基于水平集的动态接触角算法及在硅橡胶憎水性检测中的应用

Level set based dynamic contact angle algorithm and its application in silicone rubber hydrophobicity detection

浸泡、染污后硅橡胶由于表面变得粗糙和溶质沉淀导致其接触角测量存在滞后效应,为了更加准确表征其憎水性,提出将动态接触角方法应用于此种情况下硅橡胶憎水性的检测。基于动态接触角法的硅橡胶憎水性测量中接触角计算的工作量大,接触角的自动算法对其研究具有重要意义。研究通过水平集方法获得液滴的边缘,该方法基于偏微分方程,能获得全局最优的液滴边缘,抗干扰能力强,与常规方法不同,本文方法获得的边缘点是按顺序排列的,方便后续处理。此后根据液滴边缘拟合误差的大小选择圆拟合方法或多项式拟合方法拟合水珠边缘,最终获得接触角。将常规边缘检测算子、水平集方法均用于水珠图形边缘的获得,然后计算接触角,结果表明了水平集方法的有效性。将动态接触角方法应用于浸泡后的室温硫化(room temperature vu lcanization,RTV)硅橡胶涂层的憎水性的检测,结果表明动态接触角方法能更加有效表征浸泡后硅橡胶表面的憎水性。

Because of the coarseness and solute deposition of surface,contact angle measurement of immersed,contaminated silicone rubber has hysteresis phenomenon.To accurately measure hydrophobicity,a dynamic contact angle method was used to characterize the hydrophobicity of this kind of silicone rubber.Contact angle calculation in silicone rubber hydrophobicity measurement based on dynamic contact angle method is a large workload task,so contact angle automatic algorithm is important to hydrophobicity study.This paper uses level set algorithm to obtain globule edge;the algorithm is based on solving partial differential equation and can be used to obtain global optimal globule edge.Compared with conventional methods,the algorithm has high adaptability and strong noise suppression ability,and what is more,the edge curve data obtained using this algorithm is ordinal,which makes subsequent processing much easier.Then,circle equation or polynomial equation fitting methods can be selected to carry out least square fitting of the globule edge according to the fitting error,and the contact angle is obtained.Conventional edge detection operator and level set algorithm were implemented and used to detect the globule edge and calculate contact angle;results indicate that the contact angle calculated with the proposal algorithm is accurate and reliable.Finally,the dynamic contact angle method was used to study the hydrophobicity of immersed room temperature vulcanization（RTV） silicone rubber coating,and result indicates that the proposed dynamic contact angle method is more suitable for characterization of immersed silicone rubber coating surface hydrophobicity.