Abstract: A thrust propeller variable pitch actuator is controlled by a governor that uses propeller pitch as a variable to increase or decrease torque—not to maintain the propeller speed or RPM but instead to maintain certain established electric current supplied to rotate the thrust propeller.

Abstract: A thermobimetal heat driven turbine having a rotor, and a series of vanes extending from the rotor wherein the vanes comprise two or more separate materials laminated together, said two separate materials having different coefficients of expansion whereby exposure to a heat source causes the two separate materials to expand at different rates thereby re-shaping the vanes to drive the rotor. The rotating turbine is thus able to generate power using direct heat from an energy source. The heat source may be radiant, convection and/or conduction type heat.

Abstract: A spring for a spring shoe, the spring including a conical disk, the conical disk having a flexible flange around the perimeter of the conical disk. A spring comprising a conical disk and a ring spring around the conical disk, the ring spring being movable up and down relative to the conical disk to adjust the spring force of the spring. A threaded engagement between the ring spring and the conical disk so that rotation of the conical disk moves the ring spring up or down relative to the conical disk. A damper ring around the perimeter of the conical disk to resist the expansion of the circumference of the conical disk. An eccentric ring or cam to adjust the position of the apex of the conical disk relative to an insole by rotating the eccentric ring or cam. An asymmetric conical disk to adjust the position of the apex of the conical disk by rotating the conical disk. A damper for a spring shoe comprising a flexible container containing a material with little or no propensity to return to its original shape.

Abstract: A closed cycle regenerative heat engine has a housing (12) defining a chamber (14). A displacer (18) is housed in the chamber. A shaft (24) is connected with the displacer and extends from the chamber. A power piston (30) is housed in the chamber. The displacer (18) is secured to the housing (12) and is resiliently deformable from a rest condition in response to movement of the shaft (24) to displace the working fluid in the chamber. The displacer may be a multi-start volute spring. The displacer (18) may be provided with a heat storage reservoir to store heat received from a working fluid as the working fluid is displaced from a heating location in the chamber (14) to a cooling location in the chamber and reject heat to the working fluid when the working fluid is displaced from the cooling location to the heating location.

Abstract: A rotary engine that generates electricity using differences in relative humidity. A water-responsive material expands and contracts as water evaporates which drives the rotation of two wheels. The rotary motion drives an electrical generator which produces electricity. In another embodiment, the water-responsive material is used to actuate an artificial muscle of a robotic device.

Abstract: A heat sensitive actuator uses a shape memory material layer which is thermally stimulated to change shape, in response to a rise in temperature, from a first shape at a first temperature to a second shape at a second temperature. A layer stack is associated with the shape memory material layer, and it can adopt the first shape at the first temperature. In this way, the layer stack is used to return the shape memory material to its original shape after cooling.

Abstract: A thermal energy harvesting device includes a rotatable shaft and a shape memory alloy element secured to rotatable shaft. The shape memory alloy element is adapted to undergo a shape memory effect upon reaching a transition temperature, which causes rotation of the rotatable shaft. The rotatable shaft may be operatively connected to a generator or tachometer to convert the rotation of the shaft into electrical energy, which may then be stored in a rechargeable battery. In certain embodiments a gear box may be provided to increase the speed of rotation, and thereby increase the amount of electrical energy created.

Abstract: The invention relates to a solar-powered apparatus, comprising a housing (1), a shield panel (5) disposed on the housing (1), and a transmission apparatus (2) disposed inside the housing (1). The transmission apparatus (2) is provided with eight or more memory alloy sheets (3). The housing (1) is also provided with a ratchet pawl (13). The shield panel (5) is provided with a light-focusing apparatus (51) used for focusing light. The apparatus is capable of converting solar energy into mechanical energy.

Abstract: A deformable component which is initially flat and which can be caused to buckle by the application of a radially inward preload force, applied using an outer clamp. The deformable component in the buckled configuration then exhibits negative stiffness over a portion of its range of travel, when an axial force is applied. The deformable component may be fabricated from metal sheet, and may take the form of a polygonal central portion and at least two arms extending radially outwards.

