The Development Of Nondestructive Methods For Predicting Mechanical Properties Of Advanced Reinforced Nonmetallic Composites

This report concerns itself with a detailed evaluation and development of ultrasonic interval velocity measurement technique. Results indicate that it is a practical and powerful tool applicable to the evaluation of boron/epoxy laminates for structural hardware components. Best results are achieved in the 0 and 90 degree directions of the laminates studied. Unbalanced laminates lead to greater errors in the 45 degree direction. Measurements off-angle with respect to reinforcing filaments do not now seem to be reliable. Based on interval velocity measurements, correlations have been developed for modulus calculation and tensile strength prediction. Accuracies appear to be better than tensile tests for modulus (less scatter) and as good as tensile tests for strength determination. Yield strengths did not appear to be predictable because of excessive scatter in the densile data. Degradation of boron/epoxy laminates studied, because of prior tensile loading did not exist. (Author-PL).