Nonlinear dispersion wave characteristics of thin-walled box beam based on 1D higher-order beam theory

When thin-walled box beam is subjected to dynamic torsional load, its cross-section undergoes warping and distortion deformation, they are coupled with torsional deformation. Due to coupling effect, propagation of stress waves along thin-walled box beam axis becomes very complex. However, at present, study on dispersion phenomena is not deep enough, and it is difficult to observe interrelations among various branches of dispersion curve by using numerical solutions of 3D elastic dynamic equations. Here, the 1D higher-order beam theory being able to express the 3 kinds of displacement deformations was used to study dispersion relation. The study revealed inter-relations among imaginary and real branches of low-frequency dispersion relation. In numerical example analyses, the nonlinear dispersion effect caused by the geometric effect of thin-walled box beam was studied. It was shown that the larger the wall thickness of thin-walled box beam, the smaller the beam ultimate wave velocity; the larger the width-height ratio of cross-section, the larger the frequency of branch 1 and the smaller the frequencies of branch 2 and branch 3. © 2023 Chinese Vibration Engineering Society. All rights reserved.