基于NCPP平面波算法磁记忆信号特征研究

磁记忆检测技术能够对铁磁性金属构件的应力集中区和微观裂纹进行有效的检测。但是,由于缺乏科学的理论解释和系统的实验研究,磁记忆信号特征和磁力学定量变化关系至今没有定论,严重影响了该项技术的发展。本文利用固体电子理论,采用模守恒赝势(NCPP)算法建立了全电子势磁力学模型,计算了固体屈服时,原子磁矩、晶格结构及磁记忆信号的变化特征。计算结果表明:固体的原子磁矩、晶格常数和漏磁信号强度与应力成线性变化趋势,当应力集中程度达到固体的屈服强度时,晶格结构发生畸变,磁记忆信号会产生突变。本文的实验结果与理论计算结果具有很好的一致性。

Study on magnetic memory signal characteristics based on NCPP plane wave algorithm

Magnetic memory testing (MMT) technology has been used to effectively detect the stress concentration areas and micro cracks of ferromagnetic metal components. However, because of lacking profound theoretical basis and systematic experiment research, the relationship between the magnetic memory signal characteristics and magnetomechanical quantitative change has not yet been determined, which seriously affects the development of the technology. In this paper, a full electronic potential magnetomechanical model is established using the norm conserving pseudo-potential (NCPP) algorithm based on solid electronic theory. And the changing features of the atomic magnetic moment, lattice structure and magnetic memory signal in solid yield condition are calculated. The calculation results show that the wave function change resulted from the stress concentration in the solid band electron is the fundamental cause of magnetic memory phenomenon, and the changing trend of the atomic magnetic moment, lattice constant and magnetic flux leakage signal strength vs. the stress is linear. When the stress concentration reaches the yield strength of the solid, the lattice structure is damaged, and the mutation of the magnetic memory signal appears. The experimental results in this paper and the theoretical calculation results have good consistence.