The influence of aircraft fluid ingression on tensile properties of aramid fiber composites

Aramid fiber composites that are used in aircraft can be exposed to various fluids from inside and outside the aircraft during maintenance and flight operations. This article investigates how the aircraft fluid affected the tensile properties, including ultimate tensile strength, tensile modulus, and strain at break of aramid fiber composites. Two different types of aramid fiber composite test specimens were prepared; Kevlar® laminate (para-aramid) and Nomex® paper (meta-aramid). The test specimens were soaked in four different types of aircraft fluid, jet fuel, engine oil, hydraulic fluid, and water and tested to measure their tensile properties. The influence of fluid ingression on the test specimens was analyzed by comparing the test data of each fluid group to the control group. Digital image correlation (DIC) was used during the tensile test for strain calculation and better understanding of local strain change during the test. The test results showed that the test specimens soaked in hydraulic fluid and water had an evidence of tensile property change.