Stochastic nonlinear aeroelastic models subject to unsteady loads

准确有效地估计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大影响。对这些负荷的不准确估计将导致糟糕的设计选择，最典型的是保守的结构设计会超重，增加能源消耗，有毒排放和噪音污染。本研究将开发有效识别飞机结构部件不确定性和非线性的工具，并研究它们如何影响飞机载荷。本项目仅考虑关节的非线性和不确定性，但所开发的框架可用于其他非线性和不确定性来源，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需求迅速增加，但为了克服飞机设计局限于确定性和线性制度的主流做法，开发这样一个框架至关重要。在这个项目中，将使用一个详细而复杂的飞机结构数值模型来明确地确定由于机翼连接的几何和材料不确定性以及非线性而导致的动态响应的可能变化范围。然后，这些数据将用于确定降阶模型（ROMs）的参数。rom对于提高计算效率非常有用，可用于有效地预测极端非定常载荷。经过验证的降阶结构模型将被纳入气动弹性模型，并允许设计者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视野。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。由于已经观察到非线性和不确定性的多种来源影响飞机性能，本研究旨在探讨以下问题：1-如何使用详细的数值模型来识别非线性和不确定性的来源？如何使用结构模型更新工具（将用于验证基于实验数据或详细有限元预测的数值模型的工具）来获得能够包括详细数值模型估计的非线性和不确定效应的rom ？如何使用这些经过验证的ROMs有效地研究飞机载荷预测（对飞机性能有重大影响的重要参数）中的不确定性和非线性的影响？上述问题将通过考虑飞机结构中非线性和不确定性的一个重要来源，即结构关节来回答。

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.