Research Interests

Data-Driven Paradigms for
​Dynamic Validation

modeling, control, testing and validation of engineering structures

Bio-Inspired 
​​Structural Dynamics

design of composite structures mimicking biological phenomenon

​Internet-of-Vibrations

sensing, monitoring, & analyzing vibrational data

Some Research Projects

Anechoic Traveling Waves in Dynamic Structures 

Traveling wave generation and analysis of propagation to characterize the role of structural and electromechanical parameters 
  • A mechanical wave is generated as a result of an oscillating body interacting with the well-defined medium and it propagates through that medium transferring energy from one location to another. 
  • The ability to generate and control the motion of the mechanical waves through the finite medium opens up the opportunities for creating novel actuation mechanisms. 
  • The focus of this study is on understanding the traveling wave generation and propagation by establishing the relationships that illustrate the role of structural and electromechanical parameters.
  • Waves with desired characteristics are generated by the excitation of piezoelectric elements through coupled system dynamics.

Publications
  1. Anakok, I., Malladi, V. S., & Tarazaga, P. A. (2019). A Study on the Generation and Propagation of Traveling Waves in Strings. In Topics in Modal Analysis & Testing, Volume 9 (pp. 257-261). Springer, Cham.
  2. Malladi, V. V. S., Albakri, M. I., Gugercin, S., & Tarazaga, P. A. (2017). Application of projection-based model reduction to finite-element plate models for two-dimensional traveling waves. Journal of Intelligent Material Systems and Structures, 28(14), 1886-1904.
  3. Musgrave, Patrick F., VVN Sriram Malladi, and Pablo A. Tarazaga (2017). "Investigation into the superposition of multiple mode shape composed traveling waves." In Active and Passive Smart Structures and Integrated Systems 2017, vol. 10164, p. 1016408. International Society for Optics and Photonics.
  4. Malladi, V. V. S., Albakri, M., & Tarazaga, P. A. (2017). An experimental and theoretical study of two-dimensional traveling waves in plates. Journal of Intelligent Material Systems and Structures, 28(13), 1803-1815.
  5. Avirovik, D., Malladi, V. S., Priya, S., & Tarazaga, P. A. (2016). Theoretical and experimental correlation of mechanical wave formation on beams. Journal of Intelligent Material Systems and Structures, 27(14), 1939-1948.
  6. Musgrave, P. F., Malladi, V. S., & Tarazaga, P. A. (2016). Generation of traveling waves in a 2D plate for future drag reduction manipulation. In Special Topics in Structural Dynamics, Volume 6 (pp. 129-138). Springer, Cham.
  7. Malladi, V. V. N. S., Avirovik, D., Priya, S., & Tarazaga, P. (2015). Characterization and representation of mechanical waves generated in piezo-electric augmented beams. Smart Materials and Structures, 24(10), 105026.
  8. Phoenix, A., Malladi, V. S., & Tarazaga, P. A. (2015, September). Traveling wave phenomenon through piezoelectric actuation of a free-free cylindrical tube. In ASME 2015 conference on smart materials, adaptive structures and intelligent systems (pp. V002T04A018-V002T04A018). American Society of Mechanical Engineers.
  9. Malladi, V. S., Albakri, M., Tarazaga, P. A., & Gugercin, S. (2015, September). Reduced plate model used for 2D traveling wave propagation. In ASME 2015 conference on smart materials, adaptive structures and intelligent systems(pp. V001T03A021-V001T03A021). American Society of Mechanical Engineers.
  10. Malladi, V. S., Avirovik, D., Priya, S., & Tarazaga, P. A. (2014, September). Travelling wave phenomenon through a piezoelectric actuation on a free-free beam. In ASME 2014 conference on smart materials, adaptive structures and intelligent systems (pp. V001T03A017-V001T03A017). American Society of Mechanical Engineers.​

Experimental Data-Driven Determination of Dispersion Characteristics of Structures 

  • Developed a data-driven technique to estimate dispersion relations that are experimentally tedious . 
  • Utilized easy-to-measure Frequency Response Functions (FRFs) to develop a numerical model of the structure under test.
  • Constructed group velocity curves through a series of numerical simulations.
  • Validated the experimental data-driven approach by analytical calculation for a one-dimensional homogeneous beam.

