SMA stack structure for improved heat transfer and structural stability
The present application relates to a superelastic SMA structure, with enhanced power density and compressive stability, comprising two or more connected plate sections to form an overall substantially closed perimeter, wherein the structure comprises an opening positioned in the centre of the structure, and wherein the connected plate sections are dimensioned with a circular symmetry to allow a stacking assembly, and wherein each section includes an array of hollow perforated cells formed between one or more thin vertical walls of a thickness within a predefined range of values, and wherein at least one perforated cell defines a fluid passageway within a predefined range of hydraulic diameter values.
1 . A superelastic SMA structure, comprising:
an opening positioned in the centre of the structure;
two or more connectable plate sections forming a connected plate section with a substantially closed perimeter, the two or more connectable plate sections being dimensioned with a circular symmetry to allow a stacking assembly of a plurality of connected plate sections that includes the connected plate section, the circular symmetry being relative to the opening;
wherein each of the two or more connectable plate sections includes an array of hollow perforated cells formed across a surface of the two or more connectable plate sections, the array of hollow perforated cells being separated by one or more vertical walls of a thickness within a predefined range of values, the thickness of the one or more vertical walls being a dimension between adjacent cells of the array of hollow perforated cells; and
wherein at least one perforated cell of the array of hollow perforated cells defines a fluid passageway within a predefined range of hydraulic diameter values.
2 . The superelastic SMA structure of claim 1 , wherein the thickness of the one or more vertical walls is selected from the range of between 0.75 millimeters (mm) and 1.25 mm.
3 . The superelastic SMA structure of claim 1 , wherein the thickness of the one or more vertical walls is 1 millimeter (mm).
4 . The superelastic SMA structure of claim 1 , wherein a hydraulic diameter of the fluid passageway for one or more cells is selected from the range of between 2 millimeter (mm) and 3 mm.
5 . The superelastic SMA structure of claim 1 , wherein the opening is dimensioned to accommodate a support element.
6 . The superelastic SMA structure of claim 5 , wherein the support element comprises a central pillar and dimensioned to support a plurality of superelastic SMA structures.
7 . The superelastic SMA structure of claim 1 , wherein each of the two or more connectable plate sections has a substantially hexagonal structure shape or a circular shape.
8 . The superelastic SMA structure of claim 1 , wherein each cell of the array of hollow perforated cells has a substantially hexagonal honeycomb shape or a circular shape.
9 . The superelastic SMA structure of claim 1 , wherein the two or more connectable plate sections comprises three or six sections.
10 . The superelastic SMA structure of claim 1 , wherein the two or more connectable plate sections are dimensioned with such a pattern to allow full or partial nesting during manufacture from larger sheets.
11 . The superelastic SMA structure of claim 1 , wherein each of the two or more connectable plate sections is configured to interlock with an adjacent section to define the superelastic SMA structure.
12 . The superelastic SMA structure of claim 1 , wherein a tensioning element is positioned around an outer perimeter of the structure.
13 . The superelastic SMA structure of claim 1 , wherein a tensioning element is positioned around an inner perimeter of the structure opening.
14 . The superelastic SMA structure of claim 1 , wherein a tensioning element is positioned around an exterior perimeter of the opening, and/or an array of individual tension elements so arranged around an exterior of the stacking assembly and positioned to reduce SMA loading during operation.
15 . The superelastic SMA structure of claim 1 , wherein one or more tensioning elements are positioned internally and externally to reduce SMA loading during operation.
16 . The superelastic SMA structure of claim 1 , further comprising a tensioning element that is thermally insulated from, or insulated with respect to, the SMA structure to reduce SMA loading during operation.