Past research projects
Here are a few of our past and completed projects. For our current efforts and collaborative projects please visit those sections of our website.
Continuous acoustic field characterization using one sensor
Picture by C. Garcia ©
Carlos E. Garcia, our visiting scholar from UNSL Argentina, is primarily heading this effort with the supervision of Mr. Malladi. The goal here is to characterize an acoustic field by way of a single sensor. This would alleviate the need for sensor arrays in order to achieve the same goal. Like any technique, it will have its advantages and disadvantages and we hope to thoroughly investigate these.
Publication
Garcia, C. E., Malladi, S., Tarazaga, P.A., 2013. “Continuous Scanning for Acoustic Field Characterization,” IMAC XXXI, Orange County, CA, February 11-14.
Publication
Garcia, C. E., Malladi, S., Tarazaga, P.A., 2013. “Continuous Scanning for Acoustic Field Characterization,” IMAC XXXI, Orange County, CA, February 11-14.
Shape changing maneuverable munition using novel alloys/materials for flight performance enhancements
Figure by Malladi ©
Funded through a Small Business Innovation Research (SBIR) grant provided by the U.S. Army through AVID LLC, this projects leverages VAST's shape memory alloy expertise to achieve shape changing munitions. This project is headed by Jeremy Kolansky.
Sensorless control of shape memory alloys using thermoelectric properties
Picture by Sriram Malladi ©
This project, headed by Mr. Sriram Malladi, investigates the use of Seebeck voltage in a thermocouple junction made of SMA and constantan in order to obtain the SMA state. Seeback voltage is related to temperature, and temperature of an SMA yields information about its condition. At this stage, preliminary work has been done and we hope to extend this work further on. A picture of our prototype SMA-constantan thermocouple can be seen on the left.
Publication: V V N Sriram Malladi and Pablo Tarazaga. 2012, Sensorless control of SMA using Seebeck voltage, Proceedings of ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. Stone Mountain,GA, September 19th-21st, SMASIS2012-8062.
Publication: V V N Sriram Malladi and Pablo Tarazaga. 2012, Sensorless control of SMA using Seebeck voltage, Proceedings of ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. Stone Mountain,GA, September 19th-21st, SMASIS2012-8062.
Propulsion by traveling waves
The concept of traveling waves is explored in order to generate propulsion of small vehicle-like structures. This program will investigate the combination of modes in order to induce traveling waves as the fundamental mechanism to generate movement. The traveling waves of the structure will be generated with the use of smart materials such as piezoceramics. This project forms part of a senior design project and is headed by Bryan Joyce. The senior design members are: Jacob Aber, Nick Meligari, Edan Fletcher and Jordan Mullins.
Structural mechanics for adaptive optics
ODS and modes of a membrane-cavity coupled system. Theory and Exp.
Optical membranes are currently pursued for their ability to replace the conventional rigid mirrors that are used in space-based telescopes. Among some of the many benefits of using optical membranes, is their ability to considerably reduce the weight of the structure. Given the low density of these thin-film membranes, the lower-end dynamics play a more significant role than in their rigid plate-like counterparts. Space-based mirrors are subjected to a series of disturbances. Among those encountered are thermal radiation, debris impact, and slewing maneuvers. Thus, being able to model the dynamics appropriately is essential for the adequate performance of thin-film membrane mirrors.
With this in mind, the work studied used an impedance based modeling approach to describe the coupled dynamics of a pressurized optical membrane mirror with the end goal of performing vibration suppression of a membrane through acoustic excitation. First, the effects of mass loading due to air surrounding a membrane and energy loss due to sound radiation to the far field were modeled in the case of a single membrane. These results are compared to the case of a membrane in vacuum. Second, the membrane is then coupled to a cylindrical cavity where the modeling takes into account the structural acoustic coupling between a cylindrical membrane and a rigid cylindrical cavity, similar to a drum. The coupled model also takes into account the energy loss by sound radiation to the far field due to the membrane's vibration. Thirdly, a positive position feedback controller for vibration suppression of the membrane was implemented. This was done using a centralized acoustic source at the base of the cavity as the method of actuation. The acoustic actuation is of great interest since it does not mass load the membrane in the conventional way, as most methods of actuation would.
