曲轴弯曲疲劳试验圆角应变电测的误差  

Stain Measurement Error Near Crankshaft Fillet in Bending Fatigue Test

作　　者：鲍珂[1] 李文[1] 李继山[1] 廖日东[1] 左正兴[1] 

机构地区：[1]北京理工大学机械与车辆学院,北京100081

出　　处：《内燃机学报》2011年第4期337-341,共5页Transactions of Csice

摘　　要：由于曲轴特殊的几何形状及较小的圆角尺寸,在曲轴弯曲疲劳试验中通过电测方法得到的圆角应变与真实应变峰值之间存在较大误差.采用模态叠加法的瞬态动力学计算得到了谐振式弯曲疲劳试验时曲轴圆角表面疲劳危险位置附近的弯曲正应变,并将其沿圆角周向的分布表示为一阶傅里叶级数的形式.基于计算得到的圆角应变分布规律,分析了应变电测法中以应变片敏感栅覆盖范围内的平均应变代替峰值点应变所引入的误差,结果表明,这种误差可以通过选择栅长较小的应变片予以控制.进一步讨论了应变片黏贴位置偏移对应变峰值测量误差的影响,偏移量较大时,测量误差迅速增大.Due to the complexity of shape and small fillet size,large error exists in the electrical meas-urement on strain near crankshaft fillet during bending fatigue test.Transient dynamic computation of fa-tigue test is carried out by modal superposition method,and the normal strains near critical position in fillet surface are obtained.The distribution of strain along the hoop direction of fillet section is expressed as the first-order Fourier series.Based on strain distribution regularity,the error due to the replacement of maximum stress by average strain in the sensitive grid field is analyzed.Result shows that this error can be controlled by choosing the foil gage with small size.Measurement error which caused by position offset of strain foil is discussed.Measurement error will be unacceptable as offset increases.

关 键 词：曲轴 疲劳 应变 测量误差 

分 类 号：TK413[动力工程及工程热物理—动力机械及工程]