CAREER: Structural Stability and Thin-walled Structures

摘要：职业：结构稳定性和薄壁结构，CMS建议0448707 PI：Ben Schafer，Johns Hopkins薄壁结构构成了国家工业基础设施的支柱，在民用和机械系统中得到了广泛的应用。稳定是任何成功结构的基本要求，而对于薄壁结构，截面稳定是主要的约束条件。尽管薄壁结构分析复杂，设计困难，但效率很高。在薄壁构件中最大限度地减少材料，这是在我们的高容量、低成本的物理基础设施中使用昂贵的新材料时的必备条件。这项建议推进了理论、计算和实验工作的综合计划，以(1)实施计算稳定性方面的新技术，以满足薄壁构件的特殊需要；(2)开发和验证提供更高效、可靠和可靠设计的新方法；以及(3)创建新的资源，以增加PI在结构稳定性教育方面努力的广度和深度，同时加强霍普金斯大学和社区的合作伙伴关系。截面失稳使薄壁杆件的行为变得非常复杂；目前的计算稳定性技术几乎没有增加清晰度。本文提出了一种新的模态分解技术，它提供了(I)模型降阶，能够分离出与特定的截面失稳类别一致的应变场，然后进行仅有一个自由度的有意义的分析，以及(Ii)模态识别，即将一般构件的变形场分类为构成该场的截面失稳的基本模式，从而量化模态相互作用。模态分解的发展为研究结构稳定性中的各种悬而未决的问题提供了独特的手段，特别是与耦合和混合模态有关的问题。经验主义和对经典板屈曲解的过度依赖使薄壁结构的设计变得复杂，并阻碍了效率，因为设计师被捆绑在过去的解决方案中。由PI开发的一种新的薄壁钢结构设计方法，旨在通过计算来解决截面失稳问题，并将结果整合到一个全面的设计过程中，从而提供灵活性和可靠性。提出了将这种设计方法推广到梁柱和有穿孔构件上的新发展。在设计上的重大变化，如这里提出的那些，需要仔细的实验和计算来理解其后果，并提供有效和经过验证的方法。此外，还提出了将新的设计方法推广到由铝和热塑性材料以外的材料制成的薄壁构件的具体计划。智能优点：该建议提供了(I)开发一种新的用于计算结构稳定性问题的模型简化和模态识别的模态分解技术，并将其应用于各种重要的稳定性问题，以及(Ii)将计算结构稳定性的实际扩展和验证应用到薄壁钢构件的日常设计中，包括在梁柱和有穿孔的构件中在复杂荷载下的截面稳定性的独特作用。提出的模态分解技术和发展的设计方法代表了薄壁构件理论和设计的重大进步，并有可能刺激新的发现和创新。提出了将设计方法推广到包括铝和热塑性塑料在内的各种其他重要薄壁材料的计划。拟议的活动广泛依赖于PI在薄壁构件的试验和计算结构稳定性方面的经验，并为持续发展提供了所需的平台。广泛的影响：PI参与设计规范和技术委员会的开发，确保实践工程社区和研究社区都将从研究结果中受益。此外，这里详述的教育计划确保高中生、本科生和研究生都将从拟议的工作中受益。高中外展工作的重点是丰富PI与巴尔的摩理工高中(Poly)正在进行的合作，Poly是一所招收主要是少数族裔学生的学校。加强与保利的关系为代表不足的群体提供了科学和工程活动的重要场所。本科生教育工作与霍普金斯教育资源中心合作，将有助于开发结构稳定的、具有良好教学效果的在线教学指南。研究成果，包括教育工作，将通过期刊论文、会议演讲以及国际和平协会与几个技术委员会的持续努力来传播。

Abstract for: CAREER: STRUCTURAL STABILITY AND THIN-WALLED STRUCTURES, CMS proposal 0448707 PI: Ben Schafer, Johns HopkinsThin-walled structures form the backbone of the nation's industrial infrastructure and enjoy wideapplication in civil and mechanical systems. While stability is a fundamental requirement for anysuccessful structure, for thin-walled structures, cross-section stability is the primary constraint. Complex to analyze and difficult to design, thin-walled structures are nevertheless highly efficient. Material is minimized in thin-walled members, a must when embracing costly new materials for use in our high volume, low-cost, physical infrastructure. This proposal advances an integrated plan of theoretical,computational, and experimental work to (1) implement new techniques in computational stability of particular need for thin-walled members; (2) develop and verify new methods that provide more efficient, robust, and reliable designs; and (3) create new resources that increase the breadth and depth of the PI's efforts in structural stability education while strengthening partnerships at Hopkins and in the community. Cross-section instability greatly complicates the behavior of thin-walled members; and current computational stability techniques do little to add clarity. Proposed here is a new modal decomposition technique that provides (i) model reduction, the ability to isolate the strain fields consistent with specific classes of cross-section instability, and then perform meaningful analysis with as little as one degree of freedom, and (ii) modal identification, a means to classify a general member deformation field into the basic modes of cross-section instability which make up that field, and thus quantify modal interactions. Development of modal decomposition provides a unique means to investigate a variety of open questions in structural stability, particularly related to coupled and mixed modes. Empiricism and an over-reliance on classical plate buckling solutions complicates the design of thin walled structures and hinders efficiency as designers are tied to the solutions of the past. A new design method, developed by the PI for thin-walled steel structures, seeks to provide flexibility and reliability by attacking cross-section instability computationally and integrating the results into a comprehensive design process. New developments to extend this design methodology to beam-columns and members with perforations are proposed. Large changes in design such as those proposed here require careful experimentation and computation to understand the ramifications and provide a valid and verified methodology. Further, a specific plan is provided for extending the new design method to thin-walled members made of materials other than steel, including aluminum and thermoplastics.Intellectual Merit: this proposal provides for (i) the development of a novel modal decompositiontechnique of use in model reduction and modal identification in computational structural stabilityproblems and its application to a variety of important stability issues, and (ii) the practical extension and verification of computational structural stability into everyday design of thin-walled steel members, including the unique role of cross-sectional stability under complex loading as in beam-columns, and members with perforations. The proposed modal decomposition technique and the developed design methodologies represent significant advances for both the theory and design of thin-walled members and have the potential to spur new discoveries and innovation. A plan is proposed for extending the design methods to a variety of other important thin-walled materials including aluminum and thermoplastics. The proposed activity relies extensively on the PI's experience in experimental and computational structural stability for thin-walled members and provides a needed platform for continued development.Broader impact: The PI's involvement in development of design specifications and technical committees ensures that both the practicing engineering community and the research community will benefit in the findings. Additionally, the education plan detailed herein insures that high school, undergraduate, and graduate students will also all benefit from the proposed work. The high school outreach efforts focus on enriching the PI's ongoing collaboration with Baltimore Polytechnical High School (Poly), a school with predominately minority student enrollment. Strengthening the relationship with Poly provides an important venue for science and engineering activism with underrepresented groups. The undergraduate education efforts are teamed with the Hopkins Center for Educational Resources and will enable the development of pedagogically sound online teaching guides in structural stability. Research findings, including the educational efforts, will be disseminated by journal papers, conference talks, and by the PI's ongoing efforts with several technical committees.