颗粒增强金属基复合材料搅拌摩擦焊残余应力的多尺度模拟

Residual stresses of friction stir welded (FSWed) particle reinforced metal matrix composites (PRMMC) affect the dimensions, the shapes and the performances of the FSWed joints. However, the residual stresses in PRMMC include three types, i.e. the macro residual stresses, the elastic misfit residual stresses and the thermal misfit residual stresses. This makes the investigation on the residual stresses of FSWed PRMMC very difficult and limits the intensive investigation on the relationship between the residual stresses of FSWed PRMMC and the performances of FSWed joints. In the present project, the SiCp/2009Al composite is studied. Multi-scale thermal-elastoplastic finite element model is constructed to simulate all the three types of residual stresses of FSWed SiCp/2009Al composite. The residual stresses of FSWed SiCp/2009Al composite are measured by means of neutron diffraction to prove simulation results. The effects of FSW heat input, the size and content of reinforcing particles on the residual stresses are analyzed in order to establish the optimization mechanism of the residual stresses of FSWed PRMMC. Through these investigations, a new method will be established to characterize the residual stresses of FSWed PRMMC accurately. This will provide fundamental data for investigating the relationship between the residual stresses and performances of PRMMC-FSW. This project will also provide theoretical basis for the industrial applications of friction stir welding of PRMMC.

颗粒增强金属基复合材料（PRMMC）搅拌摩擦焊（FSW）残余应力对焊接件的尺寸、形状和性能有显著影响。但PRMMC残余应力包含了宏观残余应力、弹性错配残余应力和热错配残余应力三类组元，使得对其研究非常困难，这限制了对PRMMC的FSW残余应力与接头性能的相互关系进行深入研究。本项目以SiCp/2009Al复合材料为研究对象，通过建立三维多尺度热-弹塑性变形有限元模型，实现对PRMMC的FSW残余应力各组元的预测。采用中子衍射对残余应力各组元进行测量，对模拟结果进行验证。通过研究FSW热输入、增强相颗粒尺寸和体积分数对残余应力的影响，建立PRMMC的FSW残余应力的调控机制。通过以上研究建立精确表征PRMMC的FSW残余应力的新方法，为下一步研究残余应力对力学行为的影响奠定基础，为PRMMC的FSW残余应力的预测和调控以及FSW工程应用提供理论依据。

颗粒增强金属基复合材料（PRMMC）的搅拌摩擦焊（FSW）接头残余应力对焊接件的尺寸、形状和性能有显著影响，但PRMMC残余应力包含了显著的微观和宏观残余应力，对其进行研究非常困难。本项目以SiCp/Al复合材料为研究对象，开展了SiCp/Al的FSW接头残余应力的中子衍射表征研究，首次实现了焊接接头各复合相中宏观和微观残余应力的精细表征，阐明了各复合相中宏观和微观残余应力的分布特点。逐步建立了PRMMC的热力耦合多尺度非线性有限元模型，实现了PRMMC的FSW接头宏观和微观残余应力的多尺度预测，并采用中子衍射实验数据对模型进行了校验。系统研究了PRMMC的FSW残余应力的影响因素，研究了FSW热输入、增强相含量与残余应力的相互关系，为调控宏观和微观残余应力奠定了理论基础。开展了新型多尺度本构模型的研究，阐明了颗粒/基体界面结合力、颗粒长径比和取向对PRMMC宏观力学性能的影响，为进一步提高多尺度模型预测精度和计算能力奠定理论基础。在理论研究基础上，自主开发了大型多尺度热力耦合非线性有限元软件MSFESL（Multi-scale finite element simulation laboratory），软件包括前处理、求解器、后处理等系列模块，C++代码6万余行，具有自主知识产权。本项目研究成果为下一步研究残余应力对力学行为的影响奠定了坚实基础，为PRMMC的FSW残余应力的预测和调控以及FSW工程应用提供了理论工具；所开发的多尺度有限元软件为PRMMC或其它多相材料的多尺度力学行为研究提供了有力的理论工具。