Numerical Modelling of Wave Propagation in Granular Crystals for Aero-Engine Applications

The aviation sector is at a pivotal point, facing the need to develop environmentally sustainable and efficient engines while remaining lightweight. A critical factor to consider during the design phase is the dynamic response of the engine, which, given its construction from millions of components, presents challenges in correlating experimental friction data with computational models. This Master Thesis aims to overcome some of these challenges by using wave propagation to improve the understanding of friction. Specifically, a numerical model in MATLAB that simulates the propagation of solitary waves in granular crystals, incorporating frictional effects, is developed. Like traditional ultrasonic waves, solitary waves are used as tools for non-destructive evaluation. However, the innovation presented here lies in using solitary waves to monitor friction, as unlike ultrasonic waves, they have not been applied to this purpose before. After an initial section on the state of the art and relevant literature, the project progresses to the development of a MATLAB computational model for simulating the propagation of solitary waves through a chain of granular crystals (modeled via Discrete Element Method, DEM) and a metal block (modeled via Finite Element Method, FEM). This setup will enable a series of physical insights by observing how friction alters the system. Once validated, the model may be applied to analyze components affected by friction, such as turbine-bladed disks with friction dampers. This project's ultimate goal is to first correlate changes in solitary wave propagation through a medium with the friction properties of sliding contacts, thereby developing a novel tool that could drive significant advancements in tribology and dynamics.