ABSTRACT

Collapse Characteristic of CFRP Hat Shaped Sectional Members under Temperature Changes of Moisture Absorption


Kook, Hyun
Advisor : Prof. Yang, In-Young, Ph. D.
Dept. of Advanced Parts & Materials Engineering
Graduate School of Chosun University


CFRP composites have light weight, high strength. CFRP Composite material features superior heat and corrosion resistance, and these benefits enable the gradual applications on aerospace industries and sports-entertainment business. However, CFRP Composite material has the weakness in hygrothermal environment and shock resistance. Especially, moisture absorption into composite material under hygrothermal environment can change molecule arrangement and chemical properties. Therefore, this study considered the moisture absorption behavior of CFRP composites associated temperature changes such as 60 and 80℃ and following the strength evaluation after experimentally setting hygrothermal environment by producing the CFRP hat shaped sectional member currently used as automobile structural material. Interface numbers (2, 3, 4, 6 and 7) CFRP hat shaped sectional members were made. This study performed collapse characteristics and moisture absorption movements of CFRP structure members when CFRP laminates are under the hygrothermal environment. In particular, the max clollapse load, mean collapse load and absorbed energy collapse mode were analyzed.

1. Temperature changes CFRP hat shaped section member of the absorption at 60 ℃ the initial results of experiments conducted initial absorption rate increased sharply to about 0.5%, 80 ℃ up to approximately 1.0% was found to be increased dramatically. Slowing the rate of absorption after approximately 2,500 hours in 60 ℃, 80 ℃ reached approximately 1800 hours, all specimens that they can see that saturation was reached.

2. CFRP hat shaped section member of the moisture absorption behavior of the specimen inside the higher the temperature, the fewer the interface, 0 ° direction of the thickness of the interfacial thicker, 0 ° direction closer to the surface of the specimen surface layer increases the absorption rate of the large to the point of saturation is reached gradually reduced water absorption was found hours.

3. Dry specimen and temperature changes due to the interlaminar fracture in both shear and bending modes with mixed mode of brittle fracture was observed. However, the Wet specimen with carbon fiber reinforced epoxy bonding between the degradation due to the weakening of the collapse, which leads to forming a stable crushing mode was known to 60 ℃, 80 ℃ absorption in of the CFRP members Mode to crush almost all showed.
4. Through the static collapse test the strength degradation due to temperature changes, compare the results, the higher temperature strength degradation was noticeable response, especially CFRP structural members compared to non-hygroscopic moisture absorption at 60 ℃, the decrease was 40% in the case If moisture absorption at 80 ℃ and 50% was found to be decreased.