双相材料的微塑性棘轮变形机理及细观循环本构模型研究

The dual-phase materials are being widely used in the high temperature components of many advanced equipments,such as aeroengine and ultra- supercritical steam turbine. In this project, the study on the microscopic mechanism and meso-mechanical cyclic constitutive model about the microplastic ratcheting of the dual-phase material will be carried out.The systematic macro and in situ experiments will be carried out to investigate the generation mechanism and evolution rule of the microplastic ratcheting in the dual-phase materials. By employing the meso-mechanical finite element method on the crystal particle scale, the relationship between the microstructure features and the microplastic ratcheting deformation of dual-phase materials will be discussed. Then a new homogenization scale-transition rule considering shape and size of the two different phases will be developed in the frame work of the homogenization theory in meso-mechanics. Finally, a meso-mechanical cyclic constitutive model will be proposed to describe the microplastic ratcheting behaviour of the dual-phase materials from the crystal plasticity theory and the developed homogenization scale-transition rule. The reasonability of the proposed model will be varified by comparing with the corresponding experimental results. The findings will enhance the knowledge level of the solid mechanics on the aspect of microplasticity significantly. Furthermore, the related achievements will also give important theoretical supports for the structure design, safety assessment and life prediction of the advanced high temperature components.

双相材料广泛应用于航空发动机、超超临界汽轮机等先进装备的高温部件，本项目拟开展关于"双相材料的微塑性棘轮变形机理及细观循环本构模型"的研究。通过系统的宏观实验和微观原位实验研究，揭示双相材料微塑性棘轮变形行为的产生机理和演化规律；通过晶粒尺度的细观有限元分析，探索双相材料微结构特征与微塑性棘轮行为之间的关系；基于细观力学均匀化理论和晶体塑性理论，发展能够考虑各组相形态、尺寸的均匀化过渡准则，建立可以合理描述双相材料微塑性棘轮行为的细观循环本构模型，并通过与相关实验结果的比较验证模型的合理性。研究成果将会有力提高固体力学在材料微塑性领域的认识水平，同时为先进高温构件的结构设计、安全评估和寿命预测提供理论支持。

双相不锈钢具有优异的综合性能和良好的可设计性，已广泛应用于航空发动机、超超临界汽轮机和核反应堆压力容器等先进装备的高温部件。本项目针对双相不锈钢，通过系统的宏观实验和微观原位实验研究，揭示双相材料宏观塑性和微塑性棘轮变形行为的产生机理和演化规律；通过对两相微观压痕棘轮行为的实验研究，揭示了其微观棘轮演示规律，为均匀化本构模型的建立提供了依据；最后基于自洽理论建立了均匀化本构模型，并对其进行了有限元实现，对双相不锈钢的循环变形行为进行了合理的描述。研究成果将会有力提高固体力学在材料微塑性领域的认识水平，同时为先进高温构件的结构设计、安全评估和寿命预测提供理论支持。