Prepreg platelet molding compound (PPMC) can be used to create structural grade material with a heterogeneous mesoscale morphology. The present work considered various platelet lengths of the prepreg system IM7/8552 to study the effect of platelet length on the flexural behavior of PPMC composite. A progressive failure finite-element analysis was used to understand competing failure modes in PPMC with the different platelet length. The interlaminar and in-plane damage mechanisms were employed to describe complex failure modes within the mesostructure of PPMCs. Experimental results of the flexural tests of the PPMC with different platelet length sizes were used to validate the modeling prediction. The experimental and modeling results revealed complex behavior of the flexural mechanical properties (modulus and strength) on the platelet length. The experimental results indicate that PPMC composites processed with a plate length of 12.7 mm have a higher flexural modulus and strength than 25.4 and 6.35 mm. The platelet length effect on the flexural mechanical behavior was attributed to interactions between various damage mechanisms and the stochastic fiber orientation distribution variability in the material
