寿命限制件概率失效风险评估材料缺陷数据模型

Material defects data model of probabilistic risk assessment on life limited part

从满足适航性要求的角度出发,探索出一种获取典型钛合金材料缺陷(硬α夹杂)分布数据的方法,即以理论模型模拟钛合金轮盘的加工过程,利用加工过程中被检出缺陷的分布和无损检测检出率(POD)等相关数据,获得部件缺陷分布基线。提出满足适航要求的超声POD试验和金相切片试验方案,确定了试件规格数量、缺陷含氮质量分数及分布规律、超声检测方法、金相切片获取缺陷三维尺寸等关键技术,用以获取POD曲线和检出的缺陷等相关数据。利用以上数据通过理论推导和对数线性拟合获得部件缺陷分布超越数曲线。明确了材料缺陷的数据特点和适航要求,详细分析了模型试验参数的选取原则,提出了获取POD曲线和缺陷分布曲线的方法。该方法为航空发动机轮盘概率失效风险评估提供缺陷数据输入,以支撑国产发动机的适航取证工作。

In order to meet the airworthiness requirements,a method for obtaining material defect（hardαinclusions）distribution data of typical titanium alloy was explored.According to the theoretical model of titanium alloy disk manufacturing process,the defect distribution baseline was acquired,using the detected defect distribution and the probability of detection（POD）of nondestructive test in the manufacturing process.The programs of POD test and microsection test,which meet the airworthiness requirements,were proposed.The key test technologies were determined to obtain POD curve and detected defects data,including specimen specifications,nitrogen mass fraction and distribution of hard alpha inclu-sions,ultrasonic test standard,steps of microsection,etc.Then,the exceedance curve of defect distribution was acquired by the use of theoretical deduction and logarithm linear fitting.The characteristics of material defects and airworthiness requirment were determines,then a method of obtaining POD curve and defect distribution curve was put forword.The method provides inputs for probabilistic risk assessment on aero-engine disk,supporting the airworthiness forensics of aero-engine disk.