Abstract: A hydraulic valve for a vehicle transmission includes a housing, a valve piston, an actuating piston, and a bi-stable spring. The housing is connectable with an inlet passage and an outlet passage for the transmission. The valve piston is sealed to the housing and selectively blocks a fluid flow between the inlet passage and the outlet passage. The actuating piston is sealed to the housing and is arranged to be displaceable by a hydraulic pressure in the inlet passage. The bi-stable spring is engaged with the valve piston and the actuating piston. In some example embodiments, the bi-stable spring is axially fixed with regards to the valve piston and displaceable by the actuating piston.

Abstract: Shape memory alloy (SMA) actuating elements are commonly simpler and of lower mass than alternative actuator designs and may find particular application in the transportation industry. Such SMA-powered devices are usually reliable and long-lived but the phase transformations which occur in the SMA alloy and are responsible for its utility are not totally reversible. This irreversibility, a consequence of irrecoverable strain, may progressively degrade the long-term actuator performance as the irrecoverable strain accumulates over many operating cycles. Methods and devices for compensating for these effects and extending the useful cycle life of SMA actuators are described.

Abstract: Disclosed is a thermal actuator that utilizes the dimensional change of a phase change media hermetically sealed within a shell. This thermal actuator may be utilized in a variety of environments where electric thermostatic actuators are impossible or impractical.

Abstract: An actuator using a superelastic material characterized by a low heating temperature, excellent durability, and no necessity of composition adjustment is provided. An actuator (1) according to the invention includes a movable member operable in two directions, one direction and the other direction, and a pair of wire-like members made of a superelastic alloy and so attached to the movable member that the pair of wire-like members extend in the two respective directions and the same tensile force is applied thereto. The movable member is moved from a neutral position and left stationary in a predetermined position located along the one direction by applying a load to the movable member in the one direction and then removing the load, and the movable member is moved back from the predetermined position located along the one direction to the neutral position by applying a load to the movable member in the other direction and then removing the load.

Abstract: An energy harvesting system for converting thermal energy to mechanical energy includes a heat engine that operates using a shape memory alloy active material. The shape memory alloy member may be in thermal communication with a hot region at a first temperature and a cold region at a second temperature lower than the first temperature. The shape memory alloy material may be configured to selectively change crystallographic phase between martensite to austenite and thereby one of contract and expand in response to the first and second temperatures. A thermal conduction element may be in direct contact with the SMA material, where the thermal conduction element is configured to receive thermal energy from the hot region and to transfer a portion of the received thermal energy to the SMA material through conduction.

Abstract: The invention relates to a device for converting heat energy into mechanical energy comprising a first (4) and a second (6) bistable area passing from a first stable state to a second stable state by means of a thermal effect or mechanical action, said areas (4, 6) being mechanically coupled such that the passage from one state to the other of one area (4, 6) by means of a thermal effect causes the other area (6,4) to pass from one state to the other, each area (4, 6) having a blistering temperature and an unblistering temperature, the blistering temperature being higher than the unblistering temperature. Said device is intended to be placed in contact with an environment (SC) having at least one given temperature, such that the temperature of the environment (SC) is lower than the blistering temperature of the first area (4) and is higher than the blistering temperature (Tc6) of the second area (6).

Abstract: A heat-driven engine includes a thermally conductive path into the engine, from a heat source and a working medium of a thermostrictive material, having a first temperature of transformation, positioned adjacent to the thermally conductive path. Also, a heat pump of phase change material is positioned adjacent to the working medium and an actuator is controlled to apply stimulus to the heat pump, causing a phase change and an associated release of thermal energy, to drive the working medium above its low-to-high temperature of transformation and controlled to alternatingly remove the stimulus from the heat pump, causing the phase change to reverse, and an associated intake of thermal energy, to drive the working medium below its high-to-low temperature of transformation. Also, heat flow through the thermally conductive path maintains the working medium at a temperature range permitting the heat pump to drive the working medium temperature, in the manner noted.

Abstract: A temperature-driven mechanical system includes a first effector, made of temperature-induced shape-changing material, having first and second ends and a longitudinal axis running through the ends, as well as a suspension system that mounts an assembly including the effector, to support rotation of the assembly about the longitudinal axis. The suspension system has a first rotational limit stop associated with a first angular position of the assembly at or below a first temperature limit and a second limit stop associated with a second angular position of the assembly at or above a second temperature limit. An array of such systems is similarly provided.

