Detection of Compressive Forces Applied to Tubes and Estimation of Their Locations with the Surface Response to Excitation (SuRE) Method

The fuselages and outer cases of the engines of many fixed wing drones are made of tubes because of their aerodynamic characteristics and strengths. Most of the structural health monitoring (SHM) methods were developed for the large flat plates used to manufacture the fuselages of conventional airplanes. Recently, drones have been used at many military and civilian applications. The current trend shows that, their fuselages will be made of additively manufactured composite tubes in near future. Most of the expensive drones operate out of the sight during their missions. An SHM system at the critical locations such as their cylindrical bodies and outer engine covers would provide very valuable information to their operators in emergencies to return the system before catastrophic failure occurs. Surface response to excitation (SuRE) method is a sensitive SHM method, which can detect defects of small structures. In this study, SuRE method is used for detection of compressive forces applied to the small hollow tubes and estimation of their location. A steel and an additively manufactured (AM) tubes were tested without and with applied compressive force by using the SuRE method. The existence of the compressive force was detected in all cases. The location of the compressive force was estimated accurately in 2 out of 3 cases for both materials.