Volume 2, 2009DYMAT 2009 - 9th International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading
|Page(s)||1443 - 1447|
|Published online||15 September 2009|
Flow stress peaks at high strain rates in PMMAH.H. Forrester and G.M. Swallowe
Department of Physics, Loughborough University, Loughborough LE11 3TU, UK
Published online: 15 September 2009
The results of an investigation into the stress-strain behaviour of PMMA in the strain rate region of 102 to 104 s−1 over a range of temperatures from room temperature up to 90°C are reported. The investigation was carried out in an effort to detect the presence, or absence, of peaks in the flow stress – strain rate response. All tests were carried out in compression on a standard Hopkinson Bar system. Although not as clearly defined as the sharp peak in flow stress reported by previous workers in PEEK, there is good evidence of a peak in the flow stress in the strain rate range 102 to 103 which both narrows and moves to a higher strain rate as the temperature approaches the glass transition. Previously reported peaks in flow stress had only been observed in semi-crystalline polymers. The current observations in PMMA suggest that this may be a universal phenomenon. Preliminary work at similar strain rates and temperature ranges on PCTFE, show less conclusive indications of peaks in the flow stress at strain rates around 3×103 s−1.
© EDP Sciences 2009