航空有机玻璃加工工艺对其残余应力影响的光弹性技术研究

STUDY ON INFLUENCE OF PROCESSING TECHNOLOGY TO RESIDUAL STRESS FOR AERONAUTICAL PMMA BY PHOTOELASTICITY

航空有机玻璃在使用过程中的破坏主要是由于残余应力导致疲劳裂纹所致。残余应力会使航空有机玻璃材料链段或基团取向进而产生双折射效应。主要基于残余应力导致的双折射效应,运用数字相移光弹性法实现由钻孔工艺产生残余应力的无损检测,并对测试结果进行分析得出:钻头进给速度越小,加工时间越长,冻结的残余应力越大;而钻头转速越大,加工温度越高,冻结的残余应力越大。控制装卡使各个方向受到相同的约束,能够使孔周残余应力均匀,防止出现较大应力集中区域。加工直径稍大的孔时,应采用分级钻孔的方式,先钻小孔然后逐级扩大,能够保证孔周残余应力低。

The damage of the aeronautical PMMA is mainly due to the fatigue cracking leaded by the residual stress.Residual stress will produce the orientated segment or group in the aeronautical PMMA which produce the birefringence effect. In this paper,based on the birefringence effect,the digital phase-shift photoelasticity is used to test the residual stress for drilling the hole. For the test results some conclusions are summarized. When the feed speed is smaller,for the longer processing time the larger residual stress is frozen. When the rotational speed is greater,for the higher processing temperature the larger residual stress is frozen. Though controlling the chucking the constraints are the same in all directions. This can make the residual stress uniform and prevent the large stress concentration area. As machining the larger hole the smaller hole should be drilled firstly.This can ensure the smaller residual stress around the hole.