Numerical Simulation And Experimental Research Of Nanosecond Pulse Laser Paint Stripping On Marine Steel Surface

Laser cleaning uses high-energy laser to irradiate the surface of the materials,which makes the removed material vaporize and separate from the surface,so as to achieve the purpose of cleaning the work piece.The epoxy resin paint on AH36 marine steel surface was selected as the research object,and the nanosecond pulse laser paint removal process was studied by combining theoretical analysis,numerical simulation,experimental research and performance detection.This paper provides technical support for laser cleaning technology in ship surface paint removal through exploring the mechanism of laser paint stripping,studying the key technology of digital modeling,and establishing the process control and quality evaluation method of paint removal.The main research work is as follows:(1)Based on the adhesion theory,the physical-chemical mechanism of the combination of epoxy resin coating and marine steel substrate was studied.According to the laser irradiation theory,the thermal effect induced by pulsed laser was explored,and the partial differential equation of heat conduction was solved.Based on the thermal response characteristics under laser irradiation,the mechanism of paint fragmentation and separation evolution during laser paint stripping was studied.The model of laser paint stripping was established,and the relationship between process parameters and its influence on cleaning efficiency were analyzed,which provide theoretical basis for the cooperative control of parameters.(2)Based on ANSYS finite element software,the digital analysis model of laser paint stripping process was established.The key technologies such as high-speed moving heat source loading,displacement change of ablation layer and “Birth & Death”grid processing were solved,which broke through the technical bottleneck of laser cleaning morphology simulation.The influence of process parameters on the temperature field and surface cleaning profile formed by single pulse crater,multi pulse trench and plane,and surface cleaning were researched.The visualization of laser cleaning surface morphology under different process parameters combination was realized,which provided the basis for the selection of process window and parameter optimization of specific cleaning objects.(3)The fiber laser was used to carry out a series of laser dry cleaning tests for epoxy resin coating on marine steel surface by selecting different combinations of laser irradiation parameters,including energy density,scanning speed,scanning distance,etc.A variety of surface detection technologies were adopted,and the surface quality evaluation system and criteria for laser cleaning were put forward.The cleaning threshold and damage threshold were calculated,and the surface morphology and element content of the material after paint removal were analyzed to study the influence of different cleaning conditions on the removal behavior of paint layer,and to optimize the process parameters of laser paint removal.Finally,a path planning scheme for high efficiency laser cleaning was proposed.(4)On the basis of laser paint removal,the material performance after paint removal was tested.The influence of treatment process on the micro hardness,corrosion resistance and recoating bonding performance of ship plate was studied respectively.Compared with traditional paint removal technology,the feasibility of laser dry cleaning in ship surface paint removal was explored.