Study on Dynamic Environmental Strength of Advanced High-Strength, High-Rigidity Fiber Reinforced Composites.

所研究的先进复合材料是1)两种类型的碳纤维增强环氧树脂(CFRP)(普通型和耐热型)，2)碳纤维增强PEEK树脂(CFRTP)，3)两种芳纶纤维增强环氧树脂(ARFRP)(芳纶49；lt；(R)&gt；和Technola^&lt；(R)&gt；纤维增强)，以及4)碳化硅晶须增强铝合金。本研究通过声发射(AE)分析的现场观察、扫描声学显微镜(SAM)的内部损伤评价和断口的扫描电子显微镜(SEM)观察相结合的方法来阐明拉伸和疲劳断裂机制和疲劳裂纹扩展特征。此外，还研究了玻璃钢的湿热降解和SiCw/Al复合材料在水中的腐蚀损伤。SAM可以清楚地观察到内部损伤的二维图像，并证明SAM断口图像是非常有用的。声发射综合分析包括声发射幅度、声发射事件持续时间和声发射频率的分布，为分析复合材料复杂的断裂机理提供了有用和有力的信息。吸水性能在很大程度上取决于环氧树脂的类型。吸水使环氧树脂塑化，从而提高玻璃钢的力学性能。吸水还会导致树脂降解和纤维/树脂界面的弱化，从而降低玻璃钢的强度。此外，芳纶纤维的吸水裂解进一步降低了ARFRP的强度。碳化硅晶须显著提高了SiCw/Al合金的力学性能，但碳化硅晶须与铝基之间的局部晶胞降低了复合材料的强度。CFRTP在水中的I型分层抗力几乎不会加速，其损伤容限能力比CFRP高。

The advanced composite materials investigated are 1) Two types of carbon fiber reinforced epoxy resins (CFRP) (normal type and heat-resistant type), 2) A carbon fiber reinforced PEEK resin (CFRTP), 3) Two types of aramid fiber reinforced epoxy resins (ARFRP) (Kevlar 49^<(R)> and Technola^<(R)> fiber reinforcements), and 4) A silicon carbide whisker reinforced aluminum alloy. In the present study, in-situ observation by means of an acoustic emission (AE) analysis, evaluation of internal damage by means of a scanning acoustic microscope (SAM), and SEM observation of fracture surface are combined to elucidate tensile and fatigue fracture mechanisms and fatigue crack growth characteristics. Moreover, hygrothermal degradation of FRP and corrosion damage in water of SiCw/Al are made clear. Two-dimensional images of internal damages can be clearly observed by SAM, and SAM fractography is proved to be quite useful. Synthesized AE analyses including the distributions of AE amplitude, AE event duration, and AE frequency, give us useful and powerful information to analyze the complicated fracture mechanisms of composite materials. The water absorption characteristics depends upon the type of epoxy resins so much. Water absorption causes plasticization of epoxy resin, thereby improving mechanical properties of FRP. Also water absorption causes resin degradation and weakening of fiber/resin interfaces, thereby reducing the strength of FRP. In addition, splitting of aramid fibers by water absorption further decreases the strength of ARFRP. SiC whisker so much improves mechanical properties of SiCw/Al alloy, but local cells composed between SiC whisker and Al matrix lower the strength of the composite. The mode I delamination resistance of CFRTP hardly accelerated in water, and the capability of damage tolerance of CFRTP is so high compared to that of CFRP.