【摘要】：具有隨機性結(jié)構(gòu)的響應預測分析,近年來受到了很大的關(guān)注,在結(jié)構(gòu)聲振領域更是如此。在預測結(jié)構(gòu)聲輻射時,分析頻域往往很寬,結(jié)構(gòu)的聲輻射對制造工藝誤差會變得高度敏感,尤其在高頻段。理想的情況是,這種敏感性能在設計階段確定,以便確保生產(chǎn)設備的整體性能。本文以此為研究背景,針對結(jié)構(gòu)噪聲預示中的一個基本問題—薄板振動聲輻射問題,研究薄板參數(shù)隨機性對其聲輻射的影響。 通過在薄板上隨機布置質(zhì)量點模擬薄板參數(shù)的隨機性,采用Monte Carlo方法,開展薄板聲輻射參數(shù)隨機性研究。由于增加的隨機質(zhì)量點改變了結(jié)構(gòu)的自振頻率,為了避免每次求解結(jié)構(gòu)的自振頻率和模態(tài),本文通過結(jié)構(gòu)局部修改的方法,直接得到結(jié)構(gòu)的聲輻射,顯著降低了隨機聲輻射分析的計算量。另外,傳統(tǒng)基于模態(tài)疊加的聲輻射預示方法,隨著分析頻率的增高,需要選取更多模態(tài),從而增大了計算量。本文引入了辛空間波傳播方法,只需選取少量的波形便可獲得板的精確動力響應,而且適用于任意邊界條件。 本文的主要內(nèi)容包括如下幾個方面： (1)采用傳統(tǒng)的模態(tài)疊加法求解隨機薄板聲輻射問題。通過隨機布置質(zhì)量點考慮參數(shù)隨機性,采用Monte Carlo方法進行隨機聲輻射分析。由于隨機質(zhì)量點附加到系統(tǒng)的質(zhì)量陣中,在每次分析中需要重新求解結(jié)構(gòu)的自振頻率和模態(tài),通過系統(tǒng)的穩(wěn)態(tài)響應,進而分析隨機薄板的聲壓分布。 (2)應用結(jié)構(gòu)局部修改方法分析薄板隨機聲輻射問題。采用結(jié)構(gòu)局部修改方法,從原系統(tǒng)響應出發(fā),疊加修正項,得到新系統(tǒng)的穩(wěn)態(tài)響應,進而求解隨機薄板的直接聲輻射問題。這種方法避免了每次求解結(jié)構(gòu)的自振頻率和模態(tài),算例分析表明,這種方法與傳統(tǒng)方法的計算精度相當,但顯著降低了隨機聲輻射分析的計算量。 (3)采用辛空間波傳播方法,研究薄板的直接聲輻射問題。以四邊簡支板為例,得出簡諧激勵下薄板的穩(wěn)態(tài)響應計算公式,并利用這些結(jié)果,進一步研究薄板向外輻射的聲壓。通過與傳統(tǒng)基于模態(tài)疊加法的聲壓計算方法計算結(jié)果的對比,驗證了辛空間波傳播方法的有效性。
[Abstract]:In recent years, the response prediction analysis of random structures has attracted much attention, especially in the field of structural acoustic vibration. In the prediction of structural acoustic radiation, the frequency domain of analysis is very wide, and the structural acoustic radiation will become highly sensitive to the manufacturing process error, especially in the high frequency range. Ideally, this sensitivity can be determined at the design stage to ensure the overall performance of the production equipment. In this paper, the influence of the randomness of thin plate parameters on the acoustic radiation of thin plate vibration is studied, which is a basic problem in the prediction of structural noise. The randomness of sound radiation parameters of thin plates is studied by means of Monte Carlo method through random placement of mass points on thin plates. Because the increase of random mass point changes the natural vibration frequency of the structure, in order to avoid solving the natural vibration frequency and mode of the structure every time, the sound radiation of the structure is directly obtained by the method of local modification of the structure. The computational complexity of stochastic acoustic radiation analysis is significantly reduced. In addition, with the increase of analytical frequency, more modes need to be selected in the traditional prediction method of acoustic radiation based on modal superposition, thus increasing the computational complexity. In this paper, the symplectic spatial wave propagation method is introduced. The exact dynamic response of the plate can be obtained by selecting only a few waveforms, and it is suitable for arbitrary boundary conditions. The main contents of this paper are as follows: (1) the traditional modal superposition method is used to solve the acoustic radiation problem of stochastic thin plates. Considering the randomness of parameters, the random acoustic radiation analysis is carried out by Monte Carlo method. Because the random mass points are attached to the mass matrix of the system, the natural frequencies and modes of the structure need to be solved again in each analysis, and the sound pressure distribution of the stochastic thin plate is analyzed through the steady state response of the system. (2) the problem of random acoustic radiation of thin plate is analyzed by local modification method. Based on the response of the original system, the steady-state response of the new system is obtained by using the structural local modification method, and the direct acoustic radiation problem of the stochastic thin plate is solved. This method avoids each calculation of the natural frequency and modal of the structure. The numerical examples show that this method has the same accuracy as the traditional method, but the computational complexity of the stochastic acoustic radiation analysis is significantly reduced. (3) the direct acoustic radiation of thin plate is studied by symplectic spatial wave propagation method. Taking simply supported plates with four sides as an example, the formulas for calculating the steady response of thin plates under harmonic excitation are obtained, and the sound pressure of thin plates radiated out is further studied by using these results. The validity of the symplectic spatial wave propagation method is verified by comparing the calculated results with the traditional acoustic pressure calculation method based on modal superposition method.
【學位授予單位】：大連理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TB532

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本文編號：2375036