Tensile Stress Measurement Applied in Small Rockets Fins Using Force Gauges in the Quarter Bridge Method

Flight stability of experimental rockets depends on the fin's mechanics resistance and aerodynamic design. Therefore, monitoring the fins behavior after or since at the flight moment gives information to prevent accidents in future launches. This work details a methodology of sensing uniaxial tensile stress in an experimental subsonic rocket (Mach number of 0.5) fins based on fiber carbon. We used the quarter bridge method gauges in a low-cost embedded system for testing three specimens according to ISO 527-2 (Model 1A). The tensile stress (σz) was measured by WAW 600B Hydraulic Universal Testing Machine for comparison with data of the low-cost system at the same time. For this investigation we analyze the error of the stress values in each of the specimens at 25°C without temperature correction, obtaining a similar tendency in RMSE 3.933, 3.8796 and 7.7087, first, second and third specimens respectively.