PSI - Issue 71

Oleg Plekhov et al. / Procedia Structural Integrity 71 (2025) 10–17

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coupling with the specimen. In contrast, titanium specimens exhibit a gradual increase in pressure amplitude with rising power density, though the increment between 12 and 19 GW/cm² is minimal. At 6 GW/cm², titanium shows negligible plastic deformation, highlighting a threshold below which energy coupling remains insufficient for meaningful material modification. Analysis of amplitude saturation trends (Fig. 4a) demonstrates that for copper, pressure peaks near 10 GW/cm² and declines with increasing specimen thickness, stabilizing beyond 1 mm. This behavior predicts a residual stress penetration depth limit of approximately 1 mm and underscores energy transfer constraints to surface plasma, potentially linked to secondary plasma formation at interfaces. Titanium, however, displays fundamentally divergent dynamics: pressure amplitudes rise consistently with power density, but significant wave dispersion in thicker specimens (e.g., 1.4 mm) equalizes amplitudes across tested power levels. At 6 GW/cm², titanium’s near -elastic response and thickness-independent amplitude further confirm minimal plastic deformation under low-energy conditions.

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Fig. 3: (a) The free surface velocity (b) pressure of the copper specimens with a thickness of 0.5 mm (averaging over 6-8 profiles), (c) The free surface velocity (d) pressure of titanium specimens with a thickness of 0.8 mm (averaging over 6-8 profiles)

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Fig. 4: Dependence of pressure amplitude on the power density of the laser pulse for the specimens of different thicknesses: (a) copper (b) Ti 6Al-4V ; dependence of the pressure amplitude on the thickness of the specimens for different power density: (c) copper, (d) Ti-6Al-4V.