Direct measurement of high rate stress-strain curves using instrumented falling weight and high-speed photography

Development of a dropweight system was used to obtain stress-strain data for polymeric materials under high strain rate impact. The system consisted of a combination of a high-speed camera and a dropweight instrumented with an accelerometer. Sample deformation during impact was recorded photographically, and the images were then scanned into a PC in order to measure sample deformation strain. The combination of the accelerometer signal and the camera results allowed sample deformation stress to be measured. The stress-strain curves enable the energy of fracture and the temperature rise of the polymer to be calculated. In addition. the high-resolution images enable the flow mechanism and the deformation mode to be viewed clearly.