Abstract: A seat belt retractor utilizing active material actuation for selectively modifying the tension in a seat belt.

Abstract: A method of controlling and/or predicting the remaining useful life of an active material actuator, such as a shape memory alloy wire, includes obtaining historical actuation data of an inherent system variable, such as electrical resistance, over a secondary variable, such as time, determining a normal operating envelope having upper and lower bounds based on the data, determining a current profile for a given actuation cycle, and comparing the shape of the current profile to the envelope to determine an out-of-bounds event.

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 first spring coil and a first fiber core within the first spring coil. A timing cable is disposed about 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: 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: 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: An energy harvesting system in thermal communication with a hot region and a cold region includes a hot end heat engine in thermal communication with the hot region, a cold end heat engine in thermal communication with the cold region, and an intermediate heat engine disposed between the hot end heat engine and the cold end heat engine. The hot end heat engine includes a hot end shape memory alloy (SMA) element, the cold end heat engine includes a cold end SMA element disposed, and the intermediate heat engine includes an intermediate SMA element. A hot side of the intermediate SMA element is in thermal communication with a cold side of the hot end SMA element. A cold side of the intermediate SMA element is in thermal communication with a hot side of the cold end SMA element.

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 driven component, such as an electric generator, may be selectively coupled with the heat engine through a coupling device, which may be controlled via a controller.

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: A method of controlling a shape memory alloy actuator utilizing the change in resistance exhibited by the actuator over an actuation cycle, or a derivative thereof, to identify at least one event, such as, for example, a peak, valley, change in slope without reaching a valley, or a jump in resistance within the signal plot that corresponds to the start of actuation, end of actuation, an overload case, and the introduction of a resistive element respectively, and generating a response based upon the event.

Abstract: Active texturing systems adapted for selectively and reversibly modifying the texture of a surface utilizing a variably foldable structure in communication with the surface, and active material actuation to enable and/or cause folding.

Abstract: A method of sensing an ambient heat transfer condition surrounding a shape memory alloy element includes heating the shape memory alloy element, sensing the resistance of the shape memory alloy element, and measuring the period of time taken to heat the shape memory alloy element to a pre-determined level of a resistance characteristic. The ambient heat transfer condition surrounding the shape memory alloy element is calculated by referencing a relationship between the period of time taken to heat the shape memory alloy to the pre-determined level of the resistance characteristic and the ambient heat transfer condition.

Abstract: A method of improving the speed and consistency of response of a shape memory alloy actuator under varying ambient and operating conditions. The method includes probing the shape memory alloy by periodically determining an electric signal strength at which it will undergo forward or reverse phase transformation, while avoiding actual phase transformation; priming the shape memory alloy by bringing it close to phase transformation; initiating phase transformation; and maintaining the shape memory alloy in the phase transformed state. The electric signal strength at which the shape memory alloy will undergo phase transformation is determined by identifying a cusp feature in the electric resistance of the shape memory alloy which closely precedes phase transformation.

Abstract: An overheating protection system adapted for use with a shape memory alloy actuator element, includes at least one switching shape memory alloy element presenting a slower activation period than that of the actuator element, and configured to selectively prevent activation of the actuator element, when the actuator element is actually or predicted to be experiencing overheating; and a circuit comprising the system, wherein the switching element and/or a circuit implement functions to modify activation of the actuator element.

Abstract: Methods for varying seal force in active seal assemblies for doors employ active materials that can be controlled and remotely changed to alter the seal effectiveness, wherein the active materials actively change modulus properties such as stiffness, or a combination of modulus and shape in response to an activation signal. In this manner, in seal applications such as a vehicle door application, door opening and closing efforts can be minimized yet seal effectiveness can be maximized.

Abstract: Actively controlled texturing systems for and methods of selectively and reversibly forming wrinkles, or modifying the amplitude, wavelength, or pattern of existing wrinkles upon a surface using active material actuation.

Abstract: Methods and systems for controlling a three(3)-dimensional distribution of structural reinforcement elements in a polymer-matrix composite. One embodiment of the invention provides a method that includes adding and curing a shape memory polymer in a plurality of flexible preforms attached with each other after preforming each of the flexible preforms to form a spatially controlled preform and variable stiffness material composite laminate. Here, in this embodiment, at least one of the preforms includes a flexible support formed from a patterned supporting material on a first surface of a stiff-structural sheet and the stiff-structural sheet that has been patterned on the support.

Abstract: A reversibly deployable energy absorbing assembly includes a rigid support structure having at least one inlet and at least one outlet; a flexible covering sealingly engaged with the rigid support structure to define an inflatable interior region; a gas source in fluid communication with the at least one inlet; an inlet control valve positioned intermediate the gas source and the at least one inlet; and an actively controlled pressure relief valve in fluid communication with the at least one outlet. The inlet control valve and the pressure relief valve are adapted to provide a response suitable for use in vehicle impact management.

Abstract: Systems for and methods of determining at least one mid-stroke position of an active material actuated load by causing a stress induced rapid change in electrical resistance within the active material element, or modifying an ancillary circuit, when the load is at the mid-stroke position(s).

Abstract: Apparatus and associated methods for actuating variable stiffness material (VSM) structures and achieving deformation of the structures. The apparatus and the associated methods use internal embedded actuation elements and/or externally attached elements to the VSM structures to achieve the desired deformation. In particular, the actuation can be changed due to the variable stiffness nature of the materials. That is, the invention provides the ability to control the deformation of structures using local stiffness control over subregions of the component in addition to or in substitution for actuation. Furthermore, the invention exploits the variable stiffness properties of the VSM structures to enable new functionalities impossible to realize with conventional constant stiffness materials.

Abstract: An airflow control device comprises a body and an active material in operative communication with the body. The active material, such as shape memory material, is operative to change at least one attribute in response to an activation signal. The active material can change its shape, dimensions and/or stiffness producing a change in at least one feature of the airflow control device such as shape, dimension, location, orientation, and/or stiffness to control vehicle airflow to better suit changes in driving conditions such as weather, ground clearance and speed, while reducing maintenance and the level of failure modes. As such, the device reduces vehicle damage due to inadequate ground clearance, while increasing vehicle stability and fuel economy. An activation device, controller and sensors may be employed to further control the change in at least one feature of the airflow control device such as shape, dimension, location, orientation, and/or stiffness of the device.