Publications
  1. ​Malladi V.V.N.S., Albakri M., Gugercin S.,and Tarazaga, P.A., 2018 ,"Data-driven Modeling Techniques to Estimate Dispersion Relationships of Structural Components". Proceedings of ASME 2018 Conference on Smart Materials, Adaptive structures and Intelligent Systems, San Antonio, TX.,September 10-13.
  2. Albakri., Malladi V.V.N.S., and Tarazaga P.A., and Gugercin S., 2018, "Data-driven Modeling for Dispersion Relations Estimation. Part I: Numerical Investigation". (Under review)
  3.  Malladi V.V.N.S., Albakri., Tarazaga P.A., and Gugercin S., 2018, "Data-driven Modeling for Dispersion Relations Estimation. Part II: Experimental Investigation". (Under review)

Multi Degree of Freedom (MDOF) Environmental Testing 

  • Purpose: to validate a structure's integrity to withstand the operational conditions of an environment.
  • Challenges: monitoring environmental conditions, replicating them in a controlled environment, and developing a test procedure, all, inevitably, while lacking complete information. 
  • Procedure:, The structural vibrations are measured at some representative points in operational environment and spectral densities are replicated in a lab set-up by exciting the structure with shakers/actuators. The forcing conditions are determined by solving an inverse problem based on reconstructing the multi-input multi-output frequency response function that maps the actuator input to sensor output.

Publications
  1. ​Devine A. T., Malladi V.V.N.S., and Tarazaga, P.A., 2018 ,"Environmental Testing of Unknown Boundary Conditions". 2018 Conference on Shock and Vibration Exchange, Dallas, TX.,Nov 4-8.
  2. ​Devine A. T., Malladi V.V.N.S., and Tarazaga, P.A., 2019 ,"Replicating Responses: A Virtual Environmental Test of Unknown Boundary Conditions". 2019 International Modal Analysis Conference, Orlando, FL.,Jan 29-31.

​Development of Artificial Hair Cells with Nonlinear Characteristics

​Studying Dynamics of Micro Scale Artificial Hair Cell

  • The cochlea, in the mammalian inner ear, transduces acoustic waves into electrical signals that are transmitted to the brain. One of the critical functions of the cochlea is its biological nonlinear behavior that amplifies faint sounds and compresses high sound levels. 
  • This study develops micro-electro-mechanical system (MEMS) scale artificial hair cells (AHC).
  • The current research investigates the potential of transforming MEMS scale cantilevers, initially designed for use as scanning thermal microscopy probes, into micro-scale artificial hair cells.
  • These cantilever structures are fabricated by employing electron beam- and photo-lithography, together with Low Pressure Chemical Vapor Deposition (LPCVD), metal evaporation, dry- and wet-etching on n-type silicon wafer substrates. ​
  • Collaboration with University of Glasgow, UK

Bio-Inspired Nonlinear Control of Artificial Hair Cells 

  • The human auditory mechanism can detect sound frequencies ranging from 20 Hz to 20 kHz, over a broad pressure range of 0–120 dB SPL due to its nonlinear amplification performed by the cochlea.
  • Sound waves travel through the ear canal, eardrum and the three bones of the middle ear. The last bone of the middle ear (stapes) pushes on the oval window and creates propagating waves in the cochlea.
  • These are then coupled to the hair cells, which apply their nonlinear compressibility and amplification behavior to improve sound detection. These functions of the cochlea are the inspiration to design more sensitive and capable sensors.
  • The primary objective of this work is to mimic the nonlinear amplification of cochlea by developing piezoelectric based active artificial hair cells (AHCs). 
Publications
  1. Davaria, S., Malladi, V. S., & Tarazaga, P. A. (2019). Bio-inspired Nonlinear Control of Artificial Hair Cells. In Structural Health Monitoring, Photogrammetry & DIC, Volume 6 (pp. 179-184). Springer, Cham.​
  2. ​Davaria S., Malladi V.V.N.S., Motaharibidgoli S., and Tarazaga P.A., 2018, "Cochlear Amplifier Inspired Two-channel Active Artificial Hair Cells", Smart Materials and Structures (under review).
  3. ​Davaria S., Malladi V.V.N.S., , Avilovas  L., Dobson P. , Cammarano A. and Tarazaga, P.A., 2019 ,"Replicating Responses: A Virtual Environmental Test of Unknown Boundary Conditions". 2019 International Modal Analysis Conference, Orlando, FL,Jan 29-31.

