Sheath-based rollable lenticular-shaped and low-stiction composite boom
View Patent ↗Various embodiments provide rollable and deployable composite booms that may be used in a wide range of applications both for space and terrestrial structural solutions. Various embodiment composite booms may be bistable, i.e. having a stable strain energy minimum in the coiled configuration as well as the in the deployed configuration. In various embodiments, a boom may be fabricated by aligning two independent tape-springs front-to-front encircled by a durable seamless polymer sleeve. The durable seamless polymer sleeve may allow the two tape-springs to slide past each other during the coiling/deployment process so as to reduce, e.g., minimize, shear and its derived problems.
1. A bistable composite boom having a coiled configuration in which the bistable composite boom is roiled onto a spindle and a deployed configuration in which the composite boom is unrolled from the spindle, the bistable composite boom comprising:
a polymer sleeve flattened in the coiled configuration to form two permanent creases, the two permanent creases providing the bistable composite boom with a lenticular cross-section when the bistable composite boom is in the deployed configuration;
a first tape-spring that is not bistable; and
a second tape-spring that is bistable, wherein:
with respect to the spindle in the coiled configuration, the first tape-spring forms an inner tape-spring and the second tap spring forms an outer tape-spring;
the first and second tape-springs are encircled by the polymer sleeve without being structurally affixed together; and
the first and second tape-springs slide relative to one another inside the polymer sleeve during coiling and deployment of the bistable composite boom;
wherein the bistable composite boom is shearless and has a predetermined stable strain energy minimum in the coiled and deployed configurations.
2. The composite boom of claim 1 , wherein the first tape-spring is configured to subtend to a first angle and the second tape-spring is configured to subtend to a second angle to create a space between the first and second tape-springs inside the polymer sleeve during deployment of the bistable composite boom.
3. The bistable composite boom of claim 2 , wherein the first angle and the second angle in the deployed configuration sum together to be less than 360 degrees.
4. The bistable composite boom of claim 3 , wherein the first angle and the second angle in the deployed configuration are each between 90 degrees and 170 degrees.
5. The bistable composite boom of claim 2 , wherein the polymer sleeve is a seamless polymer sleeve.
6. The bistable composite boom of claim 5 , wherein the polymer sleeve comprised of Kapton, Teflon or Fluorinated Ethylene Propylene.
7. The bistable composite boom of claim 6 , wherein the polymer sleeve is coated with Aluminum, Chromium, Silver or Silicon Dioxide.
8. The bistable composite boom of claim 2 , wherein the first tape-spring has a bending stiffness in a composite boom axial direction less than that of the second tape-spring.
9. The bistable composite boom of claim 8 , wherein the first and second tape-springs comprise Fiber Reinforced Plastics (FRPs).
10. The bistable composite boom of claim 8 , wherein first tape-spring has a thickness that is less than a thickness of the second tape-spring.
11. The bistable composite boom of claim 1 , wherein the first and second tape-springs are encircled by the polymer sleeve such that top and bottom edges of the first tape-spring and the second tape-spring align with the two permanent creases in the polymer sleeve.
12. A method for fabricating a bistable composite boom, the method comprising:
aligning a non-bistable first tape-spring and a bistable second tape-spring independently front-to-front;
flattening a polymer sleeve to thereby, create two permanent creases in the polymer sleeve, the two permanent creases providing the composite boom with a lenticular form in cross-section when the composite boom is in a deployed configuration;
encircling the first tape-spring and second tape-spring with the polymer sleeve; and
rolling the first and second tape-springs onto a cylindrical spindle to form a coiled configuration, such that with respect to the cylindrical spindle in the coiled configuration the first tape-spring forms an inner tape-spring and the second tape-spring forms an outer tape-spring.
13. The method of claim 12 ,
wherein aligning the first tape-spring and the second tape-spring independently front-to-front comprises sliding the first tape-spring and the second tape-spring inside the polymer sleeve such that top and bottom edges of the first tape-spring and the second tape-spring align with the two permanent creases in the polymer sleeve.
14. The method of claim 13 , wherein the first tape-spring and the second tape-spring are slid inside the polymer sleeve one at a time.
15. The method of claim 13 , wherein the polymer sleeve is a seamless polymer sleeve.
16. The method of claim 15 , wherein the polymer sleeve is comprised of Kapton, Teflon or Fluorinated Ethylene Propylene.
17. The method of claim 15 , further comprising coating the polymer sleeve with Aluminum Chromium, Silver, or Silicon Dioxide.
18. The method of claim 13 , wherein the first and second tape-springs comprise Fiber Reinforced Plastic.
19. The method of claim 12 , the first and second tape-springs are not affixed structurally to one another.