Tri-layer bladder and related systems and methods for fabricating composite structures
Disclosed is an elastomeric bladder tool and related systems and methods. In one embodiment, the elastomeric bladder tool comprises an elastomeric inner layer substantially defining an inner cavity of the elastomeric bladder tool, an elastomeric outer layer substantially defining an outer surface of the elastomeric bladder tool, and a permeable middle layer positioned between the elastomeric inner layer and the elastomeric outer layer. The permeable middle layer has greater permeability than both the elastomeric outer layer and the elastomeric inner layer to allow for evacuating of gases that have entered the permeable middle layer.
1. A method comprising:
laying a composite on an elastomeric bladder tool, wherein the elastomeric bladder tool comprises
an elastomeric inner layer substantially defining an inner cavity of the elastomeric bladder tool,
an elastomeric outer layer substantially defining an outer surface of the elastomeric bladder tool, and
a permeable middle layer positioned between the elastomeric inner layer and the elastomeric outer layer;
connecting the permeable middle layer to a low pressure source; and
evacuating gas from between the elastomeric outer layer and the elastomeric inner layer via the permeable middle layer.
2. The method of claim 1 , wherein the permeable middle layer comprises a fibrous material.
3. The method of claim 2 , wherein the fibrous material is a woven, fibrous material.
4. The method of claim 2 , wherein the fibrous material comprises a fiber selected from the group consisting of glass fibers and polymer fibers.
5. The method of claim 1 , wherein the permeable middle layer is a textured surface on at least one of the elastomeric outer layer or the elastomeric inner layer.
6. The method of claim 1 , wherein connecting the permeable middle layer to a low pressure source comprises:
securing the elastomeric bladder tool to a vent plug assembly, and
connecting the vent plug assembly to a low pressure source.
7. The method of claim 6 , wherein
the vent plug assembly comprises an inner plug and a vent plug body, and
securing the elastomeric bladder tool to the vent plug assembly comprises
securing an open end of the elastomeric bladder tool between the inner plug and the vent plug body.
8. The method of claim 7 , wherein:
when the open end of the elastomeric bladder tool is secured between the inner plug and the vent plug body, the permeable middle layer of the elastomeric bladder tool terminates within a cavity formed by the inner plug and the vent plug body.
9. The method of claim 1 , wherein connecting the permeable middle layer to a low pressure source comprises connecting the permeable middle layer to a breather layer laid over the composite, wherein the breather layer is connected to the low pressure source.
10. The method of claim 1 , wherein the elastomeric inner layer is substantially impermeable.
11. The method of claim 1 , wherein the elastomeric outer layer is substantially impermeable.
12. The method of claim 1 , wherein both the elastomeric inner layer and the elastomeric outer layer are substantially impermeable.
13. The method of claim 12 , wherein the permeable middle layer has greater permeability than both the elastomeric outer layer and the elastomeric inner layer.
14. The method of claim 1 , wherein the elastomeric outer layer comprises an embedded heater.
15. The method of claim 1 , wherein the permeable middle layer includes an embedded heater.
16. The method of claim 8 , wherein the cavity is in fluid communication with the low pressure source.