摘要
磁记忆法对铁磁性金属构件的应力集中区域具有很好检测效果。但是,目前构件在弹性阶段和塑性阶段的磁记忆信号特征很难被区分,从而无法对构件的应力集中程度和使用寿命进行有效评估。基于固体电子理论建立了磁记忆效应的边界滑移模型,利用线性化M-T轨道算法(LMTO)计算了固体在弹性、塑性阶段,系统的能量变化、不同轨道电子的自旋态密度的变化情况,进而定量分析了构件发生屈服后的磁记忆信号变化规律。研究结果表明,应力集中程度与系统边界滑移能量呈线性正比例关系,与电子自旋态密度峰峰值、磁记忆信号呈线性反比例关系;构件发生塑性形变后,体系能量和电子自旋发生不可逆的变化,磁记忆信号曲线出现转折点;构件每发生一次塑性变形,磁记忆信号初始值都会变小,曲线斜率变小。
The magnetic memory method can effectively determine the stress concentration areas of ferromagnetic metal components. However, at present, the magnetic memory signals in the elastic stage and plastic stage of the components are hard to he distinguished, and the stress concentration degree and service life of the components cannot he evaluated effectively. In this paper, the boundary slip model of the magnetic memory effect is built based on the theory of solid-state electronics, and the linear muffin-tin orbital （LMTO） algorithm is used to calculate the variations of the system energy of the solid and the spin density of states of the electrons at different orbits in the elastic stage and plastic stage. Then, the changing rules of the magnetic memory signals of the components after yielding are quantitatively analyzed. The research resuhs show that the stress concentration degree is in direct linear proportional relationship with the system boundary slip energy and in the inverse linear proportional relationship with the peak to peak value of the electron spin density of states and the magnetic memory signals. After the plastic deformation of the components, the system energy and electronic spin are changed irreversibly, and a turning point appears in the magnetic memory signal curve. The initial value of the magnetic memory signal is getting less and the slope of the curve is getting lower after every plastic deformation of the component.
出处
《仪器仪表学报》
EI
CAS
CSCD
北大核心
2017年第6期1413-1420,共8页
Chinese Journal of Scientific Instrument
基金
国家重大科学专项(2012YQ090175)
国家自然科学基金(61571308)
辽宁省教育厅项目(L2015388)资助
关键词
磁记忆
屈服
滑移
应力集中
铁磁性
magnetic memory
yield
slip
stress concentration
ferromagnetism