Developing a Passive Vibration Absorber for Bio-Inspired Anechoic Traveling Waves Generation

  • ​Sound waves enter the outer ear and pass into the ear canal where the waves cause the eardrum to vibrate. Those acoustics are transmitted to the middle ear, and then pass through the innermost part of the ear, called the cochlea.
  • The basilar membrane (BM), the main structural element of the cochlea, analyzes the waves propagating through it much like a biological Fourier analyzer. The waves travel from the base of the cochlea through the BM and get absorbed at the apex of the cochlea.
  • These latter feature of the human auditory system is the inspiration to study waves propagating from one end of a beam to the other without reflections at the boundary.
  • Inspired by this, the work in this project numerically studies the dynamics of a uniform beam connected to a spring-damper system, in order to study some of the observed phenomenological behaviors of the basilar membrane. 
  • The various structural parameters of the setup have effects on the frequency bandwidth of the absorber and the portion of the beam with traveling waves. 

Publications
  1. Motaharibidgoli, S., Malladi, V. V. N. S., & Tarazaga, P. A. (2019). Developing a Passive Vibration Absorber to Generate Traveling Waves in a Beam. In Special Topics in Structural Dynamics, Volume 5 (pp. 245-248). Springer, Cham.
  2. Motaharibidgoli, S., Malladi, V. V. N. S., & Tarazaga, P. A. (2019). Generating Anechoic Traveling Wave in Beams with Various Boundary Conditions​​. 2019 International Modal Analysis Conference, Orlando, FL,Jan 29-31.

​Smart Gait Analysis for Human Condition Inference

  • Gait induced floor-based vibrational data comprises of fundamental biomechanical information that is useful to quantitatively monitor patient health as part of diagnosis and rehabilitation.
  • The research goal of this project is to test the nature of the fundamental biomechanical information extracted human induced floor vibrations for monitoring various gait parameters and quantitatively assess the reliability of vibrational based features to detect pathological precursors. 
  • Although gait analysis is readily used to infer information about a patient, it relies on subjective, qualitative and experiential analysis by health care providers.
  • The work described here in uses commercially available low-cost accelerometers places on the ground to gather gait signatures which are later processed for critical information. 
Publications
  1. Diffenbaugh, T. E., M. A. Marti, J. Jagani, V. Garcia, G. J. Iliff, A. Phoenix, A. G. Woolard, V. V. N. S. Malladi, D. B. Bales, and P. A. Tarazaga. "Design and development of a prototype platform for gait analysis." In Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2017, vol. 10168, p. 1016818. International Society for Optics and Photonics, 2017.
  2. ​Kessler E., Malladi V.V.N.S., and Tarazaga P.A., 2019 ,"Normal and Abnormal Gait Analysis Using Underfloor Mounted Accelerometers". 2019 International Modal Analysis Conference, Orlando, FL,Jan 29-31.
  3. Kessler E., Malladi V.V.N.S., and Tarazaga P.A., 2018, "Gait Analysis Based on Floor Mounted Accelerome-
    ters", Journal of Biomechanics (under review).

Shaping FRFs of a MDOF Structure using Arrays of Tuned Vibration Absorber

  • Tuned vibration absorbers (TVA) provide passive energy dissipation from their primary structure but are limited to only having significant impact on a single frequency. 
  • This study provides the method and results of designing and implementing multiple arrays of TVAs to flatten the FRF at and around both modal frequencies of a two-degree-of-freedom (2DOF) structure. 
  • TVAs were cantilever beams made of varied length dry fettuccini pasta with some including modeling-clay tip masses. 
  • The final design successfully reduced the original 2DOF structure’s first natural frequency response by more than 9 dB and second natural frequency response by more than 19 dB for both primary masses.
​
Publications
​
  1. ​ Neighborgall C.R., Kothari K., Malladi V.V.N.S., Tarazaga P.A., Paruchuri S., Kurdila A. 2019 ,"Shaping The Frequency Response Function (Frf) Of A Multi-Degree-Of-Freedom (Mdof) Structure Using Arrays Of Tuned Vibration Absorbers (Tva)". 2019 International Modal Analysis Conference, Orlando, FL,Jan 29-31.

Occupation Monitoring in an Active Building

  • Human activity in a building generate vibrational waves that is evident in the acceleration data captured by sensors in the building. In this scenario, human induced vibrations is not limited to their footsteps but also includes other activities such as opening and closing of doors, moving furniture, etc.
  • Furthermore, each of these activities impart energy over various frequencies bandwidths.  Such broadband behavior of human activity presents a challenge in separating human activity from other events. 
  • Therefore, to detect human activity in a building, it is important to first separate human induced vibrations from other nominal events. ​For this study, we considered a data from the first floor of Goodwin hall sampled at 256 S/s.
  • A university classroom building is most active during day time with students attending classes. However, the same building has no human activity during night time. This variation in the human activity levels in an university building is used to study the frequency bandwidth of non-human activities. 

