用于预腐蚀航空铝合金材料疲劳寿命分析的腐蚀当量裂纹的抛物线模型  

Parabolic model of equivalent crack approach for predicting fatigue life of pre-corroded aluminum alloys

作　　者：邓景辉[1] 陈平剑[1] 付裕 

机构地区：[1]中国直升机设计研究所结构强度研究室,景德镇333000

出　　处：《航空学报》2018年第2期146-156,共11页Acta Aeronautica et Astronautica Sinica

基　　金：国家自然科学基金(51375033)~~

摘　　要：为了节省直升机材料研制费用并缩短研发周期,本文试图以理论模拟方法代替腐蚀疲劳试验。试验测定了2种航空铝合金材料LD2CS和LD10CS的预腐蚀疲劳性能,根据试验观测现象和断口扫描电子显微镜(SEM)分析结果,建立了新的腐蚀凹坑当量裂纹的抛物线模型,并基于线弹性断裂力学方法推导了预腐蚀铝合金表面腐蚀凹坑当量裂纹的应力强度因子新公式,发展了疲劳载荷作用下航空铝合金材料的预腐蚀疲劳寿命估算方法。最后,采用本文的模型和算法对2种铝合金材料LD2CS和LD10CS的预腐蚀疲劳性能进行了模拟,发现本文所提新模型和算法的模拟结果与试验数据吻合良好,预测得到的预腐蚀铝合金疲劳性能比传统的半椭圆模型和半圆模型具有更高的预测精度。In order to save the investigating costs and reduce the research periods of the helicopter materials,the theoretical simulation method is attempted to take the place of the corrosion fatigue tests in this paper.The fatigue behaviors of the precorroded LD2 CS and LD10 CS aluminum alloys were tested in this paper.A parabolic model was presented based on the observed test phenomenon and morphology characteristics of the Scanning Electron Microscope（SEM）.The novel formulations were deduced base on linear elastic fracture mechanics to calculate stress intensity of equivalent crack of corrosion pits on the surfaces of pre-corroded aluminum alloys.An algorithm was developed to predict the fatigue life of the pre-corroded aluminum alloy subjected to fatigue loading.The fatigue behaviors of pre-corroded aluminum alloys LD2 CS and LD10 CS were modelled using the new model and algorithm proposed.Comparison shows good agreement between experimental data and predictions based on the new model and algorithm proposed,demonstrating that the fatigue behaviors of pre-corroded aluminum alloys can be predicted more accurately by the new parabolic model than by the traditional half elliptical and semicircle models.

关 键 词：铝合金 腐蚀 疲劳 扫描电子显微镜(SEM) 腐蚀凹坑 当量裂纹 

分 类 号：V215.6[航空宇航科学与技术—航空宇航推进理论与工程]