基于FBG应变传感器的焊接接头疲劳试验
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摘要
针对焊接接头疲劳实验中裂纹萌生阶段关键信息难以精准获取的问题,提出了一种基于光纤布拉格光栅(FBG)应变传感器的试验方法。采用十字焊接接头开展疲劳试验,通过在薄板焊趾圆弧段凸顶点布置FBG应变传感器,获取应变时间历程,以应变范围斜率突变点作为裂纹萌生的时间点。疲劳断口与焊趾形貌的对照表明焊趾圆弧段凸顶点是裂纹的易萌生位置,应变测试结果表明,焊接接头疲劳试件的疲劳失效呈现为多裂纹形式,多裂纹的萌生时间不同步且裂纹尺度不同。相较于传统的检测手段,FBG应变传感器操作简便,抗干扰能力强,稳定性好,并能较有效地捕捉焊趾多裂纹的萌生行为。
Aiming at the problem that the key information of crack initiation stage is difficult to obtain accurately in the fatigue test of welded joints,a test method based on FBG strain sensor is proposed. The fatigue test was carried out by using a cross-welded joint. The strain time history was obtained by arranging the FBG strain sensor at the convex apex of the thin-weld toe arc segment,and the strain range slope mutation point was taken as the time point of crack initiation.The comparison between the fatigue fracture and the weld toe geometry shows that the convex apex of the weld toe arc is the easy location of the crack. The strain test results show that the fatigue failure of the welded joint fatigue specimen is in the form of multiple cracks,and the initiation time of multiple cracks is not synchronized. The crack scale is different. Compared with the traditional detection methods,the FBG strain sensor is easy to operate,has strong antiinterference ability,good stability,and can effectively capture the initiation behavior of multiple weld toe cracks.
Aiming at the problem that the key information of crack initiation stage is difficult to obtain accurately in the fatigue test of welded joints,a test method based on FBG strain sensor is proposed. The fatigue test was carried out by using a cross-welded joint. The strain time history was obtained by arranging the FBG strain sensor at the convex apex of the thin-weld toe arc segment,and the strain range slope mutation point was taken as the time point of crack initiation.The comparison between the fatigue fracture and the weld toe geometry shows that the convex apex of the weld toe arc is the easy location of the crack. The strain test results show that the fatigue failure of the welded joint fatigue specimen is in the form of multiple cracks,and the initiation time of multiple cracks is not synchronized. The crack scale is different. Compared with the traditional detection methods,the FBG strain sensor is easy to operate,has strong antiinterference ability,good stability,and can effectively capture the initiation behavior of multiple weld toe cracks.
引文
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[14]李晓波,王强,李鹏.光纤光栅传感器在结构应变检测中的应用研究[J].工程质量,2008(5):40-43.
[15]李云鹏,丁彦闯,薛立成.基于光纤光栅传感器的动车组结构累积损伤预测系统设计[J].电子测量技术,2018(6):95-98.
[16]魏国前,罗玉兵,黄发超,等.考虑焊趾形貌的十字焊接接头疲劳评定研究[J].机械强度,2018(2)):418-423.
[2]赵少汴,王忠保.抗疲劳设计:方法与数据[M].北京:机械工业出版社,1997.
[3] D.拉达伊.焊接热效应:温度场、残余应力、变形[M].北京:机械工业出版社,1997.
[4]魏国前,胡政豪,党章,等.十字焊接接头疲劳试验与宏观断口分析[J].实验室研究与探索,2017(12):5-8.
[5]陈群志,毕世权,魏金龙,等.复杂飞机结构裂纹萌生寿命确定的工程方法[J].实验室研究与探索,2007,36(10):252-255.
[6] Shirahata H,Miki C,Yamaguchi R,et al. Fatigue crack detection by the use of ultrasonic echo height change with crack tip opening[J]. Welding in the World,2014,58(5):681-690.
[7] Nemati N,Metrovich B,Nanni A. Acoustic Emission Assessment of Through-Thickness Fatigue Crack Growth in Steel Members[J].Advances in Structural Engineering,2015,18(2):269.
[8]张善智,闫云聚.构件表面裂纹损伤电位检测法[J].测控技术,2008,27(6):1-4.
[9] An Y K,Shen Z,Wu Z. Stripe-PZT sensor-based baseline-free crack diagnosis in a structure with a welded stiffener[J]. Sensors,2016,16(9):1511.
[10]夏鹏,刘志平,华琳,等.基于PZT的金属结构焊缝裂纹检测仿真研究[J].武汉理工大学学报(交通科学与工程版),2014,38(1):208-211.
[11] Ryles M,Ngau F H,Mcdonald I,et al. Comparative study of nonlinear acoustic and Lamb wave techniques for fatigue crack detection in metallic structures[J]. Fatigue&Fracture of Engineering Materials&Structures,2010,31(8):674-683.
[12] Li X,Wang Y H, Jiang L, et al. Research on the damage identification of weld metal cracking of metal structure based on PVDF[J]. Applied Mechanics&Materials,2015,751(9261):143-149.
[13]孙昌之.用应力测试法判断起重机金属结构裂纹[J].起重运输机械,2001(11):26-27.
[14]李晓波,王强,李鹏.光纤光栅传感器在结构应变检测中的应用研究[J].工程质量,2008(5):40-43.
[15]李云鹏,丁彦闯,薛立成.基于光纤光栅传感器的动车组结构累积损伤预测系统设计[J].电子测量技术,2018(6):95-98.
[16]魏国前,罗玉兵,黄发超,等.考虑焊趾形貌的十字焊接接头疲劳评定研究[J].机械强度,2018(2)):418-423.
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