Modal Testing and Analysis of the NPS Space Truss

摘要

This thesis deals with modal testing and analysis of the Naval PostgraduateSchool (NPS) Space Truss. A finite element model (FEM) was developed for the truss using a MATLB program called NRLFEMI (developed at the Naval Research Laboratory). Analytical predictions of the natural frequencies for this 3.76 meter by 0.35 meter precision structure were calculated using the NRLFEMI code. These calculated natural frequencies were then compared to experimental data collected during modal testing of the truss in the NPS Dynamics and Control Laboratory. Through analysis, the predicted results of the measurements (from the FEM) were satisfactorily correlated to the experimentally obtained results, validating the FEM program. Additionally, a technology demonstration of Fiber Bragg Grating Sensors (FBGSs) was performed. These laser etched, fiber optic sensors are ideally suited for real time evaluation of load, strain, vibration, and other health monitoring functions of structures.