管状杆件受到剪力和弯矩作用,将产生应力和应变,通常采用应变片测量杆件的应变。应变片粘贴难以避免地将发生偏移和偏转,导致应变测量产生误差。基于应力状态和应力-应变弹性理论的分析,研究了直径为14～20 mm管状杆件不同位置的应力和应变及其误差,并分析了杆件泊松比对应变测量误差的影响。算例分析发现,应变片粘贴偏移不超过4 mm和偏转角度不超过4°导致的应变测量误差通常不超过5%。杆件的泊松比对于应变误差的影响基本可以忽略不计。

Tubular bar will produce stress and strain when bearing shear force and bending moment. Strain of bar is usually measured by strain gauge. Strain gauge will deviate and deflect inevitably when pasted to the tubular bar, resulting in strain measurement errors. According to stress state and elastic theory of stress-strain, the stress, strain and their errors at different positions of tubular bars with diameters of 14-20 mm were analyzed. Example analysis indicates that the strain error is not more than 5% when the deviation is not more than 4 mm and the deflection is not more than 4°. The influence of Poisson ratios of tubular bar on strain error can be basically neglected.