Development of a compressive failure model for carbon fiber composites and associated uncertainties

An approach to increase the value of carbon fiber for wind turbines blades, and other compressive strength driven designs, is to identify pathways to increase its cost-specific compressive strength. A finite element model has been developed to evaluate the predictiveness of current finite element methods and to lay groundwork for future studies that focus on improving the cost-specific compressive strength. Parametric studies are conducted to understand which uncertainties in the model inputs have the greatest impact on compressive strength predictions. A statistical approach is also presented that enables the micromechanical model, which is deterministic, to efficiently account for statistical variability in the fiber misalignment present in composite materials; especially if the results from the hexagonal and square pack models are averaged. The model was found to agree well with experimental results for a Zoltek PX-35 pultrusion. The sensitivity studies suggest that the fiber packing and the interface shear strength have the greatest impact on compressive strength prediction for the fiber reinforced polymer studied here. Based on the performance of the modeling approach presented in this work, it is deemed sufficient for future work which will seek to identify carbon fiber composites with improved cost-specific compressive strength.

Automated summary

The study aims to increase the value of carbon fiber in wind turbine blades using a finite element model to evaluate and improve cost-specific compressive strength. Parametric studies identify key uncertainties in model inputs affecting compressive strength predictions, and a statistical approach is proposed to account for fiber misalignment in composite materials. Sensitivity studies show that fiber packing and interface shear strength have the greatest impact on compressive strength predictions for the fiber reinforced polymer studied.