| Vibration-based damage detection methods are of great interest because of their global nature as compared to standard localized non-destructive methods which are time consuming for large structures.;In this work, vibration-based damage detection procedures are developed around a robust iterative algorithm that has been expanded to include two new optimization procedures, an improved computer program, and procedures for feature selection on structures with or without tension. The previous implementation of the iterative algorithm was successfully applied to beams and lightning masts using a few lower natural frequencies. The new implementation was successful at detecting stiffness changes in rectangular beams with and without tension, circular beams, and wire ropes modeled with beam elements. Detection of mass increase in a pipeline system using solid and shell elements is also shown. The new computer implementation allows for easy use of external models by computing the sensitivity matrices using the finite difference method. Including mass modification, new methods to overcome symmetry using length modification and targeted investigation are presented. The importance of step length is shown when the method fails because full step length is used. The importance of choosing a detection parameter is demonstrated when some the natural frequencies of a circular bar and a tensioned beam system increase and some decrease.;Currently, there are two main methods used to perform modal testing: impact testing or shaker testing. The random impact method was successfully used on lightning masts to overcome external noise due to wind and on heavily damped elevator ropes. The main drawback is that for large structures, a heavy hammer has to be swung for 2-6 minutes for each test which is tiring. To overcome problems associated with the random impact method, a mechanical system was designed, built, and tested to implement the method.;In the current research funding process educational outreach for the benefit of society is often required. Demonstrations of how this research and that of the Dynamic Systems and Vibrations Laboratory benefits society the development, delivery, and evaluation of an educational summer camp for high school students over six summers is presented. |
