The Mechanics of Debonding of Foam Core Sandwich Structure Under Cyclic Loading

泡沫夹层结构在循环载荷作用下的剥离力学这项工作旨在增加对泡沫夹层结构疲劳的理解。泡沫夹芯结构是由两个面板(通常是铝或纤维增强聚合物)和一个泡沫塑料组成的复合材料结构。由于夹层结构是由非常不同的材料组成的，它们表现出特殊的、有时甚至是意想不到的破坏模式。传统上，裂纹在循环(疲劳)加载过程中的扩展速率是通过广泛的(因此昂贵的)材料试验来确定的。本研究发展了描述裂纹尖端的损伤(如塑性耗散能)和随后的裂纹扩展速率的理论。这些理论在计算机数值模拟中得到了量化。只需要有限的实验研究来确定重要的材料参数，作为计算机代码的输入。由数值模拟预测的疲劳寿命将通过全尺寸疲劳试验进行验证。复合材料夹层结构是一种轻质结构，具有高强度、高抗冲击、高耐腐蚀性、低雷达和声学信号等特点。目前的应用范围从飞机结构到风力涡轮机叶片，再到船体。这项研究的成功结果将导致一种依赖有限实验投入的寿命预测方法。这反过来将导致可靠的轻量化，因此更节能的工程结构。这项研究包括一个重要的教育组成部分，包括让本科生参与？尤其是来自代表人数不足的群体？在研究中。结果还将通过特拉华大学工程学院外联计划传播给K-12学生和科学教师。

The mechanics of debonding of foam core sandwich structure under cyclic loadingAnette M. Karlsson, University of Delaware, Newark, DELeif A. Carlsson, Florida Atlantic University, Boca Raton, FLThis work aims to increase the understanding of fatigue in foam core sandwich structures. Foam core sandwich structures are composite structures consisting of two face sheets (typically aluminum or fiber reinforced polymer) and a cellular foamed polymer. Since sandwich structures are composed of widely dissimilar materials, they display peculiar and sometimes unexpected failure modes. Traditionally, the rate in which the cracks grow during cyclic (fatigue) loading is established by extensive (and therefore expensive) material testing. Theories describing damage (e.g., plastically dissipated energy) at the crack tip and the ensuing crack growth rate are developed in this research. These theories are quantified in numerical computer simulations. Only limited experimental investigations for determining important materials parameters will be needed as input to the computer code. The fatigue life predicted from the numerical simulations will be verified by full scale fatigue testing. Composite sandwich structures are light-weight structures with high strength, high impact resistance, and high resistance to corrosion along with low radar and acoustics signals. Current applications range from aircraft structures, to wind turbine blades, to ship hulls. Successful outcome of the research will result in a life prediction methodology relying on limited experimental input. This in turn will lead to reliable light-weight, and therefore more energy efficient, engineering structures. The research includes a significant educational component, including involving undergraduate students ? in particular from underrepresented groups ? in the research. The results will also be disseminated to K-12 students and science teachers through the University of Delaware, College of Engineering Outreach Programs.