The Nonlinear Dynamics Research Laboratory (NDRL) was established in 1992 by Dr. Suzanne Weaver Smith for testing, analysis and test/analysis correlation of nonlinear structural systems. Vibration-based damage detection, inverse problem formulation, signal processing, experiment design, phenomena model development/testing and other topics in structural model identification are considered. Support for NDRL has been provided by NASA, NSF, the Kentucky Space Grant Consortium, and McDonnell Douglas Aerospace.

Experimental techniques and analysis algorithms are developed for and applied to vibration tests conducted in the laboratory. Current capabilities include a 4-channel pc-based National Instruments data acquisition system with high-resolution audio input/output, digital signal processing, and data management cards. Structure excitation is provided by a Ling 100-lbf modal thruster/base exciter driven by amplified programmable signals. Access to an MB Dynamics 1200-lbf shaker is also available. A variety of force transducers and accelerometers (PCB Piezotronics and Kistler) are used, including very low-mass/very low-frequency options.

In addition to the ground-based tests, data from on-orbit vibration tests of flexible spacecraft has been and is being studied. Data from the Hubble Space Telescope was analyzed for indications of nonlinear modal interactions. A Mir Space Station Solar Array was excited by various events so that responses could be optically recorded (NASA PASDE experiment). Analysis of extracted displacement time-histories is currently underway for indications of nonlinear behaviors to aid mathematical model development. Scheduled on-orbit tests of the Mir Space Station (NASA/McDonnell Douglas Aerospace MiSDE experiment) will provide data which will be analyzed at NDRL for determination of modal characteristics and nonlinear behaviors.

Ground-based tests of a phenomena model solar array (NASA DSMT hardware on loan to NDRL) conducted recently have led to improved understanding of the complex nonlinear behaviors of these flexible structures. Also, a generic-truss testbed and experiments to evaluate damage detection for damped structures was recently completed in the laboratory. Applications to machine dynamics, robot calibration, and power transmission line dynamics, among others, have been addressed by students of NDRL.

Graduate and undergraduate students in various disciplines, including Mechanical, Civil, Electrical, and Materials Science Engineering, have participated in NDRL research.