CPC B29C 70/549 (2021.05) [B29C 35/0288 (2013.01); B29C 70/08 (2013.01); B29C 70/342 (2013.01); B29C 70/44 (2013.01); B29C 70/528 (2013.01); B29C 70/546 (2013.01); B29C 70/88 (2013.01); H10N 30/1061 (2023.02); H10N 30/1071 (2023.02); B29C 35/0261 (2013.01)] | 18 Claims |
1. A method of in-process cure monitoring of fiber reinforced polymer matrix composite material, the method comprising:
exciting, while a fiber reinforced polymer matrix material is being cured from a liquid state to a state other than the liquid state, one or more vibrational waves into the fiber reinforced polymer matrix material at a first location of the fiber reinforced polymer matrix material using a first piezoelectric transducer as an actuator during curing of the fiber reinforced polymer matrix material, the one or more vibrational waves configured to generate at least a first guided wave and a second guided wave in the fiber reinforced polymer matrix material itself such that that the first guided wave and the second guided wave are internally reflected waves within the fiber reinforced polymer matrix and the first guided wave and the second guided wave have center frequencies that are not equal, and wherein center frequencies of the one or more vibrational waves are within a range from 100 kHz to 350 kHz;
measuring, using a second piezoelectric transducer as a first sensor and while the fiber reinforced polymer matrix material is being cured, at least one frequency dependent wave metric of both the first guided wave and the second guided wave at a second location of the fiber reinforced polymer matrix material that is laterally spaced apart from the first location of the fiber reinforced polymer matrix material a spacing distance that is at least ten times greater than a thickness of the fiber reinforced polymer matrix material;
measuring, using a third piezoelectric transducer as a second sensor and while the fiber reinforced polymer matrix material is being cured, at least one frequency dependent wave metric of both the first guided wave and the second guided wave at a third location of the fiber reinforced polymer matrix material that is spaced apart from both the first location and the second location, and wherein a distance from the first location to the third location is greater than the spacing distance; and
utilizing the measured frequency dependent wave metrics to determine a material property of the fiber reinforced polymer matrix material during the curing,
wherein the first piezoelectric transducer, the second piezoelectric transducer, and the third piezoelectric transducer are disposed on a plate adjacent to the fiber reinforced polymer matrix material in a curing chamber,
wherein at least one of the one or more vibrational waves is excited into the fiber reinforced polymer matrix material during the liquid state of the fiber reinforced polymer matrix material, and
wherein the one or more vibrational waves are a Hanning window toneburst of vibrational waves having a center frequency within a range from 100 kHz to 225 kHz.
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