Co-authors​ :

 Gábor SZEBÉNYI (HUNGARY), Gergő Zsolt MARTON (HUNGARY), Gábor ROMHÁNY  

With the widespread use of high-performance composite structures, they are emerging in safety-critical applications. While in their first decades of development, stronger and stronger composites were developed, nowadays, the exploitation of some key composite properties is aimed by several research groups. The failure process of composites is complex, consisting of several concurrent processes leading to the final failure of a composite part. With the proper design of the composite system, this can be turned to our advantage. Our research group developed a novel method to create composites with designed interface via 3D printing specific patterns on the reinforcement system [1-3]. One possibility provided by this method is to control delamination and achieve a pseudo-ductile behaviour and an option for healing by remelting the interface material to fill and stop cracks. The second option is that with the placement of clever interfacial patterns in the composite structure, the formation of damage and, finally, the location of the failure can be predefined in form and position. In our current study, we present a method to localize failure in a carbon fibre-reinforced epoxy composite system and a method for non-destructively evaluating the formation of the damage inside the structure by digital image correlation (DIC) and acoustic emission (AE). With our interfacial modification method, the failure of the composite can be preset to provide maximum safety for people and surroundings, to add extra safety functions to composites, and to help recycling with predefined fracturing zones. The presented non-destructive DIC-based technique provides a possibility to gain insight into the formation of delaminated zones and damage propagation inside the composite structure.
In our research, firstly, we have used specific tests on the composite and its constituents to provide characteristic AE data for the proper description of AE events related to damage modes inside the composite (fibre fracture, fibre-matrix debonding, matrix cracking, delamination). Secondly, we have created some interfacially engineered carbon fibre (CF)/epoxy (EP) unidirectional composites with polycaprolactone (PCL) interlaminar patterns to achieve predefined failure. During the tensile testing we have used the AE method and our previously developed DIC-based damage localization method [4-5] to characterize the formation of damage inside the structure and to provide reliable baseline data for our further research.
Acknowledgements:
The research has been supported by the NRDI Office (OTKA FK 142540, 2019-1.1.1-PIACI-KFI-2019-00139) and by the Ministry of Culture and Innovation of Hungary Project no. 2022-2.1.1-NL-2022-00012 „National Laboratory for Cooperative Technologies”. Gábor Szebényi acknowledges the financial support received through János Bolyai Scholarship and INKP 2024/I. project of the Hungarian Academy of Sciences and ÚNKP-23-5-BME-415 New National Excellence Program.