Abstract: A method of reducing an initial stress on a cable includes stretching the cable to a first length to thereby define the initial stress. The cable has a central longitudinal axis, and includes a plurality of wires each twisted around the axis and formed from a shape memory alloy transitionable in response to a signal between a first state wherein each of the wires has a first temperature-dependent length, and a second state wherein each of the wires has a second temperature-dependent length that is less than the first. After stretching, the method includes activating the alloy by exposing the alloy to the signal such that the alloy transitions from the first to the second temperature-dependent state. Concurrent to activating, the method includes elongating the cable to a second length that is greater than the first to define a second stress on the cable that is less than the first.

Abstract: A heat engine includes a first rotatable pulley and a second rotatable pulley spaced from the first rotatable pulley. A shape memory alloy (SMA) element is disposed about respective portions of the pulleys at an SMA pulley ratio. The SMA element includes a first wire, a second wire, and a matrix joining the first wire and the second wire. The first wire and the second wire are in contact with the pulleys, but the matrix is not in contact with the pulleys. A timing cable is disposed about respective portions of the pulleys at a timing pulley ratio, which is different than the SMA pulley ratio. The SMA element converts a thermal energy gradient between the hot region and the cold region into mechanical energy.

Abstract: This disclosure describes an apparatus having a valve and an elongated shape memory alloy element. The valve has a lever in a first position, whereby the valve is closed. The elongated shape memory alloy element has a first end connected to the lever. The shape memory alloy element has been strained to have a first length, wherein exposure of at least a portion of the shape memory alloy element to a temperature at or exceeding its austenite transformation temperature causes the shape memory alloy element to shorten to a second length, the second length being less than the first length, thereby causing the first end of the shape memory alloy element to pull the lever to a second position, whereby the valve is opened.

Abstract: An energy harvesting system comprises a first region and a second region having a temperature difference therebetween. A heat engine is configured for converting thermal energy to mechanical energy. The heat engine includes a first discrete element of a shape memory alloy having a crystallographic phase changeable between austenite and martensite in response to the temperature difference between the first region and the second region. The first discrete element of the shape memory alloy expands and contracts in response to the phase change to exert a linear force. A motion conversion mechanism is operatively connected to the first discrete element to be driven by the linear force and a component is driven by the motion conversion mechanism.

Abstract: A shape memory alloy (SMA) heat engine includes a first rotatable pulley, a second rotatable pulley, and an SMA material disposed about the first and second rotatable pulleys and between a hot region and a cold region. A method of starting and operating the SMA heat engine includes detecting a thermal energy gradient between the hot region and the cold region using a controller, decoupling an electrical generator from one of the first and second rotatable pulleys, monitoring a speed of the SMA material about the first and second rotatable pulleys, and re-engaging the driven component if the monitored speed of the SMA material exceeds a threshold. The SMA material may selectively change crystallographic phase between martensite and austenite and between the hot region and the cold region to convert the thermal gradient into mechanical energy.

Abstract: Provided is a heat storage device which can stably store heat by storing heat within a fixed temperature range. A heat storage device (10) of the present invention is characterized in being provided with a heat resistant frame (11), which is filled with one kind of alloy or mixed salt having a predetermined eutectic temperature, alternatively, a heat resistant frame (11), which is filled with two or more kinds of alloys or mixed salts having different eutectic temperatures, by having the alloys or the mixed salts adjacent to each other in the order of eutectic temperature levels with a partitioning wall (11a) therebetween.

Abstract: An energy harvesting system includes a heat engine and a component configured to be driven by operation of the heat engine. The heat engine includes a first member, a second member, a shape memory alloy material, and a tensioner. The second member is spaced from the first member. The shape memory alloy material operatively interconnects the first member and the second member. The shape memory alloy material is configured to selectively change crystallographic phase from martensite to austenite and thereby contract in response to exposure to a first temperature. The shape memory alloy material is also configured to selectively change crystallographic phase from austenite to martensite and thereby expand in response to exposure to a second temperature. The tensioner is configured to apply tension to the shape memory alloy material as the shape memory alloy material selectively expands and contracts such that the shape memory alloy material is taut.

Abstract: A shape memory stored energy assembly includes a projectile housing having a projectile lumen. A projectile is within the projectile lumen and the projectile is movable relative to the projectile housing. A shape memory actuator is coupled between the projectile anchored end and the projectile housing. The shape memory actuator is configured to transition from a strained energy stored configuration to a fractured kinetic delivery configuration at a specified temperature range to propel the projectile through the projectile lumen. A method includes storing energy in a shape memory actuator coupled with a projectile. The stored energy in the shape memory actuator is released and propels the projectile. Releasing the stored energy includes heating the shape memory actuator, tensioning the shape memory actuator, and fracturing the tensioned shape memory actuator at a fracture locus to propel the projectile away from the fracture locus.

