International Research Journal of Engineering and Technology (IRJET) Volume: 11 Issue: 12 | Dec 2024
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e-ISSN: 2395-0056 p-ISSN: 2395-0072
Stress Analysis and Testing Method for Combined Bending and Twisting Deformation of Thin-Walled Circular Tubes Jilei DONG，Guanghong MIAO，Liang LI，Hongxue ZHANG School of Mechanics and Optoelectronics Physics, Anhui University of Science and Technology, Anhui Huainan 232001，China -------------------------------------------------------------------------***------------------------------------------------------------------------
Abstract: The thin-walled circular tube bending and twisting combined deformation experiment is a typical representative of combined deformation experiments. Through this experiment, one can master the principles of strain gauge placement, learn to analyze the strain components of corresponding strain gauges, and thus design bridge paths appropriately to measure the strain components generated by a certain internal force separately. This article first conducts stress analysis o n the bending and twisting combined deformation of thin-walled circular pipes, in order to understand the stress state at any point on the surface of thin-walled circular pipes; Then analyze the magnitude and direction of the principal strain at the designated point of the thin-walled circular tube under three different strain flower pasting methods; Finally, the electrical measurement method is used to study the magnitude and direction of the principal stress at a specified point on the surface of a thin-walled cylinder, as well as the normal stress caused by the bending moment in the specified section, the shear stress caused by the torque, and the shear stress caused by the shear force. This technology can lay a solid practical foundation for students to engage in work related to engineering monitoring. Keywords: Thin walled circular tube; Combination deformation; Stress analysis; Electrical measurement method
1. INTRODUCTION Resistance strain measurement (electrical measurement) technology is an important and practical technique in the field of mechanics. The use of resistance strain effect can convert the measured mechanical quantities into electrical quantities for testing. Mastering this technology can lay a solid practical foundation for students to engage in engineering monitoring work[1]. In engineering practice, components often undergo two or more basic deformations under load, namely combined deformation [2]. The experiment of thin-walled cylinder under combined bending and twisting deformation is a typical representative. The determination of internal forces during the combined bending and twisting deformation of thin-walled cylinders is one of the teaching experiments in the course of materials mechanics, and it also has practical value in engineering. Through this experiment, one can master the principle of arranging strain gauges, learn to analyze the strain components of strain gauges, and be able to design bridges appropriately to measure the strain components generated by certain internal forces separately [3].
2 STRESS ANALYSIS OF COMBINED BENDING AND TWISTING DEFORMATION The experimental apparatus for combined bending and twisting deformation and the cross-section of the thin-walled circular tube are shown in Figure 1. One end of the circular tube is a fixed end, and the other end is fixedly connected to a
a . The circular tube undergoes a combination of bending and twisting deformation under the action of concentrated force F , and the distance from the tested section I-Ito the free end is L. According to the stress steel crank arm with a length of
state theory analysis, all points on the surface of the thin-walled cylinder are in a plane stress state [4].
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