曲型加筋板结构的声振特性研究

发布时间：2018-06-12 07:53

本文选题：曲型加筋板 + 曲型加强筋　；参考：《重庆大学》2016年硕士论文

【摘要】：加筋结构是一种经济、方便可以极大提高结构的刚度和承载性的方式,现已广泛应用在航空航天、船舶舰艇、汽车以及大型工程设备当中。然而加筋会直接影响结构的声振特性,而结构的声振特性将直接影响装备的整体性能。因此,研究加筋结构的振动特性与声辐射特性的重要性不言而喻。曲型加强筋作为加筋结构的一种新形式,具有传统加筋结构不具备的优势,其能够根据实际需要按照任意的曲率铺设在薄板的任意位置,从而使结构获得更优的声振特性。因此,研究曲型加强筋对结构声振特性的影响规律有着重要的意义。本文以曲型加强筋为研究对象,从曲型加强筋的铺设位置、形状、周期、振幅以及铺设阻尼层等几个方面入手,探究它们的变化对结构声振特性的影响。本文主要研究工作包括以下几个部分:(1)基于薄板和空间曲型梁的有限元理论,分别建立了薄板和曲型梁的有限元模型,然后借助坐标转换将曲型梁所有单元的刚度矩阵与节点载荷向量从局部坐标系转化到整体坐标系中,从而建立曲型加筋板结构的有限元模型。最后,借助声学软件virtual.lab计算出薄板结构的固有频率以及辐射声功率级等,并将其与现有研究计算结果进行对比,验证了分析方法的正确性。(2)研究普通圆弧曲型加强筋与正弦周期加强筋在不同形式和工况下,如外载荷激励位置,基板的厚度,加强筋的高度,加强筋的宽度,加强筋在薄板上铺设的位置,加强筋形状、周期和振幅等参数对结构声振特性的影响。通过研究这些参数的改变对结构固有频率、辐射声功率级的影响规律,从中得出有用的结论,为进一步的研究和实验提供一定的参考。(3)研究自由阻尼层的厚度以及阻尼材料的属性对曲型加筋板声辐射的影响。通过计算分析阻尼层厚度、阻尼材料的杨氏模量、密度以及其损耗因子对结构辐射声功率级以及场点声压级的影响。发现随着阻尼层厚度的增加,阻尼层对结构辐射声功率的抑制作用增加,随着激励频率的增加,阻尼层对结构的声辐射功率级的抑制作用变大,并且阻尼层厚度越厚,抑制作用越明显。阻尼材料的密度对结构减振降噪的效果并不明显,但阻尼材料的损耗因子越大,辐射声功率级的峰值越小。这为在结构表面铺设阻尼层参数的选择提供一定的依据。
[Abstract]:Reinforced structure is an economical and convenient way to greatly improve the stiffness and bearing capacity of the structure. It has been widely used in aerospace, ship, automobile and large-scale engineering equipment. However, the reinforcement will directly affect the acoustic and vibration characteristics of the structure, and the acoustic and vibration characteristics of the structure will directly affect the overall performance of the equipment. Therefore, the importance of studying the vibration and acoustic radiation characteristics of reinforced structures is self-evident. As a new form of stiffened structures, curved stiffeners have advantages that traditional stiffened structures do not have, and they can be laid in any position of thin plates according to actual needs according to arbitrary curvature, thus making the structure obtain better acoustic and vibration characteristics. Therefore, it is of great significance to study the influence of curved reinforcement on the acoustic and vibration characteristics of the structure. In this paper, we take the curved reinforcement as the research object, from the position, shape, period, amplitude and damping layer of the curved reinforcement, and explore the influence of their changes on the acoustic and vibration characteristics of the structure. Based on the finite element theory of thin plate and space curved beam, the finite element models of thin plate and curved beam are established respectively. Then, the stiffness matrix and node load vector of all elements of curved beam are transformed from local coordinate system to global coordinate system by coordinate transformation, and the finite element model of curved stiffened plate structure is established. Finally, the natural frequency and radiated sound power level of thin plate structure are calculated by means of acoustic software virtual.lab, and the results are compared with the existing results. The correctness of the analysis method is verified. (2) the common circular curved stiffeners and the sinusoidal periodic stiffeners are studied in different forms and working conditions, such as the external load excitation position, the thickness of the substrate, the height of the stiffeners, and the width of the reinforcing tendons. The influence of the position of stiffener on thin plate, the shape, period and amplitude of stiffener on the acoustic and vibration characteristics of the structure is discussed. By studying the influence of these parameters on the natural frequency and radiation power level of the structure, some useful conclusions are drawn. The influence of the thickness of free damping layer and the properties of damping material on the acoustic radiation of curved stiffened plate is studied. The effects of the thickness of damping layer, Young's modulus, density and loss factor of damping material on the radiation sound power level and the sound pressure level at the field point are calculated and analyzed. It is found that with the increase of the thickness of the damping layer, the suppression effect of the damping layer on the radiated sound power of the structure increases, and with the increase of the excitation frequency, the suppression effect of the damping layer on the acoustic radiation power level of the structure becomes greater, and the thicker the damping layer is, the more the thickness of the damping layer is. The more obvious the inhibitory effect was. The density of damping material has no obvious effect on structure vibration and noise reduction, but the larger the loss factor of damping material is, the smaller the peak value of radiated sound power level is. This provides a certain basis for the selection of damping layer parameters on the surface of the structure.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TB535

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