基于并行耦合多尺度建模的混杂增强铝基复合材料切削亚表面损伤机理研究

The subsurface damage in machining hybrid reinforced aluminium matrix composites is one of the key bottlenecks for the reliability application of its machining structures. Due to ignoring the interaction of the tool with reinforcement and the coupling analysis between scales, the existing multi-scale modeling method based on micro-mesoscale cannot provide accurate prediction and analysis of local microscopic variables within sub-surface. This project intends to take the particle/whisker hybrid reinforced aluminium matrix composites as the research target. While considering the influence of the materials microscale structure (interface and micro voids), mesoscale representative volume element modeling method is introduced to realize the interaction representation of the tool with hybrid reinforcements. A micro-meso-macro scale concurrent coupled multi-scale model is thus established through studying the coupling mechanism and damage transition criterion. Based on the aforementioned method, the change regulation and difference of microscopic stress field, strain field and temperature field around the four kinds of location as well as the particles, whiskers, interface, and particles around the whiskers are investigated systematically. Finally, the deformation mechanism of hybrid reinforcement and subsurface damage mechanism influenced by the cooperative interaction of hybrid reinforced aluminium matrix composites will be revealed. The research provides theoretical guidance for the development and application in the paramount field of the national economy, e.g. aviation, aerospace, automobile.

混杂增强铝基复合材料的切削亚表面损伤是制约其结构件可靠性应用的关键瓶颈之一。现有的基于微-宏观的多尺度方法由于忽略刀具-增强相的交互作用及各尺度间的耦合，无法对切削亚表面的局部微观变量实现准确预测及分析。本项目拟以颗粒/晶须混杂增强铝基复合材料为研究对象，考虑材料微尺度结构特征(界面和微空洞)的影响，引入混杂增强相嵌入式的细观代表性体积元建模方法，实现刀具-混杂增强相交互作用的表征及分析；通过研究各个尺度的耦合机理及损伤传递准则，建立微-细-宏观并行耦合的多尺度有限元模型，系统探索亚表面层颗粒、晶须、界面、晶须周围颗粒四种位置处的微观应力场、应变场、温度场的变化规律及差异特性，揭示混杂增强铝基复合材料的协同交互机制及其影响下的混杂增强相变形机理和亚表面损伤形成机理。项目的研究对该类材料在我国航空、航天、汽车等重要领域的可靠性应用提供理论指导。

本项目针对铝基复合材料切削亚表面损伤主要完成了以下四部分的研究工作。1）铝基复合材料切削亚表面损伤深度建模。综合考虑铝基复合材料的增强颗粒特性、刀具磨损特性以及热-机械应力耦合因素的影响，建立了铝基复合材料切削亚表面损伤深度模型。获得了刀具磨损、切削参数对亚表面损伤的影响规律，揭示了机械应力和热应力对亚表面损伤深度影响的重要度。2）颗粒损伤建模及考虑增强相损伤的铝基复合材料钻削力解析建模。提出了一种新的颗粒损伤模型，该模型综合考虑颗粒断裂、颗粒剥离和颗粒挤压损伤特性。建立了考虑颗粒损伤特性的铝基复合材料钻削全周期切削力模型。揭示了铝基复合材料切削过程中各消耗能的占比。3）多尺度特性下铝基复合材料切削（车削、钻削）亚表面损伤形成机理。铝基复合材料车削的亚表面损伤主要是刀具-增强相-基体三者的交互作用引起的，主要包括微观尺度下的颗粒破裂、颗粒脱粘、颗粒剥离和宏观尺度基体裂纹等。颗粒和铝合金基体在剪应力作用下破裂，产生了与加工表面约45°的裂纹。除了以上损伤特性，还发现了颗粒团聚、基体烧蚀的钻削亚表面损伤，同时获得了基体裂纹随颗粒体积分数的形态变化规律。4）亚表面损伤特性对材料力学性能的影响规律及材料在宏-微观多尺度下的断裂失效机制。研究了铝基复合材料切削亚表面损伤对其材料力学性能的影响规律，获得了材料拉伸过程中不同应力状态下各方向应变对亚表面损伤的敏感性及变化规律，揭示了材料的断裂失效机制。项目的研究成果对铝基复合材料在我国航空、航天、汽车、电子等领域的可靠性应用提供理论支撑。共发表SCI论文8篇，其中JCR一区论文4篇，TOP期刊论文1篇。参加国际学术会议2次。培养博士研究生1名，硕士研究生4名。