Dr. Travis L. Turner Profile

Dr. Travis L. Turner

Research Scientist at NASA Langley Research Ctr

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Author

Publications (15)

Proceedings Article | 23 March 2012 Paper

Modeling fluid structure interaction with shape memory alloy actuated morphing aerostructures

Stephen Oehler, Darren Hartl, Travis Turner, Dimitris Lagoudas

Proceedings Volume 8343, 834305 (2012) https://doi.org/10.1117/12.918061

KEYWORDS: Shape memory alloys, Finite element methods, 3D modeling, Fluid dynamics, Solids, Data modeling, Computational fluid dynamics, Calibration, Actuators, Prototyping

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Proceedings Article | 18 April 2008 Paper

Testing of SMA-enabled active chevron prototypes under representative flow conditions

Travis Turner, Randolph Cabell, Roberto Cano, Richard Silcox

Proceedings Volume 6928, 69280Y (2008) https://doi.org/10.1117/12.776309

KEYWORDS: Actuators, Shape memory alloys, Prototyping, Composites, Infrared cameras, Denoising, Aerodynamics, Cameras, Control systems, Data acquisition

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Proceedings Article | 27 April 2007 Paper

Development of a SMA hybrid composite jet engine chevron concept

Travis Turner, Randolph Cabell, Roberto Cano, Richard Silcox

Proceedings Volume 6525, 65250J (2007) https://doi.org/10.1117/12.716023

KEYWORDS: Actuators, Shape memory alloys, Infrared cameras, Composites, Cameras, Temperature metrology, Denoising, Data acquisition, Lead, Infrared imaging

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Proceedings Article | 5 April 2006 Paper

Design, fabrication, and testing of a SMA hybrid composite jet engine chevron

Travis Turner, Randolph Cabell, Roberto Cano, Gary Fleming

Proceedings Volume 6173, 61731B (2006) https://doi.org/10.1117/12.660844

KEYWORDS: Actuators, Shape memory alloys, Composites, Temperature metrology, Infrared cameras, Control systems, Electronic test equipment, Cameras, Data acquisition, Lead

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Proceedings Article | 19 May 2005 Paper

Measurement and prediction of the thermomechanical response of shape memory alloy hybrid composite beams

Brian Davis, Travis Turner, Stefan Seelecke

Proceedings Volume 5757, (2005) https://doi.org/10.1117/12.614140

KEYWORDS: Shape memory alloys, Thermal modeling, Composites, Temperature metrology, Beam shaping, Actuators, Numerical simulations, Thermography, Data modeling, Cameras

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Proceedings Article | 16 May 2005 Paper

Finite element analysis of adaptive-stiffening and shape-control SMA hybrid composites

Xiujie Gao, Travis Turner, Deborah Burton, L. Catherine Brinson

Proceedings Volume 5761, (2005) https://doi.org/10.1117/12.624676

KEYWORDS: Shape memory alloys, Composites, Finite element methods, Beam shaping, Switching, 3D modeling, Polymers, Prototyping, Systems modeling, Human-machine interfaces

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Proceedings Article | 26 July 2004 Paper

Design, fabrication, and testing of SMA-enabled adaptive chevrons for jet noise reduction

Travis Turner, Ralph Buehrle, Roberto Cano, Gary Fleming

Proceedings Volume 5390, (2004) https://doi.org/10.1117/12.540013

KEYWORDS: Actuators, Shape memory alloys, Temperature metrology, Infrared cameras, Control systems, Composites, Cameras, Transducers, Denoising, Prototyping

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Proceedings Article | 26 July 2004 Paper

Analysis of SMA hybrid composite structures using commercial codes

Travis Turner, Hemant Patel

Proceedings Volume 5383, (2004) https://doi.org/10.1117/12.540002

KEYWORDS: Shape memory alloys, Composites, Actuators, Analytical research, Chemical elements, Thermal modeling, Thermal effects, Structural analysis, Systems modeling, Beam shaping

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Proceedings Article | 15 July 2002 Paper

Structural acoustic response of a shape memory alloy hybrid composite panel (lessons learned)

Travis Turner

Proceedings Volume 4701, (2002) https://doi.org/10.1117/12.474695

KEYWORDS: Shape memory alloys, Actuators, Composites, Acoustics, Control systems, Aluminum, Infrared cameras, Temperature metrology, Infrared radiation, Infrared imaging

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Proceedings Article | 11 July 2002 Paper

Effects of thermomechanical history on the tensile behavior of Nitinol ribbon

Cynthia Lach, Travis Turner, Karen Taminger, Ravi Shenoy

Proceedings Volume 4699, (2002) https://doi.org/10.1117/12.474990

KEYWORDS: Actuators, Shape memory alloys, Neodymium, Composites, Temperature metrology, Heat treatments, X-rays, X-ray diffraction, Calorimetry, Crystals

