摘要
材料表面微裂纹的存在会大幅度降低在役设备的使用寿命,因此开展金属构件表面微裂纹的无损检测研究是至关重要的。本文利用ABAQUS有限元软件构造含表面微裂纹的损伤模型,开展基于非线性超声谐振谱技术(NRUS)检测304不锈钢表面微裂纹的模拟研究。结果表明:随激励载荷的增加,高阶谐波向低频方向发生明显偏移,其相对频率偏移量近似线性递减;高阶谐波的Δf/f可用于描述微裂纹尺寸的变化;微裂纹深度增加时,三阶谐波的α可以清晰反映微裂纹深度的变化;随微裂纹宽度的增加,三阶谐波的α单调递增;相对于深度变化,三阶谐波α对微裂纹宽度变化的响应更加敏感。上述现象的产生归因于:声波与微裂纹交互作用引起的接触非线性效应,使材料应力-应变曲线呈现明显的迟滞现象,随激励载荷的增强,材料的迟滞效应越发显著,从而引起明显的频率偏移。
The existence of microcracks on the surface of materials will greatly reduce the service life of equipment in service, so it is vital to carry out the research of non-destructive detection of microcracks in metal components.In this paper, ABAQUS finite element software was used to construct a damage model containing surface microcracks, and a simulation study was carried out to detect surface microcracks of 304 stainless steel based on nonlinear ultrasonic resonance spectrum technology(NRUS).The results show that the frequency of fundamental wave and high order harmonic wave shift to the low frequency direction with the increase of excitation load, and the relative frequency offset decreases approximately linearly.The higher-order harmonic Δf/fcan be used to describe the change of microcrack size.When the microcrack depth increases, the third order harmonic α can clearly reflect the change of microcrack depth.The α of the third harmonic increases monotonically with the increase of the microcrack width. The third order harmonic α is more sensitive to the change of microcrack width than the change of depth.The above phenomena can be attributed to the nonlinear contact effect caused by the interaction between acoustic waves and microcracks, which makes the stress-strain curve of materials show obvious hysteresis.The hysteresis effect becomes more and more significant with the increase of the excitation load, then resulting in obvious frequency offset.
作者
李玮
李萍
陈海燕
LI Wei;LI Ping;CHEN Haiyan(Institute of Nondestructive Testing,School of Material Science and Engineering,Dalian University of Technology,Dalian 116024,China)
出处
《无损探伤》
2022年第4期15-21,共7页
Nondestructive Testing Technology
基金
国家自然科学基金资助项目(51171037)
2016NSFC-山西煤基低碳联合基金重点项目(U1610256)。
关键词
非线性超声技术
表面微裂纹
非线性系数
弹性迟滞非线性
Nonlinear ultrasonic technique
Surface microcrack
Nonlinear coefficient
Elastic hysteresis nonlinear