Abstract: A position control device 1 and a position control method of the present invention are a technology used in a shape memory alloy actuator for moving a movable member using a shape memory alloy member. In controlling the position of the movable member, an instruction value indicating a position of the movable member as a control target is changed to reduce the temperature of a shape memory alloy member when an amount of power supplied to the shape memory alloy member is in excess of a predetermined first threshold value. A drive device and an imaging device C of the present invention include a shape memory alloy actuator and the position control device 1.

Abstract: A microactuator for displacing a platform vertically with respect to a substrate includes a first rigid frame, a first flexible bimorph beam connecting the first frame to the substrate, a second rigid frame, a second flexible bimorph beam connecting the second frame to the first frame, and a third flexible bimorph beam connecting a platform to the second frame. Activation of the first, second, and third flexible bimorph beams allows vertical displacement of the platform with respect to the substrate, with negligible lateral shift. A microactuator assembly includes a substrate, a plurality of first rigid frames, a plurality of first flexible bimorph beams, a plurality of second rigid frames, a plurality of second flexible bimorph beams, a platform, and a plurality of third flexible bimorph beams. Activation of the first, second, and third bimorph beams allows vertical displacement of the platform with respect to the substrate, with negligible lateral shift.

Abstract: A cooling system configured for converting thermal energy to mechanical energy includes a source of thermal energy provided by a temperature difference between a heat source having a first temperature and a coolant having a second temperature that is lower than the first temperature. The cooling system includes a cooling circuit configured for conveying the coolant to and from the heat source. The cooling circuit includes a conduit and a pump in fluid communication with the conduit and configured for delivering the coolant to the heat source. The cooling system also includes a heat engine disposed in thermal relationship with the conduit and configured for converting thermal to mechanical energy. The heat engine includes a first element formed from a first shape memory alloy having a crystallographic phase changeable between austenite and martensite at a first transformation temperature in response to the temperature difference between the heat source and coolant.

Abstract: An exhaust system configured for converting thermal energy to mechanical energy includes a source of thermal energy provided by a temperature difference between an exhaust gas having a first temperature and a heat sink having a second temperature that is lower than the first temperature. The exhaust system also includes a conduit configured for conveying the exhaust gas, a heat engine disposed in thermal relationship with the conduit and configured for converting thermal energy to mechanical energy, and a member disposed in contact with the conduit and configured for conducting thermal energy from the conduit to the heat engine. The heat engine includes a first element formed from a first shape memory alloy having a crystallographic phase changeable between austenite and martensite at a first transformation temperature in response to the temperature difference between the exhaust gas and the heat sink.

Abstract: An electro-thermal actuator device includes a case defining a cavity in which are housed a thermal actuator, an electrical heater and, at least partially, an actuating shaft. The device comprises a multipolar connector for the rapid, secure and reliable coupling to a respective source of electrical power supply for the heater. The connector can be configured as an adapter unit distinct from the case, suitable to transform a traditional electro-thermal actuator device into the actuator device described above.

Abstract: A device and method for controlling a phase transformation temperature of a shape memory alloy is provided. The device includes a primary wire composed of the shape memory alloy. The primary wire defines first and second ends, the first end being attached to a fixed structure and the second end being able to displace. An activation source is thermally coupled to the wire and is operable to selectively cause the primary wire to reversibly transform from a Martensitic phase to an Austenitic phase during a cycle. A loading element is operatively connected to the primary wire and configured to selectively increase a tensile load on the primary wire when an ambient temperature is at or above a threshold temperature, thereby increasing the phase transformation temperature of the primary wire.

Abstract: A thermally-activated material assembly transformable between an actuated condition and a non-actuated condition including an actuator material that, in response to being heated and cooled above/below an actuation temperature, causes the actuator element to actuate from a non-actuated shape to an actuated shape, and vice versa, respectively. The assembly also includes a drive mechanism connected to the actuator element and a phase-change material (PCM) associated with the drive mechanism. The drive mechanism causes the PCM to either (i) directly engage the actuator element when the actuator assembly is in the non-actuated condition and to be disengaged from the actuator element when the actuator assembly is in the actuated condition or (ii) directly engage the actuator element when the actuator assembly is in the actuated condition and to be disengaged from the actuator element when the actuator assembly is in the non-actuated condition.

