Prediction and Control of Interface Damping in Built-up Structures

在武器系统、航天器、飞机、船舶、汽车、建筑物、桥梁和涡轮发动机等组合结构中，界面阻尼是能量损失的主要来源。对于组合结构在动态条件下运行的安全性、可靠性和能效而言，准确的界面阻尼预测和控制是至关重要的。界面阻尼主要是由接触表面的摩擦能损失引起的。接触相互作用中的可变性、非线性和不确定性限制了准确预测和模拟界面阻尼的能力。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。该项目将调查并概述将这些特性调整为所需值的有效方法。这一奖项的结果将使具有所需界面阻尼的结构界面设计成为可能。预期的结果是提高组合结构的安全性、可靠性和能效。研究结果将通过简单组合结构的振动和声学设计项目与社区和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引入了界面阻尼的非线性，并阻止了动态响应的可预测性。目前估计界面衰减的最新技术是通过现象学模型，这种模型不能确保对未测试条件的预测结果。基于物理的模型不能考虑在界面上发生的所有可能的事件和变化。这项研究为复杂的建模提供了一种有效的替代方案，通过调整界面弹性特性的失配，识别加载条件来减少并在可能的情况下消除界面阻尼的非线性和可变性。这种替代方法的另一个好处是能够根据操作需要在几个数量级上调整界面衰减。研究方法是在建模和实验方面共同努力，将摩擦学和结构动力学等两个截然不同的学科联系起来。PI将系统地研究界面力学、几何、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因素。将设计和建造包含具有受控材料属性、预载荷和几何形状的界面的组合结构。最后，对组合结构进行强迫振动和自由振动试验，以探索动力响应中的可调界面阻尼。还将开展一项教育和外展计划，向更广泛的受众传播研究成果，并向学生介绍教育过程中不同阶段的重要概念--减震和摩擦。

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.