A spring assembly includes a first coil spring and a second coil spring. The second coil spring includes a first winding portion and a second winding portion. The first winding portion includes a plurality of windings from a first winding to at least a second winding. The second winding portion is a portion except for the first winding portion. An outer diameter of each of the plurality of windings of the first winding portion is smaller than an outer diameter of each of at least one winding of the second winding portion. Each of the plurality of windings of the first winding portion includes the substantially same outer diameter.

Embodiments of the present invention generally relate to a novel system, device, and methods for providing an isolator for components and instrumentation to isolate vibrations, shock, static or quasi-static loads, thermal loads, and electrical currents. The novel isolator has an asymmetrical shape, experiences uniform motion under quasi-static loading, and reduces the effective modal mass across a range of frequencies. The novel isolator outperforms conventional vibration isolators in terms of cost, schedule (manufacturing time and lead time), heat dissipation, and performance.

An additively manufactured cushion includes an array of interconnected surface lattice unit cells. The surface lattice unit cells are comprised of a unit cell surface portion configured as a Schoen F-RD minimal surface unit cell, and the unit cell surface portion is comprised of a rigid, flexible, or elastic polymer. In some embodiments, the surface lattice unit cells have an average width of from 1 to 100 millimeters and an average volume fraction of from 5 or 10 percent to 50 or 60 percent.

An elastic wave cloaking lattice-based metamaterial for cloaking an object within a void includes a lattice of connected unit cells arranged to form a void, each unit cell comprising a mass and a plurality of connecting springs, the mass coupled by the plurality of connecting springs to masses in adjacent unit cells, the plurality of connecting springs comprising at least two large springs of a first length and at least two short springs of a second length, the first length greater than the second length, the springs and masses having relational and mechanical characteristics to facilitate elastic wave cloaking in the totality of the lattice. The lattice as a whole has metamaterial properties resulting from the positional relationship and mechanical properties of masses and connecting springs of the unit cells such that the lattice at least partially cloaks an object or material portioned within the void from elastic waves.

A retention assembly for a fan case liner including a retention bracket including a tab; a damper comprising a forward end opposite an aft end, the damper comprising an exterior surface extending between the forward end and the aft end, the damper having at least one slot formed in the exterior surface; a bracket slot formed in the damper proximate the aft end, the bracket slot configured to receive the tab; and the fan case liner comprising a fan case liner receiver configured to receive the damper, wherein the retention bracket and damper support the fan case liner.

An elastic wave cloaking lattice-based metamaterial for cloaking an object within a void includes a lattice of connected unit cells arranged to form a void, each unit cell comprising a mass and a plurality of connecting springs, the mass coupled by the plurality of connecting springs to masses in adjacent unit cells, the plurality of connecting springs comprising at least two large springs of a first length and at least two short springs of a second length, the first length greater than the second length, the springs and masses having relational and mechanical characteristics to facilitate elastic wave cloaking in the totality of the lattice. The lattice as a whole has metamaterial properties resulting from the positional relationship and mechanical properties of masses and connecting springs of the unit cells such that the lattice at least partially cloaks an object or material portioned within the void from elastic waves.

Shock absorbers, shock absorbing structures, shoe soles and shoes are disclosed herein. In an embodiment, the shoe includes a shoe sole and a show upper. The shoe sole has a first end surface, a second end surface and a circumferential surface. The first end surface has an outer shape of an N-sided polygon. The second end has an outer shape of an M-sided polygon. The circumferential surface includes a plurality of connection surfaces connecting peripheral edges of the first end surface and the second end surface. The plurality of connecting surfaces are defined by a plurality of ridgelines including a first ridgeline extending from a first N vertex to an intermediate vertex, a second ridgeline extending from a first M vertex to the intermediate vertex, and a third ridge line extending from a second N vertex to a second M vertex.

A magnetorheological apparatus includes a flexible body formed of an elastomer material, a plurality of cell cavities defined by the flexible body, a magnetorheological (MR) fluid disposed within each cell cavity of the plurality of cell cavities, and a magnetic field inductor positioned adjacent to at least one of the cell cavities. Each cell cavity of the plurality of cell cavities is fluidly encapsulated within the flexible body. The magnetic field inductor is selectively operable to vary a magnetic field, and the MR fluid within the at least one cell cavity is configured to vary a stiffness of the at least one cell cavity in response to the magnetic field.

A phase transformational cellular material, including a plurality of bistable cells, each respective bistable cell operationally connected to at least one other respective bistable cell. Each bistable cell enjoys a first stable phase and a second stable phase. The first stable phase is a first geometric configuration and the second stable phase is a second geometric configuration different from the first geometric configuration. An energy transaction is required to shift each respective cell between stable phases. A mechanical energy transaction is required to shift from the first to the second phase, while a thermal energy transaction is required to shift from the second to the first phase.

The technology of increasing space efficiency and vibration damping performance by designing a structure capable of sufficiently reducing low-frequency vibrations while occupying a relatively small space is proposed. In particular, a cut-on frequency of an acoustic black hole is reduced so that low-frequency vibrations may be absorbed by increasing a length of an effective wave propagation path using geometric characteristics of a vortex shape even when it occupies the same area.