Entrapment and venting of bubbles during vacuum bag prepreg processing
Entrapment and venting of bubbles during vacuum bag prepreg processing
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DOI：
10.1177/0021998316676325
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发表时间：
2017-08-01
影响因子：
2.9
通讯作者：
Advani, Suresh G.
中科院分区：
文献类型：
--
作者：
Gangloff, John J., Jr.;Cender, Thomas A.;Advani, Suresh G.
在使用部分预浸渍纤维(即预浸料)的复合材料制造过程中，未浸渍的织物横截面用作空气通道，以排出空气、湿气或挥发物的气泡。在加工过程中，层压板中的气泡会导致结构性能下降。在这项工作中，树脂和气泡在特征预浸料加工过程中的运动被直接在现场可视化。这是利用先前开发的流动可视化技术在已知的压力和温度条件下进行的。这项研究调查了气泡成功或失败的加工条件，以及气泡与可用空气通道结合以逃离层合板的工艺条件。这项研究的一个关键发现是，与预浸料中树脂浸渍的初始状态相比，可调的工艺参数，如压力和温度，对成功去除气泡不那么重要。最初树脂浸渍状态较高的预浸料通常无法通过纤维两个横截面的中心将气泡吸引到空气通道中，而最初树脂浸渍状态较低的预浸料具有清晰的路径，使气泡与局部树脂流动前沿相遇、合并和逃逸。对受限空间中气泡运动的相关文献进行了讨论。观察到小毛细管数理论(即
During composites manufacturing with partially pre-impregnated fibers (i.e. prepregs) in Out-of-Autoclave processes, non-impregnated fabric cross-sections serve as air pathways to evacuate entrapped bubbles of air, moisture, or volatiles. The bubbles trapped within a laminate during processing lead to decreased structural performance. In this work, the motion of resin and bubbles during the processing of a characteristic prepreg is directly visualized in situ. This is performed utilizing a previously developed flow visualization technique under known pressure and temperature conditions. This study investigates the processing conditions under which a bubble succeeds or fails to meet and coalesce with available air pathways in order to escape the laminate. A key finding of this study is that tunable process parameters, such as pressure and temperature, are less important for successful bubble removal as compared to the initial state of resin impregnation in the prepreg. Prepregs with initially high states of resin impregnation will often fail to draw bubbles into air pathways through the center of fiber tow cross sections, whereas prepregs with initially low states of resin impregnation have clear pathways for bubbles to meet local resin flow fronts, coalesce, and escape. The relevant literature on the motion of bubbles in confined spaces is discussed. It is observed that small Capillary number theory (i.e. Ca