Prediction and Control of Interface Damping in Built-up Structures

界面阻尼是组合结构如武器系统、航天器、飞机、船舶、汽车、建筑物、桥梁和涡轮机发动机中能量损失的主要来源。界面阻尼的准确预测和控制对于组合结构在动态条件下的安全、可靠和节能至关重要。界面阻尼主要来自于接触表面上的摩擦能量损失。接触相互作用的可变性、非线性和不确定性限制了准确预测和建模界面阻尼的能力。该研究项目旨在确定控制界面阻尼的主要机制，其大小及其非线性特性。该项目将调查和概述将这些特点调整到理想值的有效方法。该奖项的结果将使结构界面设计具有所需的界面阻尼。预期成果是提高组合结构的安全性、可靠性和能源效率。研究结果将透过简单组合结构的振动和声学设计项目，与社区、K12、本科生和研究生分享。与时间和载荷相关的随机界面事件将非线性引入界面阻尼，并阻止动态响应的可预测性。目前的状态的最先进的估计界面阻尼是通过现象学模型，这不能确保预测结果的未经测试的条件。基于物理的模型无法解释界面上发生的所有可能事件和变化。这项研究提供了一个有效的替代复杂的建模，从而调整跨接口的弹性性能的不匹配，并确定加载条件，以减少，如果可能的话，消除非线性和界面阻尼的变化。这种替代方法的额外好处是能够基于操作需要在几个数量级上调谐界面阻尼。研究方法是建模和实验的协调努力，桥接两个不同的学科，如摩擦学和结构动力学。PI将系统地研究界面力学、几何形状、摩擦、材料特性和载荷条件，以确定界面能量耗散的主要贡献者。将设计和建造含有受控材料特性、预载荷和几何形状的界面的组合结构。最后，将对组合结构进行强迫和自由振动试验，以探索动态响应中的可调界面阻尼。还将开展教育和推广计划，向更广泛的受众传播研究成果，并在教育过程的各个阶段向学生介绍阻尼和摩擦的重要概念。

Interface damping is a primary source of energy losses in built-up structures such as weapon systems, space vehicles, aircrafts, ships, automobiles, buildings, bridges, and turbine engines. Accurate prediction and control of interface damping is critical for safety, reliability and energy efficiency of built-up structures operating in dynamic conditions. Interface damping results mainly from frictional energy losses over contacting surfaces. Variability, nonlinearity and uncertainty in contact interactions limit the ability to accurately predict and model interface damping. This research project aims at identifying the main mechanisms that govern interface damping, its magnitude and its nonlinear characteristics. The project will investigate and outline effective methods to adjust such characteristics to desired values. Results from this award will enable designs of structural interfaces with desired interface damping. The expected outcome is the improvement of safety, reliability and energy efficiency of built-up structures. The results from the research will be shared with the community and K 12, undergraduate and graduate students through design projects involving vibrations and acoustics of simple built-up structures.Time and load dependent stochastic interfacial events introduce nonlinearity to interface damping, and deter predictability of dynamical response. The current state-of-the-art in estimating interface damping is through phenomenological models, which cannot ensure predictive results for untested conditions. Physics-based models cannot account for all possible events and changes occurring at the interfaces. This research offers an effective alternative to complicated modeling whereby the mismatch of elastic properties across interfaces are adjusted, and loading conditions are identified to reduce and if possible eliminate nonlinearities and variability in interface damping. Additional benefit of this alternative approach is the ability to tune interface damping over several orders of magnitude based on operational needs. The research approach is a concerted effort in modeling and experimentation that bridges two distinct disciplines such as tribology and structural dynamics. The PI will systematically study interfacial mechanics, geometry, friction, material properties and loading conditions to identify the major contributors to interfacial energy dissipation. Built-up structures containing interfaces with controlled material properties, preloads and geometries will be designed and constructed. Finally, forced and free vibrations tests will be performed on the built-up structures to explore tunable interface damping in dynamic response. An education and outreach program will also be conducted to disseminate the research results to a broader audience, and introduce important concepts of damping and friction to the students at various stages of their education process.