CFRP[±45°]_4積層円管の繰返し引張-圧縮応力下における内部損傷の発達と定量的評価

概要

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Development of internal damage in CFRP [±45°]_4 laminate tubes free from the edge effect under cyclic tension-compression with stress ratio R=-0.25 was evaluated quantitatively. The damaged specimens subjected to specific life fractions were sliced perpendicularly to the specimen axis. Then the development and distribution of matrix cracks and delamination were observed on the sliced surfaces with a microscope. The matrix cracks were classified into three stages of degradation with respect to the crack length, and the number and the location of these three kinds of cracks were measured. The length and the location of the delamination were also measured. It was observed that once a matrix crack initiates, it grows rapidly and traversely through the layer. The matrix cracks developed uniformly in the radius and circumferential direction. The delamination appeared in the last stage of fatigue as the result of the extension of the matrix cracks to the interlayer, and progressed mainly in the fiber direction. The influence of internal damage on Young's modulus was also discussed.
1995-03-25