基于非线性电磁超声吸波涂层弱黏合损伤检测方法研究

As high-strength anti-stealth weapons become more mature, the high temperature gradients acting on stealth weapons will accelerate the aging of wave absorbing coatings, during which the weak adhesion failure of early coating occurs occasionally and needs to be resolved. In our previous research, it was found that the conductive polymer absorbing coating has eddy current effect under the excitation of the MHz frequency band. Therefore, a non-linear electromagnetic ultrasonic testing method is proposed to evaluate the weak adhesion damage of the microwave absorbing coating, and to investigate the electromagnetic properties of the conductive polymer absorption material and the nonlinear acoustic response of weakly adhesion materials, etc. This project intends to take electromagnetic modeling as the main issue, and to systematically investigate the influence of conductive particle filling on the electromagnetic properties of electromagnetic wave absorbing materials from the perspective of electromagnetic-structure-ultrasonic field coupling problem; besides, it also aims to accomplish the modelling of medium transduction process in electromagnetic non-destructive testing through the bridge domain multi-scale method; it also studies the relationship between the weak adhesion damage and the nonlinear acoustic wave, accurately identifies and evaluates the close-mesh damage based on the dynamic wavelet fingerprint identification method; in addition, by revealing the vibration absorption correlation analysis of the coating adhesion interface, it could further improve the assessment theory and experimental model of nonlinear electromagnetic ultrasonic weak adhesion. The implementation of this project can provide important theoretical basis and technical support for the early non-destructive evaluation of the absorbing coating weak adhesion damage.

随着强脉冲反隐身武器日渐成熟，对隐身武器抗击作用的高温度梯度将加速吸波涂层老化，早期涂层老化中弱黏合损伤漏检问题时有发生并亟需解决。本课题组前期研究发现导电高分子吸波涂层在MHz频段激励下涡流效应显著，由此提出基于非线性电磁超声的检测方法实现对吸波涂层弱黏合损伤评估方案，并探究导电高分子吸波材料电磁特性以及涂层弱黏合非线性声学响应等问题。本课题拟以电磁特性建模为主线，从电磁-结构-声场等多场耦合问题研究切入，系统探究导电颗粒填充对于吸波材料电磁特性的影响规律；通过桥域多尺度方法实现电磁无损检测中换能过程的建模；研究弱黏合损伤与非线性声波对应关系，并基于动态小波指纹识别方法表征紧密啮合损伤并进行准确评估辨识；通过揭示对吸波涂层黏合界面振动关联分析，进一步完善非线性电磁超声弱黏合评估理论及实验模型。本项目的实施可为吸波涂层弱黏合损伤的早期无损评估提供重要的理论依据和技术支持。

强脉冲反隐身武器日渐成熟，其具有的高功率、宽频谱、窄脉宽等特点能有效克制隐身目标，其带来的热效应将引起吸波材料产生老化加速、脱粘、剥离等一系列基体损伤，并最终导致吸波材料快速失效。为了保障武器装备的隐身性能，需要对吸波涂层材料的弱黏合损伤缺陷进行精确检测。本课题基于导电吸波材料的电磁特性搭建离散导电颗粒填充的吸波涂层电磁-结构-声场耦合有限元模型，提出一种针对吸波涂层弱黏合损伤的非线性电磁超声检测方案。对高频激励加载下的涂层内部涡流、洛伦兹力分布进行求解，并分析了离散电磁力加载下超声波的激发、传播与接收特性，仿真结果显示所提出的吸波涂层填充导电颗粒骨料投放建模算法具有良好的可重复性，导电颗粒的分布将会对涂层内部的涡流分布产生影响，导电颗粒半径越小、面积占比越大、涂层越薄均能够产生更强的涡流；纳米导电颗粒在吸附力的作用下将会形成团聚，团聚程度越大，涡流强度越小；在离散电磁力的加载下，超声波将会在涂层内部产生并不断穿过介质面进入基体内部。根据检测需求设计了Halbach阵列电磁超声换能器，并利用有限元仿真软件对其进行优化设计，优化后的换能器相较于优化之前幅值提升了83%。最后，在对吸波涂层模型进行求解的基础上，搭建非线性超声无损检测试验平台，对不同黏结强度的吸波涂层试件进行检测，研究弱黏合损伤与非线性声波的对应关系，使用混沌算法和Lyapunov指数显著减少了噪声对谐波信号的干扰，提高了信号噪声免疫能力。试验结果表明，涂层在固化早期相对非线性系数较大，随着固化时间的推移相对非线性系数值逐渐减小；基体表面粗糙程度越大，则涂层黏结强度越高，相对非线性系数越小，因此可以通过导电涂层的相对非线性系数来判断涂层的黏结状态。本课题为吸波涂层的弱黏合损伤提供了一种有效的检测手段，能够应用于未来隐身武器的无损检测当中，提高武器的战场隐蔽能力，为我军占据战场主动性创造有利条件。