A NEW METHOD FOR DYNAMIC ANALYSIS OF PLATES AND PLATE ASSEMBILES

确定结构的振动特性是飞机和其他主要工业设计中的一项重要活动。这些结构中的许多都被建模为板和板组件。提出的研究重点是提高准确解决板振动问题的能力，从而提高结构的设计和制造效率，改善结构的振动性能。将发展一种新的方法，称为动力有限条法。这将通过将现有的三种众所周知的方法--动力刚度法、有限条法和有限元方法--结合起来并发挥其最大的作用来实现。新公式的一个重要特点是将一维精细梁理论用于金属梁和组合梁，并将其推广到二维结构的重要情况，如板，以研究其自由振动特性。在这项工作中，金属或复合材料板将被分成若干条，由承受动态运动的梁表示。板的动态行为将通过组合各个条带的行为来获得，其中每个条带被理想化为经历动态运动的梁。众所周知，符号计算是处理结构力学中经常需要的复杂代数表达式的有力工具。在发展新理论时，将充分利用这一工具。在七十年代早期，由维特里克和威廉姆斯发展的一种已建立的算法(称为W-W算法)将被扩展用于新方法，并随后用作求解技术以获得结果。最后，为了验证该方法的有效性，对某运输型客机的重要结构部件--翼盒进行了动力特性分析。

Establishing the vibration behaviour of structures is an important activity in design within the aircraft and other major industries. Many of these structures are modelled as plates and plate assemblies. The proposed research is focused on improving the capabilities of solving plate vibration problems accurately that will lead to more efficient design and manufacture of structures with improved vibration performance. A new method, called the dynamic finite strip method will be developed. This will be achieved by bringing together and getting the best out of three well-known existing methods, the dynamic stiffness, the finite strip and the finite element methods. An important feature of the new formulation will be the use of one-dimensional refined beam theories for both metallic and composite beams and extend them to the important cases of two dimensional structures such as plates to investigate the free vibration characteristics. In this work, a metallic or composite plate will be split into a number of strips represented by beams subjected to dynamic motion. The dynamic behaviour of the plate will be obtained by combining the behaviour of the individual strips where each strip is idealised as a beam undergoing dynamic motion. It is well known that symbolic computation is a powerful tool in manipulating complicated algebraic expressions often required in structural mechanics. Full advantage of this tool will be taken of when developing the new theory. An established algorithm developed by Wittrick and Williams in the early seventies (known as the W-W algorithm) will be extended for the new method and subsequently used as solution technique to obtain the result. Finally in order to verify the method, a wing box which is an important structural part of a transport airliner will be analysed for its dynamic properties.