The paper proposes a method to compute the elastic properties degradation level in composite panels exposed to the low-velocity impact action. The method makes it possible to reduce the panel defects to a linear statement based on the impact energy and thickness of the panel under study. The study was conducted to determine an elastic properties degradation level in the heavy gage composite panels exposed to the low-velocity impact action leading to defects of the 1st category. To present the developed method, a series of numerical simulations of the orthotropic composite panels of different thicknesses was carried out based on the experimental standard for the ASTM D7136 hardness drop testing to simulate impact damage in a composite panel. The presented method is a combination of both numerical analysis and empirical approach in identifying the elastic properties degradation level in the heavy gage composite panels exposed to the low-velocity impact loads, as well as in calculating the empirical coefficient. The paper determines that this method could be introduced in preliminarily assessment of residual strength and critical force in the stability loss for the composite panels at early stages of the aircraft design without complex and resource-intensive computation. During testing, the proposed method demonstrated good convergence between the obtained numerical results and the experimental data. The paper notes acceptable qualitative similarity of the destruction simulated mechanism and form with those observed in the experiments.

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