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Tham khảo tài liệu 'hydrodynamics advanced topics part 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 436 Hydrodynamics - Advanced Topics 3 0 2 4 6 8 10 12 14 Time us Fig. 3. Comparison of the present solution with analytic solution and other numerical solution for conventional structural materials given by other authors H ao 10 ao 15 a0 20 a0 30 a0 40 K 0.9259 0.94829 0.9229 0.97723 0.99516 Errors 7.410 5.171 3.771 2.277 0.484 Table 1. The normalized static S.I.F. of quasicrystals for different space steps that are subjected to a rapidly varying applied load p t Pof t where Po is a constant with stress dimension and f t is taken as the Heaviside function. It is well known the coupling effect between phonon and phason is very important which reveals the distinctive physical properties including mechanical properties and makes quasicrystals distinguish the periodic crystals. So studying the coupling effect is significant. The dynamic stress intensity factor Kj t for quasicrystals has the same definition given by equation 10 whose numerical results are plotted in Fig. 4 where the normalized dynamics stress intensity factor Kj t ự7ta0p0is used. There are two curves in the Fig. 4 one represents quasicrystal i.e. R M 0.01 the other describes periodic crystals corresponding to R M 0 the two curves of the Fig. 4 are apparently different though they are similar to some extends. Because of the phonon-phason coupling effect the mechanical properties of the quasicrystals are obviously different from the classical crystals. Thus the coupling effect plays an important role. In Fig. 4 t0 represents the time that the wave from the external boundary propagates to the crack surface in which t0 2.6735 ps . So the velocity of the wave propagation is Vo H 10 7.4807 km s which is just equal to the longitudinal wave speed C1 .j L 2M p . This indicates that for the complex system of wave propagation-motion of diffusion coupling the phonon wave propagation presents dominating role. Elasto-Hydrodynamics of Quasicrystals and Its Applications 437 Fig. 4. Normalized dynamics stress intensity
