Methods of making a specimen with a predetermined wrinkle defect
In a first aspect, there is a method of making a specimen with a predetermined wrinkle defect, the steps including orienting a composite material around a layup tool at a wrap angle to form a closed loop; and generating at least one wrinkle with a predetermined characteristic in a portion of the closed loop to form a specimen. The predetermined characteristic is at least one of the following: wrinkle location, an outward wrinkle, an inward wrinkle, a wrinkle width, a wrinkle height, and a wrinkle length. In another aspect, there is a method of determining allowable defects for a composite component.
1. A method of making a specimen with a predetermined wrinkle defect, the steps comprising:
orienting a composite material around a layup tool at a wrap angle to form a closed loop including a hollow portion;
removing the layup tool;
generating at least one wrinkle with a predetermined characteristic in a portion of the closed loop to form a specimen by positioning a stretcher including an expansion member in the hollow portion of the closed loop and moving the expansion member therein to generate the at least one wrinkle with a predetermined characteristic;
prior to a curing step, removing the stretcher from the closed loop; and
after the steps of generating the at least one wrinkle and removing the stretcher, curing the specimen;
wherein the predetermined characteristic is at least one of the following: wrinkle location, an outward wrinkle, an inward wrinkle, a wrinkle width, a wrinkle height, and a wrinkle length.
2. The method according to claim 1 , wherein the expansion member is in mechanical communication with an actuating mechanism.
3. The method according to claim 1 , wherein the closed loop has an oval cross-sectional shape, the closed loop includes a top arcuate portion, a bottom arcuate portion, and with the hollow portion between the top and bottom arcuate portions.
4. The method according to claim 3 , wherein the layup tool has a rectangular cross-sectional shape.
5. The method according to claim 1 , wherein the stretcher includes an actuating mechanism, the actuating mechanism comprises at least one of a pneumatic actuator and an air cylinder.
6. The method according to claim 5 , wherein the expansion member includes a head portion in mechanical communication with the actuating mechanism, the head portion is actuated upward to generate the desired shape of the at least one wrinkle with a predetermined characteristic.
7. The method according to claim 6 , wherein the shape of the outer dimension of the head portion generates the predetermined characteristic of the at least one wrinkle.
8. The method according to claim 7 , wherein the head portion includes an outer dimensional portion with at least one of the following shapes: round, square, square with rounded corners, and rectangular.
9. The method according to claim 1 , wherein after the generating a wrinkle step, the specimen includes an unwrinkled portion adjacent to the wrinkled portion.
10. The method according to claim 1 , further comprising:
curing the specimen step, cutting coupons from the specimen.
11. The method according to claim 1 , further comprising:
after removing the stretcher from the closed loop, the specimen is cut into a flat specimen prior to curing.