Bending and twisting combined test device and its use in measuring internal force

Abstract

The test unit includes cantilever of cylinder in aluminum alloy, and bell crank in 90 degrees to the cantilever. According to strain rosette A, strain rosette B, strain rosette C, and strain rosette D sequence, four pieces of 45 degrees -3 right angle strain rosette are arranged with 90 degrees angular interval in sequence on excircle of cross section to be measured of the cantilever of cylinder in aluminum alloy. Characters are that in axial direction of the cantilever, strain rosette B, strain rosette C, and strain rosette D are in same direction, and strain rosette A is in opposite direction by using circle the measuring point located being as center of symmetry. The invention obtains high precision of measuring bending moment and torsional moment, and can measure shearing force effectively. The invention adds new content of teaching experiment, and provides reference for measurement of internal force of similar component in engineering structure.

Description

Technical field: [0001] The invention relates to a bending-torsion combined test device and an internal force measurement method. Background technique: [0002] Resistance strain measurement technology is one of the main means of stress analysis of engineering structure test, and is widely used in various engineering and technical fields such as machinery, civil engineering, aerospace and so on. Learning the principle of resistance strain measurement, mastering its measurement methods and techniques, and being able to apply them proficiently is a basic experimental skill that students in engineering colleges, especially those majoring in engineering technology, must master. Therefore, the electrical stress measurement experiment is one of the essential and important contents in the experimental teaching, among which the "cylinder bending and torsion combination experiment" is the basic experimental content of the electrical stress measurement experiment. The experimental co...

AI Technical Summary

Problems solved by technology

When measuring with a 45°-3 right-angle strain rosette, since the center of the sensitive grid does not coincide with the measuring point, when using the full bridge to measure the bending shear stress, only the torsional shear stress can be offset, and the additional bending normal stress cannot be eliminated, thus lead to large measurement errors due to Figure 5 It can also be seen that, in addition to the influence of the lateral effect and the paste orientation, the main error of the shear force measurement is caused by the inconsistency between the stress state at the center of the strain rosette and the pure shear stress state of the measured point

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