航空学报 > 1984, Vol. 5 Issue (4): 451-458

航空用丙烯酸酯板材的断裂特性

陈若喜   

  1. 北京航空材料研究所
  • 收稿日期:1984-03-10 修回日期:1900-01-01 出版日期:1984-12-25 发布日期:1984-12-25

FRACTURE CHARACTERISTICS OF AVIATION ACRYLATE SHEETS

Chen Ruoxi   

  1. Beijing Institute of Aeronautical Materials
  • Received:1984-03-10 Revised:1900-01-01 Online:1984-12-25 Published:1984-12-25

摘要: 本文根据断裂力学基本观点以及高分子材料固有的大分子运动特征,论证了具有特殊断面形貌的玻璃态聚合物裂纹引发时的应力强度因子,应该定义为断裂韧性KIc,而缓慢-快速转变时的K(失稳)则表示不同聚合物的分子运动概貌。依据断面显微观察提出交变载荷作用下丙烯酸酯板裂纹亚临界扩展的微观机理模型直接受△K的控制。

Abstract: A considerable number of studies on fracture toughness of glassy polymers have been done, yet there is still much controversy about the definition of its KIc because of unique features of the polymer fracture behavior. In this paper, an attempt is made to discuss the plane strain fracture toughness KIc of polymethyl methacrylate (PMMA) according to the principles of linear elastic fracture mechanics and considering the intrinsic characteristics of macromolecular motion in polymeric materials. It is reasonable that the stress intensity factor for crack initiation is defined as plane strain fracture toughness KIC, while K (instability) at crack slow growth--fast fracturing transition indicates the aspects of macro-molecular motion of different polymers.Based on fractographic survey, two models of micromechanism of sub-critical fatigue crack propagation under cyclic loading are proposed to explain the fatigue fracture processes of glassy polymers.From the fractographic survey in subcritical crack region, inclusive of mirror and mist regions of fatigue crack propagation(FCP), it is concluded that occurrence of fatigue striations is dependent on the level of K and independent of the abrupt transition of K. No fatigue striations at low K indicate continuous crack growth. At high K, discontinuous crack growth is illustrated by appearance of fatigue striations on the fracture surface of either mirror or mist region while one striation corres ponds to one loading cycle.