High Strain Rate Mechanical Behavior of Polyamide 66 and Polyamide 66-Glass Fiber Reinforced

Abstract

The effect of glass fiber-reinforcement polymer Polyamide 66 on the uniaxial compressive mechanical response was measured over a wide strain-rate range from quasi-static tests with strain rate of 5×10–3 s–1 to impact tests with strain rate of 2×103 s–1. Dynamic compressive load was applied using a split Hopkinson pressure bar, whereas an electromechanical testing machine was used to carry out quasi-static experiments in displacement control to determine strain-rate sensitivity. The results demonstrate that strain rate significantly influences yield stress, post-yield behavior, and ductility of the two polymers under study. The yield stress experimental data are consistent with thermally activated processes. The aim of this paper is to examine the effect of adding short glass fiber reinforcement in the mechanical response of polyamide 66 under a wide range of strain rates. Tests at different strain rates were performed in an electromechanical testing machine and in a SHPB. In the next Sections, details of the experiments are described, and the results presented and discussed taking into account the strain rate influence on the yield/post yield behavior and the role of the reinforcement fibers. Using the results obtained from the tests over a wide range of strain rates we model the compressive yield stresses according to the Eyring model (to thermal activated processes) in order to be able to predict the mechanical behavior for future condition and applications. This model was created initially to simulate amorphous materials, but it has also been successfully used to simulate semi-crystalline polymers.