Non-linear aeroelasticity and health monitoring of anisotropic curved structures

拟议的工作包括基础研究和应用研究。它是上述研究的延续，整合了更现实和复杂的结构和流动方面，其中将考虑结构的非线性方面以及流体非线性和非比例阻尼。研究进展。近年来，我们的团队主要研究了流体结构系统的数值分析和振动的信号处理方法两个方面。我们的研究成果被IREQ、Spar航空航天/EMS技术、CAE电子、NRC航空航天研究所的结构、材料和推进小组、庞巴迪和P&WC等公司所采用。这些研究产生了以下结果：圆柱壳和锥形壳在可压缩或不可压缩流体作用下振动的数值模拟。由于这些壳体元件在航空航天结构中的广泛应用，因此预测壳体在流动作用下的动力不稳定性是航空工程师面临的一个具有挑战性的课题。对于这种包含复杂结构、边界条件、材料和载荷的问题，当影响颤振边界的因素发生变化时，解析模型变得非常复杂。因此，建立了一种基于混合有限元方法的数值包来描述弯曲壳的气动弹性行为。与现有的商业有限元软件相比，它以更少的计算时间和成本提供了非常快速和精确的收敛。这些工作的结果已经在一个国际会议上提出，并在国际期刊上发表[1,2]。所建立的线性理论足以预测颤振的开始，然而，为了捕捉颤振的实际极限环幅值，所需要的非线性壳理论被留给了本研究。

The proposed work involves both fundamental and applied research. It is a continuation of the aforementioned research study by integrating more realistic and complex aspects of structure and flow, in which nonlinear aspects of structure as well as fluid nonlinearity and non-proportional damping will be considered. PROGRESS OF RESEARCH. In recent years, our team has studied two major areas: numerical analysis of fluid structure systems and signal processing methods for vibration. These studies led to the publication of numerous scientific articles and our results were used by companies such as IREQ, Spar Aerospace/EMS Technologies, CAE Electronics the NRC aerospace research institute’s structure, materials and propulsion group, Bombardier and P&WC. These studies produced the following results: Numerical simulation of vibration of cylindrical and conical shells subjected to compressible or incompressible fluid flow. Since these shell elements are used widely in aerospace structures, predicting the dynamic instability of shells subjected to flow is a challenging subject that aeronautical engineers are confronted with. For such a problem that contains complex structures, boundary conditions, materials and loading, an analytical model becomes very complicated when undergoing a change of factors affecting the flutter boundaries. Therefore, a numerical package based on a hybrid finite element method has been developed to describe the aeroelastic behavior of curved shells. It provides very fast and precise convergence compared to existing commercial FEM software at less computational time and cost. The results of these works have been presented at an international conference and published in international journals [1, 2]. The linear theory developed is adequate to predict the onset of flutter, however nonlinear shell theory required to capture the actual limit cycle amplitude of the flutter is left for this proposed research.   OBJECTIVES. The main goal of this research is to provide new insights on the subject of flutter of curved structures such as cylindrical and conical shells. Particular attention is paid to the influence of parameters such as dynamic pressure, flow angles and panel curvature on aeroelastic behavior. Consistent nonlinear hybrid finite element formulations and efficient solution procedures are developed and presented. The short-term objectives will address the following points: A) Bifurcation and nonlinear dynamic analysis of curved structures. B) Nonlinear aeroelastic analysis of shells of revolution subjected to supersonic flow. C) Sloshing effect on the aeroelastic stability of curved structures. D) Development of a nonlinear method to predict the response of anisotropic curved structures subjected to a turbulent boundary-layer-induced random pressure field.