Abstract: The fractions of the phases of a composite material are determined utilizing a calibration relationship between at least one nondestructively measured quantity and a destructively measured phase fraction. The proper calibration relationship is selected from a multiple-variable regression relation, a single-variable regression of a product of two measured quantities, one of two single-variable regressions, or a weighted average of the results of two single-variable regressions, all four approaches utilizing nondestructive measurements of specimen consolidated height and specimen consolidated ultrasonic transit time. When prepreg material having uniaxial fibers is analyzed, multiple-layer specimens are formed by stacking the individual plies so that the fiber directions in adjacent layers are not parallel.

Abstract: The weight fractions of the phases of a composite material working specimen are determined nondestructively by first performing a sufficient number of nondestructive and destructive calibration measurements on the properties of calibration specimens. The information learned from the calibration specimens is used in combination with nondestructive measurements of the working specimen to determine the fractions of the phases therein, without damaging the working specimen. In one version of this approach, ultrasonic measurements are used to determine fractions of the fiber and matrix in a nonmetallic composite material.

Abstract: An apparatus for performing ultrasonic measurements of compliant material specimens includes a pair of facing but spaced apart ultrasonic transducers between which the specimen is placed, and which transmits signals into the specimen and receives signals from the specimen, a structure which presses the transducers against the opposite surfaces of the specimen with a reproducibly controllable force so that the same compressive force may be applied for successive measurements, a gauge that measures the separation of the two transducers, and a controller which drives the transmitting transducer and receives the signals from the receiving transducer. The apparatus permits the determination of comparable ultrasonic properties for different points on one specimen, and the determination of comparable properties of a number of specimens, by making the measurements under identical conditions.

Abstract: The weight fractions of the phases of a composite material working specimen are determined nondestructively by first performing a sufficient number of nondestructive and destructive calibration measurements on the properties of calibration specimens. The information learned from the calibration specimens is used in combination with nondestructive measurements of the working specimen to determine the fractions of the phases therein, without damaging the working specimen. In one version of this approach, ultrasonic measurements are used to determine fractions of the fiber and matrix in a nonmetallic composite material.

Abstract: A standard reference deformation of a composite material containing a flowable phase and compressible inclusions, such as a prepreg, is measured as the deformation whereat the dominant compressive mode of composite deformation changes from that characteristic of compressible inclusion collapse to that characteristic of resin flow, termed the optimal consolidation deformation. Establishment of this point permits measurement and correlation of physically significant composite properties. For example, material properties of such composite materials are measured under a compressive loading by an ultrasonic transducer at the optimal consolidation deformation. At this point, normally determined to be the deformation at which the second derivative of compressive displacement falls to about zero, compressible inclusions such as voids are eliminated but the flowable phase has not yet begun to flow significantly so as to change the fractions of the phases.

Abstract: The weight fractions of the phases of a composite material working specimen are determined nondestructively by first performing a sufficient number of nondestructive and destructive calibration measurements on the properties of calibration specimens. The information learned from the calibration specimens is used in combination with nondestructive measurements of the working specimen to determine the fractions of the phases therein, without damaging the working specimen. In one version of this approach, ultrasonic measurements are used to determine fractions of the fiber and matrix in a nonmetallic composite material.