基于FLAPW算法屈服极限磁记忆信号特征的研究

Study on characteristics of magnetic memory signal of yield limit based on FLAPW algorithm

磁记忆法可以有效判断铁磁性金属构件的应力集中区域。但是,目前铁磁性构件屈服极限处的磁记忆信号特征尚不明确,因此难以根据磁记忆信号对构件的使用寿命进行有效评估。根据电子自旋理论和洪德法则,建立了磁力学模型,分析了材料电子壳层的电荷密度、原子磁矩与磁记忆信号的关系,基于全势线性缀加平面波法（FLAPW）,计算了铁磁性金属构件屈服极限前后系统能量、原子磁矩、电子自旋分布以及电荷密度的变化规律,分析了屈服极限前后的磁记忆信号特征。研究结果表明：铁磁性构件在屈服极限前,随着应力增加,电荷密度和原子磁矩减小,磁记忆信号与应力呈线性变化关系,具有很好的重复性;在屈服极限后,由于铁磁性金属构件的加工硬化能力减小,随着应力继续增加,电荷密度与原子磁矩增加,磁记忆信号出现反转特性。

The magnetic memory method can effectively determine the stress concentration areas of the ferromagnetic metal components. However,the magnetic memory signal of yield limit of the ferromagnetic metal components is not clear yet,so it is difficult to evaluate the service life of the components based on the magnetic memory signal. According to the theory of the electron spin and the Hund rule,the magnetic mechanical model is firstly built. The relationship between the electronic density of the electronic shell,the atom magnetic moment and the magnetic memory signal is analyzed. Based on full-potential linear augmented plane-wave algorithm,the changing rules of the system energy,the atom magnetic moment,the distribution of the electronic spin and the electronic density before and after the yield limit are calculated. In addition,the characteristics of magnetic memory signal before and after the yield limit is analyzed. Results show that before the yield limit of the ferromagnetic metal components,the electronic density and the atom magnetic moment decreases along with the increase of the stress,and the magnetic memory signal varies linearly with the stress. The phenomena are with well repeatability. After the yield limit,due to the decrease of the work hardening capacity of the components,the electronic density and the atom magnetic moment increases along with the increase of the stress,and the magnetic memory signal appears inversion characteristics.