考虑晶粒尺寸效应的梯度NiTi合金拉伸断裂行为模拟  

SIMULATION OF TENSILE FRACTURE BEHAVIOR OF GRADIENT NiTi ALLOY CONSIDERING GRAIN SIZE EFFECT

作　　者：陈翔 黄正雄 禄盛 Chen Xiang;Huang Zhengxiong;Lu Sheng(Advanced Manufacturing Engineering College of Chongqing University of Posts and Telecommunications,Chongqing 400065,China;State Key Laboratory of Mechanical Transmission,Chongqing University,Chongqing 400044,China;State Key Laboratory of Mechanical Structure Strength and Vibration,Xi'an Jiaotong University,Xi'an 710049,China)

机构地区：[1]重庆邮电大学先进制造工程学院,重庆400065 [2]重庆大学机械传动国家重点实验室,重庆400044 [3]西安交通大学机械结构强度与振动国家重点实验室,西安710049

出　　处：《力学学报》2025年第1期116-135,共20页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金(11802047);重庆大学机械传动国家重点实验室开放基金(SKLMT-KFKT-201711);西安交通大学机械结构强度与振动国家重点实验室开放基金(SV2018-KF-28)资助项目。

摘　　要：NiTi合金因其独特的形状记忆特性和超弹性而备受关注,被广泛认为是功能材料领域中最具研究潜力和发展前景的材料之一.梯度晶粒结构作为一种有效提升材料强度与延展性的方法,通过在材料内部实现晶粒尺寸的梯度分布,能够进一步提升NiTi合金的性能.文章通过考虑晶粒尺寸效应的晶体塑性理论模型和cohesive单元,并根据晶粒分布函构建了梯度有限元模型,模拟了匀晶和梯度多晶NiTi在单轴和紧凑拉伸断裂过程中的力学行为,讨论了晶粒尺寸、取向、不同应变速率和不同梯度结构对多晶NiTi的强度与延展性的影响特征,并分析其宏-微观力学规律.研究结果表明,晶粒尺寸对NiTi多晶材料的断裂行为有显著影响:晶粒尺寸越小,多晶体抵抗裂纹萌生的能力越强,晶粒尺寸越大,多晶体阻碍裂纹扩展的能力越强;NiTi多晶的断裂行为呈现出明显的取向相关性,其中{110}织构在3种典型取向中展现出最佳的抗断裂性能;高应变速率提升屈服强度但降低延展性,低应变速率则展现均匀应力分布和优异塑性变形能力;梯度多晶结构在NiTi合金材料的强度与延展性之间起到协调作用,细晶结构分布在多晶体的两端,能够承受较高的应力并有效抑制裂纹的产生,粗晶结构则分布于多晶体的中间,通过提供曲折的晶界形态来阻碍裂纹的扩展.NiTi alloy is widely regarded as one of the most promising materials in the field of functional materials due to its unique shape memory properties and superelasticity.Implementing a gradient grain structure is an effective method for enhancing the strength and ductility of the material,and the performance of the NiTi alloy can be further improved by achieving a gradient distribution of grain sizes within the material.In this study,a gradient finite element model is constructed based on the grain distribution function,which incorporates the crystal plasticity theory model and cohesive elements.The mechanical behavior of both homocrystalline and gradient polycrystalline NiTi during uniaxial and compact tensile fracture is simulated.The effects of grain size,orientation,strain rate,and gradient structure on the strength and ductility of polycrystalline NiTi are discussed.The results indicate that grain size significantly influences the fracture behavior of NiTi polycrystalline materials.Specifically,smaller grain sizes enhance the polycrystalline resistance to crack initiation,while larger grain sizes improve resistance to crack propagation.The fracture behavior of NiTi polycrystals exhibits a clear orientation correlation,with the{110}texture demonstrating the highest fracture resistance among the three typical orientations.High strain rates increase yield strength but reduce ductility,whereas low strain rates promote uniform stress distribution and excellent plastic deformation capabilities.The graded polycrystalline structure serves a coordinating role between the strength and ductility of NiTi alloy materials.A fine crystalline structure is located at both ends of the polycrystal,enabling it to withstand high stress and effectively inhibit crack formation.In contrast,a coarse crystalline structure is situated in the middle of the polycrystal,preventing crack propagation by providing a zigzag grain boundary morphology.

关 键 词：NITI 合金 尺寸效应 梯度多晶 裂纹扩展 

分 类 号：O34[理学—固体力学]