碳纤维复合材料破坏的超声波检测

ULTRASONIC EVALUATION ON FAILURE OF CARBON FIBER REINFORCED COMPOSITE MATERIALS

本文对碳纤维增强复合材料O°、±45°和0°/ 90°铺层的无缺口、有直边缺口、有中心圆孔和有中心缺口层板,作了静态拉伸试验研究。采用超声波扫描成象检测方法,检测了碳/环氧复合材料在不同加载区域内的损伤分布及损伤程度,得到了载荷—损伤程度曲线和材料内部缺陷分布的分层图象。结果表明:带有垂直于载荷方向直边缺口的试件在受静态拉伸时,裂缝不是沿缺口长度方向作自相似扩展,而是沿纤维方向的界面扩展,缺口基本上不影响试件无缺口部分的承载能力;对于带中心缺口的试件,首先出现缺口尖端的界面分离;带中心圆孔的试件,损伤从孔周开始,逐渐沿纤维方向扩展。本文还分析了试件的损伤和破坏机理。

The static tensile tests of carbon fiber reinforced composite specimens ([0°], [±45°],[0°/90°]s) without notch, with double edge notch, central hole and central notch have been investigated experimentally. Using ultrasonic scanning and imager method, internal damage and damage persentage in different loading regions of carbon/epoxy composite were detected. The curves of loading-damage percentage and pictures of internal flaw distribution in different depths were obtained. The results show that during static tensile test, the crack propagates along the direction of the fiber interface instead of that of the edge notch in specimen. The notch doesnot affect the load-bearing capacity of ligament of the specimen. For the specimen with central notch, interface crack occurs at the tip of the notch. And the specimen with central hole, damage initiates around the hole, later, it extends along the fiber direction. In this paper, the failure mecha nism is analysed also.