薄板结构的振动功率流特性研究

发布时间：2018-10-10 14:06

【摘要】：随着现代工业的高速发展,对飞机,舰艇,船舶等结构的强度、自重以及振动与噪声等方面提出了较高要求,复合材料由于具有高的比强度、比刚度和抗疲劳性、可设计性等优良性能,这就使层合板结构等复合材料构件得到了广泛的应用。在工程应用中,层合板结构等薄板结构必然会因受到激励而产生振动,层合板结构的振动易导致整个航空结构产生损伤。振动功率流是一个理想的反映结构振动能量在结构中传递的物理量,因此研究复合材料结构的振动功率流特性,对航空航天领域等结构的减振降噪与损伤探测具有重要的指导意义。本文主要对复合材料层合板结构等薄板结构的振动功率流特性进行了理论研究。首先,对薄板结构的振动功率流的数值解进行了理论计算。在基本假设的基础之上,建立了薄板结构的有限元模型。引入了振动功率流的概念并加以重点阐述,求解了矩形单元的刚度矩阵和质量矩阵,并以板壳单元为例,推导了该种单元的结构声强,对结构声强在板厚方向进行积分,进而得出薄板结构的振动功率流。在计算得到功率流的数值解后,绘制出了前几阶频率下的功率流的矢量场分布图。对振动能量在薄板结构表面的分布以及传播实现了可视化,并对比分析了四边简支和四边固支边界条件下的功率流矢量场分布图。其次,以复合材料层合板结构为研究对象,基于一阶剪切理论建立了不同于单层薄板结构的有限元模型。详细介绍了利用振型叠加法来计算层合板结构的动态响应的过程,推导了位移与内力等与功率流相关量的计算公式。最后,对受迫振动下的复合材料层合板结构的振动功率流特性进行了研究。利用MATLAB软件计算了已有算例的层合板结构的固有频率,结果表明:本文推导的公式及编写的程序是可靠的。接着同时对比分析了分别在四边简支以及四边固支条件下,改变激励点位置以及层合板纤维铺设角度、跨厚比和弹性模量比等结构参数对振动功率流数值结果的影响。结果表明:纤维铺设角度和跨厚比对振动功率流的影响明显。
[Abstract]:With the rapid development of modern industry, the strength, self-weight, vibration and noise of aircraft, warship, ship and other structures are required. The composite materials have high specific strength, specific stiffness and fatigue resistance. Good properties such as designability make laminated structures and other composite components widely used. In engineering application, the vibration of laminated plate structure and other thin plate structures will inevitably be caused by excitation, and the vibration of laminated plate structure will easily cause damage to the whole aeronautical structure. The vibration power flow is an ideal physical quantity reflecting the vibration energy transfer in the structure, so the vibration power flow characteristics of composite structure are studied. It has important guiding significance for vibration and noise reduction and damage detection of structures in the field of aeronautics and astronautics. In this paper, the vibration power flow characteristics of laminated laminates and other thin plate structures are studied theoretically. Firstly, the numerical solution of the vibration power flow of thin plate structure is calculated theoretically. Based on the basic assumptions, the finite element model of thin plate structure is established. The concept of vibration power flow is introduced, and the stiffness matrix and mass matrix of rectangular element are solved. Taking the plate and shell element as an example, the structural sound intensity of the element is deduced, and the structural sound intensity is integrated in the direction of plate thickness. Then the vibration power flow of thin plate structure is obtained. After the numerical solution of the power flow is obtained, the vector field distribution of the power flow at the previous frequency is plotted. The distribution and propagation of vibration energy on the surface of thin plate are visualized, and the distribution of power flow vector field under the condition of simply supported on four sides and fixed on four sides is compared and analyzed. Secondly, based on the first order shear theory, the finite element model of composite laminated plate structure is established, which is different from that of single-layer thin plate structure. The process of calculating the dynamic response of laminated plate structure by mode superposition method is introduced in detail. The formulas for calculating the correlation between displacement and internal force and power flow are derived. Finally, the vibration power flow characteristics of composite laminated plates under forced vibration are studied. The natural frequencies of laminated plate structures with existing examples are calculated by using MATLAB software. The results show that the formula and the program are reliable. At the same time, the effects of structural parameters such as the position of excitation point, the angle of fiber laying, the ratio of span to thickness and the ratio of elastic modulus to the numerical results of vibration power flow under the condition of simply supported on four sides and fixed on four sides are compared and analyzed at the same time. The results show that the influence of fiber laying angle and span thickness ratio on vibration power flow is obvious.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

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