Nonlinear Localization for Shock Isolation of Flexile Structures

亚历山大F.作者：Lawrence A. Bergman，University of Illinois at Urbana-ChampaignProposal No. CMS-0000060 Proposal Title：Nonlinear Localization for Shock Isolation of Flexible Structures Project Abstract：针对复杂结构的冲击振动，提出了一种独特的响应降低策略。柔性结构对大幅度瞬态输入的脆弱性是有据可查的。已经提出了各种方法，并且在某些情况下，通过这些方法可以增强这些结构的可靠性。典型的解决方案包括被动隔离和辅助阻尼装置，这些装置已经使用多年，并取得了不同程度的成功。基于非线性局部化的概念，提出了一种新型的被动非线性冲击隔离系统，用于保护柔性结构。在这里，而不是严格依赖于顺应性和足够的“敲击空间”，系统采取诱导振动能量和被动地限制它到一个预先指定的次级系统远离主结构被隔离，在那里它可以被动地消散。该技术已成功地应用于复杂的系统受到周期性的负载，在这个项目中，其在瞬态条件下的功效将进行研究，分析和实验。该项目包括三个主要任务。首先，将进行一系列一维模拟和比例模型实验，以验证在保护受到大的瞬态输入的柔性结构的背景下的非线性局部化的概念。接下来，将通过建模和仿真来评估应用于遭受一系列多轴瞬态的大型复杂结构的冲击隔离系统的性能。最后，将在多轴模拟器上使用较大尺度的结构进行概念验证实验。通过使用非线性局部化，所得到的冲击隔离系统将起到双重作用，在线性状态下为小尺度输入提供保护，在非线性状态下为较大尺度瞬态提供保护，同时限制后一状态下通常需要的变形。预算修订的影响：最初的两年预算为两名PI中的每一个提供了总共两个月（每年一个月）的夏季支持，为两名博士中的每一个提供了两个日历年的支持。研究生水平。为了将总预算从261，868美元减少到180，000美元，对每个研究员的夏季支助减少到每年0.10个月。这一变化将影响研究生的夏季进展，但希望不会以实质性的方式。此外，一个博士-学生被一个硕士取代了。在实验方面，一维实验将不会有任何变化。然而，我们将尝试与另一个拥有适当振动台设施的学术机构协调多轴试验计划。假设可以以最低的成本进行一些协调，项目的目标将基本保持不变。已对预算进行了修订，以反映这一点。

Alexander F. Vakakis / Lawrence A. Bergman, Univ. of Illinois at Urbana-ChampaignProposal No. CMS-0000060Proposal Title: Nonlinear Localization for Shock Isolation of Flexible StructuresProject Abstract:A unique response reduction strategy for complex structures subjected to shock-induced vibrations is proposed. The vulnerability of flexible structures to large magnitude transient inputs is well documented. Various methods have been proposed and, in some cases, implemented through which the reliability of these structures can be enhanced. Typical solutions include passive isolation and auxiliary damping devices, which have been employed for many years with varying degrees of success. The primary focus of the proposed research is the development of a new type of passive nonlinear shock isolation system for protection of flexible structures, based upon the concept of nonlinear localization. Here, rather than relying strictly on compliance and adequate "rattle space," the system takes induced vibrational energy and passively confines it to a preassigned secondary system away from the primary structure to be isolated, where it can be passively dissipated. The technique has been applied successfully to complex systems subjected to periodic loading, and in this project its efficacy under transient conditions will be studied, both analytically and experimentally.The project consists of three main tasks. First, a series of one-dimensional simulations and scale model experiments will be conducted to validate the concept of nonlinear localization in the context of protecting flexible structures subjected to large, transient inputs. Next, performance of a shock isolation system applied to a large, complex structure subjected to a series of multi-axial transients will be evaluated by modeling and simulation. Finally, a proof of concept experiment will be conducted using a larger scale structure on a multi-axis simulator.Through the use of nonlinear localization, the resulting shock isolation system will serve a dual purpose, providing protection in the linear regime for small-scale inputs and in the nonlinear regime for larger scale transients, while limiting the deformation ordinarily required for protection in the latter regime. The potential payoff is more compact and efficient passive protective systems.Impact of Budget Revision: The original two year budget provided for a total of two months (one month per year) of summer support for each of the two PI's and two calendar years of support for each of 2 Ph.D.-level graduate students. In order to reduce the overall budget from $261,868 to $180,000, summer support for each investigator is reduced to .10 month per year for each PI. This change will impact the summer progress of the graduate students, though hopefully not in a substantial way. Further, one Ph.D.-level student has been replaced by an M.S.-level student.On the experimental side, there will be no change to the one-dimensional experiment. We will, however, attempt to coordinate the multi-axial test program with another academic institution having an appropriate shaker facility. Assuming some coordination is possible at minimal cost, the goals of the project will remain fundamentally unchanged. The budget has been revised to reflect this.