Interfacial Evaluation and Microfailure Mechanisms of Carbon Fiber/Bismaleimide (BMI) Composites using Tensile/compressive Fragmentation Tests and Acoustic Emission

인장/압축 Fragmentation 시험법과 음향방출을 이용한 Carbon Fiber/Bismaleimide (BMI) Composites 의 계면 평가와 미세파괴 메커니즘 연구

Interfacial and microfailure properties of carbon liber/bismaleimide (BMI) composites were evaluated using both tensile fragmentation and compressive Broutman tests with acoustic emission (AE). Since BMI is rather difficult matrix to apply for the conventional fragmentation test because of its too low elongation and too brittle and high modulus properties, dual matrix composite system was applied. After carbon fiber/BMI composite was prepared for rod shape by controlling differing curing stage, composites rod was embedded in toughened epoxy as outer matrix. The typical microfailure modes including fiber break, matrix cracking, and interlayer failure were observed during tensile testing, whereas the diagonal slippage in fiber ends was observed during compressive test. On the other hand, AE amplitudes of BMI matrix fracture were higher than carbon fiber tincture under tensile test because BMI matrix has very brittle and high modulus. The waveform of signals coming from BMI matrix fractures was consistent with AE amplitude result under tensile tests.