Isochronous circumferential trajectory method for the rapid and accurate location of impact damage of CFRP plate

The symmetry of the fiber layering and the anisotropy of the guided wave propagation of carbon fiber reinforced plastic (CFRP) plate were considered. A rapid and accurate method for locating CFRP impact damage in the isochronous circumferential trajectory method was proposed. By means of damage index and simulation calculation, the propagation velocity of guided wave around CFRP plate and the flight time of damage reflected wave were determined. According to the trigonometric function relationship between the transducer, the sensor and the damage location, the likelihood point which satisfies both the propagation velocity of guided wave in each direction and the flight time in CFRP plate was calculated. The linear fitting likelihood points formed isochronous circumferential trajectory curve spline. According to the laminated symmetry of CFRP plate, the mirrored trajectory curve spline formed a closed isochronous circumferential trajectory curve, and the damage location was realized by the intersection point of three curves. The impact damage detection experiment of CFRP plate was carried out by using a four-point rectangular array diagonally excitation method. The experimental results show that the damage index value increases significantly due to damage, and the flight time of damage reflected wave can be obtained. The number of likelihood points needed to fit the trajectory is only 155, which has a small amount of calculation. The localization error of the isochronous circumferential trajectory method is controllable, and the localization accuracy is good under the expected error, and is not beyond the damaged area.