Publications
  1. Poston, J. D., Buehrer, R. M., Malladi, V. V. N. S., Woolard, A. G., & Tarazaga, P. A. (2015). Vibration sensing in smart buildings. In Proc. Int. Conf. Indoor Position. Indoor Navig.(IPIN).

Localization of Vibrational Events in an Active Building

  • Smarter buildings: energy efficient and proactive in decision making  by instrumentation of structures with sensors such as accelerometers and thermocouples to generate vast data
  • Challenge: screening away noise realized concurrently with the event
  • Contribution: Proposing methods to process sensor data efficiently and effectively to make user interaction with the building more intuitive and enhance user experience.

Publications
  1. ​Woolard, A. G., Malladi, V. S., & Tarazaga, P. A. (2017, April). Classification of event location using matched filters via on-floor accelerometers. In Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2017 (Vol. 10168, p. 101681A). International Society for Optics and Photonics.
  2. Bales, D., Tarazaga, P. A., Kasarda, M., Batra, D., Woolard, A. G., Poston, J. D., & Malladi, V. S. (2016). Gender classification of walkers via underfloor accelerometer measurements. IEEE Internet of Things Journal, 3(6), 1259-1266.
  3. Schloemann, J., Malladi, V. S., Woolard, A. G., Hamilton, J. M., Buehrer, R. M., & Tarazaga, P. A. (2015). Vibration event localization in an instrumented building. In Experimental Techniques, Rotating Machinery, and Acoustics, Volume 8 (pp. 265-271). Springer, Cham.
  4. Poston, J. D., Schloemann, J., Buehrer, R. M., Malladi, V. S., Woolard, A. G., & Tarazaga, P. A. (2015, June). Towards indoor localization of pedestrians via smart building vibration sensing. In Localization and GNSS (ICL-GNSS), 2015 International Conference on (pp. 1-6). IEEE.

​On Wave Propagation in Buildings

  • ​​​In this work, the problem of wave propagation in a smart building, Virginia Tech’s Goodwin Hall, is investigated. Goodwin Hall is a five-story, L-shaped Engineering building that is instrumented with 225 accelerometers.
  • The accelerometers are permanently mounted on the building’s steel columns and girders allowing for a continuous monitoring of vibration activities.
  • Using the building’s accelerometers, the propagation of elastic waves emitted from a series of floor impact excitations is studied.
  • Wave propagation within a given floor as well as floor-column interaction are investigated in this study.
  • Experimental results suggest that waves of the first anti-symmetric modes are induced in the floor due to impact excitation.
  • Wave mode conversion takes place at the floor-column interface, and the waves propagating along the column are found to be of the first symmetric mode. ​
Publications​
  1. Maza M.S., Albakri, J. D., Malladi, V. V. N. S., & Tarazaga, P. A. (2019). On Wave propagation in Smart Buildings​. 2019 International Modal Analysis Conference, Orlando, FL,Jan 29-31.

In-field Implementation of Impedance-based Structural Health Monitoring for Insulated Rail Joints

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  • ​​Track defects are a major safety concern for the railroad industry. Among different track components, insulated rail joints, which are widely used for signaling purposes, are considered a weak link in the railroad track.
  • Several joint-related defects have been identified by the railroad community, including rail wear, torque loss, and joint bar breakage. Current track inspection techniques rely on manual and visual inspection or on specially equipped testing carts, which are costly, time consuming, traffic disturbing, and prone to human error.
  • To overcome the aforementioned limitations, the feasibility of utilizing impedance-based structural health monitoring for insulated rail joints is investigated in this work. 
  • The instrumented joint is then installed and tested at the Facility for Accelerated Service Testing, Transportation Technology Center Inc. The effects of environmental and operating conditions on the measured impedance signatures are investigated through a set of experiments conducted at different temperatures and loading conditions. 

