In this study, a novel phase field framework is introduced to model dynamic brittle fracture in quasicrystals (QCs) by integrating elasto-hydrodynamic theory. The characteristic quasi-structure of QCs offers diverse potential technological applications, allowing for the design of materials with tailored mechanical, electrical and thermal properties. The fundamental aspect that is addressed in this study is the impact of the interaction of low energy excitations – phonon and phason, during the dynamic process. Furthermore, our work highlights the previous studies by Trebin et. al [1] and Mikulla et. al [2], where they introduced the concept of “phason walls” through atomistic simulations. Phason walls, which are low-energy crack paths, play a crucial role in crack propagation. The effect of phason wall in crack initiation and propagation at a continuum scale is analyzed by incorporating the degree of quasi-periodicity in elastic and fracture parameters. Various test cases under dynamic loading, illustrate crack nucleation and propagation in 2D decagonal QCs, emphasizing the interplay between the phonon and phason fields. It is observed that an increase in phonon-phason coupling constant accelerates both crack initiation and propagation. Furthermore, variations in the coupling constant lead to distinct crack trajectories under different geometric and loading scenarios. REFERENCES [1] Trebin, R. Mikulla, J. Stadler, G. Schaaf, P. Gumbsch, Molecular dynamics simulations of crack propagation in quasicrystals, Computer physics communications 121: 536–539, 1999. [2] R. Mikulla, J. Stadler, F. Krul, H.-R. Trebin, P. Gumbsch, Crack propagation in quasicrystals, Physical Review Letters 81 (15): 3163, 1998.