Since the shear directly determines the displacement gradients of both out-of-plane and in-plane in the shearing speckle interferometry, the measurment precision of the shear should be improved to obtain the accurate strain distribution during the measurements of out-of-plane and in-plane strains. In this paper, four methods for the shear measurement: formula method,imaging method, Moire fringe method and correlation method are compared in detail. An experimental setup is established to measure the shear using the imaging method, Moire fringe and correlation method. The measurement results based on the three methods are compared with that of the formula method as a criterion. The result shows that when the shear is more than 3 mm, the correlation method has higher accuracy; however, once the shear is less than 3 mm, the Moire fringe has higher accuracy. It suggests that the appropriate measurement method can be chosen after estimating the amount of the shear to obtain the higher out-of-plane and in-plane strains.%由于采用剪切散斑干涉术测量离面应变和面内应变都与剪切量有关,所以剪切量的测量精度决定了应变场分布测量的准确性.本文论述了公式法、成像法、莫尔条纹法和相关法等4种剪切量测量法的测量原理,定性分析了它们的测量范围.搭建了一套剪切量测量系统,利用成像法、莫尔条纹法、相关法测量剪切散斑系统的剪切量,并以公式法计算的结果为准,比较其他3种方法的测量结果.结果表明:剪切量＞3 mm时,利用相关法测量具有较高的测量精度；剪切量＜3 mm时,奠尔条纹法测量效果会更好.因此,实际应用中,应该先根据实际测量条件估算剪切量的大致范围,然后依据估算范围选择合适的测量方法.
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