The analysis of fibre-reinforced porous composite materials by the measurement of ultrasonic wave velocities

It is shown that simple accurate calculations can now be made of the elastic constants of fibre-reinforced materials containing matrix voids, using theoretical ideas due to Boucher. This permits the construction of calibration curves for given materials by means of which the measurement of two or more ultrasonic wave velocities may be converted to separate estimates of fibre volume fraction and matrix porosity with predictable accuracy. It is also concluded that in some cases it would be necessary to measure some additional property, such as density, but the measurement of suitable velocities could be used to quantify many defect observations made by existing conventional techniques.