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EAGER: The Surrogate System Hypothesis for Joint Mechanics

EAGER：关节力学的替代系统假说

基本信息

批准号：
1744327
负责人：
Matthew Brake
金额：
$ 20万
依托单位：
William Marsh Rice University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-08-15 至 2019-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1744327&HistoricalAwards=false
关键词：
EAGER Surrogate System Hypothesis Joint

项目摘要

This project is aimed at understanding the fundamental physics governing the behavior of mechanical joints in engineered structures. Mechanical joints are essential and integral parts of engineered systems and yet the physics governing them is largely unknown. This lack of knowledge prevents engineers and designers from developing predictive models of a jointed structure that can be used to guide its design. As a result, jointed structures are often overdesigned to prevent failure from occurring. In low consequence applications, such as an office chair, home electronic appliance, etc., overdesign of the jointed interface has little practical consequence. For high consequence applications, such as aero-turbines for passenger jets, the fuselage of rockets, defense applications, or the frame of an automobile, overdesign can have significant ramifications in terms of fuel efficiency and safety. If a predictive model of jointed structures existed (i.e. one that predicts both the stiffness of a joint and how much energy it dissipates), then joints could be properly designed contributing their appropriate weight to the structure, with the potential of reducing fuel consumption. A second outcome is that the predictive model could be used in design of jointed interfaces to dissipate energies that might otherwise damage other components of the assembly, such as sensitive electronics within a rocket. This EArly-concept Grant for Exploratory Research (EAGER) project seeks to address this gap in predictive capability by developing a rigorous framework, the surrogate system hypothesis, in which a jointed interface can be characterized out of context (avoiding complications associated with high manufacturing expenses for the real system or multiple sources of contamination in measurements such as from other joints within the system) and then used to predict the response of the joint within the system of interest with high accuracy.The surrogate system hypothesis states that a surrogate structure that contains the same joint as the system of interest can be used to deduce the properties of the joint. These properties, once accounting for the properties of the surrogate structure, can then be substituted directly into the system of interest as a spatially discrete joint model (as opposed to a modal model). The goal of this project is to test the surrogate system hypothesis to determine if, under varied loading conditions and in realistic structures, it is supported by experimental evidence. The experimental investigations must, by nature of the hypothesis, be in combination with numerical modeling efforts, which will be built upon recently matured reduced order modeling techniques from the dynamic substructuring community for studying the response of a jointed structure. The work is divided into several objectives: testing the surrogate system hypothesis in new regimes in order to challenge its underlying assumptions, determining the bounds of the hypothesis' limitations, and demonstrating proof-of-concept on a realistic system with more complex geometries. If the surrogate system hypothesis finds support, it will enable several significant advances for contact mechanics in addition to the design and optimization of assemblies. This research will enable a new approach for predictive models of joints based off of well-characterized surrogate systems. Once a predictive approach is developed, it will be possible to detect potential failures at the design phase before hardware is manufactured. The ramification of this research is that, if successful, this hypothesis indicates that micro- and nano-scale effects, such as the distribution of asperities, are secondary to determining the dynamics of a structure behind the macro-scale features such as geometry and mean roughness.

本项目旨在了解工程结构中机械接头行为的基本物理学。机械接头是工程系统的基本组成部分，但其物理原理在很大程度上是未知的。这种知识的缺乏阻碍了工程师和设计师开发可用于指导其设计的关节结构的预测模型。因此，接缝结构往往过度设计，以防止发生故障。在诸如办公椅、家用电器等低后果应用中，接合界面的过度设计几乎没有实际后果。对于后果严重的应用，例如客机的航空涡轮机，火箭的机身，国防应用或汽车的框架，过度设计可能在燃料效率和安全性方面产生重大影响。如果存在连接结构的预测模型（即预测接头刚度和消耗多少能量的模型），则可以适当设计接头，为结构提供适当的重量，并有可能降低燃料消耗。第二个结果是，预测模型可以用于设计接合界面，以耗散否则可能损坏组件的其他组件的能量，例如火箭内的敏感电子器件。这个早期概念探索性研究资助（EAGER）项目旨在通过开发一个严格的框架，替代系统假设，其中接合界面可以脱离上下文来表征（避免与真实的系统的高制造费用或测量中的多个污染源（例如来自系统内的其它接头）相关联的复杂性）替代系统假设指出，包含与感兴趣的系统相同的关节的替代结构可以用于推断关节的特性。这些属性，一旦考虑到替代结构的属性，然后可以直接代入感兴趣的系统作为空间离散的关节模型（与模态模型相反）。该项目的目标是测试替代系统假设，以确定在不同的载荷条件下，在现实的结构，它是由实验证据支持。实验研究必须，由性质的假设，结合数值模拟的努力，这将是建立在最近成熟的降阶建模技术，从动态子结构社区研究的一个关节结构的响应。这项工作分为几个目标：在新的制度下测试替代系统假设，以挑战其基本假设，确定假设的限制范围，并在具有更复杂几何形状的现实系统上演示概念验证。如果替代系统假说得到支持，除了组件的设计和优化之外，它还将使接触力学取得一些重大进展。这项研究将为基于良好表征的替代系统的关节预测模型提供一种新的方法。一旦开发出预测方法，就有可能在硬件制造之前的设计阶段检测到潜在的故障。这项研究的结果是，如果成功的话，这一假设表明，微观和纳米尺度的影响，如粗糙度的分布，是次要的，以确定背后的宏观尺度特征，如几何形状和平均粗糙度的结构的动态。