A 3D incremental sectional micromechanics model is developed for strain rate dependent inelastic polymer matrix composite materials. A repeating unit cell is identified within the material system, which is then divided into several subcells. Uniform stress and uniform strain assumptions are applied in each subcell. Appropriate stress and strain continuity assumptions are made between subcells. A two-level approach is developed for solving the system of equations of the micromechanics model in order to improve the computational efficiency. The developed micromechanics model is implemented into a commercial finite element analysis package. The results show that the current 3D micromechanics model can address the rate dependent inelastic behavior of polymer composite materials accurately and efficiently. Numerical results are also presented to demonstrate the applicability of the micromechanics theory in modeling high velocity impact of composite laminates. Good correlation is observed with experimental observation.