Mechanical behavior of random fiber composite perforated plates

In this study, the mechanical behavior of perforated, chopped fiber reinforced polymer plates is investigated. These plates serve as a manifold for polymer heat exchangers, where each perforation would be connected to a tube carrying pressurized fluid. Thus, the plates are subjected to a pressure loading. In order to predict the plate deformation due to the pressure loading, the mechanical bending behavior of these plates is quantified by an equivalent plate modulus E* and equivalent Poisson's ratio ν*, such that the perforated plate can be modeled as a solid plate. Previous research has shown that by normalizing E* with respect to the modulus of a non-perforated plate, the bending behavior of perforated plates fabricated from isotropic elastic materials was a function of the hole size, spacing and plate thickness. Machining holes in a random fiber composite creates local areas of reduced stiffness due to fiber chopping, while the previous methods used to characterize E*/E assumed uniform, isotropic material properties. The objective of this study is to demonstrate that machined chopped fiber reinforced perforated plates, which have local areas of reduced modulus near the holes, can be characterized by E*/E (an approach which assumes global isotropy). Experimental values for E*/E for non-reinforced (isotropic) and chopped fiber reinforced polymer plates are obtained for a range of hole geometries and two different polymers. These experimental results for E*/E are compared to a model developed for isotropic, elastic materials and also to a finite element solution.