Publications
  1. Albakri, M. I., Malladi, V. V. S., & Tarazaga, P. A. (2017, September). Acoustoelastic-based stress measurement utilizing low-frequency flexural waves. In ASME 2017 Conference on Smart Materials, Adaptive Structures and Intelligent Systems (pp. V002T05A004-V002T05A004). American Society of Mechanical Engineers.
  2. Albakri, M. I., Malladi, S., & Tarazaga, P. A. (2015, September). Non-Linear Impedance-Based Structural Health Monitoring for Damage Detection and Identification. In ASME 2015 Conference on Smart Materials, Adaptive Structures and Intelligent Systems (pp. V002T05A008-V002T05A008). American Society of Mechanical Engineers.
  3. Albakri, M. I., Malladi, V. S., & Tarazaga, P. A. (2018). Low-frequency acoustoelastic-based stress state characterization: Theory and experimental validation. Mechanical Systems and Signal Processing, 112, 417-429.
  4. Albakri, M. I., Malladi, V. S., Woolard, A. G., & Tarazaga, P. A. (2017, April). In-field implementation of impedance-based structural health monitoring for insulated rail joints. In Nondestructive Characterization and Monitoring of Advanced Materials, Aerospace, and Civil Infrastructure 2017 (Vol. 10169, p. 101690E). International Society for Optics and Photonics.

Towards a Self-powered Structural Health-Monitoring Smart Tire

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​​​The work will study the feasibility of using impedance-based structural health monitoring (SHM) on a tire specimen. The project will also study the possibility of establishing an energy-harvesting concept capable of powering the SHM device and creating a self sustained system. This will be carried out with the aid of a representative experiment in order to understand the technique’s capabilities and limitations. The project forms part of the NSF I/UCRC Center for Tire Research (CenTiRe).

Aquatic Vehicle Propulsion by means of Travelling Waves

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  • The purpose of this project is to couple a solid-state structural propulsion design with a wireless control system to navigate through a liquid medium.
  • This novel approach leverages the structural design capabilities and ties them to performance requirements through solids state manipulation and activation.  
  • The solid-state structural propulsion will be generated by traveling waves which will eliminate the need for conventional propulsion methods, such as propellers or jet propulsion.  
  • This design also incorporates the steering component with the propulsion as opposed to having separate systems. The vehicle will excel in withstanding high-pressures and moving through difficult or sensitive environments. ​
Publications
  1. Jones, Lucas, Josh Spahnie, Kevin Lefeave, Charles Haltom, Adam Underwood, Jacob Aber, VVN Sriram Malladi, Bryan S. Joyce, and Pablo A. Tarazaga. "Vehicle propulsion by solid state motion." In ASME 2014 conference on smart materials, adaptive structures and intelligent systems, pp. V002T04A007-V002T04A007. American Society of Mechanical Engineers, 2014. 
  2. ​Malladi, V. V. S., Albakri, M., Musgrave, P., & Tarazaga, P. A. (2017, April). Investigation of propulsive characteristics due to traveling waves in continuous finite media. In Bioinspiration, Biomimetics, and Bioreplication 2017 (Vol. 10162, p. 101620O). International Society for Optics and Photonics.
  3. Davari, S., Krishnan M., Malladi, V. V. N. S., & Tarazaga, P. A. (2019). Miniature underwater robot – An experimental case study​. 2019 International Modal Analysis Conference, Orlando, FL,Jan 29-31.

Nonlinear dynamics of jointed structures

  • The constitutive behavior of mechanical joints is largely responsible for the energy dissipation and vibration damping in mechanical transmission lines. One such joint which is highly useful in transferring mechanical energy from one rotating shaft to another is the flange joint.
  • A flanged lap joint is commonly used to transfer the rotational energy from the motor or engine to the output shaft. Depending on different applications of this joint, it is excited at the higher frequencies. 
  • Due to the excitation of complex modes at these high frequencies a nonlinear phenomenon called “slap” occurs. Impulse blows are delivered from one shaft to the other in the longitudinal direction.
  • This results in activation of all the fundamental modes of the system resulting in catastrophic effects on the system. Developments of such non-linearities are studied by a much simpler bolted L-shaped joint.​

Acoustic Field Characterization using a Scanning Microphone

  • The development of the Continuous Acoustics Scanning Technique (CAST) is studied in order to characterize an acoustic field.
  • Furthermore, the acoustic emissions of a vibrating source is incorporated in order to analyze the relationship between the source characteristics and its acoustic field.
  • Initial findings suggest that the CAST may be capable of not only characterizing the acoustic field at a  distance from the source, but also be capable to characterize the velocity profile of the source itself. 
  • The CAST approach utilizes the side bands in a fast Fourier Transform (FFT) of the time-based-data collected by a roving microphone. The present work herein, is an extension and in-depth study of the different parameters affecting these side bands.

