Effect of nanosecond laser pulse width and energy on damage characteristics in carbon fibre reinforced plastic (CFRP) laminates

This study explores the effects of laser pulse width and energy on CFRP laminates damage in laser bond inspection technology. Three testing programs were used, including varying laser energy while keeping pulse width constant, altering pulse width while maintaining constant power density, and modifying pulse width while keeping energy constant. The results show that when the pulse width remains constant, increased laser energy has a minimal effect on the initial damage location but leads to gradual interlayer delamination and fiber fracture propagation toward the impact surface. With constant laser energy, a specific threshold for pulse width is observed. When the laser pulse width is below this threshold, it exhibits a positive correlation with the damage characteristics of CFRP laminates, whereas when it exceeds this threshold, it shows a negative correlation. Power density correlates with damage when pulse width is constant, but there is no direct correlation when pulse width varies. Highlights: CFRP laminates underwent laser shock tests with varying pulse widths. Power density is positively correlated with damage under specific conditions. There exists a specific threshold for laser pulse width. In single-sided laser shock, initial damage spreads within a specified range.