Numerical simulation method of pulsed laser paint removal and use thereof

Patent metadata

Field	Value
Publication number	US-11625514-B2
Application number	US-202117614569-A
Country	US
Kind code	B2
Filing date	Jun 18, 2021
Priority date	Aug 13, 2020
Publication date	Apr 11, 2023
Grant date	Apr 11, 2023

Abstract

The present disclosure provides a numerical simulation method of pulsed laser paint removal and a use thereof. This method establishes a three-dimensional (3D) temperature field model by ANSYS software to perform a numerical simulation of nanosecond pulsed laser paint removal. A high-speed moving pulsed laser is loaded on a surface of the model in a form of heat flux, and a coordinate system is moved to realize loading on different paths. A special surface mesh screening method is used to realize loading on any surface, and it ensures that laser energy distribution on a material surface is in line with reality. In addition, an element birth/death technology is combined to remove an element that exceeds a threshold, so as to intuitively present the surface morphology after laser paint removal. The present disclosure can realize the prediction of the contour of a paint layer ablated by a pulsed laser.

First claim

What is claimed is:

1. A numerical simulation method of pulsed laser paint removal, comprising the following steps:
step 1: establishing a two-layer three-dimensional (3D) solid model of a paint layer and a substrate, and conducting meshing, wherein in the 3D solid model, a selected element type is an 8-node hexahedral thermal element;
step 2: setting an initial condition of a temperature field of the model to an ambient temperature, and setting a load option to transient analysis and a load mode to step load;
step 3: establishing a coordinate system with a center of a single-pulse spot on an upper surface of the paint layer as an origin, taking an axial incident direction of a laser as a z-axis, taking the origin of the coordinate system as a pulsed laser loading position, and defining the upper surface of the paint layer as a z=0 plane;
step 4: selecting nodes having a perpendicular distance not exceeding a radius of the spot from the z-axis in the 3D solid model to form a laser irradiation coverage zone, and selecting nodes with less than 8 surviving elements attached, among the nodes in the laser irradiation coverage zone, to form a laser irradiated surface;
step 5: loading a pulsed laser onto a surface of the model in a form of heat flux, the elements attached to the nodes at the laser irradiated surface being laser irradiated elements; and calculating an energy load q received by a node on an upper surface of a laser irradiated element whose center has a distance of h from the z-axis:

q
⁡
(

h
,
t

)

=

12
·
aP

f
⁢

τ
·
π

⁢

d
2

·

exp
⁡
(

-

12
·

h
2

d
2

)

·

(

t
τ

)

7

⁢

exp
[

7
⁢

(

1
-

t
τ

)

]

(
1
)

wherein, a is an absorption rate of laser energy by a material, P is a laser output power, f is a laser repetition frequency, d is a spot diameter, τ is a laser pulse width, and t is a time, 0<t<τ;
step 6: performing iterative solution in a form of time integration according to a heat conservation law of a heat transfer theory, to calculate an instantaneous temperature of each of the nodes; and
step 7: defining an instantaneous temperature of the surviving elements reaching a threshold temperature or above as a condition for an element birth/death operation, and killing a surviving element whose instantaneous temperature exceeds the threshold temperature, to obtain morphology after the removal of the paint layer by a single pulsed laser.

2. The numerical simulation method of pulsed laser paint removal according to claim 1 , wherein the threshold temperature is a vaporization temperature of a material of the paint layer.

3. The numerical simulation method of pulsed laser paint removal according to claim 1 , wherein the heat conservation law of the heat transfer theory is that a temperature change of the material subjected to laser irradiation satisfies:

∂
T

∂
t

=

k
⁡
(

∂
2

T

∂

x
2

+

∂
2

T

∂

y
2

+

∂
2

T

∂

z
2

Assignees

• Univ Jiangsu

Inventors

• Zhou Jianzhong
• Gou Yanqiang
• Yang Jianian
• Meng Xiankai
• Sun Qi
• Huang Shu
• Fu Qiang

Classifications

• G06F30/23 Primary

  using finite element methods [FEM] or finite difference methods [FDM] · CPC title

• B23K26/40

  taking account of the properties of the material involved · CPC title

• B23K26/0622 Primary

  by shaping pulses · CPC title

• G06F2111/10

  Numerical modelling · CPC title

• G06F30/20 Primary

  Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30) · CPC title