Acoustic Emission for Experimental Study on the Translaminar Fracture Toughness of a Glass Fiber Plastic
摘要
The translaminar fracture toughness of a STEF-1 glass fiber plastic was studied on extended compact tension (ECT) specimens. Acoustic emission (AE) signals were recorded with video filming of the specimen surface under loading to identify the specific features of plastic fracture, crack nucleation and propagation. Additional AE parameters were proposed to be determined, viz the total count–event count ratio, their rates, and the source activity index after the local-dynamic criterion. The behavior of varying AE parameters under loading and video filming results revealed two basic fracture mechanisms: matrix cracking and crack nucleation and propagation at the specimen notch root. The crack extension on reaching the maximum force was evaluated by the total AE count, and the calculation of the translaminar fracture toughness of a STEF-1 glass fiber plastic after ASTM E1922 was validated. The relation of stress intensity factor KTL for translaminar fracture vs test machine crosshead travel speed was established.