Complex-Shaped Lightweight Structures with Adaptive Dynamic Behaviour through Evanescent Morphing

轻量化设计原则的一致实施是未来车辆、机器和设施实现更高能效和新性能水平的重要先决条件之一。一个有前途的解决方案是应用纤维增强聚合物（FRP）与“定制”增强，使高质量的节省相比，传统的单片材料。增强纤维的重量轻的最佳和负载适应的分布实现了高强度和刚度，但通常导致部件的低机械阻尼。同时，在现代设计解决方案中，减少了在系统级对耗散有贡献的接头数量。由此产生的问题振动敏感性，不寻常的或过度的噪音排放，即使在低激励水平，现在解决的二次被动或主动阻尼措施，限制了玻璃钢结构的轻量化潜力。因此，所要求的项目的目标是开发的基本原理，为建模和尺寸的新，基于流体致动原理的渐逝变形的轻质结构自适应振动控制的几乎重量中性系统。这里引入的术语“渐逝变形”是指这样一个小的形状变化，只影响所考虑的振动结构的动态行为，而其对结构的主要承载功能的影响是可以忽略的。为了有效地控制动力学行为，提出了一种新的概念，称为可压缩约束层阻尼（CCLD）。这种剪切粘弹性层以材料和技术兼容的方式集成在部件的内部，具有由流体致动控制的厚度，并构成具有可变阻尼和刚度的自适应元件。为了实现采用流体激活CCLDs的FRP结构，必须解决几个科学任务。首先，发生在CCLD的耗散机制的模型将详细说明和参数化的适应不同的泡沫材料进行表征实验的结果。其次，将创建承载各向异性FRP结构的数值模型，并将其与先前详细描述的CCLD模型合并，从而能够识别由于流体驱动引起的变形场。第三，后一种模型将通过CCLD的方向相关FRP阻尼特性和压力相关阻尼特性得到增强。最后，系统的数值研究的整体阻尼行为在广泛的振幅和频率范围将进行考虑到可变CCLD参数和可能的结构效应，由于驱动的几何形状的变化。这些结果将在项目期间制造的通用演示器的实验测试中得到验证。

A consistent implementation of lightweight design principles is one of the important prerequisites for the achievement of improved energy efficiency and new performance levels of future vehicles, machines, and facilities. A promising solution is the application of fibre-reinforced polymers (FRP) with "tailored" reinforcement enabling high mass savings compared to the conventional monolithic materials. The lightweight optimal and load adapted distribution of reinforcing fibres enables high strength and stiffness but typically leads to low mechanical damping of components. At the same time, number of joints contributing to the dissipation at the system level, is reduced in modern design solutions. The resulting problematic vibration susceptibility, unusual or excessive noise emission even at low excitation levels are nowadays addressed by secondary passive or active damping measures limiting the lightweight potential of FRP structures.The objective of the requested project is therefore the development of fundamentals for modelling and dimensioning of novel, almost weight-neutral systems for adaptive vibration control of lightweight structures based on evanescent morphing using fluidic actuation principles. The here introduced term "evanescent morphing" means such a small shape change that only influences the dynamic behaviour of the considered vibrating structure whereas its effect on the primary load carrying function of the structure is negligible. For an effective controllability of the dynamic behaviour, a novel concept called Compressible Constrained Layer Damping (CCLD) is proposed. Such sheared viscoelastic layer, integrated in the inward of a component in a material and technology compatible manner, has thickness controlled by the fluidic actuation and constitutes an adaptable element with variable damping and stiffness.For the realisation of FRP structures implementing fluidically activated CCLDs, several scientific tasks must be solved. First, models of dissipative mechanisms occurring in the CCLD will be elaborated and parametrised using results of adapted material characterising experiments conducted on different foams. Second, numerical models of the load bearing anisotropic FRP structures will be created and merged with the previously elaborated models of the CCLD, enabling the identification of deformation fields due to fluidic actuations. Third, the latter models will be enhanced by the direction dependent FRP damping properties and pressure dependent damping properties of the CCLD. Finally, a systematic numerical investigation of the overall damping behaviour in broad amplitude and frequency range will be conducted taking into account both the variable CCLD parameters and possible structural effects due to actuated geometry change. The results will be validated in experimental tests on generic demonstrators manufactured during the project.