LOFAMO Development of a local fatigue model of machining affected surface layers that includes surface integrity and mechanical properties

LoFaMo的目的是基于表面完整性(SI)和机械加工影响层的局部力学性能之间的关系，建立航空用镍合金已加工表面的局部疲劳模型。越来越多的航空发动机要求在更高的温度和效率下运行，具有前所未有的机械性能的新型耐热合金已经被开发出来满足这些需求。制造链的最后阶段通常是进行关键航空发动机部件的加工操作的阶段。如果加工参数选择不当，可能会对已加工部件的SI产生不利影响，从而显著降低其疲劳寿命。虽然许多研究人员研究了耐热合金加工后的SI，但到目前为止，分析其对疲劳寿命的影响的研究非常有限，SI参数和疲劳行为之间的联系还没有得到广泛的了解和量化。在这个项目中，样品将在三种不同的表面条件下制造，并将使用共焦和分析电子显微镜的预先高分辨率表面映射来表征它们的SI。然后，创新的原位实验技术将被用来表征局部力学性能和疲劳裂纹扩展：i)原位力学测试和X射线衍射，以及ii)原位力学测试和X射线成像技术。最后，在有限元模型中，将SI和机械加工影响层的力学性能相结合，建立了局部疲劳模型。LoFaMo结合了制造、材料科学和先进的实验技术的知识来实现这一目标。其结果将是镍合金加工的一个阶段性变化(提高生产率；减少1%的废料)，并将提高预测模型的准确性，以产生更有效的设计(朝着欧洲绿色交易战略)和延长使用寿命。

The aim of LoFaMo is to develop a local fatigue model of machined surfaces of nickel alloys for aerospace based on the relationship of surface integrity (SI) and local mechanical properties of the machining-affected layer. Increasingly, aero-engines are required to operate at higher temperatures & efficiencies, and new heat resistant alloys with unprecedented mechanical properties have been developed to meet those needs. The last stage of the manufacturing chain is usually where the machining operations of critical aero-engine components are carried out. If machining parameters are not selected correctly, the SI of the machined components can be adversely affected and thus, their fatigue life can be dramatically reduced. Although many researchers have studied the SI of heat resistant alloys after machining, very limited studies have so far analysed the effect on fatigue life, and the links between SI parameters and fatigue behaviour are not widely understood and quantified.In this project, specimens will be manufactured at three different surface conditions and the SI of them will be characterised using upfront high-resolution surface mapping using confocal and analytical electron microscopy. Then, innovative in-situ experimental techniques will be used to characterise the mechanical properties locally and fatigue crack-growth: i) in-situ mechanical tests and X-ray diffraction and ii) in-situ mechanical tests and X-ray imaging techniques. Finally, a local fatigue model will be developed integrating in a FEM model the SI and mechanical properties of the machining-affected layer. LoFaMo combines knowledge of manufacturing, material science and advanced experimental techniques to reach the goal. The results will be a step change in the machining of nickel alloys (increased productivity; reduction of scraps in 1%) and will enhance the accuracy of predictive models to produce more efficient designs (towards the European Green Deal Strategy) and extended service life.