脉冲激光去除绝缘子表面污秽热应力分析

Stress Analysis of Surface Contamination of Insulator Cleaned by Pulse Laser

脉冲激光清洗绝缘子表面污秽会产生较大的热应力,热应力大于黏附力则污秽层脱落。本文以瓷式绝缘子及其表面污秽为对象,建立有限元模型,分析在不同能量密度下,由温差产生的热应力场变化规律,研究脉冲激光清洗绝缘子污秽机制,确定最佳清洗能量密度,并以激光实验证明清洗效果。结果表明,绝缘子表面的第一主应力先表现为压应力,在光斑中心处达到最大值,安全工况下最大可达到1240 MPa,随着径深的增加逐渐转化为拉应力,中心以下0.014 mm处拉应力达到最大值,为105 MPa,此处污秽先被清除;激光能量密度为2.52 J/cm2~3.81 J/cm2可实现安全有效清洗。此研究成果为脉冲激光清洗瓷式绝缘子能量密度的选择提供了重要依据。

When the surface pollution of the insulator is cleaned by pulsed laser,the great temperature difference will produce great thermal stress.If the thermal stress is greater than the adhesive force,the pollution layer will fall off.This paper took porcelain insulator and its surface pollution as the object,established the finite element model,analyzed the change law of thermal stress field generated by temperature difference under different energy density,studies the pollution mechanism of pulsed laser cleaning insulator,and determined the optimal cleaning energy density.Also,the cleaning effect has proved by laser experiment.The results show that the first principal stress first presents as compressive stress,which reaches the maximum value at the center of the spot,and the maximum value can reach 1240 MPa under the condition of ensuring safe cleaning.With the increase of diameter and depth,it is gradually transformed into tensile stress,and the maximum value at 0.014 mm below the center is 105 MPa,where the dirt is removed first.The laser energy density is 2.52 J/cm^2~3.81 J/cm^2,which can realize safe and effective cleaning.The results of this study provide an important basis for the selection of energy density of pulsed laser cleaning porcelain insulator.