The effect of thermal aging degradation of CFRP composite on its mechanical properties using destructive and non-destructive methods and the DIC system

Abstract

This paper presents the results of laboratory tests for CFRP (Carbon Fiber Reinforced Polymer) composite subjected to aging in different conditions: temperature (250 °C and 300 °C) and time (60, 65, 75 and 90 min) to assess its thermal degradation and mechanical response. The tests were conducted for six batches of five samples each. The last batch was treated as reference and was not subjected to aging. To evaluate the effect of thermal degradation both nondestructive and destructive measurement techniques were used to study changes in mechanical properties including damage growth. The nondestructive ODS (Operational Deflection Shapes) technique concerned estimation of natural frequency measurements for cantilever beams, while the destructive technique involved uniaxial tensile tests. In both cases, the whole deformation and degradation processes were monitored by the Aramis system using the Digital Image Correlation (DIC) technique. The results show that despite changes in Young's modulus of aging specimens and their thickness, the natural frequency remains constant for the first and second modes. However, for specimens with higher levels of thermal aging degradation two additional modes of natural vibration were observed, i.e. the third and fourth. The aging process caused a 21% decrease in Young's modulus, an increase in Poisson's ratio by 340%, and finally a reduction in the strength of the CFRP composite by 34%.