摘要
点蚀是导致结构失效的重要机理之一,点蚀形貌中隐含了大量的有用信息。针对点蚀形貌及尺寸的演化情况,采用三维元胞自动机技术对腐蚀环境中的金属腐蚀生长演化过程进行模拟。将腐蚀损伤生长过程模拟成一个离散的动力学系统,在模拟过程中着重考虑了腐蚀过程中发生的质量转移、金属溶解及钝化、IR降等基本化学物理现象,并定义了相应的局部规则。通过模拟得到了在不同环境下蚀坑的腐蚀损伤形貌。将蚀坑看做半椭球体,可以得到蚀坑的等效深度,定义蚀坑深度比为蚀坑等效深度与蚀坑模拟深度的比值,利用该参数对蚀坑趋近于半椭球体的程度进行分析;对等效为半椭球体的蚀坑,采用蚀坑尺寸比率对等效蚀坑的几何形貌进行研究。结果表明:蚀坑在生长过程中,几何形貌会达到一种相对稳定的状态。初步的研究将有助于进一步理解点蚀生长机理,为疲劳寿命预测及结构完整性分析提供有用信息。
Pitting corrosion is one of the most significant degradation mechanisms that affect the integrity of a structure, and a great deal of useful information may be revealed by a study on corrosion pit growth morphology. To obtain the corrosion pit morphology as well as the aspect characteristics of an object subjected to a corrosive environment, a three-dimensional model is developed to simulate the evolution of pitting corrosion damage based on cellular automaton （CA） technology. The corrosion damage evolution process is simulated as a discrete dynamical system, and the following elementary physieoehemical processes are taken into account in the proposed model： mass transport, IR drop, metal dissolution and repassivasion, which are described by a number of local rules. The pitting corrosion morphology at different corrosive environments is obtained by implementing the simulation procedure. The pit depth ratio, which is defined as the ratio of the equivalent pit depth to the simulated pit depth, is introduced to characterize the tendency of a pit to a semi ellipsoid; and the pit aspect ratio is used to study the equivalent pit morphology characteristic for the corrosion pit considered as the semillipsoid. The results show that pit growth can achieve a relative steady state during the pitting corrosion process. These preliminary investigation results will motivate further work to understand the pitting corrosion mechanism, and provide valuable information for fatigue life prediction and structural integrity analysis
出处
《航空学报》
EI
CAS
CSCD
北大核心
2009年第11期2185-2192,共8页
Acta Aeronautica et Astronautica Sinica
关键词
点蚀
元胞自动机
蚀坑形貌
深度比
尺寸比率
模拟
pitting corrosion
cellular automaton
pit morphology
depth ratio
aspect ratio
simulation
