Dynamic parameters identification of waveguides using reflection and transmission coefficients
Zhang Bing1;Sun Yong2; Fan Qiang3;Huang Zhenyu3
Shanghai Jiao Tong University,School of Electronic, Information and Electrical Engineering,Institute of Intelligent Mechatronics Research,Shanghai, 200240, China
Abstract:Thin and long structures like uniform beams and pipes are widely used in many engineering fields. These structures usually act as waveguides, conveying vibrational energy away from the source of excitation via wave propagation through the structure. Built-up beam or piping systems often comprise many joints or discontinuities in the form of flanges, hangers, supports, valves, pumps and changes in section. Dynamically, these discontinuities contribute stiffness, inertia and damping and can dramatically alter the response of the system. A robust technique for parametric joint identification would benefit many areas of dynamic modeling. Because of the complexity of discontinuities in practice, experiments are normally introduced to determine their dynamic parameters. Based on the wave propagation method, this paper presents a general analytical relationship between the dynamic parameters of a discontinuity and the reflection and transmission coefficients of the discontinuity. This relationship can be adopted to identify the dynamic parameters of the discontinuity by using the optimization curve-fit method. The case study, which involves an infinite uniform beam with a mass-like discontinuity formed by an attached steel block, is proposed to identify the dynamic parameters of the discontinuity through the wave reflection and transmission coefficients. The Monte Carlo simulation is applied to investigate the influence of the simulated measurement noise on the reflection coefficients. The experimental results show that the accuracy of the identified parameters has close relation with the identification frequency range and the errors of the identified mass and moment of inertia are within 5% and 15%, respectively.