Dr. Christopher P. Henry Profile

Dr. Christopher P. Henry

Staff Research Scientist at HRL Labs LLC

SPIE Involvement:

Author

Proceedings Article | 1 April 2014 Paper

Theoretical and experimental investigation of architected core materials incorporating negative stiffness elements

Chia-Ming Chang, Andrew Keefe, William Carter, Christopher Henry, Geoff McKnight

Proceedings Volume 9057, 905723 (2014) https://doi.org/10.1117/12.2051036

KEYWORDS: Foam, Finite element methods, Neodymium, Composites, Electroluminescence, Performance modeling, Chemical elements, Surface conduction electron emitter displays, Solids, Vibration control

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Proceedings Article | 29 March 2010 Paper

Active material based active sealing technology: Part 1. Active seal requirements vs. active material actuator properties

Christopher Henry, William Carter, Guillermo Herrera, Geoffrey McKnight, Alan Browne, Nancy Johnson, Imad Bazzi

Proceedings Volume 7645, 76450H (2010) https://doi.org/10.1117/12.843834

KEYWORDS: Polymers, Liquid crystals, Actuators, Manufacturing, Electrodes, Carbon, Shape memory alloys, Dielectrics, Electroactive polymers, Metals

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Proceedings Article | 2 April 2008 Paper

3D FEA simulation of segmented reinforcement variable stiffness composites

C. Henry, G. McKnight, A. Enke, R. Bortolin, S. Joshi

Proceedings Volume 6929, 69290X (2008) https://doi.org/10.1117/12.778891

KEYWORDS: Composites, 3D modeling, Kinematics, Shape memory polymers, Finite element methods, Strain analysis, Matrices, Systems modeling, Homogenization, Aluminum

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Reconfigurable and morphing structures may provide significant improvement in overall platform performance through optimization over broad operating conditions. The realization of this concept requires structures, which can accommodate the large deformations necessary with modest weight and strength penalties. Other studies suggest morphing structures need new materials to realize the benefits that morphing may provide. To help meet this need, we have developed novel composite materials based on specially designed segmented reinforcement and shape memory polymer matrices that provide unique combinations of deformation and stiffness properties. To tailor and optimize the design and fabrication of these materials for particular structural applications, one must understand the envelope of morphing material properties as a function of microstructural architecture and constituent properties. Here we extend our previous simulations of these materials by using 3D models to predict stiffness and deformation properties in variable stiffness segmented composite materials. To understand the effect of various geometry tradeoffs and constituent properties on the elastic stiffness in both the high and low stiffness states, we have performed a trade study using a commercial FEA analysis package. The modulus tensor is constructed and deformation properties are computed from representative volume elements (RVE) in which all (6) basic loading conditions are applied. Our test matrix consisted of four composite RVE geometries modeled using combinations of 5 SMP and 3 reinforcement elastic moduli. Effective composite stiffness and deformation results confirm earlier evidence of the essential performance tradeoffs of reduced stiffness for increasing reversible strain accommodation with especially heavy dependencies on matrix modulus and microstructural architecture. Furthermore, our results show these laminar materials are generally orthotropic and indicate that previous calculations of matrix gap and interlaminar strains based on kinematic approximations are accurate to within 10-20% for many material systems. We compare these models with experimental results for a narrow geometry and material set to show the accuracy of the models as compared to physical materials. Our simulations indicate that improved shape memory polymer materials could enable a composite material that can accommodate ~30% strain with a cold state stiffness of ~30GPa. This would improve the current state of the art 5-10x and significantly reduce the weight and stiffness costs of using a morphing component.

Proceedings Article | 2 April 2008 Paper

Large strain variable stiffness composites for shear deformations with applications to morphing aircraft skins

G. McKnight, C. Henry

Proceedings Volume 6929, 692919 (2008) https://doi.org/10.1117/12.778888

KEYWORDS: Composites, Kinematics, Skin, Shape memory polymers, Photogrammetry, Resistance, Aerodynamics, Polymers, Temperature metrology, Prototyping

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Morphing or reconfigurable structures potentially allow for previously unattainable vehicle performance by permitting several optimized structures to be achieved using a single platform. The key to enabling this technology in applications such as aircraft wings, nozzles, and control surfaces, are new engineered materials which can achieve the necessary deformations but limit losses in parasitic actuation mass and structural efficiency (stiffness/weight). These materials should exhibit precise control of deformation properties and provide high stiffness when exercised through large deformations. In this work, we build upon previous efforts in segmented reinforcement variable stiffness composites employing shape memory polymers to create prototype hybrid composite materials that combine the benefits of cellular materials with those of discontinuous reinforcement composites. These composites help overcome two key challenges for shearing wing skins: the resistance to out of plane buckling from actuation induced shear deformation, and resistance to membrane deflections resulting from distributed aerodynamic pressure loading. We designed, fabricated, and tested composite materials intended for shear deformation and address out of plane deflections in variable area wing skins. Our designs are based on the kinematic engineering of reinforcement platelets such that desired microstructural kinematics is achieved through prescribed boundary conditions. We achieve this kinematic control by etching sheets of metallic reinforcement into regular patterns of platelets and connecting ligaments. This kinematic engineering allows optimization of materials properties for a known deformation pathway. We use mechanical analysis and full field photogrammetry to relate local scale kinematics and strains to global deformations for both axial tension loading and shear loading with a pinned-diamond type fixture. The Poisson ratio of the kinematically engineered composite is ~3x higher than prototypical orthotropic variable stiffness composites. This design allows us to create composite materials that have high stiffness in the cold state below SMP T_g (4-14GPa) and yet achieve large composite shear strains (5-20%) in the hot state (above SMP T_g).

