Abstract: An apparatus for performing nondestructive evaluation of a specimen comprises a first ultrasonic shear wave transducer configured to be coupled to a first side of a specimen to be tested; a second ultrasonic shear wave transducer configured to be coupled to the first side of the specimen at a predetermined distance from the first ultrasonic shear wave transducer. The first ultrasonic shear wave transducer is configured to transmit a guided wave into the specimen, and the second ultrasonic shear wave transducer is configured to receive the guided wave from the first ultrasonic shear wave transducer. The first ultrasonic shear wave transducer and the second ultrasonic shear wave transducer are low frequency shear transducers that are capable of operating at or below 0.5 MHz (500 kHz). The specimen has a planar surface or a curved surface, and a membrane may be used as the couplant between the specimen and the transducers.

Abstract: An apparatus for performing nondestructive evaluation of a specimen comprises a first ultrasonic longitudinal wave transducer configured to be coupled to a first edge of a specimen to be tested; a second ultrasonic longitudinal wave transducer configured to be coupled to the first side of the specimen at a predetermined distance from the first ultrasonic shear wave transducer, wherein the first ultrasonic longitudinal wave transducer is configured to transmit a guided wave into the specimen, and the second ultrasonic longitudinal wave transducer is configured to receive the guided wave from the first ultrasonic longitudinal wave transducer. The first ultrasonic longitudinal wave transducer and the second ultrasonic longitudinal wave transducer are low frequency longitudinal transducers that are capable of operating at or below 0.5 MHz (500 KHz). A membrane may be used as the couplant between the transducers and the specimen.

Abstract: An apparatus for performing non-destructive evaluation of the through-thickness modulus of a specimen comprises: a first low-frequency ultrasonic longitudinal wave transducer configured to be coupled to a first surface of a specimen to be tested with a first delay line, the specimen having a layer of fibers perpendicular to the first surface and the second surface; a second low-frequency ultrasonic longitudinal wave transducer configured to be coupled to a second surface of the specimen with a second delay line, the second contact point at a predetermined distance from the first contact point, the predetermined distance corresponding to the distance between the first surface and second surface, wherein the first low-frequency ultrasonic longitudinal wave transducer is configured to transmit a guided wave into the specimen in plane with layer of fibers, and the second low-frequency ultrasonic longitudinal wave transducer is configured to receive the guided wave from the first ultrasonic longitudinal wave trans