Local buckling of shear-deformable composite laminated beams with flanges and webs made of unsymmetrically layered laminates

翼缘和腹板由不对称层合板制成的剪切变形复合材料层合梁的局部屈曲

• 批准号: 421986570
• 负责人: Professor Dr.-Ing. Christian Mittelstedt
• 金额: --
• 依托单位: Fachgebiet Konstruktiver Leichtbau und Bauweisen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/421986570?language=en
• 关键词: Local; buckling; shear; deformable; composite

Composite structures in the form of thin laminated plates or shells have found an increasing use in many different branches of engineering science, e.g. in aerospace or automotive engineering, but also in civil engineering applications over the last few decades. Due to their excellent specific strength and stiffness properties, composite laminates or shells are prominently found in lightweight engineering applications. Generally, composite laminates are layered plates or shells consisting of anisotropic and unidirectionally fiber-reinforced layers, e.g. carbon or glass fibers in a plastic matrix.In civil engineering applications, the most basic structural elements are prismatic beams under axial and bending load. Due to their slenderness and their overall thin-walled nature, stability problems such as global buckling (i.e. flexural buckling, flexural-torsional buckling and lateral buckling) as well as local buckling need to be taken into account. The current research project is devoted to the investigation of local buckling problems, i.e. the local buckling of flanges and webs of thin-walled composite laminated beams. For this purpose, discrete plate models shall be used in which webs and flanges are considered as being separate plates considering elastic clampings at those locations where adjacent beam segments intersect. Besides purely closed-form analytical solutions using the Rayleigh quotient employing adequate shape functions for all relevant buckling degrees of freedom, series expansions in conjunction with the Ritz method will enable the analysis and investigation of the local buckling behavior of composite laminated beams under consideration of transverse shear deformations and typical coupling effects as they occur in composite laminates. Specifically, bending-extension coupling in the case of unsymmetric laminates as well as bending-twisting coupling in the case of non-orthotropic laminate layups shall be taken into account explicitly. To this day, no investigations are available that would treat these effects in a systematic manner so that a significant requirement for research exists. Once adequate methods for the local buckling analysis have been developed, the buckling problem will be transformed into an optimization problem. By means of mathematical programming and nonlinear optimization, beam designs will be determined which exhibit the highest possible buckling resistance which is an important factor for any practical application where composite laminated beams are employed. Lastly, all developed analysis methods and the main buckling characteristics will be validated by sys-tematic buckling experiments.

薄层板或贝壳形式的复合结构发现在工程科学的许多不同分支中，例如在过去的几十年中，在航空航天或汽车工程中也是土木工程应用。由于其出色的特异性强度和刚度特性，复合层压板或壳在轻质工程应用中显着。通常，复合层压板是由各向异性和单向纤维增强层组成的分层板或壳，例如塑料基质中的碳或玻璃纤维。在土木工程应用中，最基本的结构元素是轴向和弯曲负荷下的棱柱梁。由于它们的细长性和整体薄壁性质，需要考虑到全球屈曲（即弯曲屈曲，弯曲屈曲和侧向屈曲）等稳定性问题以及需要考虑当地的屈曲。当前的研究项目致力于研究局部屈曲问题，即局部法兰的局部屈曲和薄壁复合层压梁的网。为此，应使用离散的板模型，其中将网和法兰视为在相邻光束段相交的那些位置考虑弹性夹具的单独板。除了使用瑞利商纯封闭形式的分析解决方案外，使用适当的形状功能来实现所有相关屈曲程度的自由度，串联扩展与RITZ方法相结合还可以对横向考虑的复合层压束的局部屈曲行为进行分析和研究复合层压板中发生的剪切变形和典型的耦合效应。具体而言，在非对称的层压板以及在非正性层压板层压板的情况下，弯曲伸展耦合以及弯曲的耦合应明确考虑。直到今天，尚无任何调查可以以系统的方式处理这些效果，因此存在重大要求。一旦开发出适当的局部屈曲分析方法，屈曲问题将转变为优化问题。通过数学编程和非线性优化，将确定光束设计表现出最高可能的屈曲阻力，这对于采用复合层压梁的任何实际应用都是重要的因素。最后，所有开发的分析方法和主要的屈曲特性将通过Sys-Tematic屈曲实验来验证。