Journal of Applied Polymer Science, Vol.62, No.1, 181-198, 1996
Damage Process Modeling on SMC
The damage processes taking place in SMC, which has been subjected to monotonically increasing tensile loads, are analyzed and the stress-strain curves are calculated. SMC is viewed as a laminate consisting of fiber bundles embedded in a resin/filler matrix. The stiffness of bundles and matrix is expected to be influenced by developing cracks, which lead to a reduction of the total stiffness of the SMC. Crack creation, and consequent bundle and matrix stiffness reduction, are viewed as a statistical process. The quadratic criterion in stress space and the maximum strain criterion are used to predict failure in the fiber bundles and in the matrix, respectively. Residual stresses resulting from the high curing temperatures, anisotropic fiber orientation, and varying content of filler particles in the matrix, inside and outside of the fiber bundles, are taken into account. The comparison of predicted stress-strain curves to experimental results, obtained on almost 20 different SMC materials, shows very good agreement, especially at elongations less than 1%. The model developed in this work allows us to appreciate quantitatively the influence of different material and processing parameters on the behavior of SMC, and in this way, to optimize its composition.