Mechanism and technology of laser adaptive cleaning for aircraft skin multilayer coatings of airbus A320

Aircraft skin is composed of multilayers of heterogeneous functional coatings, and it is often necessary to selectively remove one or several layers of coatings during aircraft maintenance and repair. However, it presents a significant challenge in laser micro/nano processing because the spatial structure and physicochemical properties of the coatings are difficult to identify online. A laser adaptive cleaning technology (LACT) based on coaxial spectral monitoring is proposed in consideration of the synchronous induction of plasma spectra during laser processing, which utilizing the differences in wavelength and amplitude of characteristic spectral lines from heterogeneous materials. Combined with spectral/photoelectric online monitoring modes, element recognition and interface sensing with MHz high-speed of multilayer heterogeneous materials were completed during laser scanning processing. Meanwhile, two closed-loop feedback strategies were established by combining FPGA (Field Programmable Gate Array) control hardware and intelligent algorithms, including interface adaptive and energy adaptive. As a result, with the two intelligent processing strategies, the precision and efficiency of laser selective processing of multilayer heterogeneous materials are simultaneously improved, and the laser adaptive cleaning of multilayer heterogeneous skin coating is finished. As an innovative technology, it is expected to provide a new method and technology for high-precision selective processing of multilayer heterogeneous materials.