Method and system to reduce porosity in composite structures
First Claim
1. A method to reduce porosity in a composite structure, the method comprising:
- adding an additive to a resin material to form an additive-resin mixture, the additive comprising a phase transition material having an additive phase transition temperature greater than a resin cure temperature of the resin material;
combining the additive-resin mixture with a plurality of reinforcement fibers to form a composite prepreg material;
forming the composite prepreg material into a composite structure;
heat curing the composite structure in a heating apparatus under a vacuum device at an effective vacuum pressure for an effective time period at the resin cure temperature sufficient to decrease a viscosity of the resin material;
heating the composite structure to an increased temperature above the additive phase transition temperature and above the resin cure temperature and maintaining the increased temperature for a time period sufficient for the additive to undergo a phase transition and to form an additive gas that substantially displaces one or more gases out of the composite structure;
reducing the increased temperature back down to the resin cure temperature to allow the additive gas to undergo a phase transition to a condensed phase, resulting in a substantially reduced vacuum pressure in the composite structure, and resulting in a reduction in porosity of the composite structure; and
,cooling the composite structure.
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Abstract
In an embodiment of the disclosure, there is provided a method to reduce porosity in a composite structure. The method adds an additive to a resin material to form an additive-resin mixture. The method combines the additive-resin mixture with reinforcement fibers to form a composite prepreg material, and in turn, a composite structure. The method heat cures the composite structure in a heating apparatus under a vacuum device at the resin cure temperature, heats the composite structure to an increased temperature above the additive phase transition temperature, and maintains the increased temperature for a time period sufficient. The method reduces the increased temperature back down to the resin cure temperature to allow the additive gas to undergo a phase transition to a condense phase, resulting in a substantially reduced vacuum pressure, resulting in a reduction in a porosity of the composite structure.
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Citations
13 Claims
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1. A method to reduce porosity in a composite structure, the method comprising:
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adding an additive to a resin material to form an additive-resin mixture, the additive comprising a phase transition material having an additive phase transition temperature greater than a resin cure temperature of the resin material; combining the additive-resin mixture with a plurality of reinforcement fibers to form a composite prepreg material; forming the composite prepreg material into a composite structure; heat curing the composite structure in a heating apparatus under a vacuum device at an effective vacuum pressure for an effective time period at the resin cure temperature sufficient to decrease a viscosity of the resin material; heating the composite structure to an increased temperature above the additive phase transition temperature and above the resin cure temperature and maintaining the increased temperature for a time period sufficient for the additive to undergo a phase transition and to form an additive gas that substantially displaces one or more gases out of the composite structure; reducing the increased temperature back down to the resin cure temperature to allow the additive gas to undergo a phase transition to a condensed phase, resulting in a substantially reduced vacuum pressure in the composite structure, and resulting in a reduction in porosity of the composite structure; and
,cooling the composite structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method to reduce a porosity in an aircraft composite part, the method comprising:
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adding an additive to a resin material to form an additive-resin mixture, the additive comprising a phase transition material having an additive phase transition temperature greater than a resin cure temperature of the resin material; combining the additive-resin mixture with a plurality of reinforcement carbon fibers to form a composite prepreg material; laying up the composite prepreg material via a forming process comprising a manual layup or an automated layup; surrounding the aircraft composite part under a vacuum bag under a vacuum pressure; heat curing in a heating apparatus comprising an autoclave or an oven, the aircraft composite part surrounded under the vacuum bag at an effective vacuum pressure, for an effective time period, to the resin cure temperature sufficient to decrease a viscosity of the resin material; maintaining the resin cure temperature for an effective resin cure time period; heating the aircraft composite part to an increased temperature in a range of from about 5 degrees Fahrenheit to about 20 degrees Fahrenheit above the additive phase transition temperature and above the resin cure temperature; maintaining the increased temperature for a time period sufficient for the additive to undergo a liquid to gas phase transition and to form an additive gas that substantially displaces one or more gases out of the aircraft composite part; reducing the increased temperature back down to the resin cure temperature to allow the additive gas to undergo a phase transition to a condensed phase, resulting in a substantially reduced vacuum pressure in the aircraft composite part, and resulting in a reduction in a porosity of the aircraft composite part; cooling the aircraft composite part; and
,removing the cooled aircraft composite part out of the autoclave. - View Dependent Claims (12, 13)
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Specification