Gkartzou Eleni, Zafeiris Konstantinos, Tsirogiannis Christos, Pedreira Alberto, Rodríguez Adrián, Romero-Rodriguez Pablo, Gakis Giorgos P, Kosanovic-Milickovic Tatjana, Kyritsis Apostolos, Charitidis Costas A
Research Lab of Advanced, Composite, Nano-Materials and Nanotechnology (R-NanoLab), School of Chemical Engineering, National Technical University of Athens, 9 Heroon Polytechniou, GR-15780 Zografou, Greece.
AIMEN Technology Center, 36418 O Porriño, Spain.
Polymers (Basel). 2024 Sep 30;16(19):2760. doi: 10.3390/polym16192760.
In the present study, the feasibility to achieve localized induction heating and debonding of multi-material composite structures is assessed in testing coupons prepared by Automated Fiber Placement (AFP) and extrusion-based additive manufacturing (AM) technologies. Nano-compounds of Polyether-ketone-ketone (PEKK) with iron oxide nanoparticles acting as electromagnetic susceptors have been processed in a parallel co-rotating twin-screw extruder to produce filament feedstock for extrusion-based AM. The integration of nanocomposite interlayers as discrete debonding zones (DZ) by AFP-AM manufacturing has been investigated for two types of sandwich-structured laminate composites, i.e., laminate-DZ-laminate panels (Type I) and laminate-DZ-AM gyroid structures (Type II). Specimens were exposed to an alternating magnetic field generated by a radio frequency generator and a flat spiral copper induction coil, and induction heating parameters (frequency, power, heating time, sample standoff distance from coil) have been investigated in correlation with real-time thermal imaging to define the debonding process window without compromising laminate quality. For the optimized process parameters, i.e., 2-3 kW generator power and 20-25 mm standoff distance, corresponding to magnetic field intensities in the range of 3-5 kA m, specimens were effectively heated above PEKK melting temperature, exhibiting high heating rates within the range of 5.3-9.4 °C/s (Type I) and 8.0-17.5 °C/s (Type II). The results demonstrated that localized induction heating successfully facilitated debonding, leading to full unzipping of the debonding zones in both laminate structures. Further insight on PEKK nanocomposites debonding performance was provided by thermal, morphological characterization and non-destructive inspection via X-ray micro-computed tomography at different processing stages. The developed framework aims to contribute to the development of rapid, on-demand joining, repair and disassembly technologies for thermoplastic composites, towards more efficient maintenance, repair and overhaul operations in the aviation sector and beyond.
在本研究中，通过自动纤维铺放（AFP）和基于挤出的增材制造（AM）技术制备测试 coupons，评估实现多材料复合结构局部感应加热和脱粘的可行性。聚醚酮酮（PEKK）与作为电磁感受器的氧化铁纳米颗粒的纳米化合物已在平行同向旋转双螺杆挤出机中加工，以生产用于基于挤出的增材制造的长丝原料。通过AFP-AM制造将纳米复合中间层作为离散脱粘区（DZ）集成到两种类型的夹层结构层压复合材料中，即层压-DZ-层压板（I型）和层压-DZ-AM类螺旋结构（II型）。将试样暴露于由射频发生器和平板螺旋铜感应线圈产生的交变磁场中，并结合实时热成像研究感应加热参数（频率、功率、加热时间、样品与线圈的间距），以确定脱粘过程窗口，同时不影响层压板质量。对于优化的工艺参数，即2-3kW的发生器功率和20-25mm的间距，对应于3-5kA/m范围内的磁场强度，试样被有效地加热到PEKK的熔化温度以上，加热速率在5.3-9.4℃/s（I型）和8.0-17.5℃/s（II型）范围内。结果表明，局部感应加热成功促进了脱粘，导致两种层压结构中的脱粘区完全拉开。通过在不同加工阶段进行热、形态表征以及通过X射线微计算机断层扫描进行无损检测，进一步深入了解了PEKK纳米复合材料的脱粘性能。所开发的框架旨在为热塑性复合材料的快速、按需连接、修复和拆卸技术的发展做出贡献，以实现航空领域及其他领域更高效的维护、修理和大修作业。
