【摘要】：工作模態(tài)分析(OMA)一直是國(guó)內(nèi)外研究的重點(diǎn)對(duì)象。基于二階盲辨識(shí)(SOBI)和獨(dú)立成分分析(ICA)方法,本文分別提出了線性時(shí)不變結(jié)構(gòu)、復(fù)雜三維連續(xù)體結(jié)構(gòu)和線性時(shí)變結(jié)構(gòu)工作模態(tài)參數(shù)識(shí)別方法,主要研究?jī)?nèi)容包括:(1)研究了基于SOBI和ICA的線性時(shí)不變結(jié)構(gòu)工作模態(tài)參數(shù)識(shí)別方法。首先從理論上分析工作模態(tài)識(shí)別方法和盲源分離之間的相似之處,并得出了分離矩陣與模態(tài)振型之間、分離信號(hào)和模態(tài)坐標(biāo)響應(yīng)之間的一一對(duì)應(yīng)關(guān)系,指出了基于盲源分離(BSS)工作模態(tài)參數(shù)識(shí)別方法識(shí)別模態(tài)順序不確定、振型能量不確定、模態(tài)缺失的根本原因。其次,從目標(biāo)函數(shù)和優(yōu)化方法出發(fā),比較不同ICA方法應(yīng)用于時(shí)不變結(jié)構(gòu)工作模態(tài)分析領(lǐng)域時(shí)的優(yōu)缺點(diǎn)。最后,由于ICA方法使用的是高階統(tǒng)計(jì)量,本文還研究基于二階統(tǒng)計(jì)量的SOBI方法。在離散三自由度和簡(jiǎn)支梁上的線性時(shí)不變數(shù)值仿真驗(yàn)證中,對(duì)比和分析SOBI方法和各種ICA方法線性時(shí)不變結(jié)構(gòu)工作模態(tài)參數(shù)識(shí)別的優(yōu)缺點(diǎn)。(2)研究了基于SOBI的復(fù)雜三維連續(xù)體結(jié)構(gòu)的工作模態(tài)參數(shù)識(shí)別方法。本文利用在笛卡爾坐標(biāo)系下三維結(jié)構(gòu)三個(gè)方向的模態(tài)坐標(biāo)矩陣相同的特性,先使用SOBI方法識(shí)別出響應(yīng)最大的那個(gè)方向的模態(tài)坐標(biāo)響應(yīng),再利用最小二乘廣義逆的方法將該模態(tài)坐標(biāo)矩陣回代到其它兩個(gè)方向上識(shí)別其它兩方向的模態(tài)振型,最后完成三維模態(tài)振型組裝。在三維圓柱殼上的仿真驗(yàn)證結(jié)果表明,基于SOBI和最小二乘廣義逆的方法能有效地識(shí)別出三維圓柱殼上的模態(tài)參數(shù)。(3)研究了基于滑動(dòng)窗SOBI的線性時(shí)變結(jié)構(gòu)工作模態(tài)參數(shù)在線識(shí)別方法。此方法利用“短時(shí)時(shí)不變”理論,假設(shè)在一個(gè)很小的時(shí)間窗內(nèi),結(jié)構(gòu)是時(shí)不變的,此時(shí)可以利用SOBI方法識(shí)別結(jié)構(gòu)在中間時(shí)刻的工作模態(tài)參數(shù),隨著時(shí)間的推移,窗口也不斷向前滑動(dòng),從而識(shí)別出每個(gè)時(shí)刻的模態(tài)參數(shù),最后將每個(gè)時(shí)刻的模態(tài)參數(shù)連起來,從而形成時(shí)變結(jié)構(gòu)的模態(tài)參數(shù),并給出方法中滑動(dòng)窗的選取規(guī)則和應(yīng)用范圍。在線性時(shí)變?nèi)杂啥认到y(tǒng)和時(shí)變懸臂梁上的仿真驗(yàn)證結(jié)果表明,在選擇合適的滑動(dòng)窗窗口的大小的情況下,基于滑動(dòng)窗SOBI方法能有效地識(shí)別出時(shí)變結(jié)構(gòu)的模態(tài)參數(shù),識(shí)別效果比基于滑動(dòng)窗ICA方法更好。
[Abstract]:Working mode analysis (OMA) has been the focus of research at home and abroad. Based on the second order blind identification (SOBI) and the independent component analysis (ICA) method, this paper presents the methods for identifying the operating modal parameters of linear time-invariant structures, complex three-dimensional continuum structures and linear time-varying structures, respectively. The main contents are as follows: (1) the identification method of working modal parameters of linear time-invariant structures based on SOBI and ICA is studied. Firstly, the similarities between the working mode identification method and blind source separation are analyzed theoretically, and the one-to-one correspondence between the separation matrix and the modal mode type, the separation signal and the modal coordinate response is obtained. The identification method of operating modal parameters based on blind source separation (BSS) is presented to identify the fundamental causes of modal sequence uncertainty, mode energy uncertainty and modal missing. Secondly, based on the objective function and optimization method, the advantages and disadvantages of different ICA methods in the field of time-invariant structure working modal analysis are compared. Finally, because the ICA method uses high order statistics, this paper also studies the SOBI method based on the second order statistics. In the linear time-invariant numerical simulation of discrete three-degree-of-freedom and simply supported beam, The advantages and disadvantages of SOBI method and ICA method are compared and analyzed. (2) the working modal parameter identification method of complex 3D continuum structure based on SOBI is studied. In this paper, using the same characteristic of modal coordinate matrix of three directions of three-dimensional structure in Cartesian coordinate system, we first use SOBI method to identify the modal coordinate response of the direction in which the maximum response is obtained. Then, the modal coordinate matrix is replaced by the least square generalized inverse method to identify the modal modes in the other two directions. Finally, the three-dimensional modal mode assembly is completed. The simulation results on a three-dimensional cylindrical shell show that, Based on SOBI and least square generalized inverse method, the modal parameters on three-dimensional cylindrical shells can be effectively identified. (3) the on-line identification method of working modal parameters of linear time-varying structures based on sliding window SOBI is studied. Using the theory of "short time invariance", this method assumes that the structure is time-invariant in a very small time window. At this time, the SOBI method can be used to identify the working modal parameters of the structure at the middle time. The window also slips forward continuously to identify the modal parameters at each moment. Finally the modal parameters of each moment are connected to form the modal parameters of the time-varying structure. The selection rules and application range of the sliding window in the method are given. The simulation results on linear time-varying 3-DOF system and time-varying cantilever beam show that the modal parameters of time-varying structures can be effectively identified based on sliding window SOBI method under the condition of selecting the appropriate sliding window size. The recognition effect is better than that based on sliding window ICA method.
【學(xué)位授予單位】：華僑大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB12

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