This work proposes a novel reduced-order modelling approach in time domain for the coupled flight dynamics and aeroelastic response of manoeuvring very flexible aircraft. Theudstarting point is the coupling of a displacement-based, geometrically-nonlinear flexible-bodyuddynamics formulation with a 3-D unsteady vortex-lattice method. This is followedudby a linearisation of the structural degrees of freedom, which are assumed to be small inuda body- fixed reference frame. The translations and rotations of that reference frame andudtheir time derivatives, which describe the vehicle flight dynamics, can be arbitrarily large.udAs a result, all couplings between the rigid and elastic motions are introduced withoutudthe a priori assumptions of the mean axes approximation, traditionally used to decoupleudthe equations in flexible-aircraft dynamics. The resulting system can be projected ontouda few vibration modes of the unconstrained aircraft with geometrically-nonlinear static deflections at a trim condition. Equally, the unsteady aerodynamics are approximatedudon a fixed lattice defined by the deformed static geometry. The resulting high-orderudaerodynamic system, which defines the mapping between the small number of generalisedudcoordinates and unsteady aerodynamic loads, is then reduced through balanced truncation.udThis unified description of the flexible aircraft dynamics provides a hierarchy of aeroelasticudmodel fidelities, which will be illustrated on a representative high-altitude, long-enduranceudaircraft to identify the importance of geometrically-nonlinear wing deformations on theudvehicle dynamics. Application of the reduced-order modelling approach further shows audvery substantial reduction in model size that leads to model orders (and computationaludcost) similar to those in conventional frequency-based methods but with higher modelling fidelity to compute manoeuvre loads. Closed-loop results for the Goland wing finally demonstrate the application of this approach in the synthesis of a robust flutter suppressionudcontroller.
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机译：这项工作提出了一种新颖的时域降阶建模方法，用于机动非常灵活的飞机的耦合飞行动力学和气动弹性响应。 起点是基于位移的，几何非线性的柔性体 uddynamics公式与3-D非定常涡旋-晶格方法的耦合。这之后是对结构自由度的线性化，它在人体固定参考系中被认为很小。描述车辆飞行动力学的参考系和其时间导数的平移和旋转可以任意大。 ud因此，引入了刚性运动和弹性运动之间的所有耦合，而无需 u n先验假设均值轴近似值，传统上用于在飞机动态动力学中解耦方程。可以将所得系统投影到修剪状态下几何非线性静挠度不受限的飞机的几种振动模式上。同样，非稳态空气动力学近似于由变形的静态几何形状定义的固定晶格。由此产生的高阶空气动力学系统定义了少量的通用坐标和不稳定的空气动力学负载之间的映射，然后通过平衡截断来减小。 ud这种对飞机动力学的统一描述提供了空气弹性 udmodel逼真度的层次结构，这将在具有代表性的高空，长寿命飞机上进行说明，以识别几何非线性机翼变形对汽车动力学的重要性。降阶建模方法的应用进一步显示出模型尺寸的 u u u u u u u u >大幅减少，这导致了模型订单（和计算 udcost）与传统的基于频率的方法类似，但是具有更高的模型保真度来计算机动负荷。 Goland机翼的闭环结果最终证明了该方法在鲁棒颤振抑制 udcontroller合成中的应用。
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