Prediction of critical crack opening and crack-tip stresses in polymer structural elements of unmanned aerial vehicles considering creep

Thermoplastics are widely used in the manufacturing of structural components for unmanned aerial vehicles (UAVs). Under sustained and variable loading, polymers exhibit creep, which significantly affects crack development. Therefore, determining critical crack opening and stresses acting at the crack tip, with consideration of material creep, is of practical importance. The study presents formulas for evaluating the mechanical properties of a polymer over time under creep conditions. A methodology for calculating crack opening in a polymer plate subjected to stresses acting in the near-tip region has been developed using the boundary element method. It has been established that critical crack opening is characterized by the condition Dymax ≥ DC, where Dymax and DC denote the maximum and critical crack opening, respectively. The practical significance of the proposed methodology is demonstrated through the calculation of crack opening and crack-tip stresses in a polypropylene plate under creep conditions.