Abstract: A method of cooling a first region that is above the transition temperature of a phase change material having a cold phase and a warm phase and that is proximal to a second region into which heat may be exhausted. The method utilizes an article of the phase change material, and starting in the cold phase, places the article into thermal contact with the first region, thereby causing the phase change material to undergo a phase transition, changing size. When the phase transition is substantially complete, the article is taken out of thermal contact with the first region and is placed into thermal contact with the second region. At this point, force is applied to the article, causing it to transition to the cold phase, thereby exhausting heat into the second region. The process is begun again, by placing the article, once again, into thermal contact with the first region.

Abstract: A shape memory alloy (SMA) actuator includes an SMA element and a flexible outer coating or layer. The element is respectively activated by a heating source. The layer surrounds the element, and enhances the heat transfer characteristics of the element to increase the speed of the actuation cycle. The nominal geometry and/or thermal conductivity may be altered during an activation phase, and may include discrete elements oriented with respect to the element, and partially embedded in the layer. An end gripper assembly may be used to cause the layer to move in concert with the element during a phase transformation. An electro-mechanical system includes the cooling source and the actuator. A method includes connecting the actuator to a load, activating the element using the heating source, and deactivating the element using a cooling source or free/ambient air.

Abstract: Actuation assemblies for and methods of activating a thermally actuated active material actuator utilizing wireless transmissions of energy.

Abstract: An apparatus for and method of displacing a body, such as a projectile, piston, or the distal edge of a sunshade cover or energy absorbing honeycomb matrix, utilizing momentum generated by the rapid actuation of an active material element, such as a Martensitic shape memory alloy wire.

Abstract: A self-aligning memory alloy wire actuator has a memory alloy wire having first and second ends with at least one terminal coupled to one end of the memory alloy wire. The terminal includes two wings and an extended piece connected in the shape of a T. The two wings are disposed on opposite sides of the extended piece and perpendicular to the extended piece. Each wing comprises top and bottom surfaces, a front surface, and an outside end. The top surfaces of the two wings lie on a common top plane and the front surfaces of the two wings lie on a common front plane. The memory alloy wire is coupled to the extended piece of the terminal.

Abstract: An actuator comprising an SMA element and a thermally responsive element that adjusts bias stress improves high ambient temperature operation.

Abstract: An actuating apparatus which may be arranged to provide an actuating rotation or force on demand. The actuating apparatus comprises a resilient member having a plurality of co-acting elements such as a plurality of elongate rods and end-mounts arranged to move relative to each other. The resilient member is arrangeable in a first configuration and a second configuration such as a twisted configuration. An actuator which is preferably elongate is secured to the resilient member at least two points, preferably to each of the end mounts of the resilient member. The actuator is arranged to force the resilient member into one of or between the two configurations. The resilient member preferably includes a matrix which preferably surrounds at least a portion of the elongate rods.

Abstract: An actuator includes a thermally activated active material element, such as at least one shape memory alloy wire, and a heat sink configured to operatively engage the element and accelerate cooling after activation, so as to improve bandwidth.

Abstract: An energy harvesting system includes a heat engine and a component. The heat engine includes first and second regions, a conduit, and a shape memory alloy (SMA) material. The conduit extends along a central axis. The SMA material surrounds the conduit and is disposed in one of the regions. The SMA material is radially spaced from a secondary axis that surrounds the central axis. A localized region of the SMA material changes crystallographic phase from martensite to austenite and contract in response to exposure to the first temperature. The localized region of the SMA material also changes crystallographic phase from austenite to martensite and expands in response to exposure to the second temperature. The SMA material rotates about the secondary axis in response to the contraction and expansion of the localized region of the SMA material. Rotation of the SMA material about the secondary axis drives the component.

Abstract: A heat-driven engine includes a thermally conductive input path, from a heat source and a working medium of a thermostrictive material positioned adjacent to the thermally conductive path. Also, a heat pump of phase change material is positioned adjacent to the working medium and an actuator is controlled to apply stimulus to the heat pump, causing a phase change and an associated release of thermal energy, to drive the working medium above its low-to-high temperature of transformation and controlled to alternatingly remove the stimulus from the heat pump, causing the phase change to reverse, and an associated intake of thermal energy, to drive the working medium below its high-to-low temperature of transformation. Also, heat flow through the thermally conductive path maintains the working medium at a temperature range permitting the heat pump to drive the working medium temperature, in the manner noted.

