Comparing Compressive Strength of PAN Based Carbon Fibers by Direct Compression Test

Abstract

Longitudinal direct compression testing of a single polyacrylonitrile-based carbon fiber was performed with a piezo-actuated testing machine installed in a scanning electron microscope, and the longitudinal compressive stress–compressive strain relation was measured. The variability of the compressive strength was evaluated via Weibull analysis, and was found to be smaller than the tensile strength variability. The compressive strength of intermediate tensile strength carbon fiber was almost the same to the tensile strength. By contrast, the compressive strength of high tensile strength carbon fiber was about a half of the tensile strength. The compressive strength to the tensile strength ratios of the carbon fibers were almost coincided to the ratio of the unidirectional carbon fiber reinforced plastics. The low compressive strength of a unidirectional high strength carbon fiber reinforced plastic would be attributed to the low compressive strength of the carbon fiber