Reconfigurable shape memory polymer tooling supports
A method and support apparatus for providing structural support to a mold or mandrel, such as a shape memory polymer (SMP) apparatus configured for shaping a composite part. The support apparatus may comprise a rigid structural member and a plurality of SMP cells attached thereto and configured to inflate or deploy in a malleable state toward and against a surface of the SMP apparatus, mold, or mandrel. Then the SMP cells may be returned to a rigid state while still pressed against this surface, thereby providing structural support when composite material is applied to an opposite surface of the SMP apparatus, mold, or mandrel. After the composite material is cured into the finished composite part, the SMP cells may be deflated or otherwise collapse toward the structural member to provide enough clearance to be removed from the cured composite part.
1. A support apparatus configured for providing internal support to a mold for forming composite parts, tooling for forming composite parts, or SMP apparatus for forming composite parts, the support apparatus comprising:
a rigid structural member that remains rigid when heated to a temperature sufficient for curing a composite part, wherein the rigid structural member has a plurality of openings formed therethrough;
a plurality of inflatable SMP cells made of shape memory polymer (SMP) configured to be actuated to transition between a rigid state and a malleable state, wherein the SMP cells are aligned with the openings of the rigid structural member and are each inflatable through or in fluid communication with the openings formed through the rigid structural member; and
a pressurization system configured to inflate the SMP cells to extend from the rigid structural member when in the malleable state.
2. The support apparatus of claim 1 , wherein the SMP cells are configured to be in the rigid state at a temperature below T g and to become malleable at a temperature above T g .
3. The support apparatus of claim 1 , wherein the rigid structural member comprises a flat, contoured, or hollow rigid sheet of material with the openings formed therethrough.
4. The support apparatus of claim 1 , wherein the SMP cells are formed in the shape of hollow blocks, hollow cylinders, or hollow domes, each having an opening aligned with one of the openings formed through the rigid structural member.
5. The support apparatus of claim 1 , wherein the SMP cells are formed in the shape of hollow blocks or hollow cylinders, each having an open end aligned with one of the openings formed through the rigid structural member and a dome-shaped end opposite of the open end.
6. The support apparatus of claim 1 , wherein the pressurization system is configured to circulate liquid or pressurized gas through the plurality of openings formed through the rigid structural member into the SMP cells.
7. The support apparatus of claim 2 , wherein the pressurization system comprises a pressure source and a heat source, wherein the heat source comprises at least one of an oven, an autoclave, and a heat exchanger configured to circulate heated or cooled liquid or gas through the SMP cells to actuate the SMP cells from the rigid state to the malleable state or from the malleable state to the rigid state.
8. The support apparatus of claim 1 , wherein the pressurization system comprises a pressure source, one or more tubes through which pressurized gas from the pressure source flows to the SMP cells, and a plurality of valves configured to independently control pressurization of one or more of the SMP cells.
9. An apparatus for forming composite parts, wherein the apparatus comprises:
an SMP apparatus formed of shape memory polymer (SMP), having an inner surface and an outer surface, wherein the outer surface of the SMP apparatus is shaped and configured to form an inner surface of the composite part; and
a support apparatus in contact with the inner surface of the SMP apparatus, the support apparatus comprising:
a rigid structural member that remains rigid when heated to a temperature suitable for curing a composite part, wherein the rigid structural member is a monolithic part having a plurality of openings formed therethrough;
a plurality of hollow inflatable SMP cells made of shape memory polymer (SMP) and configured to be rigid at temperatures below T g and to become malleable at temperatures above T g , wherein the SMP cells contact the inner surface of the SMP apparatus when inflated, wherein the SMP cells are aligned with the openings of the rigid structural member, each extending over or through one of the openings formed through the rigid structural member; and
a pressurization system configured to pressurize the SMP cells, thereby actuating the SMP cells away from the rigid structural member and against the SMP apparatus when the SMP cells are heated to a temperature above T g ,
wherein the SMP cells provide a rigid load path between the SMP apparatus and the rigid structural member when cooled below T g while pressed against the inner surface of the SMP apparatus.
10. The apparatus of claim 9 , wherein a height of any of the SMP cells relative to the rigid structural member is proportional to a distance between the SMP apparatus and the rigid structural member at an attachment location of the corresponding SMP cell.
11. The apparatus of claim 9 , wherein the SMP cells each comprise an attachment portion at which the SMP cell is attached to the rigid structural member, wherein the attachment portion is configured to remain rigid when heated to a temperature above T g .