiDAR sensor. Figure 4 shows a single measurement taken on a crack surface after laser treatment, as well as a measurement taken without cracks immediately after laser treatment and one taken with cracks 4. and with a powder feed flow of 9 g / min, using Ar as the carrier gas.
CRACK Carrier Block Load v4.18
The cracks have very little effect on the optical performance of the LiDAR sensor. Figure 4 shows a single measurement taken on a crack surface after laser treatment, as well as a measurement taken without cracks immediately after laser treatment and one taken with cracks 4. and with a powder feed flow of 9 g / min, using Ar as the carrier gas.
CRACK Carrier Block Load v4.19
The cracks have very little effect on the optical performance of the LiDAR sensor. Figure 4 shows a single measurement taken on a crack surface after laser treatment, as well as a measurement taken without cracks immediately after laser treatment and one taken with cracks 4. and with a powder feed flow of 9 g / min, using Ar as the carrier gas.
CRACK Carrier Block Load v4.20
The cracks have very little effect on the optical performance of the LiDAR sensor. Figure 4 shows a single measurement taken on a crack surface after laser treatment, as well as a measurement taken without cracks immediately after laser treatment and one taken with cracks 4. and with a powder feed flow of 9 g / min, using Ar as the carrier gas.
CRACK Carrier Block Load v4.21
The cracks have very little effect on the optical performance of the LiDAR sensor. Figure 4 01e38acffe
75
Figure 2. The FEM simulation result of cracks in each of the three cases with the laser power of 750 W. a) without cracks immediately after laser treatment, b) with cracks.
[5] Once the laser ablation process is complete, the loaded block is unloaded and a crack depth measurement is obtained ( Figure 3 ) (2, 5, 8, 11, 14, 17, 20). The laser is immediately turned off during the crack measurement process. Note that the original cracks, as shown in Figure 3( a), are usually straight and run along the edge of the block, though they may also be V-shaped and/or curved along some of the internal surface of the block. As shown in Figure 3( a), the crack depth, d, is the distance from the surface of the block to the bottom of the crack (c.f. Figure 4).
Case 0: Without Cracks
Figure 3. Crack depth measurement by 3D laser scanning. a) Without cracks immediately after laser treatment; b) with a crack 4.
CRACK
Case 1: With Cracks 4.5 V-Shaped
Figure 4. FEM simulation result of the crack depth in each of the three cases. a) Without cracks immediately after laser treatment, b) with V-shaped cracks 4.5.
Hence, the actual depth of the crack is given by ( Figure 5 ) (2, 5, 8, 11, 14, 17, 20):
Case 1: With Cracks 4.5 V-Shaped
In FEM analysis, material removal is modeled as the removal of volume elements and the increase in volume of the remaining part (i.e. powder layer) is proportional to the material removed. The removal rate depends on the direction of the flow of the gas and on the shape of the powder particle. In the present case, we found that the initial removal rate is low. When the laser irradiation is stopped and the powder layer begins to solidify, its mass starts to increase. The process can be described as:
v
CRACK
Case 2: With Cracks 4.5 V-Shaped
0=
where V represents the volume of the powder layer, t represents the time, m represents the material removal rate, and n represents the volume ratio of the powder layer and the block surface. The material removal rate can be given as a function of the
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