Abstract: Polymer bonded explosives (PBXs) are different from conventional particle reinforced composites. PBXs possess over 85% of particle volume fraction, and the elastic modulus of particle can be three or four orders of magnitude higher than that of binder. Large deviations are observed on the effective moduli predicted by micromechanical methods. The predicted results of several micromechanical methods for the effective moduli of PBX are analyzed based on finite element method. Results indicate that both Voigt-Reuss bounds and Hashin-Shtrikman bounds give rather large estimated regions; when particle fraction is less than 10%, the differences among the effective moduli estimated by the different methods are not obvious since the particle interaction is negligible; when particle fraction exceeds 20%, the estimated results of three analytic methods are different from each other gradually due to the enhancement in particle interactions, and the estimated results of differential method agree with those of finite element method. For the particle fraction of 94.9%, Young’s modulus calculated by differential method is only 3.7% higher than the experimental value of PBX, while a huge error occurs using Mori-Tanaka method or self-consistent method. For the composites that possess high particle fraction and strong contrast in their ingredient properties, the differential method provides better estimates of effective modulus owing to its relatively favorable evaluation on particle interactions. Key

Key words: ordnancescienceandtechnology, micromechanics, PBX, effectivemodulus, finiteelement, differentialmethod