Publications:
-Tarazaga, P. A., Johnson, M.E., Inman, D.J., 2012. “Vibro-acoustics of a pressurized optical membrane” Journal of Mechanical Systems and Signal Processing (MSSP) Vol. 30 pp. 373-392. http://dx.doi.org/10.1016/j.ymssp.2011.12.009
-Tarazaga, P. A., Johnson, M.E., Inman, D.J., 2010. “Experimental Validation of a Pressurized Optical Membrane ” Journal of Mechanical Systems and Signal Processing (MSSP). (under review)
-Tarazaga, P. A., Johnson, M.E., Inman, D.J., 2010. “ Vibro-acoustics of a pressurized optical membrane” RASD2010 Recent Advances in Structural Dynamics, Southampton, UK, July 12-14.
-Ameri, N., Tarazaga, P.A., DiMaio, D., Ewins, D.J., 2012. “Non-Contact Operational Modal Analysis of an Optical Membrane for Space Application,” IMAC XXX, Jacksonville Florida, January 30 - February 2, 2012.
-Tarazaga P.A., DiMaio, D., Ameri, N., Ewins, D.J., 2012. “Continuous Laser Scanning of a Lightweight Membrane with Monotone and Multi-tone Excitation Techniques,” Proceedings, 53rd AIAA/ASME/ASCE/AHS Structures, Structural Dynamics and Materials Conference (SDM), April 23-26, Honolulu, Hawaii.
With this in mind, the work studied used an impedance based modeling approach to describe the coupled dynamics of a pressurized optical membrane mirror with the end goal of performing vibration suppression of a membrane through acoustic excitation. First, the effects of mass loading due to air surrounding a membrane and energy loss due to sound radiation to the far field were modeled in the case of a single membrane. These results are compared to the case of a membrane in vacuum. Second, the membrane is then coupled to a cylindrical cavity where the modeling takes into account the structural acoustic coupling between a cylindrical membrane and a rigid cylindrical cavity, similar to a drum. The coupled model also takes into account the energy loss by sound radiation to the far field due to the membrane's vibration. Thirdly, a positive position feedback controller for vibration suppression of the membrane was implemented. This was done using a centralized acoustic source at the base of the cavity as the method of actuation. The acoustic actuation is of great interest since it does not mass load the membrane in the conventional way, as most methods of actuation would.
Publications:
-Tarazaga, P. A., Johnson, M.E., Inman, D.J., 2012. “Vibro-acoustics of a pressurized optical membrane” Journal of Mechanical Systems and Signal Processing (MSSP) Vol. 30 pp. 373-392. http://dx.doi.org/10.1016/j.ymssp.2011.12.009
-Tarazaga, P. A., Johnson, M.E., Inman, D.J., 2010. “Experimental Validation of a Pressurized Optical Membrane ” Journal of Mechanical Systems and Signal Processing (MSSP). (under review)
-Tarazaga, P. A., Johnson, M.E., Inman, D.J., 2010. “ Vibro-acoustics of a pressurized optical membrane” RASD2010 Recent Advances in Structural Dynamics, Southampton, UK, July 12-14.
-Ameri, N., Tarazaga, P.A., DiMaio, D., Ewins, D.J., 2012. “Non-Contact Operational Modal Analysis of an Optical Membrane for Space Application,” IMAC XXX, Jacksonville Florida, January 30 - February 2, 2012.
-Tarazaga P.A., DiMaio, D., Ameri, N., Ewins, D.J., 2012. “Continuous Laser Scanning of a Lightweight Membrane with Monotone and Multi-tone Excitation Techniques,” Proceedings, 53rd AIAA/ASME/ASCE/AHS Structures, Structural Dynamics and Materials Conference (SDM), April 23-26, Honolulu, Hawaii.
