Effects of Pressure and Strain Rate on the Mechanical Behavior of Glassy Polymers
In this study the mechanical response of transparent polymers under varying strain rates and hydrostatic pressures is investigated. Quasi-static and dynamic tests are performed under uniaxial and multi-axial loadings and the effect of hydrostatic pressure on the response of the material is explored. In both quasi-static and dynamic experiments, the confinement pressure was increased to a predetermined level and kept constant during the test. This test subjects specimens to confining pressure (up to 200 MPa) prior to loading. Loading was either applied quasi-statically using a servo-hydraulic load frame or at dynamic rates using a modified SHPB. The strain rate dependency of the Polycarbonate material is studied using an Instron UTM and split Hopkinson pressure bar (SHPB) technique. Digital image correlation is used to record full field deformation and calculate the strain. Ultra-high strain rate tests are also performed using a micro-Kolsky bar and small (50–100 um length) specimens. The confinement experiments show that the yield stress is linearly proportional to the confinement pressure but the elastic modulus is insensitive to confinement pressure. Significant rate sensitivity is observed at moderate strain rates and becomes insensitive to strain rate at the highest strain rates measured.
KeywordsHydrostatic pressure Multi-axial loading Polycarbonate Ultra-high strain rate
This research was supported in part by an appointment to the Postgraduate Research Participation Program at the U.S. Army Research Laboratory administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the U.S. Department of Energy and USARL.
- 1.Dwivedi, A., Bradley, J., Casem, D.: Mechanical response of polycarbonate with strength model fitsGoogle Scholar
- 2.Millet, J., Bourne, N.: Shock and release of polycarbonate under one–dimensional strainGoogle Scholar
- 3.Ravi-Chandar, K., Ma, Z.: Inelastic deformation in polymers under multiaxial compressionGoogle Scholar
- 4.Van Melick, H.G.H.: The influence of intrinsic strain softening on the macroscopic deformation behaviour of amorphous polymersGoogle Scholar