A numerical study to assess the role of pre-stressed inclusions on enhancing fracture toughness and strength of periodic composites

A rational design for simultaneous toughening and strengthening in composites would be significant for myriad applications in fracture-related problems. Nacre simultaneously exhibits extremely high toughness (approximately 3000 times the constituent materials) and high strength, being one of the classic examples of the brilliant solutions nature can come up with based on necessity. Several experimental studies have suggested that the underlying “brick and mortar” microstructure of the nacre could be responsible for the high performance (high strength and high toughness). However, it has been realized that the engineered composites can not achieve the desired performance by only mimicking the “brick and mortar” structure. Naturally, the question arises whether there is any additional mechanism that is possibly responsible for the high-performance of nacre and may be mimicked in the engineered composites to achieve the desired high performance. In this study, numerical simulations show that the design of high-performance engineered composites can be achieved by introducing pre-stress in the inclusions. We have carried out mode-I and mode-II fracture simulations in periodic composites with both hard and soft pre-stressed inclusions to assess their role in the performance of composites. For modeling crack propagation in mode I, we have adopted the surfing boundary conditions proposed by Hossain et al. (2014), and appropriately extended it for modeling crack propagation in mode II. The present work indicates that a study on the existence of a pre-stressed condition of the platelets in the nacre may be a topic of research interest to explore the origin of the high performance of the nacre.