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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

A rotating arm using shape-memory alloy

NASA's Mars Pathfinder mission, to be launched in 1996, reflects a new philosophy of exploiting new technologies to reduce mission cost and accelerate the pace of space exploration. One of the experiments on board Pathfinder will demonstrate the first use in space of a multi-cycle, electrically-activated, shape-memory alloy (SMA) actuator. SMA's are metal alloys which, when heated, undergo a crystalline phase change. This change in phase alters the alloy lattice-constant, resulting in a change of dimension. Upon cooling, the alloy returns to its original lattice formation. Wire drawn from an SMA contracts in length when heated. The reversible change in length is 3 percent to 5 percent. The wire used in this actuator is a nickel-titanium alloy known as nitinol.

Jenkins, Phillip P.↗
NASA NTRS1991

Shape-memory alloy micro-actuator

A method of producing an integral piece of thermo-sensitive material, which is responsive to a shift in temperature from below to above a phase transformation temperature range to alter the material's condition to a shape-memory condition and move from one position to another. The method is characterized by depositing a thin film of shape-memory material, such as Nickel titanium (Ni-Ti) onto a substrate by vacuum deposition process such that the alloy exhibits an amorphous non-crystalline structure. The coated substrate is then annealed in a vacuum or in the presence of an inert atmosphere at a selected temperature, time and cool down rate to produce an ordered, partially disordered or fully disordered BCC structure such that the alloy undergoes thermoelastic, martinsetic phase transformation in response to alteration in temperature to pass from a martinsetic phase when at a temperature below a phase transformation range and capable of a high level of recoverable strain to a parent austenitic phase in a memory shape when at a temperature above the phase transformation range. Also disclosed are actuator devices employing shape-memory material actuators that deform from a set shape toward an original shape when subjected to a critical temperature level after having been initially deformed from the original shape into the set shape while at a lower temperature. The actuators are mechanically coupled to one or more movable elements such that the temperature-induce deformation of the actuators exerts a force or generates a motion of the mechanical element(s).

Busch, John D.↗
NASA NTRS2004

A Shape-Memory Alloy Thermal Conduction Switch for Use at Cryogenic Temperatures

The following summarizes the activities performed under NASA grant NAG10-323 from September 1, 2002 through September 30, 2004 at the. Univ ersity of Central Florida. A version of this has already been submitt ed for publication in the international journal Swart Materials and S tructures in December 2004. Additionally, a version of this has alrea dy appeared in print in Advances in Cryogenic Engineering, American Institute of Physics, (2004) 50A 26-3; in an article entitled "A Shape Memory Alloy Based Cryogenic Thermal Conduction Switch" by V.B. Krish nan. J.D. Singh. T.R. Woodruff. W.U. Notardonato and R. Vaidyanathan (article is attached at the end of this report).

Vaidyanathan, Raj↗
NASA NTRS2008

Spray Forming of NiTi and NiTiPd Shape-Memory Alloys

In the work to be presented, vacuum plasma spray forming has been used as a process to deposit and consolidate prealloyed NiTi and NiTiPd powders into near net shape actuators. Testing showed that excellent shape memory behavior could be developed in the deposited materials and the investigation proved that VPS forming could be a means to directly form a wide range of shape memory alloy components. The results of DSC characterization and actual actuation test results will be presented demonstrating the behavior of a Nitinol 55 alloy and a higher transition temperature NiTiPd alloy in the form of torque tube actuators that could be used in aircraft and aerospace controls.

Mabe, James↗
NASA NTRS1996

Performance of a Smart Vibration Isolator for Precision Spacecraft Instruments

Under the ARPA SMS Partnership Program for Synthesis and Processing of Smart Materials, Lockheed Missiles and Space company, Inc. has developed a demonstration prototype vibration cancelling mount using electrostrictive ceramic and shape-memory alloy actuators. Shape-memory actuators provide an adaptive-passive, self-damping support for isolation, while the electrostrictive actuators are employed to provide force and position control. The demonstration device was designed to address generic requirements for vibration stabilization of precision spacecraft instruments. It is reconfigurable to operate in any of four modes; passive isolation, active-passive isolation using force cancellation, active precision positioning, and active disturbance rejection. The presentation summarizes design of the device design and results of experimental evaluations of the device in isolation (active and passive) and positioning modes. Rejection of payload-borne disturbances is also discussed with reference to predictions from experimentally calibrated simulations. Finally, avenues for further development and refinement of the device are discussed.

