Mrs. Nancy L. Johnson Profile

Mrs. Nancy L. Johnson

Lab Group Manager at General Motors Research & Development

SPIE Involvement:

Conference Program Committee | Conference Co-Chair | Author

Publications (17)

PROCEEDINGS ARTICLE | April 16, 2014

Damper-controlled switch for SMA motion smoothing

Proc. SPIE. 9059, Industrial and Commercial Applications of Smart Structures Technologies 2014

KEYWORDS: Shape memory alloys, Actuators, Switches, Switching, Prototyping, Control systems, Power supplies, Data acquisition, Computer programming, Standards development

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While the use of SMA-actuated devices continues to grow in many industries, current device limitations pose a challenge to successful adoption for certain classes of applications. SMA-actuated devices typically demonstrate motion with non-constant velocity due to the non-linear thermo-mechanically coupled behavior of SMA material transformation, and motion sensitivity to external factors such as voltage and load. This variation in motion can lead to the perception of poor device quality, limiting SMA-actuated devices to applications hidden from the sight of the product user, or requiring them to be augmented with higher cost controls to improve the motion quality. Therefore, a need exists for simple, passive, low-cost device technologies that enable the designer to prescribe desired motion characteristics with relative insensitivity to fluctuation in operating conditions. This paper presents a Damper Controlled Switch (DCS) mechanism that delivers constant velocity and relative insensitivity to operating conditions when combined with a standard SMA wire actuator. The DCS includes a damper that acts against a spring to open a switch when the velocity exceeds a tunable threshold. To validate the ability of the DCS to provide the desired motion quality, experiments were conducted comparing the normal motion of the SMA actuator to the motion produced when the same actuator was fitted with a DCS prototype. The addition of the DCS produced nearly constant actuator velocity, performing significantly better than the SMA actuator alone. The tunability of the DCS was demonstrated producing a wide range of attainable constant velocities. Finally, a set of experiments explored the DCS’s sensitivity to voltage and load, indicating a low sensitivity to a wide range of operating parameters for which the operating limits were identified. The DCS represents a simple, compact technology based on passive, low-cost components, providing a very practical solution that will enable integration of SMA-actuated devices into a broader class of applications.

PROCEEDINGS ARTICLE | March 29, 2013

SMA actuated vertical deploy air dam: part 2 operation and test performance of prototype unit

Proc. SPIE. 8690, Industrial and Commercial Applications of Smart Structures Technologies 2013

KEYWORDS: Shape memory alloys, Prototyping, Control systems, Actuators, Finite element methods, Roads, Resistance, Temperature metrology, Photography, Packaging

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PROCEEDINGS ARTICLE | March 30, 2012

Lightweight thermal energy recovery system based on shape memory alloys: a DOE ARPA-E initiative

Proc. SPIE. 8343, Industrial and Commercial Applications of Smart Structures Technologies 2012

KEYWORDS: Shape memory alloys, Thermoelectric materials, Thermal efficiency, Energy efficiency, Prototyping, Combustion, Liquids, Neodymium, Thermodynamics, Standards development

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PROCEEDINGS ARTICLE | April 28, 2011

Active materials for automotive adaptive forward lighting Part 1: system requirements vs. material properties

Proc. SPIE. 7979, Industrial and Commercial Applications of Smart Structures Technologies 2011

KEYWORDS: Actuators, Shape memory alloys, Atrial fibrillation, Reflectors, Light sources and illumination, Headlamps, Ultrasonics, Lamps, Roads, Solid state electronics

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PROCEEDINGS ARTICLE | March 29, 2010

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

Proc. SPIE. 7645, Industrial and Commercial Applications of Smart Structures Technologies 2010

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

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PROCEEDINGS ARTICLE | April 1, 2009

SMA wire actuator modular design framework

Proc. SPIE. 7290, Industrial and Commercial Applications of Smart Structures Technologies 2009

KEYWORDS: Shape memory alloys, Actuators, Computer architecture, Interfaces, Systems modeling, Human-machine interfaces, Optimization (mathematics), Data modeling, Manufacturing, Performance modeling

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PROCEEDINGS ARTICLE | April 1, 2009

A reversibly deployable air dam: a bending approach based on embedded shape memory alloy actuators, Part II: technology demonstration

Proc. SPIE. 7290, Industrial and Commercial Applications of Smart Structures Technologies 2009

KEYWORDS: Shape memory alloys, Actuators, Ferroelectric materials, Control systems, Electromagnetism, Electronics, Electronic test equipment, Polymers, Photography, Roads

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PROCEEDINGS ARTICLE | March 28, 2009

Effect of bending on the performance of spool-packaged shape memory alloy actuators

Proc. SPIE. 7290, Industrial and Commercial Applications of Smart Structures Technologies 2009

KEYWORDS: Shape memory alloys, Actuators, Motion models, Data modeling, Nano opto mechanical systems, Packaging, Performance modeling, Motion measurement, Motion analysis, Analytical research

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PROCEEDINGS ARTICLE | April 1, 2008

Behavioral model and experimental validation for a spool-packaged shape memory alloy actuator