Abstract: A shape memory alloy drive device has drive control portion for displacing a shape memory alloy up to a target displacement value by applying a voltage or an electric current to the shape memory alloy by servo control, and also has contact detection portion for detecting a predetermined change in a drive control value, or, for example, a sharp increase in the drive control value, representing the amount of the voltage of the electric current applied by the drive control portion. When detecting a predetermined change, the contact detection portion determines that a movable portion having a lens etc. mounted thereon is in contact with a stationary mechanism. The shape memory alloy drive device further has drive limiting portion which, when the determination described above is made, causes the drive control portion to limit the target displacement value within a predetermined range.

Abstract: A memory alloy spring engine includes a spring (1) made from a memory alloy, a driving stem (6) and a heat resource. The memory spring (1) is connected to the driving stem (6) and configured to move the driving stem (6) when being compressed and deformed by an external force, to restore to an original shape after being compressed and then heated, and to move the driving stem (6) again after being cooled and then compressed and deformed again so as to move the driving stem (6) up and down along therewith in continuous repeating cycles. The memory spring is equipped with a polyhedral glass ball (3), the polyhedral glass ball (3) is configured to collect sunlight from different angles and to conduct solar heat to the memory spring (1) so that the memory spring is heated and thereby restored to the original shape. The engine may utilize natural heat energy (solar energy or geo-heat) and combustible fuel alone or in combination to generate electricity according to different locations or different times.

Abstract: An actuator is described in which a functional element is made of a shape memory alloy, and the actuator includes means for increasing the load applied onto the functional element when the external temperature increases, thus causing a consequent variation of transition temperatures characterizing the hysteresis cycle of the functional element.

Abstract: A storing section (70) stores a second initial contact instruction value, which is predefined as an instruction value for positioning a movable portion (5) to a second contact position where the movable portion (5) is contacted with a stopper (8), and an initial standby instruction value, which is predefined as an instruction value for positioning the movable portion (5) to a specified standby position within a moving range of the movable portion (5). A correcting section (42) calculates an actual standby instruction value by correcting the initial standby instruction value, based on a second actual contact instruction value obtained when a contact detection section (41) has detected that the movable portion (5) is positioned to the second contact position, and the second initial contact instruction value. A setting section (43) sets a standby position corresponding to the actual standby instruction value, as an actual standby position of the movable portion (5).

Abstract: Embodiments of separating apparatuses are generally described herein. Other embodiments may be described and claimed. In an embodiment, a separating apparatus is provided that comprises a pre-strained member formed from a shape memory alloy that is configured to separate upon application of heat.

Abstract: A curved multimorph actuator is provided composed of a plurality of materials, each material exhibiting different deformations in response to a stimulus, such as heat. Application of different stimuli causes the actuator to bend and/or twist. In an embodiment, the actuator is capable of rotating an object about its center without significantly shifting the center in one or more dimensions. In a further embodiment, the actuator can be used to rotate an object about a first axis and a second axis, wherein the first axis and the second axis are mutually perpendicular. In an embodiment, rotation about the first axis and the second axis are achieved in combination. In another embodiment, rotation about the first axis is produced in response to a first stimulus and rotation about the second axis is produced in response to a second stimulus.

Abstract: An actuator includes a capturing part, a retained part and a heating element which applies heat to the retained part or the capturing part responsive to selective application of power to the at least one heating element. The capturing part attaches to a first object and has a first coefficient of thermal expansion. The retained part attaches to a second object and has a second coefficient of thermal expansion. The retained part is insertable into the capturing part in a first state of the actuator. The retained part is held in contact with the capturing part via an interference fit to hold the first and second objects proximate to each other in a second state. The retained part is ejected from the capturing part in a third state. Applying heat via the heating element causes a transition between the second and the first or third states of the actuator.

Abstract: An actuator includes a thermally activated active material member, and an external element configured to selectively engage the member and presenting a predetermined rate of thermal conductivity configured to transfer heat energy to and/or from the member, so as to reduce the actuation period or rate of cooling after actuation, when engaged.