Corrosion fatigue in biogenic fuels in the very high cycle fatigue regime

极高循环疲劳状态下生物燃料的腐蚀疲劳

• 批准号: 244527137
• 负责人: Professor Dr.-Ing. Tobias Melz
• 金额: --
• 依托单位: Leibniz-Institut für Werkstofforientierte Technologien IWT
• 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 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/244527137?language=en
• 关键词: Corrosion; fatigue; biogenic; fuels; very

Due to the increased application of biogenic fuels questions concerning the compatibility of metallic alloys are raised which are not existent in those terms for fossile fuels. Aforementioned issues mainly focus on the risk of corrosion of fuel-carrying components and systems. If components are subjected to superimposed cyclic mechanical loading corrosion supported crack formation has also to be taken into account. Besides the question concerning the political and ecological benefits, which are not subject of this project, the controversial debate about the introduction of the biogenic fuel E10 in Germany reveals major concerns regarding an inadequate reliability of the materials used in service. In the medium term, the introduction of biogenic fuels with higher ethanol contents, which has already been put into effect in other parts of the world, such as Brazil (inhibition of fuels, introduction of vehicles with compatibility with E85 fuel) is a matter of controversy (USA: E15). Instead of selective tackling of corrosion problems, the growing variety of fuels with biogenic origin requires a basic investigation of the underlying damaging mechanisms and a deduction of measures for damage prevention.For fatigue loaded vehicle components, the compatibility with fuels of biogenic origin is of major interest as the simultaneous impact of mechanical and corrosive loading leads to complex interactions and damage forms. Those system specific conditions complicate a reliable dimensioning of fuel carrying components. Moreover, components are operated in the very high cycle fatigue regime but dimensioned against a maximum number of 10^7 cycles according to the current design practice. Empirically based recommendations for a calculative extrapolation of the decrease of fatigue strength within the very high cycle fatigue regime (10^9 cycles) is not considered in current rules or standards. But due to the assumable time and load dependency of the corrosion damage, a massive underestimation (inefficient material and energy input) or overestimation (risk of failure) of the structural durability cannot be prevented without a fundamental review of the underlying damage mechanisms.For this reason, the present research project focuses on a mechanism based description of the damaging processes of fuel corrosion on the basis of steel alloys used for injection system components. The determination of the underlying damaging processes is a fundamental precondition for the deduction of an analytical damage model for the corrosion fatigue behaviour in biogenic fuels which conveys basic knowledge for a later transfer to other fuel-alloy combinations.

由于生物燃料应用的增加，提出了关于金属合金兼容性的问题，而这些问题在化石燃料的术语中是不存在的。上述问题主要集中在燃料运载部件和系统的腐蚀风险上。如果构件承受叠加的循环机械载荷，则还必须考虑腐蚀支撑裂纹的形成。除了关于政治和生态效益的问题，这不是该项目的主题，关于在德国引入生物燃料E10的有争议的辩论揭示了对服务中使用的材料可靠性不足的主要担忧。从中期来看，引入乙醇含量更高的生物燃料是一个有争议的问题(美国：E15)，这在世界其他地区已经开始实施，例如巴西(禁止使用燃料，引入与E85燃料兼容的车辆)。与选择性地解决腐蚀问题不同的是，越来越多的生物来源燃料需要对潜在的破坏机制进行基础调查，并推导出损伤预防措施。对于疲劳加载的车辆部件，与生物来源燃料的兼容性是主要关注的问题，因为机械和腐蚀载荷的同时影响导致了复杂的相互作用和损伤形式。这些系统特定的条件使燃料运载部件的可靠尺寸变得复杂。此外，部件在非常高的循环疲劳状态下运行，但根据目前的设计实践，其尺寸最大可达到107次循环。目前的规则或标准不考虑以经验为基础的建议，即在非常高的循环疲劳制度(10^9循环)内计算外推疲劳强度下降。但是，由于腐蚀损伤的假设时间和载荷相关性，如果不从根本上回顾潜在的损伤机制，就无法防止对结构耐久性的大量低估(无效材料和能量输入)或高估(失效风险)。因此，本研究项目集中在基于喷油系统部件用钢合金的燃料腐蚀损伤过程的机理描述上。确定潜在的破坏过程是推导生物燃料腐蚀疲劳行为分析损伤模型的基本前提，该模型为以后转移到其他燃料-合金组合提供基本知识。