Investigation of Unusual Peeled Yellow Dots in a UAV's Drive Belt

Adva cohen, IAF, Gedera, ישראל (advaziv@gmail.com)
Or Podval, Iaf, Gedera, ישראל
Yehonatan Ezra, Iaf, Gedera, ישראל
Yehonatan Moler, Iaf, Gedera, ישראל
Offek Pinko, Iaf, Gedera, ישראל
Romi Soroker, Iaf, Gedera, ישראל
Faran Levi, Iaf, Gedera, ישראל

A military drone crash was attributed to the failure of its drive belt, which was investigated to determine the root cause. Macroscopic examination identified a yellow "dot" region as the initiation site of a crack in the polyurethane matrix of the belt. The crack propagated via a fatigue mechanism, eventually tearing part of the matrix and causing an abnormal load on the belt fibers, culminating in complete belt failure. Further inspections of other drive belts from the same manufacturing batch revealed similar yellow "dots." Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses identified silicon (Si) in these dots, and Fourier-transform infrared (FTIR) spectroscopy confirmed the presence of poly-dimethyl sulfoxane (PDMS). The incompatibility between the polyurethane matrix and PDMS led to the formation of distinct phases, resulting in stress concentrations around the yellow dots, which likely contributed to the observed failures.