Abstract: A variable stiffness structure configured to isolate a mass from unwanted vibrations includes a negative stiffness element and an actuator operatively coupled to the negative stiffness element. The actuator is configured to be actuated to control a stiffness of the negative stiffness element. The variable stiffness structure may also include a positive stiffness element coupled to the negative stiffness element.

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: Example methods, panels, and systems are disclosed for providing noise insulation. Noise insulation may be provided by an anti-resonant panel that includes a base panel including a base panel core material and two base panel face sheets, where each of the two base panel face sheets is adjacent to an opposite side of the base panel core material. The anti-resonant panel further includes at least one stiffener-member positioned along the base panel in a defined area of the base panel, where the defined area is less than a full area of the base panel. The stiffener-member includes a stiffener-member core material and two stiffener-member face sheets the stiffener-member face sheets adjacent to an opposite side of the stiffener-member core material.

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: A variable stiffness structure includes a first negative stiffness element configured to buckle in a first direction, a second negative stiffness element configured to buckle in a second direction opposite to the first direction, and an actuator operatively coupled to ends of the first and second negative stiffness elements to control a stiffness of the variable stiffness structure. The first negative stiffness element and the second negative stiffness element are mode-3 buckling beams.

Abstract: Methods for making and curing resin-based adhesives are disclosed using encapsulated amine accelerators activated by providing ultrasonic energy.

Abstract: An adjustable negative stiffness mechanism is disclosed. The adjustable negative stiffness mechanism includes a central shaft, an outer annular member extending around the central shaft, at least two negative stiffness elements extending between the central shaft and the annular member, and an actuator coupled to the negative stiffness elements. Each of the negative stiffness elements has an inner end coupled to the central shaft and an outer end engaging the annular member. The actuator is configured to compress and expand the negative stiffness elements to adjust a negative stiffness mechanical response exhibited by the negative stiffness elements.

Abstract: Ignition-quenching systems comprise an ignition-quenching cover configured to quench an ignition event in a combustible environment triggered by an ignition source associated with a fastener stack. The ignition-quenching cover comprises a porous body that is gas permeable and that has pores sized to quench ignition in the combustible environment. The ignition-quenching cover further comprises a cover attachment feature configured to mate with a fastener attachment feature of the fastener stack. The ignition-quenching cover is configured to cover the fastener stack, which may be associated with a potential ignition source that produces an ignition event in the combustible environment. The porous body may include one or more porous elements that may be formed of various polymeric, mesh, or fabric materials. The ignition-quenching cover may comprise a non-porous frame that is bonded to the porous body and that defines the cover attachment feature.

Abstract: An isolator configured to isolate a payload from unwanted vibrations and shocks. The isolator includes a housing having a first end and a second end opposite the first end, a primary chamber defined in the housing, a backpressure chamber defined in the housing, a conduit placing the primary chamber in fluid communication with the backpressure chamber, a backpressure membrane in the housing proximate the first end, an elastomer dome in the housing proximate the second end, and a shaft connected to the elastomer dome. The primary chamber and the backpressure chamber are between the backpressure membrane and the elastomer dome. The shaft is configured to be connected to the payload.

Abstract: A system configured to provide thermal regulation and vibration isolation to one or more electronic components. The system includes a sensor chassis defining an interior chamber, an electronics housing in the interior chamber of the sensor chassis, a thermoelectric cooler coupled between the sensor chassis and the electronics housing, a thermal strap coupled to the sensor chassis, and at least one isolator coupled to the sensor chassis. The system may also include an insulating material, such as Aerogel, in the interior chamber of the sensor chassis and extending around the electronics housing.

Abstract: Described is a micro-lattice damping material and a method for repeatable energy absorption. The micro-lattice damping material is a cellular material formed of a three-dimensional interconnected network of hollow tubes. This material is operable to provide high damping, specifically acoustic, vibration or shock damping, by utilizing the energy absorption mechanism of hollow tube buckling, which is rendered repeatable by the micro-lattice architecture.

Abstract: A thermomagnetic sensor includes a thermomagnetic probe that includes a ferromagnetic material having a temperature-dependent magnetic permeability characterized by a maximum magnetic permeability value at a temperature below a Curie temperature of the ferromagnetic material. The thermomagnetic sensor further includes an alternating magnetic field source to produce an alternating magnetic field in a vicinity of the thermomagnetic probe to facilitate a measurement of the temperature-dependent magnetic permeability as function of temperature remotely using a thermomagnetic effect. A predetermined relationship between the temperature-dependent magnetic permeability and temperature in a range between the maximum magnetic permeability value and the Curie temperature provides a measurement of a temperature local to the thermomagnetic probe.

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: Techniques for fabricating a semiconductor die having a curved surface can include placing a substantially flat semiconductor die in a recess surface of a concave mold such that corners or edges of the semiconductor die are unconstrained or are the only portions of the semiconductor die in physical contact with the concave mold. The semiconductor die can include through-die cut lines that can lead to substantially less tension in the semiconductor die as compared to the case where the semiconductor die does not include through-die cut lines. Accordingly, such through-die cut lines can allow for achieving relatively large curvatures.

Abstract: A negative stiffness torsional spring. A plurality of spokes secured between a hub and an outer cylinder assembly are preloaded in compression. As the hub is rotated, the stiffness of the torsional spring is negative over a range of angles.

Abstract: A variable stiffness structure includes a first negative stiffness element configured to buckle in a first direction, a second negative stiffness element configured to buckle in a second direction opposite to the first direction, and an actuator operatively coupled to ends of the first and second negative stiffness elements to control a stiffness of the variable stiffness structure. The first negative stiffness element and the second negative stiffness element are mode-3 buckling beams.

Abstract: An adjustable negative stiffness mechanism is disclosed. The adjustable negative stiffness mechanism includes a central shaft, an outer annular member extending around the central shaft, at least two negative stiffness elements extending between the central shaft and the annular member, and an actuator coupled to the negative stiffness elements. Each of the negative stiffness elements has an inner end coupled to the central shaft and an outer end engaging the annular member. The actuator is configured to compress and expand the negative stiffness elements to adjust a negative stiffness mechanical response exhibited by the negative stiffness elements.

Abstract: A method of testing a SMA element includes connecting the SMA element to a validation tool, and applying an electrical current to the SMA element over a test cycle. A resistance of the SMA element during the test cycle is measured, while the electrical current is being applied. The measured resistance of the SMA element during the test cycle is correlated to an estimated strain value of the SMA element during the test cycle. A temperature of the SMA element during the test cycle is estimated. A stress in the SMA element during the test cycle is estimated from a stress predicting grid, using the estimated strain value and the estimated temperature of the SMA element during the test cycle. The proper functionality of the SMA element may be determined based on the estimated stress in the SMA element.

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: A variable stiffness structure configured to support a variable load, the variable stiffness structure including a shaft coupled to the variable load, a negative stiffness element, a clutch coupled to the negative stiffness element and configured to disengage and to engage the shaft, in response to a change in the variable load, while the structure supports the variable load.