Model updating with a closed form solution and preserved connectivity
The work herein developed the quadratic compression method (QCM) for model updating. The modelling error was defined in the parametric set-up, i.e. with pre-specified principal submatrices multiplied by unknown scalar parameters. The optimal parameters are obtained by minimising the error in a squared down version of the eigenvalue equation, thus with reduced computation. The method is shown to belong to the class of Minimisation of the Error in the Characteristic Equation, with a particular choice of the weighting matrix. Analysis of the propagation of the noise into the identified parameters reveals that QCM has desirable noise filtering properties. The work also presented a weighted version of the method, called WQCM, which is motivated by further reducing the effect of measurement noise. In addition to the theoretical analysis, the superior robustness to noise properties of QCM and WQCM are demonstrated by simulations and experimentally. The work was later extended to include the mass matrix in the updating process
Publications:
-Tarazaga, P.A., Halevi, Y., and Inman, D.J., 2006. “Quadratic Compression Method for Model Updating and Its Noise Filtering Properties,” Journal of Mechanical Systems and Signal Processing (MSSP) Volume 21, Issue 1, Pages 58-73. http://dx.doi.org/10.1016/j.ymssp.2005.12.006
-Tarazaga, P.A., Halevi, Y., and Inman, D.,J., 2007,”Modified Quadratic Compression Method for Mass and Stiffness,” Journal of Mechanical Systems ad Signal Processing (MSSP). http://dx.doi.org/10.1016/j.ymssp.2009.03.009
Publications:
-Tarazaga, P.A., Halevi, Y., and Inman, D.J., 2006. “Quadratic Compression Method for Model Updating and Its Noise Filtering Properties,” Journal of Mechanical Systems and Signal Processing (MSSP) Volume 21, Issue 1, Pages 58-73. http://dx.doi.org/10.1016/j.ymssp.2005.12.006
-Tarazaga, P.A., Halevi, Y., and Inman, D.,J., 2007,”Modified Quadratic Compression Method for Mass and Stiffness,” Journal of Mechanical Systems ad Signal Processing (MSSP). http://dx.doi.org/10.1016/j.ymssp.2009.03.009
Control of a Space Rigidizable-Inflatable Boom Using Macro-Fiber Composite Actuators
Picture Credit L’GARDE, Inc
An experimental investigation of vibration testing and active control of a space rigidizable inflatable composite boom containing embedded piezoelectric composite actuators was conducted. Inflatable deployable space structures offer reduced mass, higher packaging efficiency, lower life cycle cost, simpler design with fewer parts, and higher deployment reliability for many large deployable spacecraft structures applications. Enhancing deployed precision and repeatability for these structures is an ongoing research area; in particular, for rigidizable inflatable material systems. In this study we demonstrate in situ vibration testing and active damping using piezoelectric Macro-Fiber Composite actuators embedded within a typical space-rigidizable deployable composite boom. The embedded Macro-Fiber Composite are shown to be capable of surviving integration, packaging, deployment and thermal rigidization in vacuum, and subsequently operating at their full actuation capability. Positive position feedback controllers using accelerometer, laser vibrometer, and strain gage feedback signals are designed and experimentally evaluated. Velocity-proportional and acceleration proportional controllers shown to be capable of attenuating fundamental bending response significantly using only modest control authority (-23dB with 10% of available voltage).
Publications:
Tarazaga, P.A., Inman, D.J., and Wilkie, W., K., 2007. “Control of Space Rigidizable-Inflatable Boom Using Macro-Fiber Composite,” Journal of Vibration and Control, Vol. 13 n. 7, pp. 935-950. http://dx.doi.org/10.1177/1077546307078757
Publications:
Tarazaga, P.A., Inman, D.J., and Wilkie, W., K., 2007. “Control of Space Rigidizable-Inflatable Boom Using Macro-Fiber Composite,” Journal of Vibration and Control, Vol. 13 n. 7, pp. 935-950. http://dx.doi.org/10.1177/1077546307078757
VT Shape Memory Alloy
We had a little fun with some Shape Memory Alloy (SMA) wires and made a few samples of the letters "VT" shaped out of a SMA wire. Watch it in action below. We would like to thank our VAST Lab members Carlos Garcia Castro and Sriram Malladi for designing, building, and shape setting the VT SMA.