Fibre orientation in an injection moulded specimen by ultrasonic backscattering

Abstract

Ultrasonic polar backscattering (PBS) was used to determine the local fibre orientation in a short glass fibre reinforced injection moulded polypropylene specimen. The backscattered intensity as a function of fibre angle was determined from a specially prepared specimen. The information from two scans, 90° apart, was needed from the injection moulded specimen. A computer algorithm was developed to compare the backscattered intensity of the unknown fibre orientation to the calibration specimen's fibre orientation. The angle at which the difference between the functions was minimized was taken as the fibre orientation for that local region. The results were compared with the fibre orientations determined by classical methods. At regions close to the surface, a good correspondence between both methods has been obtained.