Proceedings Article | 17 April 2007 Paper

Bill Armstrong memorial session: elastic modulus and strain recovery testing of variable stiffness composites for structural reconfiguration

Geoff McKnight, Robert Doty, Guillermo Herrera, Chris Henry

Proceedings Volume 6526, 652617 (2007) https://doi.org/10.1117/12.717287

KEYWORDS: Composites, Shape memory polymers, Polymers, Matrices, Polyurethane, Kinematics, Structural design, Glasses, Manufacturing, Prototyping

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Proceedings Article | 6 April 2006 Paper

Cellular variable stiffness materials for ultra-large reversible deformations in reconfigurable structures

C. Henry, G. McKnight

Proceedings Volume 6170, 617023 (2006) https://doi.org/10.1117/12.659633

KEYWORDS: Polymers, Finite element methods, Composites, Temperature metrology, Polonium, Carbon, Shape memory alloys, Structural engineering, Shape memory polymers, Magnetism

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Proceedings Article | 16 May 2005 Paper

Variable stiffness materials for reconfigurable surface applications

Geoff McKnight, Chris Henry

Proceedings Volume 5761, (2005) https://doi.org/10.1117/12.601495

KEYWORDS: Composites, Shape memory polymers, Prototyping, Structural design, Aluminum, Carbon, Kinematics, Data modeling, Chemical elements, Matrices

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Proceedings Article | 21 July 2004 Paper

High-energy absorption in bulk ferromagnetic shape memory alloys (Ni50Mn29Ga21)

Eric Gans, Chris Henry, Gregory Carman

Proceedings Volume 5387, (2004) https://doi.org/10.1117/12.540124

KEYWORDS: Nickel, Manganese, Gallium, Absorption, Magnetism, Crystals, Shape memory alloys, Gallium nitride, Composites, Ferromagnetics

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Proceedings Article | 13 August 2003 Open Access

Magnetic field-induced strain in single-crystal Ni-Mn-Ga

Robert O'Handley, Samuel Allen, David Paul, Christopher Henry, Miguel Marioni, David Bono, Catherine Jenkins, Afua Banful, Ryan Wagner

Proceedings Volume 5053, (2003) https://doi.org/10.1117/12.498549

KEYWORDS: Magnetism, Crystals, Motion models, Anisotropy, Magnetostrictive materials, Data modeling, Shape memory alloys, Technetium, Actuators, Ferromagnetics

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Proceedings Article | 13 August 2003 Paper

Frequency response of single-crystal Ni-Mn-Ga FSMAs

Christopher Henry, Pablo Tello, David Bono, Julee Hong, Ryan Wagner, Jessica Dai, Samuel Allen, Robert O'Handley

Proceedings Volume 5053, (2003) https://doi.org/10.1117/12.484343

KEYWORDS: Magnetism, Crystals, Shape memory alloys, Information operations, Dynamical systems, Sensors, Smart materials, Mechanics, Power supplies, Ferromagnetics

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Proceedings Article | 11 July 2002 Paper

AC magnetic-field-induced strain of single-crystal Ni-Mn-Ga

Christopher Henry, Jorge Feuchtwanger, David Bono, Robert O'Handley, Samuel Allen

Proceedings Volume 4699, (2002) https://doi.org/10.1117/12.474972

KEYWORDS: Magnetism, Nickel, Manganese, Gallium, Crystals, Shape memory alloys, Anisotropy, Sensors, Crystallography, Ferromagnetics

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Proceedings Article | 11 July 2002 Paper

Microscopic considerations for models of ferromagnetic shape memory actuation

Robert O'Handley, David Paul, Miguel Marioni, Christopher Henry, Marc Richard, Jorge Feuchtwanger, Pablo Tello, Samuel Allen

Proceedings Volume 4699, (2002) https://doi.org/10.1117/12.474981

KEYWORDS: Magnetism, Anisotropy, Crystals, Interfaces, Shape memory alloys, Thermodynamics, Motion models, Smart materials, Magnetostrictive materials, Ferromagnetics

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Proceedings Article | 11 July 2001 Paper

AC performance and modeling of ferromagnetic shape memory actuators

Christopher Henry, Jorge Feuchtwanger, David Bono, Miguel Marioni, Pablo Tello, Marc Richard, Samuel Allen, Robert O'Handley

Proceedings Volume 4333, (2001) https://doi.org/10.1117/12.432751

KEYWORDS: Magnetism, Anisotropy, Data modeling, Crystals, Thermodynamics, Motion models, Performance modeling, Actuators, Shape memory alloys, Ferromagnetics

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Showing 5 of 13 publications

Conference Committee Involvement (5)

Behavior and Mechanics of Multifunctional Materials and Composites V

7 March 2011 | San Diego, California, United States

Behavior and Mechanics of Multifunctional Materials and Composites IV

8 March 2010 | San Diego, California, United States

Behavior and Mechanics of Multifunctional Materials and Composites III

9 March 2009 | San Diego, California, United States

Behavior and Mechanics of Multifunctional and Composite Materials II

10 March 2008 | San Diego, California, United States

Behavior and Mechanics of Multifunctional and Composite Materials

19 March 2007 | San Diego, California, United States

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