Publications
  1. Garcia, C. E., Malladi, S., & Tarazaga, P. A. (2014). Continuous Scanning for Acoustic Field Characterization. In Topics in Modal Analysis, Volume 7 (pp. 625-636). Springer, New York, NY.
  2. Malladi, VVN Sriram, Kevin L. Lefeave, and Pablo A. Tarazaga. "Parametric Study of a Continuous Scanning Method Used to Characterize an Acoustic Field." In Topics in Modal Analysis I, Volume 7, pp. 341-349. Springer, Cham, 2014.

Development and Design of Self-Sensing SMAs using Thermoelectric Effect

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  • Active research of SMAs has shown that its Seebeck coefficient is sensitive to its martensitic phase transformation and has the potential to determine the SMAs state of transformation.
  • The combination of Shape Memory Alloys, which have a positive Seebeck coefficient, and Constantan which has a negative Seebeck coefficient (-35 mV/K) results in a thermocouple capable of measuring temperature. 
  •  This sensor is used to study the hysteretic behavior of SMAs. Although Shape Memory Alloys (SMAs) exhibit a myriad of nonlinearities, SMAs show two major types of nonlinear hysteresis.
  • During cyclic loading of the SMAs, it is observed that one type of hysteretic behavior depends on the rate of heating the SMAs, whilst the variation of maximum temperature of an SMA in each cycle results in the other hysteretic behavior. This later hysteretic behavior gives rise to major and minor nonlinear loops of SMAs.
  • This work analyzes the nonlinearities of hysteretic envelopes which gives the different maximum temperatures reached for each hysteretic cycle with respect to stress and strain of the SMA. This work then models this behavior using Adaptive Neuro Fuzzy Inference System (ANFIS) and compares it to experimental results.
  • The nonlinear learning and adaptation of ANFIS architecture makes it suitable to model the temperature path hysteresis of SMAs.

Publications
  1. Malladi, Sriram VVN, and Pablo A. Tarazaga. "Sensorless Control of SMA Using Seebeck Voltage." In ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, pp. 367-373. American Society of Mechanical Engineers, 2012.
  2. Malladi, VVN Sriram, and Pablo A. Tarazaga. "Control of Strain Characteristics of SMA Wires Using Seebeck Voltage." In ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, pp. V001T03A020-V001T03A020. American Society of Mechanical Engineers, 2013.
  3. Malladi, Vijaya Venkta Narasimha Sriram, and Pablo A. Tarazaga. "Modeling of Hysteretic Effects of SMA using Neuro Fuzzy Inference System." In 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, p. 1918. 2013.
  4. Malladi, V. S., & Tarazaga, P. A. (2015). ANFIS Driven Strain Control of Thin-Shape Memory Alloy Wires Using Seebeck Voltage of a Shape Memory Alloy–Constantan Thermocouple. Journal of Vibration and Acoustics, 137(1), 011008.
  5. Malladi, V. V. N. S. (2013). Development and Design of Self-Sensing SMAs using Thermoelectric Effect (Masters' dissertation, Virginia Tech).​

Non-Contact Excitation Techniques for Ultra Light-Weight Systems

  • Testing of ultra lightweight structures is extremely challenging from various points of view. The use of sensors can easily mass load a structure and greatly affect its dynamic behavior.
  • This hinders the ability to properly study the systems dynamics and can frustrate the validation process between models and experiments. In some cases, the use of non-contact sensors, such as laser vibrometers, can be used to alleviate this problem, although it is not always feasible.
  • In much the same way, the excitation source can deliver many adverse effects. Although techniques such as speaker/acoustic excitation and boundary excitation are sometimes used, they both suffer from delivering a distributed load on the structure.
  • In most cases, this load distribution cannot be characterized and/or is incorrectly assumed as uniform. This also produces considerable errors in the experimental data as it is being processed, which leads to incorrect validation and updating of models.
  • The work here studies the possibility of using a single point "non-contact" excitation by characterizing a pulse of air that is used as the source of excitation. This is implemented experimentally on a 25-micron thick membrane used to simulate inflatable satellite optics.

Publications
  1. ​Tarazaga, Pablo A., and Nima Ameri. "Non-contact point excitation of ultra lightweight structures: membranes." In 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, p. 1461. 2013.