Prevention of early edge delaminations of fatigue loaded flat composite specimen via aimed internal stresses

通过目标内应力防止疲劳加载的扁平复合材料样品的早期边缘分层

• 批准号: 252190494
• 负责人: Professor Dr.-Ing. Helmut Schürmann
• 金额: --
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/252190494?language=en
• 关键词: Prevention; early; edge; delaminations; fatigue

The fatigue properties of fiber-polymer-composites are of high importance for the lightweight design with this material and there is no doubt that this will remain so in future. The necessary research cannot be done without experiments. For this reason every progress in experiments increasing the quality of the results is welcome.A well known problem testing flat laminate specimen arises from the so called edge effect. First cracks and delaminations start from the edges of the specimen. This makes it difficult to establish a clear correlation between on the one hand the specimen loading and on the other hand the failure evolution. For this reason some researcher change the specimen type from flat specimen to tubes, in spite the fact tubes are much more expensive and more difficult to handle.It is a new idea to lower the stress state of the edge effect in a narrow region of the specimen edges by introducing aimed internal stresses. By this the edges should no longer be the starting point of failure. First FE-calculations and tests validated the new concept. For this the aim of the research project is to develop this promising method to a standard in composite testing.

纤维聚合物复合材料的疲劳性能对于该材料的轻量化设计非常重要，毫无疑问，未来仍将如此。没有实验就无法进行必要的研究。因此，实验中每一次提高结果质量的进步都是值得欢迎的。平板层压板样品测试中的一个众所周知的问题源于所谓的边缘效应。首先裂纹和分层从样本的边缘开始。这使得很难在一方面样本载荷和另一方面失效演化之间建立明确的相关性。为此，一些研究人员将样本类型从扁平样本改为管状样本，尽管管状样本更昂贵且更难以处理。在狭窄的区域内降低边缘效应的应力状态是一种新的想法。通过引入目标内应力来调整样品边缘。这样，边缘就不再是失败的起点。首次有限元计算和测试验证了新概念。为此，该研究项目的目的是将这种有前景的方法开发为复合材料测试标准。