Mechanical Response of Polycarbonate with Strength Model Fits

Report No. ARL-TR-5899
Authors: Ajmer Dwivedi, Jermaine Bradley, andDaniel Casem
Date/Pages: February 2012; 32 pages
Abstract: Experiments were conducted on polycarbonate to investigate how the material responds mechanically at varying deformation rates and elevated temperatures. The data was then used to determine parameters for the Johnson-Cook strength model and the Zerilli-Armstrong polymer strength model. Quasi-static tests were conducted at strain rates between 0.005/s and 0.4/s using a servo-hydraulic load frame. Dynamic compression experiments were performed using the Split Hopkinson Pressure Bar and resulted in strain rates between 1750/s and 15,000/s. Pre-heated specimens were tested in both setups to determine the effects of thermal softening. The results indicate that the material response is rate sensitive with an enhanced hardening at rates greater than 10/s. Predictably, tests conducted at elevated temperatures cause a decrease in the apparent yield and flow stress. Model fits to the data are shown to provide a reasonable approximation of real world behavior.
Distribution: Approved for public release
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Last Update / Reviewed: February 1, 2012