  The Young's modulus of a two-dimensional truss-like structure is simulated by
using the finite element method. A power-law expression is proposed for the
effective Young's modulus of the system. The obtained numerical results are
compared with the experimental data of the {\em anisotropic thin cellular
polypropylene films}. At high solid volume fractions ($>0.4$), the average
shape of the cells are lateral, and their dimensions have around one-to-five
ratio. As the samples are inflated further, volume fraction of the solid is
decreased, the average shape approach a diamond-like structure with one-to-two
ratio. In addition the effective Young's modulus of the system increases. It is
concluded that valuable structural information can be obtained by analyzing the
experimental data and the numerical simulations, which take into account the
material's micro-structural information, simultaneously.
