环境严酷性指数腐蚀当量方法及其应用研究

Equivalent Method of Using ESI for Corrosion Damage and Its Application

建立统一的腐蚀损伤环境变量——环境严酷性指数(ESI),并研究其在飞机结构耐久性设计中的应用。在材料/结构腐蚀与单一环境类型/要素/强度关系基础上,按照《由电化学测量值计算腐蚀率和相关量的标准方法》(ASTM G102-89),引入并给出相应的ESI,并在一定工程假设下,给出在综合环境(由不同环境类型/要素/强度组成)作用下的ESI。同时,在腐蚀损伤等效原则下,用标准的环境类型/要素/强度及其作用时间当量化地表征综合环境及相应的作用时间(即环境谱),为环境加速试验环境当量提供依据并形成环境当量谱以应用于飞机结构耐久性设计中的腐蚀防护与控制(EEF),评估结构的检查周期/日历寿命。根据相关试验结果计算了典型金属材料在不同环境中的环境严酷性指数及环境当量化系数(EEF),给出了环境简化或折算的算例。

The purpose of this paper is to establish a uniform environment variable—environment severity index（ESI） for corrosion damage and study its application in durability design for aircraft structures.On the basis of the relationship between material/structure corrosion and a singularity environment type/element/intensity,according to ASTM G102-89（Standard practice for calculation of corrosion rates and related information from electrochemical measurements）,the ESI is induced and presented.Moreover,the ESI of a synthetical environment（comprised by several different environments） under certain engineering assumptions is also provided.According to the principle of equivalence of corrosion damage,the synthetical environment and its duration time（or environment spectrum） can be presented by a normal environment and its corresponding duration time.This method can be applied to provide basis for environment equivalence in accelerated corrosion tests and generate an environment equivalent spectrum to evaluate the inspection period/calendar life of a structure in aircraft durability design.According to correlation test results,the ESI and the environment equivalent factor（EEF） in different environments for a typical metal and several cases for converting environment spectrum are calculated.