Strength properties of flange structure of polyimide composite casing manufactured by RTM

Abstract

According to the flanged structure of composite casing, a typical sample with laminated structure manufactured by RTM process was designed using T800 grade carbon fiber fabrics reinforced polyimide composite. The strength property under the uniaxial tension condition was simulated by finite element method, and the calculated fracture load was 21.7 kN. The maximum strain was appeared at the corner of flanged structure, indicated that the corner area of flanged structure was weak relatively. Ultrasonic C-scan and optical microscope methods were applied to analyze the internal quality of the corner area. The results show that the overall internal quality of the sample corner area is good without obvious delamination defects. However, some micro-pores enriched at near surface and the fill region are still visible. The measured average tensile fracture load is 19.81 kN, and that is very close to the calculated value. After cyclic loading with 25% of the fracture load for 24000 times, the residual tensile fracture load is still 19.94 kN, this result means fatigue test has no effect to the mechanical property of the samples. Little interlayer defects and cracks happened in several samples at the corner area, but no visual damage. It shows that the sample can still bear the load after the delamination defects appear.

Keywords

• rtm
• polyimide
• composite
• case
• ultrasonic test
• strength