Analysis of Fiber-Reinforced Plastic Tanks by Capturing Anisotropic Material Properties

Traditional methods of structural analysis of fiber reinforced plastic tanks used in automotive applications generally consider the plastic material to be homogeneous in nature. Non-linear stress strain curve obtained from a standard tensile strength test on a fiber reinforced plastic specimen is employed for modeling the material behavior of the plastic tank. There is also a tendency to employ cross flow fiber data in the analysis as a factor of safety measure. However this approach does not account for the anisotropic properties introduced due to complex fiber orientation resulting from plastic injection molding process. Present study aims at capturing the realistic anisotropic properties of the plastic material in the structural analysis. Moldflow Plastics Insight (MPI) software has been used to obtain the fiber orientation details for the plastic tank. This fiber orientation output data has been transferred to the structural analysis software (Abaqus) using commercially available interface software (DIGIMAT). The process involves generating element specific material data card by combining basic nonlinear material data for unidirectional fiber reinforced plastic and the fiber orientation data for each element. This integrated simulation technique involving modeling of anisotropic properties of fiber reinforced plastic tank helps us in accurate prediction of burst pressure strength of tank. Comparison of results obtained by using tensile stress strain data with fibers along flow and cross flow directions has been presented.