Regelbrugge, Marc E.↗
NASA NTRS1998

Remotely controllable actuating device

An actuating device can change a position of an active member that remains in substantially the same position in the absence of a force of a predetermined magnitude on the active member. The actuating device comprises a shape-memory alloy actuating member for exerting a force when actuated by changing the temperature thereof, which shape-memory alloy actuating member has a portion for connection to the active member for exerting thereon a force having a magnitude at least as large as the predetermined magnitude for moving the active member to a desired position. Actuation circuitry is provided for actuating the shape-memory alloy actuating member by changing the temperature thereof only for the time necessary to move the active member to the desired position. The invention is particularly useful for changing the position of a camber-adjusting tab on a helicopter rotor blade by using two shape-memory alloy members that can act against each other to adjust dynamic properties of the rotor blade as it is rotating.

McKillip, Jr., Robert M.↗
NASA NTRS1993

Shape-Memory-Alloy Release Mechanism

Release-nut mechanism activated by electric current applied to shape-memory alloy. Separates attached objects quickly by remote control. Does not create hazard or cause damage. Shape-memory release-nut mechanism unaffected by moisture or vacuum. Requires sustained current lasting 5 seconds or longer, and insensitive to electromagnetic interference. Mechanism can be reused.

Mckinnis, Darin↗
NASA NTRS1995

Shape-Memory-Alloy Actuator For Flight Controls

Report proposes use of shape-memory-alloy actuators, instead of hydraulic actuators, for aerodynamic flight-control surfaces. Actuator made of shape-memory alloy converts thermal energy into mechanical work by changing shape as it makes transitions between martensitic and austenitic crystalline phase states of alloy. Because both hot exhaust gases and cryogenic propellant liquids available aboard launch rockets, shape-memory-alloy actuators exceptionally suited for use aboard such rockets.

Barret, Chris↗
NASA NTRS2000

Flight Control Using Distributed Shape-Change Effector Arrays

Recent discoveries in material science and fluidics have been used to create a variety of novel effector devices that offer great potential to enable new approaches to aerospace vehicle flight control. Examples include small inflatable blisters, shape-memory alloy diaphragms, and piezoelectric patches that may be used to produce distortions or bumps on the surface of an airfoil to generate control moments. Small jets have also been used to produce a virtual shape-change through fluidic means by creating a recirculation bubble on the surface of an airfoil. An advanced aerospace vehicle might use distributed arrays of hundreds of such devices to generate moments for stabilization and maneuver control, either augmenting or replacing conventional ailerons, flaps or rudders. This research demonstrates the design and use of shape-change device arrays for a tailless aircraft in a low-rate maneuvering application. A methodology for assessing the control authority of the device arrays is described, and a suite of arrays is used in a dynamic simulation to illustrate allocation and deployment methodologies. Although the authority of the preliminary shape-change array designs studied in this paper appeared quite low, the simulation results indicate that the effector suite possessed sufficient authority to stabilize and maneuver the vehicle in mild turbulence.

Raney, David L.↗
NASA NTRS2003

Energetics of Single Substitutional Impurities in NiTi

Shape-memory alloys are of considerable current interest, with applications ranging from stents to Mars rover components. In this work, we present results on the energetics of single substitutional impurities in B2 NiTi. Specifically, energies of Pd, Pt, Zr and Hf impurities at both Ni and Ti sites are computed. All energies are computed using the CASTEP ab initio code, and, for comparison, using the quantum approximate energy method of Bozzolo, Ferrante and Smith. Atomistic relaxation in the vicinity of the impurities is investigated via quantum approximate Monte Carlo simulation, and in cases where the relaxation is found to be important, the resulting relaxations are applied to the ab initio calculations. We compare our results with available experimental work.

