Abstract: A negative stiffness structure for vibration isolation, shock mitigation, and/or signal processing includes a flexible tensile member and a curved compressive member. A first end of the tensile member is attached to a first structure. A first end of the curved compressive member is coupled to a first structure and a second end of the curved compressive member is coupled to a second end of the flexible tensile member. A length of the tensile member is greater than a length of the compressive member. A tip of the negative stiffness structure is configured to exhibit a negative stiffness mechanical response to a load applied to the tip. The negative stiffness mechanical response acts in a direction orthogonal to the length of the tensile member.

Abstract: Techniques for fabricating a semiconductor chip having a curved surface may include placing a substantially flat semiconductor chip in a recess surface of a concave mold such that corners or edges of the semiconductor chip are unconstrained or are the only portions of the semiconductor chip in physical contact with the concave mold; and bending the substantially flat semiconductor chip to form a concave shaped semiconductor chip by applying a force on the semiconductor chip toward the bottom of the recessed surface. The corners or edges of the semiconductor chip move or slide relative to the recess surface during the bending.

Abstract: Techniques for fabricating a semiconductor chip having a curved surface include placing a substantially flat photonic sensor chip on a recessed surface of a mold such that an active region of the photonic sensor chip at least partially covers a concave central region of the mold and an inactive region of the photonic sensor chip at least partially covers a convex peripheral region of the mold. The mold has a radially varying curvature and the recessed surface includes the concave central region and the convex peripheral region concentrically surrounding the concave central region. Pressure may be applied on the photonic sensor chip to press and bend the photonic sensor chip into the mold.

Abstract: An apparatus has a first structure, a second structure, and an activated seal. The second structure has a first position adjacent to the first structure such that the first structure is not in contact with the second structure. The activated seal is attached to at least one of the first structure and the second structure. The activated seal has a variable stiffness that may be changed in response to a stimuli such that the activated seal is capable of being deformed when at least one of the first structure and the second structure are moved relative to each other.

Abstract: Some on-vehicle devices, such as air dams, air spoilers, and HVAC system baffles, may have movable components that are pulled from one position to another by shrinkage of a linear shape memory alloy (SMA) actuator. Upon an activation signal, the shrinkage of the SMA actuator occurs when it is resistance heated by an electrical current. It is found that useful information concerning the overall intended operation of the on-vehicle device may be obtained by computer analysis of the temporal variation of both current flow through the actuator and its electrical resistance as it is heated to perform its function in the device. A comparison of present current flow and variation of resistance, during activation of the device, with prescribed stored values can reveal malfunction of components of the device as it is being used, in place, on the vehicle.

Abstract: A deformable bi-stable device includes an elastically deformable member having at least two stable configurations and capable of being deformed from a first stable configuration to a second stable configuration, the element passing through an unstable configuration as it is deformed from the first stable configuration to the second stable configuration, and a shape memory polymer layer on or in the elastically deformable member. A method of using this device includes heating the shape memory polymer to a temperature sufficient to reduce the modulus of the shape memory polymer, deforming the deformable member to move from one of the first and second stable configurations to another of the first and second stable configurations, and cooling the device to a temperature sufficient to increase the modulus of the shape memory polymer.

Abstract: A microstructured reconfigurable or morphing composite material with controlled anisotropic deformation properties. The composite material provides highly controlled deformation and stiffness properties. Microscopic three dimensional structures are included in the composite material to control its deformation kinematics and stiffness properties. The composite material has highly segregated in-plane and out-of-plane stiffness properties.

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 testing a shape memory alloy (SMA) actuated device includes cyclically operating the device. The method further includes determining a number of cycles in a functional life of the device based on observations of the device during the cyclical operation. The functional life is a range of consecutive cycles of operation of the device beginning with a first cycle during which the device performs within a specified limit. The functional life is immediately followed by a cycle during which the device performs outside of the specified limit. The method still further includes applying a progressive substitution sub-process to identify an opportunity to increase the number of cycles in the functional life of the device.

Abstract: Active texturing systems adapted for selectively and reversibly modifying the texture of a surface utilizing a plurality of discrete mechanisms in communication with the reconfigurable structure.

Abstract: A variable stiffness structure configured to support a variable load, the variable stiffness structure including a positive stiffness element coupled to the variable load, a negative stiffness element, a hydraulic system coupled to the positive and negative stiffness elements and configured to adjust a relative position of the positive and negative stiffness elements in response to a change in the variable load, while the variable stiffness structure supports the variable load.

Abstract: Mechanical devices powered by Shape Memory Alloy (SMA) wires or other linear elements offer advantages in automotive applications. Such SMA-powered devices are commonly reliable and long-lived but have a finite lifetime. Measurements of the electrical resistivity of an SMA element during operation of the element may be related to the remaining lifetime of the element. Because operation of SMA elements is promoted by heating the element, usually by passage of an electric current, the resistivity measurements, and hence assessment of SMA element operation, may be made without interruption to the operation of the SMA-powered device and without addition of dedicated sensors.

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: 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: A lockable or latchable device includes first and second members proximate to each other, at least one of which is movable with respect to the other. The device also includes a magnetorheological fluid disposed in the device such that the fluid is in simultaneous contact with at least a portion of each of the first and second members when the first and second members are in a position for locking or latching. A permanent magnet is disposed in the device to inhibit displacement of the magnetorheological fluid when the first and second members are in the locked or latched position. An electromagnet is disposed in the device such that magnetic flux from the electromagnet, when activated, disrupts the magnetic flux of the permanent magnet when the first and second members are in the locked or latched position to unlatch or unlock the device.

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 sensor system includes a housing defining a cavity, an actuator formed from an alloy transitionable between first and second states, a plunger attached to the actuator, and a resilient member configured for translating the plunger within the cavity. The plunger is not translatable during a first condition in which a coating of debris is disposed on the housing as the alloy transitions between the first and second states to define a first stress on the actuator. The plunger is translatable during a second condition in which the housing is substantially free from the coating as the alloy transitions to define a second stress on the actuator that is less than the first stress. The alloy transitions from the first to the second state at a first transformation temperature during the first condition, and at a second transformation temperature that is less than the first temperature during the second condition.

Abstract: A reconfigurable bi-stable device includes an elastically deformable panel laterally disposed between and connected to one or more mounting members directly or indirectly connected to opposing ends of the panel, with the panel maintained under compressive force along at least one vector extending between the opposing ends. The compressive force deforms the panel into a one of two stable deformed positions, with the device disposed such that the panel may be moved between each of the two stable deformed positions by application of manual force to one of two opposing faces of the panel. A first shape memory alloy (SMA) or piezo actuator member is connected to the panel, the actuator member being capable of moving the panel from a first one of the two stable deformed positions to a second one of the two stable deformed positions.

Abstract: A reconfigurable bi-stable device includes an elastically deformable panel laterally disposed between and connected to one or more mounting members directly or indirectly connected to opposing ends of the panel, with the panel maintained under compressive force along at least one vector extending between the opposing ends. The compressive force deforms the panel into a one of two stable deformed positions, with the device disposed such that the panel may be moved between each of the two stable deformed positions by application of manual force to one of two opposing faces of the panel. A first shape memory alloy (SMA) or piezo actuator member is connected to the panel, the actuator member being capable of moving the panel from a first one of the two stable deformed positions to a second one of the two stable deformed positions.

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.