Griskevicius Paulius, Spakauskas Kestutis, Mahato Swarup, Grigaliunas Valdas, Raisutis Renaldas, Eidukynas Darius, Perkowski Dariusz M, Vilkauskas Andrius
Department of Mechanical Engineering, Kaunas University of Technology, Studentu St. 56, LT-51424 Kaunas, Lithuania.
Institute of Mechatronics, Kaunas University of Technology, Studentu St. 56, LT-51424 Kaunas, Lithuania.
Materials (Basel). 2023 Oct 19;16(20):6764. doi: 10.3390/ma16206764.
The integrity of delaminated composite structures can be restored by introducing a thermally-based healing effect on continuous fiber-reinforced thermoplastic composites (CFRTPC). The phenomenon of thermoplastics retaining their properties after melting and consolidation has been applied by heating the delaminated composite plates above their glass transition temperature under pressure. In the current investigation, the composite is comprised of Methyl methacrylate (MMA)-based infusible lamination resin combined with benzoyl peroxide initiator, which polymerizes into a Polymethyl methacrylate (PMMA) matrix. For the reinforcement, unidirectional 220 gr/m glass filament fabric was used. Delamination damage is artificially induced during the fabrication of laminate plates. The distributed delamination region before and after thermally activated healing was determined by using non-destructive testing with active thermography. An experimental approach is employed to characterize the thermal healing effect on mechanical properties. Experimentally determined technological parameters for thermal healing have been successfully applied to repair delamination defects on composite plates. Based on the compression-after-impact (CAI) test methodology, the intact, damaged, and healed composite laminates were loaded cyclically to evaluate the healing effect on stiffness and strength. During the CAI test, the 3D digital image correlation (DIC) technique was used to measure the displacement and deformation fields. Experimental results reveal the difference between the behavior of healed and damaged specimens. Additionally, the numerical models of intact, damaged, and healed composite laminates were developed using the finite element code LS-Dyna. Numerical models with calibrated material properties and tie-break contact constants provide good correlation with experimental results and allow for the prediction of the mechanical behavior of intact, damaged, and healed laminated plates. The comparison analysis based on CAI test results and modal characteristics obtained by the 3D Laser Doppler Vibrometer (Polytec GmbH, Karlsbad, Germany) proved that thermal healing partially restores the mechanical properties of damaged laminate plates. In contrast, active thermography does not necessarily indicate a healing effect.
通过对连续纤维增强热塑性复合材料（CFRTPC）引入基于热的愈合效应，可以恢复分层复合结构的完整性。通过在压力下将分层复合板加热到其玻璃化转变温度以上，应用了热塑性塑料在熔化和固结后保持其性能的现象。在当前的研究中，该复合材料由基于甲基丙烯酸甲酯（MMA）的不熔性层压树脂与过氧化苯甲酰引发剂组成，该引发剂聚合成聚甲基丙烯酸甲酯（PMMA）基体。为了增强，使用了单向220克/平方米的玻璃纤维织物。在层压板制造过程中人为引入分层损伤。通过使用主动热成像的无损检测来确定热激活愈合前后的分布式分层区域。采用实验方法来表征热愈合对机械性能的影响。实验确定的热愈合工艺参数已成功应用于修复复合板上的分层缺陷。基于冲击后压缩（CAI）测试方法，对完整、受损和愈合的复合层压板进行循环加载，以评估愈合对刚度和强度的影响。在CAI测试期间，使用三维数字图像相关（DIC）技术来测量位移和变形场。实验结果揭示了愈合和受损试样行为之间的差异。此外，使用有限元代码LS-Dyna开发了完整、受损和愈合的复合层压板的数值模型。具有校准材料性能和粘结破坏接触常数的数值模型与实验结果具有良好的相关性，并允许预测完整、受损和愈合层压板的力学行为。基于CAI测试结果和由三维激光多普勒振动计（德国卡尔斯巴德的Polytec GmbH）获得的模态特性的比较分析证明，热愈合部分恢复了受损层压板的力学性能。相比之下，主动热成像不一定表明有愈合效果。
