加工表面完整性影响试件疲劳性能的多因素微元分析模型及机理研究

Machined surface integrity has a direct influence on the fatigue performance of specimens. But, the influencing mechanisms of surface integrity indexes are different significantly. Taking anti-fatigue processing of aerospace titanium alloy and superalloy as the main research objects, the relationship between the key indexes of surface integrity and the factors affecting fatigue performance of specimens is established according to the results of theoretical analysis and fatigue life testes. And then, multi-factor analysis model of machined surface integrity on fatigue performance of specimens is presented based on the stress analysis on microelement material of machined surface layer. Meanwhile, the innovation influencing mechanisms are developed and analyzed deeply, including of generalized micro stress concentration, multi-scale features of surface roughness curve, microstructural deformation and its direction, surface residual stress and its relaxation. The theoretical basis of optimizing the machining processes and controlling the machined surface integrity is obtained to improve the fatigue performance of titanium alloy and superalloy workpieces, which is of great significance to enrich and develop the technology of anti-fatigue processing in the aviation field.

机械加工表面完整性对零件的疲劳性能有直接的影响，但表面完整性各指标对其影响机理和影响程度又各不相同。本项目以航空典型钛合金和高温合金材料的抗疲劳加工为出发点，采用理论分析和具体实验相结合的研究方法，以试件表面层的微元材料为对象，将加工表面完整性各重要指标与影响试件疲劳性能的因素进行关联，建立加工表面完整性影响试件疲劳性能的多因素微元分析模型。以此为基础，提出并深入研究加工表面广义微观应力集中现象及形成机理、表面粗糙度曲线多尺度特征、表面组织纤维化及方向、加工表面残余应力及其保持性等对分析模型中各因素的影响规律，进而揭示不同表面完整性重要指标对试件疲劳性能的影响机理，形成针对不同工作条件下钛合金和高温合金的抗疲劳加工工艺选择和表面完整性控制的理论基础，并为研究其它材料和实际结构零件的抗疲劳加工提供参考，这对于推动抗疲劳加工技术在我国航空领域内的发展和应用具有重要意义。

机械加工表面完整性对零件的疲劳性能有直接的影响，但机械加工表面完整性各指标对其影响机理和影响程度又各不相同。以航空典型钛合金和高温合金材料的抗疲劳加工为出发点，采用理论分析和具体实验相结合的研究方法，以试件加工表面为对象，提出了机械加工表面多尺度微观形貌的解耦分析方法；基于机械加工表面的“过塑变”现象，建立了相应的有限元分析模型，研究了影响“过塑变”现象的主要因素及其对试件疲劳性能的影响规律；提出了机械加工表面的广义微观应力集中理论，研究了影响广义微观应力集中系数的主要因素和影响规律。并结合典型钛合金和高温合金试件，验证了相关理论研究正确性，为研究实际结构零件的抗疲劳加工提供参考，推动了抗疲劳加工技术在我国航空领域内的发展和应用。