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: 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: 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 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.

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: 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: A shoelace tying apparatus allows individuals with limited or no use of one hand to tightly tie footwear with standard shoelaces. The apparatus is lightweight and portable. The apparatus alleviates the need for special shoelaces or shoes, such as those equipped with hook-and-loop fasteners.

Abstract: A shoelace tying apparatus allows individuals with limited or no use of one hand to tightly tie footwear with standard shoelaces. The apparatus is lightweight and portable. The apparatus alleviates the need for special shoelaces or shoes, such as those equipped with hook-and-loop fasteners.