Crack width variation test method based on strain gauges

Abstract

The invention provides a crack width variation test method based on strain gauge. A crack width variation test device used in the method comprises the first strain gauge and the second strain gauge, the cross-joint section of the first strain gauge is provided with a protruding part which does not generate strain along with the change of the crack width, and the cross-joint section of the second strain gauge generates strain along with the change of the crack width. When the method is used for testing, the strain difference value delta epsilon 21 of the first strain gauge and the second straingauge is measure and substituted into the formula that delta f equals to l2delta epsilon 2f and equals to l1delta epsilon 21, and the variation delta f of the crack width can be obtained, wherein l2fis the length of a sensitive grid of the cross-joint section of the second strain gauge, epsilon 2f is the strain capacity of the cross-joint section of the second strain gauge, and l1 is the lengthof a sensitive grid of the first strain gauge. It is known from the formula that the crack width variation obtained through the method can exclude size change values, generated due to stress, of components on the two sides of a crack, and therefore the measurement accuracy is improved.

Description

technical field [0001] The invention relates to the technical field of engineering structure crack measurement, in particular to a strain gauge-based crack width variation test method. Background technique [0002] Some components, such as metal components, concrete components, etc., will appear tiny cracks with a width of 0.02-2.00mm when the stress is uneven. It is particularly important to monitor the change of crack width and analyze the reasons. In the prior art, displacement gauge or dial gauge is usually used to test the variation of crack width, and its shortcoming is as follows: 1, the precision of displacement gauge test is 0.05mm, and the precision of dial gauge test is 0.001mm, and its test precision is average 2. The purchase cost of displacement gauges or dial gauges on the market ranges from a few hundred yuan to several thousand yuan, and the cost is relatively high; in addition, after using the dial gauge or displacement gauge method to test the crack width ...

AI Technical Summary

Problems solved by technology

However, the existing equipment, such as the multimeter in this patent, can only obtain the change of the overall resistance value of the strain gauge. Therefore, the change of crack width obtained by this method should actually be the change of the overall size of the component when the force is applied. value, which includes not only the change value of the crack width, but also the dimensional change value of the components on both sides of the crack due to the stress, because it cannot exclude the dimensional change of the component due to the stress when measuring the crack width change value, which leads to its The measured variation of the crack width is too large, and the measurement is inaccurate

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