Method and system for fabricating dual curvature micro-truss structures

Patent metadata

Field	Value
Publication number	US-10239237-B1
Application number	US-201514824481-A
Country	US
Kind code	B1
Filing date	Aug 12, 2015
Priority date	Aug 13, 2014
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

A method and/or system for forming a micro-truss structure in an essentially arbitrary shape. A mold that has a transparent portion, and having an interior volume in the desired shape, is filled with photomonomer resin. The material for the transparent portion of the mold is selected to be a material that is index-matched to the photomonomer resin. The filled mold, placed into a bath of transparent fluid index-matched to the transparent portion of the mold, and illuminated, from outside the fluid, through a photomask, with collimated light. The collimated light travels through the photomask forming beams of light that enter the transparent fluid, propagate into the mold, and form a micro-truss structure in the shape of the interior volume of the mold. The micro-truss structure may then be removed from the mold, or part or all of the mold may be left adhered to the micro-truss structure, forming covering face sheets.

First claim

What is claimed is:

1. A method for fabricating a micro-truss object, the method comprising:
assembling:
a reservoir;
a volume of a photomonomer resin;
a mold having an interior volume enclosing the volume of the photomonomer resin, the mold comprising a first portion comprising an index-matched mold material that is index of refraction matched with the photomonomer resin;
a volume of an index-matched fluid that is index of refraction matched with the index-matched mold material, the volume of the index-matched fluid being inside the reservoir; and
a photomask;

at least partially submerging the mold in the index-matched fluid; and
projecting a first beam of collimated light along a first direction through the photomask and into the interior volume of the mold.

2. The method of claim 1 , wherein the first portion of the mold comprises, as a major component, a material selected from the group consisting of glass, long-fiber reinforced plastic, and combinations thereof.

3. The method of claim 1 , wherein the first portion of the mold surrounds a major part of the interior volume of the mold.

4. The method of claim 3 , wherein the mold further comprises a second portion, the second portion comprising a sealing closure.

5. The method of claim 3 , wherein the first portion of the mold comprises, as a major component, a material selected from the group consisting of polyethylene terephthalate, polyethylene terephthalate glycol-modified, polyvinyl chloride, poly(methyl methacrylate), polyethylene, glass, and combinations thereof.

6. The method of claim 1 , wherein the mold further comprises a second portion, and wherein the first portion surrounds a minor part of the interior volume of the mold.

7. The method of claim 6 , wherein the first portion comprises a sealing surface, and the second portion comprises a sealing surface; the sealing surface of the first portion configured to form a seal with the sealing surface of the second portion.

8. The method of claim 7 , wherein the mold further comprises a resin in port.

9. The method of claim 8 , wherein the mold further comprises a resin out port.

10. A method for fabricating a micro-truss object, the method comprising:
assembling:
a reservoir;
a volume of a photomonomer resin;
a mold having an interior volume, the mold comprising a first portion, a second portion, a resin in port, and a resin out port, the first portion surrounding a minor part of the interior volume of the mold and comprising an index-matched mold material that is index of refraction matched with the photomonomer resin and a sealing surface, the second portion comprising a sealing surface; the sealing surface of the first portion being configured to form a seal with the sealing surface of the second portion and bisecting both the resin in port and the resin out pot;
a volume of an index-matched fluid that is index of refraction matched with the index-matched mold material;
a photomask;
the mold enclosing the volume of the photomonomer resin; and
the volume of the index-matched fluid being inside the reservoir;

the mold being at partially submerged in the index-matched fluid; and
projecting a first beam of collimated light along a first direction through the photomask and into the interior volume of the mold.

11. The method of claim 6 , wherein the first portion comprises, as a major component, a material index of refraction matched with the photomonomer resin, the material being selected from the group consisting of thermoplastics, thermoset materials, glasses, and filled plastics.

12. The method of claim 6 , wherein the first portion comprises, as a major component, a material selected from the group consisting of glass, long-fiber reinforced plastic, and combinations thereof.

13. The method of claim 6 , wherein the assembling of the reservoir, the mold, the volume of the photomonomer resin, the volume of the index-matched fluid, and the photomask comprises placing the mold in the reservoir with the first portion above the second portion.

14. The method of claim 6 , wherein:
the index-matched fluid is index of refraction matched with the index-matched mold material to have the difference between the index of refraction of the index-matched fluid and the index of refraction of the index-matched mold material to be less than 10% of the index of refraction of the index-matched mold material, and
the index-matched mold material is index of refraction matched with the photomonomer resin to have the difference between the index of refraction of the index-matched mold material and the index of refraction of the photomonomer resin to be less than 10% of the index of refraction of the photomonomer resin.

15. The method of claim 6 , wherein the assembling of the reservoir, the mold, the volume of the photomonomer resin, the volume of the index-matched fluid, and the photomask comprises fabricating the first portion of the mold by vacuum-forming.

16. The method of claim 6 , further comprising applying a coating of mold release to an interior surface of the first portion of the mold.

17. A method for fabricating a micro-truss object, the method comprising:
assembling:
a reservoir;
a volume of a photomonomer resin;
a mold having an interior volume, the mold comprising a first portion and a second portion, the first portion comprising an index-matched mold material that is index of refraction matched with the photomonomer resin and surrounding a minor part of the interior volume of the mold;
a volume of an index-matched fluid that is index of refraction matched with the index-matched mold material;
a photomask;
the mold enclosing the volume of the photomonomer resin; and
the volume of the index-matched fluid being inside the reservoir;

the mold being at least partially submerged in the index-matched fluid;
projecting a first beam of collimated light along a first direction through the photomask and into the interior volume of the mold; and
subjecting an interior surface of the first portion of the mold to an adhesion-promoting treatment.

18. The method of claim 17 , wherein the adhesion-promoting treatment comprises applying a solution of sodium hypochlorite to the interior surface of the first portion of the mold.

19. The method claim 6 , further comprising clamping together the first portion of the mold and the second portion of the mold.

20. The method of claim 1 , further comprising:
projecting a second beam of collimated light along a second direction through the photomask and into the interior volume of the mold;
projecting a third beam of collimated light along a third direction through the photomask and into the interior volume of the mold; and
forming a micro-truss in the interior volume of the mold.

21. The method of claim 20 , wherein the forming of the micro-truss comprises:
forming a plurality of first truss elements defined by a plurality of first self-propagating polymer waveguides and extending along the first direction;
forming a plurality of second truss elements defined by a plurality of second self-propagating polymer waveguides and extending along the second direction; and
forming a plurality of third truss elements defined by a plurality of third self-propagating polymer waveguides and extending along the third direction.

22. The method of claim 1 , wherein the mold includes a wall that the first beam of collimated light is projected through to reach the interior volume of the mold, the first beam of coll

Assignees

• Hrl Lab Llc

Inventors

• Ensberg Jie
• Ro Christopher J
• Yang Sophia S
• Eckel Zak C
• Clough Eric C

Classifications

• B29C2035/0838

  using laser · CPC title

• B32B2605/18

  Aircraft · CPC title

• B29C33/40 Primary

  Plastics, e.g. foam or rubber · CPC title

• B29K2105/0002

  monomers or prepolymers · CPC title

• B32B2307/558

  Impact strength, toughness · CPC title