Showing papers by "Yiu-Yin Lee published in 2019"
TL;DR: This study addresses the effects of large-amplitude vibration on the pressure-dependent absorption of a structure multiple-cavity system and the proposed harmonic balance method, which has recently been adopted to solve nonlinear beam problems and other nonlinear structural-acoustic problems.
Abstract: This study addresses the effects of large-amplitude vibration on the pressure-dependent absorption of a structure multiple-cavity system It is the first study to consider the effects of large-amplitude vibration and pressure-dependent absorption Previous studies considered only one of these two factors in the absorption calculation of a perforated panel absorber Nonlinear differential equations, which represent the structural vibration of a perforated panel absorber, are coupled with the wave equation, which represents the acoustic pressures induced within the cavities The coupled nonlinear differential equations are solved with the proposed harmonic balance method, which has recently been adopted to solve nonlinear beam problems and other nonlinear structural-acoustic problems Its main advantage is that when compared with the classical harmonic balance method, the proposed method generates fewer nonlinear algebraic equations during the solution process In addition, the solution form of the nonlinear differential equations from this classical method can be expressed in terms of a set of symbolic parameters with various physical meanings If a numerical method is used, there is no analytic solution form, and the final solution is a set of numerical values The effects of the excitation magnitude, cavity depth, perforation ratio, and hole diameter on the sound absorption of a panel absorber are investigated, and mode and solution convergence studies are also performed The solutions from the proposed harmonic balance method and a numerical integration method are compared The numerical results show that the present harmonic balance solutions agree reasonably well with those obtained with the numerical integration method Several important observations can be made First, perforation nonlinearity is a very important factor in the absorption of a panel absorber at the off structural resonant frequency range The settings of the hole diameter, perforation ratio, and cavity depth for optimal absorption differ greatly with consideration of perforation nonlinearity Second, the "jump up phenomenon," which does not occur in the case of linear perforation, is observed when perforation nonlinearity is considered Third, one or more absorption troughs, which worsen the average absorption performance, may exist in cases with multiple cavities
3 citations
TL;DR: In this article, a classic method combined with Vieta substitution technique is adopted to develop an analytic formula for computing the nonlinear structural and acoustic responses of a nonlinear duct, which is based on the classical nonlinear thin plate theory and the three-dimensional wave equation.
Abstract: This paper addresses the vibration and sound radiation of a nonlinear duct. Many related works assume that the boundaries are linearly vibrating (i.e., their vibration amplitudes are small), or that the duct panels are rigid, and their vibrations can thus be neglected. A classic method combined with Vieta’s substitution technique is adopted to develop an analytic formula for computing the nonlinear structural and acoustic responses. The development of the analytic formula is based on the classical nonlinear thin plate theory and the three-dimensional wave equation. The main advantage of the analytic formula is that no nonlinear equation solver is required during the solution procedure. The results obtained from the proposed classic method show reasonable agreement with those from the total harmonic balance method. The effects of excitation magnitude, panel length, damping, and number of flexible panels on the sound and vibration responses are investigated.
1 citations
TL;DR: In this paper, the authors propose a framework to improve the quality of the data collected by the data collection system, which is based on the concept of "metadata" and "metadata", respectively.
Abstract: 一种针对有扰动项的耦合可积非色散方程的修正残差谐波平衡求解方法 本文将改进残余谐波平衡方法用于求解有扰动项的耦合可积非色散方程,并简化取得破解方案的过程。 1. 在取得每一阶段破解方案的过程中, 只需处理一条非线性代数方程式及一组线性代数方程式;2. 能找出旧方法不能找出的非线性答案。 1. 使用理论推导、方程式替换及残余谐波平衡方法;2. 通过仿真模拟,推导震动位移与频率之间的关系(图1)以及位移与速度之间的关系(图2)。 1. 成功将改进残余谐波平衡方法应用于有扰动项的耦合可积非色散方程;2. 通过与其他方法产生的数据进行比较,验证了所提方法的可行性和有效性(表1–3)。