The evolution of the damage in polymer bonded explosives (PBXs) caused by stepwise compression is studied and xray computed microtomography (CT) is applied to investigate microstructures in PBXs. By digital images processing on CT images, the low density and high density regions of interior of PBXs are distinguished. The characteristics of damage are identified in the low density regions. Therefore, the evolution of the damage with the uniaxial compressive process of PBXs is presented by analyzing the change of the low density regions. Meanwhile, correlating CT images with the change of the Young's modulus provides insight into detailed mechanics of the fracture process. The results show that three stages on evolution of the damage are clarified. In the short elastic stage, damage is restricted. As the compressive stress increases, new damage appears and the change of damage is fluctuated. When compressive stress is close to fracture stress, damage increases and develops to form cracks. The three-stage failure model is well matched with experimental data and reveals the relation between the evolution process of damage and the nonlinear mechanics response.
material mechanics, polymer bonded explosives, damage evolvement, x-ray computed tomography, uniaxial compressive experiment