FIBER ORIENTATION IN AN INJECTION-MOLDED SPECIMEN BY ULTRASONIC BACKSCATTERING

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 f ibre angle was determined from a specially prepared specimen. The info rmation from two scans, 90 degrees apart, was needed from the injectio n moulded specimen. A computer algorithm was developed to compare the backscattered intensity of the unknown fibre orientation to the calibr ation 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 orien tations determined by classical methods. At regions close to the surfa ce, a good correspondence between both methods has been obtained. (C) 1998 Elsevier Science Ltd. Al rights reserved.