Good, Brian S.↗
NASA NTRS2003

Rollable Thin-Shell Nanolaminate Mirrors

A class of lightweight, deployable, thin-shell, curved mirrors with built-in precise-shape-control actuators is being developed for high-resolution scientific imaging. This technology incorporates a combination of advanced design concepts in actuation and membrane optics that, heretofore, have been considered as separate innovations. These mirrors are conceived to be stowed compactly in a launch shroud and transported aboard spacecraft, then deployed in outer space to required precise shapes at much larger dimensions (diameters of the order of meters or tens of meters). A typical shell rollable mirror structure would include: (1) a flexible single- or multiple-layer face sheet that would include an integrated reflective surface layer that would constitute the mirror; (2) structural supports in the form of stiffeners made of a shape-memory alloy (SMA); and (3) piezoelectric actuators. The actuators, together with an electronic control subsystem, would implement a concept of hierarchical distributed control, in which (1) the SMA actuators would be used for global shape control and would generate the large deformations needed for the deployment process and (2) the piezoelectric actuators would generate smaller deformations and would be used primarily to effect fine local control of the shape of the mirror.

Hickey, Gregory↗
NASA NTRS1992

Shape-Memory Wires Switch Rotary Actuator

Thermomechanical rotary actuator based on shape-memory property of alloy composed of equal parts of titanium and nickel. If alloy stretched while below transition temperature, it reverts to original length when heated above transition temperature. Two capstans on same shaft wrapped with shape-memory wires. As one wire heated, it contracts and stretches opposite wire. Wires heated in alternation so they switch shaft between two extreme angular positions; "on" and "off" positions of rotary valve.

Brudnicki, Myron J.↗
NASA NTRS1972

Transformation temperatures of martensite in beta phase nickel aluminide

Resistivity and thermal arrest measurements determined that the compositional dependence of Ms (martensite state) temperatures for NiAl martensite was linear between 60 and 69 atomic percent nickel, with Ms = 124 Ni - 7410 K. Resistivity and surface relief experiments indicated the presence of thermoelastic martensite for selected alloys. Some aspects of the transformation were studied by hot stage microscopy and related to the behavior observed for alloys exhibiting the shape-memory effect.

Smialek, J. L.↗
NASA NTRS1973

Transformation temperatures of martensite in beta-phase nickel aluminide.

Resistivity and thermal arrest measurements determined that the compositional dependence of M sub s temperatures for NiAl martensite was linear between 60 and 69 at. % Ni, with M sub s = (124 Ni - 7410)K. Resistivity and surface relief experiments for selected alloys indicated the presence of thermoelastic martensite. Some aspects of the transformation were studied by hot-stage microscopy and related to the behavior observed for alloys exhibiting the shape-memory effect.

Smialek, J. L.↗
NASA NTRS1992

Thermally Activated Retainers For Insertion In Gaps

Mechanical retainers of new type for use with gap filler easy to install and to attach themselves securely. Concept based on shape-memory properties of metal alloy Nitinol, alloy of nickel and titanium. Retainers conceived for use with Space Shuttle insulating tiles but used on other assemblies of blocks or tiles configured similarly. Tabs bent outward made flush by cooling below memory transition temperature. After insertion in gap and reheating, tabs spring outward.

Grimaldi, Margaret E.↗
NASA NTRS1990

Shape-memory properties in Ni-Ti sputter-deposited film

A Ni-Ti alloy, generically called nitinol, was prepared from sputtering targets of two different compositions on glass substrates using a dc magnetron source. The as-deposited films were amorphous in structure and did not exhibit a shape memory. The amorphous films were crystallized with a suitable annealing process, and the transformation properties were measured using differential scanning calorimetry. The annealed films demonstrated a strong shape-memory effect. Stress/strain measurements and physical manipulation were used to evaluate the shape recovery. These tests demonstrated sustained tensile stresses of up to 480 MPa in the high-temperature phase, and a characteristic plastic deformation in the low-temperature phase.

Busch, J. D.↗
NASA NTRS1992

Simple, Lightweight, Thermomechanical Coupling

Self-actuating thermal coupling device is light, and transfers heat efficiently. Coupling is thermostatic, making contact as necessary to maintain nearly steady temperature at hot side of interface. Hot pins on hot plate poised near cold pins on cold-plate. As temperature of hot plate rises, shape-memory wire contracts, drawing hot pin against cold pin. When temperature falls below critical level, wire expands, allowing hot pin to pull away. Critical temperature determined by composition of alloy.

Milam, M. Bruce↗