Development of new finite element models to predict the dynamic behavior of shells subjected to flowing fluids

壳体结构是航空航天和飞机工程、核电站和海军结构中的关键部件。前述行业一般使用薄壁壳体在高流体流动速率下，并且需要低壳体厚度。在这些条件下，结构变得非常容易失稳和破坏。拟议工作的目标是开发更复杂的有限元模型，其范围比现有的模型更大。这允许对更真实的案例进行建模，同时确保它们的可靠性。这项工作是我们长期目标的一部分，我们的长期目标是以比实验方法更低的成本完成基于可靠和非常准确的方法的有限元模型。第一个主题是将我们已有的轴对称混合模型推广到研究受内部湍流诱导的随机边界层的圆锥壳。这需要获得任意压力场和边界层压力下流体的互相关谱密度和壳体位移的均方根值。板壳在超音速流动作用下的情况也是本研究项目要处理的一个重要问题。这使得可以模拟受超音速流动影响的曲面和面板，如飞机尾翼或涡轮叶片。第三个研究主题涉及固体壳体与流体相互作用时的超弹性行为的积分。在这项研究中，应变不变本构模型将被用来描述超弹性材料的行为。后者使得将我们的有限元模型应用于具有更真实材料属性的结构成为可能。最后一个主题涉及到混合轴对称模型与可压缩内部流动流体耦合的重新表述。目的是解决与施加在结构进出口上的流体边界条件有关的问题。开发新的数值模型和改进现有的数值模型是因为这一领域的现有软件只涵盖非常有限的流固相互作用的情况。此外，我们对开发环状流模型的兴趣是将我们的专业知识扩展到其他应用的重要机会。所有这些进展及其结果将有助于国际科学界研究结构与流动流体相互作用的振动。实际上，NSERC资助的大部分研究项目也已经并将得到业界的支持。例如，由NSERC创建的新的联盟计划(Industry-NSERC)取代了以前的计划(RD-Coop和Engage)。申请人拥有并每三到四年有一个RD-Coop和/或Engage项目(庞巴迪、普华永道、魁北克水电、CAE等)。

Shell structures constitute critical components in aerospace and aircraft engineering, nuclear power plants and naval structures. The aforementioned industries generally use thin-walled shells under high rates of fluid flow and require low shell thicknesses. Under these conditions, the structure becomes very susceptible to instability and failure. The objectives of the proposed work is to develop more sophisticated finite element models that have a larger scope than the existing ones. This permits modeling of more realistic cases while ensuring their reliability. This work is a part of our long-term objective that consists to complete our finite element models based on a reliable and very accurate approach at lower cost relative to experimental method. The first topic is to extend our existing axisymmetric hybrid model to study truncated conical shells subjected to a random boundary layer induced by internal turbulent flow. This requires obtaining the cross-correlation spectral density of the fluid and the mean square value of the displacements of the shell for an arbitrary pressure field and for a boundary-layer pressure. The case of plates and shells subjected to supersonic flow is also an important issue to deal with in the present research project. This allows simulating curved and panels like aircraft fins or turbine blades subjected to supersonic flow. The third research subject concerns the integration of the hyperelastic behaviour of the solid shell when interacting with a fluid. In this research, strain-invariant constitutive models will be used to describe the behaviour of hyperelastic materials. The latter makes it possible to apply our finite element models to structures with more realistic material properties. The last theme concerns the reformulation of the hybrid axisymmetric model coupled with a compressible internal flowing fluid. The objective is to resolve the issue related to fluid boundary conditions imposed on the inlet and outlet of the structure. The development of new numerical models and the improvement of existing ones are motivated by the fact that existing software in this field covers only very limited cases of fluid-structure interaction. In addition, our interest to develop annular flow models is an important opportunity to extend our expertise to others applications. All these developments and their results will be useful to international scientific community working on vibrations of structures in interaction with flowing fluid. Practically, the majority of all the research projects supported by NSERC are also have had and will have the supports of the industry. For instance, the new ALLIANCE program (Industry-NSERC) created by NSERC and replacing the former programs (RD-Coop and Engage). The applicant has and had every three or four years a project of RD-Coop and/or Engage (Bombardier, PWC, Hydro Quebec, CAE, etc.).