Research On Dynamic Mechanical Behavior And Constitute Model Of Epoxy Resin Under Wet And Heat Cycle

As a new type of material,three-dimensional braided composites are applied to aero-engine fan blades.Aero-engines experience flight cycles and parking cycles with alternating wet and dry cycles,which inevitably leads to the aging of composite materials.Moreover,the aero-engine fan blades are usually in a high-speed state,and the damage to the foreign objects suffered is characterized by a significant change in load occurring on a short time scale,that is,at a high strain rate.Taking into account the stability of the carbon fiber to the hot and humid environment and the insensitivity to the strain rate,the dynamic mechanical properties and the constitutive model of the three-dimensional braided composite substrate-TDE86 epoxy resin after damp-heat evolution were studied from the microscopic mechanics perspective.In the early stage of this article,vacuum casting and high and low temperature hot and humid cycle chamber were cast and wet heat aging epoxy resin.The simulation results showed that the service life of the engine with 0,1,7,14,28,56,70 and 140 days of wet-heat cycle aging cycle was 0,1month,6months,1 year,2 years,4 years,5 years and 10 years.The quasi-static and dynamic mechanical properties of epoxy resin with different wet-heat cycles were tested by using MTS machine and Hopkinson tensile bar system.The strain rate range was 7.5×10^-61000 s^-1.Based on the ZWT viscoelastic constitutive model,combined with the different mechanical properties at high and low strain rates,viscoelastic constitutive model including the effects of wetting and heating cycle factors on the mechanical properties of the resin was obtained.The hygroscopic law,the evolution process of crack damage,and the viscoelastic constitutive relation including the hygrothermal effect and strain rate effect of the epoxy resin obtained in this paper are used to evaluate and predict the three-dimensional braided carbon fiber composite material subjected to the damp heat cycle.The effective experimental data support for foreign object damage resistance.