基于双K断裂准则的PBX炸药断裂行为研究OA

To quantitatively characterize the fracture parameters of the polymer-bonded explosive(PBX)during the entire process of crack initiation and propagation,the fracture behavior of TATB-based PBX under the temperature condition of 20 ℃→70 ℃ was investigated via three-point bending fracture tests based on the double-K fracture criterion.The results show that during the linear loading fracture process of PBX three-point bending specimens under displacement control,no crack propaga-tion occurs in the initial linear rising stage of the P—CMOD curve;the crack stable propagation initiates when the initiation load is reached,accompanied by the nonlinear rise of load;after the peak load is attained,the crack undergoes unstable propa-gation with a sharp load drop.The stage characteristics of the fracture process are consistent with the theoretical description of the double-K fracture criterion.Along with the three stages of crack initiation,stable propagation and unstable propagation,the crack mouth opening displacement(CMOD)and crack tip opening displacement(CTOD)increase steadily at first and then rise rapidly,while the CMOD rate,CTOD rate and crack propagation rate increase initially and then decrease.With the in-crease of temperature,the crack mouth opening displacement at unstable state(CMODun)and crack tip opening displacement at unstable state(CTODun)increase overall;the peak values of CMOD rate,CTOD rate and crack propagation rate decrease significantly;the cohesive fracture toughness KICC increases remarkably,while both the initiation fracture toughness KICini and un-stable fracture toughness KICun decrease on the whole.For the structural design of PBX,materials with excellent fracture tough-ness and tensile strength as well as high damage tolerance should be prioritized,and the negative effects caused by temperature rise should also be taken into consideration.