裂纹长度对PBX代用材料表观断裂韧性Kc的影响OA北大核心CSTPCD

The apparent fracture toughness Kc is an important material property that characterizes the ability to resist crack initia-tion and propagation in the polymer bonded explosive(PBX),investigating the size effect of apparent fracture toughness Kc is of great significance for predicting the crack initiation and failure behavior of PBX at different scales.This study examines the size ef-fect characteristics of the apparent fracture toughness Kc of PBX surrogates by cracked straight through Brazilian disk(CSTBD)tests.Fracture tests were conducted on CSTBD specimens to investigate the influence of pre-existing crack lengths(2,4,6,8,10 mm)on the apparent fracture toughness Kc.The size effect of the apparent fracture toughness Kc of PBX surrogates was ex-plained using the traditional maximum tangential stress(MTS)criterion and the modified maximum tangential stress(MMTS)cri-terion,which considers the higher-order coefficients of Williams series and the length estimation model of fracture process zone(FPZ).Results show that,as the crack length increases,Kc increases from 0.139 MPa·m0.5 to 0.251 MPa·m0.5,and Kc tends to stabilize with the increase in crack length.With the use of the A3 term-corrected FPZ length estimation model,the modified maxi-mum tangential stress(MMTS)criterion can effectively explain the size effect of the apparent fracture toughness Kc of PBX surro-gates compared to the traditional maximum tangential stress(MTS)criterion.