Ahmed Nisar, Smith Patrick J, Morley Nicola A
Centre for Additive Manufacturing, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK.
Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD, UK.
Sensors (Basel). 2024 Jul 18;24(14):4657. doi: 10.3390/s24144657.
Inkjet printing of magnetic materials has increased in recent years, as it has the potential to improve research in smart, functional materials. Magnetostriction is an inherent property of magnetic materials which allows strain or magnetic fields to be detected. This makes it very attractive for sensors in the area of structural health monitoring by detecting internal strains in carbon fibre-reinforced polymer (CFRP) composite. Inkjet printing offers design flexibility for these sensors to influence the magnetic response to the strain. This allows the sensor to be tailored to suit the location of defects in the CFRP. This research has looked into the viability of printable soft magnetic materials for structural health monitoring (SHM) of CFRP. Magnetite and nickel ink dispersions were selected to print using the JetLab 4 drop-on-demand technique. The printability of both inks was tested by selecting substrate, viscosity and solvent evaporation. Clogging was found to be an issue for both ink dispersions. Sonicating and adjusting the jetting parameters helped in distributing the nanoparticles. We found that magnetite nanoparticles were ideal as a sensor as there is more than double increase in saturation magnetisation by 49 Am/kg and more than quadruple reduction of coercive field of 5.34 kA/m than nickel. The coil design was found to be the most sensitive to the field as a function of strain, where the gradient was around 80% higher than other sensor designs. Additive layering of 10, 20 and 30 layers of a magnetite square patch was investigated, and it was found that the 20-layered magnetite print had an improved field response to strain while maintaining excellent print resolution. SHM of CFRP was performed by inducing a strain via bending and it was found that the magnetite coil detected a change in field as the strain was applied.
近年来，磁性材料的喷墨打印技术有所发展，因为它有潜力推动智能功能材料领域的研究。磁致伸缩是磁性材料的固有属性，可用于检测应变或磁场。这使得它在通过检测碳纤维增强聚合物（CFRP）复合材料内部应变来进行结构健康监测的传感器领域极具吸引力。喷墨打印为这些传感器提供了设计灵活性，可影响其对应变的磁响应。这使得传感器能够根据CFRP中缺陷的位置进行定制。本研究探讨了可打印软磁材料用于CFRP结构健康监测（SHM）的可行性。选用磁铁矿和镍墨水分散体，采用JetLab 4按需滴墨技术进行打印。通过选择基材、粘度和溶剂蒸发来测试两种墨水的可打印性。发现两种墨水分散体都存在堵塞问题。超声处理和调整喷射参数有助于纳米颗粒的分散。我们发现，磁铁矿纳米颗粒作为传感器非常理想，因为其饱和磁化强度增加了一倍多，达到49 Am/kg，矫顽力场降低了四倍多，降至5.34 kA/m，优于镍。发现线圈设计对应变场最为敏感，其梯度比其他传感器设计高出约80%。研究了磁铁矿方形贴片10层、20层和30层的叠加，发现20层磁铁矿打印在保持出色打印分辨率的同时，对应变的场响应有所改善。通过弯曲诱导应变来对CFRP进行结构健康监测，发现施加应变时，磁铁矿线圈检测到了场的变化。
