CAREER: Structural Stability and Thin-walled Structures

摘要：职业：结构稳定性和薄壁结构，CMS提案0448707 PI：Ben Schafer，Johns Hopkins薄壁结构构成了国家工业基础设施的支柱，并在民用和机械系统中得到广泛应用。虽然稳定性是任何成功结构的基本要求，但对于薄壁结构，横截面稳定性是主要约束。薄壁结构分析复杂、设计困难，但效率很高。薄壁构件中的材料最小化，这是在我们的高容量、低成本物理基础设施中使用昂贵的新材料时必须做到的。该建议提出了一个理论、计算和实验工作的综合计划，以（1）在薄壁构件特别需要的计算稳定性方面实施新技术;（2）开发和验证新方法，以提供更有效、鲁棒和可靠的设计;以及（3）创造新的资源，增加PI在结构稳定性教育方面努力的广度和深度，同时加强霍普金斯的伙伴关系在社区里。横截面不稳定性大大复杂的薄壁构件的行为，和目前的计算稳定性技术没有增加清晰度。本文提出了一种新的模态分解技术，它提供了（i）模型简化，能够隔离与特定类别的横截面不稳定性相一致的应变场，然后执行具有一个自由度的有意义的分析，以及（ii）模态识别，将一般构件变形场分类为构成该场的横截面不稳定性的基本模态的方法，从而量化模态相互作用。模态分解的发展提供了一种独特的手段来调查各种悬而未决的问题，在结构稳定性，特别是有关耦合和混合模式。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复杂化，并且由于设计者被束缚于过去的解而阻碍效率。PI为薄壁钢结构开发了一种新的设计方法，旨在通过计算攻击截面不稳定性并将结果整合到综合设计过程中来提供灵活性和可靠性。提出了将这种设计方法扩展到带穿孔的梁柱和构件的新发展。在设计中的大的变化，如这里提出的，需要仔细的实验和计算，以了解的后果，并提供一个有效的和验证的方法。此外，还提供了一个具体的计划，将新的设计方法扩展到由钢以外的材料（包括铝和热塑性塑料）制成的薄壁构件。该建议提供了（i）在计算结构稳定性问题中的模型简化和模态识别中使用的新型模态分解技术的开发及其对各种重要稳定性问题的应用，以及（ii）将计算结构稳定性实际扩展和验证到薄壁钢构件的日常设计中，包括复杂荷载下截面稳定性的独特作用，如梁柱和穿孔构件。提出的模态分解技术和开发的设计方法代表了薄壁构件理论和设计的重大进展，并有可能激发新的发现和创新。提出了一个计划，用于扩展设计方法，以各种其他重要的薄壁材料，包括铝和热塑性塑料。拟议的活动广泛依赖于PI在薄壁构件的实验和计算结构稳定性方面的经验，并为持续发展提供了必要的平台。更广泛的影响：PI参与设计规范和技术委员会的发展，确保实践工程界和研究界都将受益于研究结果。此外，这里详细介绍的教育计划确保高中，本科和研究生也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）的持续合作，这是一所少数民族学生占主导地位的学校。加强与保利的关系为代表性不足的群体提供了一个重要的科学和工程活动场所。本科教育工作与霍普金斯教育资源中心合作，并将在结构稳定性方面开发教学合理的在线教学指南。研究结果，包括教育工作，将通过期刊论文，会议会谈和PI与几个技术委员会的持续努力进行传播。

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.