カーボン短繊維強化ナイロン複合材料の異方クリープ変形挙動とそのモデル化

抄録

Tensile creep behavior of an injection molded short carbon fiber-reinforced polyamide (ICF/PA) composite was examined at room temperature with a particular emphasis on stress-dependence and orientation-dependence. Furthermore, a phenomenological creep model was developed and evaluated by comparing with the creep behaviors observed. Constant stress creep tests were performed on dumbbell-shaped specimens that are oriented from the flow direction at 0°, 45° and 90°, respectively. Creep strain was measured by means of a digital image correlation (DIC) method. It was observed that creep deformation develops more significantly with increasing off-axis angle from 0° to 90°. In addition, it was observed that creep deformation increases with increasing creep stress, regardless of specimen orientation. Transient creep behavior and steady creep behavior was observed over the range of time in this study, regardless of specimen orientation. An engineering model to describe the anisotropic creep deformation was developed taking into account the time-, stress-, and orientation-dependence of the creep behavior observed. It is based on the classical Bailey-Norton law that was extended to describe the creep behavior of transversely isotropic media. It is shown that the anisotropic creep behavior of ICF/PA can approximately be described by means of the transient creep model developed.