Effects of SCRIMP on Print-Through Phenomenon and Fatigue Tensile Properties of FRP
Date Issued
2007
Date
2007
Author(s)
Liao, Chin-I
DOI
zh-TW
Abstract
Vacuum Assisted Resin Transfer Molding (called VARTM for short) is one of advanced molding processes of Fiber-Reinforced Plastic (called FRP for short). If the resin flow medium patented by Seemann Corp is used in VARTM, the process will be called Seemann Composite Resin Infusion Molding Process ( called SCRIMP for short). This article studied two problems of FRP manufactured with SCRIMP. The first problem is Print-Through Phenomenon (called PTP for short) on the surface of FRP. The other problem is the effect of SCRIMP on the fatigue tensile properties of FRP.
For the study of PTP, first of all, two amplitude parameters of the surface texture properties, the average roughness (Ra) and the altitude of the surface profile (Rt), are measured to objectively determine the existence of PTP and its level. Based on the measuring results, the quantitative measurement for PTP can be reached via measuring the values of Rt and Ra. Furthermore, the measuring results also revealed that PTP can be eliminated by polishing the surface of FRP. Therefore, PTP is a visual problem of the tiny deformation of the surface. This paper presents several methods to reduce PTP, and the experimental results showed that adding core-Mat and thickening the gel-coating layer can effectively reduce PTP. Through the observation on the experiments, the origin of PTP was deduced. The main cause of PTP is the internal residual stress of FRP produced by the non-uniform contraction when FRP cool down before FRP is de-molded. The finite element analysis and test results were compared in this article. The results support the present exposition and show that the residual stress is the origin of PTP.
The fatigue tensile property of SCRIMP-FRP is the other subject in this article. Based on the practical application, the viewpoint of “force” should be used to compare the mechanical properties of HLUP-FRP and SCRIMP-FRP. This article conducted static tensile test, static three-point bending test and fatigue tensile test of SCRIMP-FRP and HLUP-FRP. Standing on the viewpoint of “force”, the static tensile test results show that SCRIMP-FRP and HLUP-FRP those possess the same fibers can take similar tensile forces. The static bending test results show that the bending force that SCRIMP-FRP can bear is smaller than that HLUP-FRP can bear. The fatigue tensile test results show that the fatigue tensile properties of SCRIMP-FRP are not as good as HLUP-FRP. From observing the specimens, the resin of SCRIMP-FRP cracks after bearing small periodic tensile forces. That will badly affect the fatigue tensile properties of SCRIMP-FRP. Two factors were proposed for this situation in this article. First, the space between two fiber bundles is very small. Second, the fibers are pressed and curved before the resin hardening. In order to study the effect of these two factors on the stresses in resin, finite element analysis was used in this article. The analytical results show that the stresses in resin substantially increase because the space between fiber bundles decreasing and fibers curved, especially the latter. For SCRIMP-FRP, the space between fiber bundles is small and fibers are pressed by flow media during the manufacturing process so fibers are curved. That is the reason why the fatigue tensile properties of SCRIMP-FRP are badly affected.
Subjects
玻璃纖維
碳纖維
真空輔助樹脂灌注成型法
螺紋印
表面性質
疲勞
FRP
VARTM
SCRIMP
Print-Through
Surface
Fatigue
Type
thesis