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Shape memory alloys (SMAs) have enormous potential for a wide variety of applications. A large body of work exists on the characterization of the microstructure and stress-strain behavior of these alloys, Nitinol (NiTi) in particular. However, many attributes of these materials are yet to be fully understood. Previous work at NASA Langley Research Center (LaRC) has included fabrication of hybrid composite specimens with embedded Nitinol actuators and modeling of their thermomechanical behavior. An intensive characterization effort has been undertaken to facilitate fundamental understanding of the stress-strain behavior of this alloy in relation to its microstructure and to promote implementation of Nitinol in aerospace applications. Previous work revealed attributes of the Nitinol ribbon that were not easily rationalized with existing data in the literature. In particular, tensile behavior at ambient temperature showed significant dependence on the thermomechanical history prior to testing. The present work is focused on characterizing differences in the microstructure of Nitinol ribbons exposed to four different thermomechanical histories and correlation of the microstructure with tensile properties. Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) analysis were employed to rationalize the microstructures present after exposure to various thermomechanical histories. Three of the Nitinol ribbon conditions were reversible upon heating (in the DSC) through the reverse transformation temperature (Af) to transform the microstructure to austenite. However, the prior thermomechanical conditioning for the Nitinol ribbon that reflected the entire fabrication procedure was found to have an irreversible effect on the microstructure, as it remained unchanged after repeated complete thermal cycles. Tensile tests were conducted to determine the effect of prior thermomechancial conditioning on both the tensile behavior of the Nitinol ribbons and the stress state of the microstructure. The stress-strain behavior of the Nitinol actuators appears to be governed by the interplay between two major variables: namely, microstructural constituents such as the R-phase and the martensite; and the stress state of these constituents (whether twinned with low residual stresses, or detwinned with high residual stresses). The most significant difference in the stress-strain behavior of the four conditions, the critical stress required to achieve an initial stress plateau, was found to depend on both the amount and stress state of R-phase present in the initial microstructure. Thus, the effect of prior thermomechanical processing is critical to the resulting tensile behavior of the Nitinol actuator. For numerical modeling inputs one must take into account the entire fabrication process on the Nitinol actuator.

Proceedings Article | 21 August 2001 Paper

Experimental validation of a thermoelastic model for SMA hybrid composites

Travis Turner

Proceedings Volume 4326, (2001) https://doi.org/10.1117/12.436475

KEYWORDS: Shape memory alloys, Temperature metrology, Composites, Actuators, Thermal modeling, Systems modeling, Transducers, Lead, Motion models, Smart materials

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Proceedings Article | 11 July 2001 Paper

Fabrication and characterization of SMA hybrid composites

Travis Turner, Cynthia Lach, Roberto Cano

Proceedings Volume 4333, (2001) https://doi.org/10.1117/12.432774

KEYWORDS: Actuators, Shape memory alloys, Composites, Temperature metrology, Data modeling, Thermal modeling, Packaging, Statistical analysis, Mechanics, Materials processing

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Proceedings Article | 12 June 2000 Paper

Dynamic response tuning of composite beams by embedded shape memory alloy actuators

Travis Turner

Proceedings Volume 3991, (2000) https://doi.org/10.1117/12.388180

KEYWORDS: Shape memory alloys, Actuators, Temperature metrology, Composites, Beam shaping, Thermal modeling, Smart materials, Thermal effects, Aerospace engineering, Acoustics

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Proceedings Article | 27 April 2000 Paper

Piezoelectric shunt vibration damping of an F-15 panel under high-acoustic excitation

Shu-yau Wu, Travis Turner, Stephen Rizzi

Proceedings Volume 3989, (2000) https://doi.org/10.1117/12.384568

KEYWORDS: Transducers, Ferroelectric materials, Acoustics, Inductance, Resistance, Vibration control, Resistors, Aluminum, Solids, Ceramics

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At last year's SPIE symposium, we reported results of an experiment on structural vibration damping of an F-15 underbelly panel using piezoelectric shunting with five bonded PZT transducers. The panel vibration was induced with an acoustic speaker at an overall sound pressure level (OASPL) of about 90 dB. Amplitude reductions of 13.45 and 10.72 dB were achieved for the first and second modes, respectively, using single- and multiple-mode shunting. It is the purpose of this investigation to extend the passive piezoelectric shunt- damping technique to control structural vibration induced at higher acoustic excitation levels, and to examine the controllability and survivability of the bonded PZT transducers at these high levels. The shunting experiments was performed with the Thermal Acoustic Fatigue Apparatus (TAFA) at the NASA Langley Research Center using the same F-15 underbelly panel. The TAFA is a progressive wave tube facility. The panel was mounted in one wall of the TAFA test section using a specially designed mounting fixture such that the panel was subjected to grazing-incidence acoustic excitation. Five PZT transducers were used with two shunt circuits designed to control the first and second modes of the structure between 200 and 400 Hz. We first determined the values of the shunt inductance and resistance at an OASPL of 130 dB. These values were maintained while we gradually increased the OASPL from 130 to 154 dB in 6-dB steps. During each increment, the frequency response function between accelerometers on the panel and the acoustic excitation measured by microphones, before and after shunting, were recorded. Good response reduction was observed up to the 148dB level. The experiment was stopped at 154 dB due to wire breakage from vibration at a transducer wire joint. The PZT transducers, however, were still bonded well on the panel and survived at this high dB level. We also observed shifting of the frequency peaks toward lower frequency when the OASPL was increased. Detailed experimental results will be presented.

Proceedings Article | 16 June 1998 Paper

Control of sonic fatigue for high-speed flight vehicles using shape memory alloys

Chuh Mei, Zhiwei Zhong, Travis Turner

Proceedings Volume 3326, (1998) https://doi.org/10.1117/12.310666

KEYWORDS: Shape memory alloys, Composites, Matrices, Acoustics, Temperature metrology, Aerodynamics, Nickel, Finite element methods, Skin, Chemical elements

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