初始残余应力的检测方法及其在薄壁叶片加工变形分析中的应用研究

Investigation on the Initial Residual Stress Detection Method and Its Application for Deformation Analysis in Machining Thin-Walled Blades

薄壁叶片是航空发动机的关键部件,在加工过程中极易发生剧烈的变形。已有的变形研究控制重点关注在减小切削力和加工残余应力(Machining‑induced residual stress,MIRS)这两方面。本文利用材料热处理和锻造过程中产生的初始残余应力(Initial residual stress,IRS)来减轻薄壁零件受切削力与加工残余应力影响所产生的变形。由于初始残余应力测量困难且具有破坏性,本文提出了一种初始残余应力逆辨识方法来测量Ti6Al4V的初始残余应力。与传统的初始残余应力测量方法相比,逆辨识方法更符合应力分布和叶片变形的分布趋势。为了研究和解耦初始残余应力、加工残余应力和切削力之间对加工变形影响的相互作用,针对钛合金直纹叶片为对象进行实验验证,并建立了有限元预测模型。在分析切削力与加工残余应力对变形的影响后,可以得到切削力占变形程度的46.17%,平均值为26.36μm,而加工残余应力占变形程度的53.83%,平均值为30.70μm。耦合初始残余应力后使得整体的变形减小,受加工残余应力影响的最大挠度变形从35.32μm降低到15.50μm,该分析为利用初始残余应力减小薄壁叶片加工变形提供了新的方法。

The thin-walled blade is a crucial component of aero engines,which is highly susceptible to significant deformation during the machining process.Existing research on deformation control focuses on reducing cutting force and machining-induced residual stress(MIRS).The initial residual stress(IRS)generated in the process of heat treatment and forging is used to reduce the deformation of thin-walled parts under the influence of cutting force and MIRS.Because the IRS measurement is difficult and destructive,this paper proposes a reverse identification method of IRS to measure the IRS of Ti6Al4V.The proposed method is more consistent with the trend of stress and deformation distribution compared with the conventional method.To investigate and decouple the interplay between IRS,MIRS and cutting force on machining deformation,this study employs a curved blade for experimental validation and develops a finite element model to predict the deformation.It is found that cutting force accounts for 46.17%of the deformation with an average value of 26.36μm,while MIRS accounts for 53.83%with an average value of 30.70μm.Coupling IRS reduces MIRS maximum deflection deformation from 35.32μm to 15.50μm,which provides a new approach to optimize machining deformation through IRS distribution.