Stochastic nonlinear aeroelastic models subject to unsteady loads

准确、有效地估算飞机载荷是航空航天工业中的一个重要问题。这些载荷的极值通常是用于确定飞机结构尺寸的关键参数，因此对飞机的性能有重要影响。对这些载荷的不准确估计将导致糟糕的设计选择，最典型的是超重的保守结构设计，增加能耗、有毒排放和噪声污染。这项研究将开发有效识别飞机结构部件中的不确定性和非线性的工具，并研究它们如何影响飞机载荷。在这个项目中，只考虑接头的非线性和不确定性，但开发的框架可以用于其他来源的非线性和不确定性，如空气动力学和飞行控制系统。尽管从技术、经济和安全方面考虑不可避免的不确定性和非线性的要求迅速增加，但为了克服飞机设计被限制在确定性和线性范围内的主要做法，开发这样一个框架是至关重要的。在这个项目中，将使用飞机结构的详细和复杂的数值模型来明确地识别由于机翼-外挂物连接的几何和材料不确定性和非线性而引起的动态响应的可能变化范围。然后，这些数据将用于识别降阶模型（ROM）的参数。ROM对于计算效率非常有用，并且用于有效地预测极端非定常载荷。经验证的降阶结构模型将被纳入气动弹性模型中，并允许设计师在载荷计算过程中考虑非线性和不确定性的影响。目标是摆脱传统的基于安全系数的方法，探索随机非线性气动弹性分析的广阔领域。该项目将与空中客车公司合作进行，空中客车公司将提供进行研究所需的数据。由于它已被观察到，多个来源的非线性和不确定性影响飞机的性能，研究的目的是调查以下问题：1-如何可以使用详细的数值模型在识别的非线性和不确定性的来源？2-如何使用结构模型更新工具（用于根据实验数据或详细有限元预测验证数值模型的工具）来获得能够包括详细数值模型估计的非线性和不确定性影响的ROM？3-如何使用这些经过验证的ROM来有效地研究飞机载荷预测中的不确定性和非线性（对飞机性能有重大影响的重要参数）的影响？通过考虑飞机结构中非线性和不确定性的一个重要来源，即结构接头，可以回答上述问题。

The accurate and efficient estimation of aircraft loads is an important problem in the aerospace industry. The extreme values of these loads are typically the key parameters used for sizing the aircraft's structure and, therefore, have a significant influence on the performance of an aircraft. Inaccurate estimations of these loads will lead to poor design choices, most typically a conservative structure design that is overweight, increasing energy consumption, toxic emissions, and noise pollution. This research will develop tools for the efficient identification of uncertainties and nonlinearities in aircraft structural components and investigate how they affect aircraft loads. Only nonlinearities and uncertainties in the joints will be considered in this project, but the developed framework can be used for other sources of nonlinearities and uncertainties, such as aerodynamics and flight control systems. Developing such a framework is crucial in order to overcome the predominant practice whereby aircraft designs are restricted to a deterministic and linear regime, despite rapidly increasing demands to consider unavoidable uncertainties and nonlinearities from technological, economic and safety considerations. In this project, a detailed and sophisticated numerical model of an aircraft structure will be used to explicitly identify the possible range of variations in the dynamic response due to geometric and material uncertainties and nonlinearities of a wing-store joint. These data will then be used to identify the parameters of reduced-order models (ROMs). ROMs are extremely useful for computational efficiency, and are used to efficiently predict extreme unsteady loads. The validated reduced-order structural model will be incorporated into the aeroelastic model and will allow the designer to include the effects of nonlinearities and uncertainties in the process of load calculations. The goal is to move away from the conventional safety-factor-based approach and explore the wide horizon of stochastic nonlinear aeroelastic analysis.This project will be carried out in partnership with Airbus, which will provide the data necessary to undertake the research. Since it has been observed that multiple sources of nonlinearities and uncertainties affect aircraft performance, the study aims to investigate the following questions: 1- How can detailed numerical models be used in the identification of sources of nonlinearities and uncertainties? 2- How can the structural model updating tools (the tools that will be used to validate the numerical model based on experimental data or detailed finite element predictions) be used to obtain ROMs that are capable of including the nonlinear and uncertain effects estimated by detailed numerical models? 3- How can these validated ROMs be used to efficiently investigate the effects of uncertainties and nonlinearities in aircraft load predictions (important parameters that have significant impact on aircraft performance)?The aforementioned questions will be answered by considering an important source of nonlinearities and uncertainties in the aircraft structure, i.e. structural joints.