预腐蚀疲劳寿命影响系数模型研究

针对腐蚀环境下飞机结构疲劳寿命评定问题,研究了恒幅应力水平下的地面停放预腐蚀影响系数C模型，根据统计分析推导出C曲线的关系式;疲劳试验数据分析结果建立了预腐蚀影响系数C模型.结果表明，随着腐蚀时间的增加,疲劳寿命影响系数C不断下降;同一时间下,应力水平S高,影响系数C大;应力水平S低,影响系数C小；在一定的腐蚀疲劳条件(时间、应力水平)下,可求出任一给定可靠度p时的Cp值和疲劳寿命预测值.

RESEARCH ON A MODEL OF THE INFLUENCE COEFFICIENT FOR PRE-CORROSION FATIGUE LIFE

In order to evaluate the fatigue life of aircraft structures in corrosive environment by ground service,the model of pre-corrosion fatigue life influence coefficient C at constant fatigue stress levels was studied.The general relational expression of the C curve was deduced by statistical analysis theory,and the model of influence coefficient C model was presented by analyzing the data of the fatigue tests.It is a general applicable formula in which both the effect of the pre-corrosion time and the fatigue stress levels were taken into account.The results show that the influence coefficient C will be decreased continuously with corrosion time.The higher stress levels,the greater C.The C_p value and the fatigue life with a given reliability p could be calculated directly under the specified corrosion fatigue condition(time,stress levels).It is valuable for fatigue life analysis in corrosive environment.