INSTRUMENTED IZOD IMPACT TESTING

The notched Izod impact test is the most prevalent technique used to characterize the effects of high-impulse loads on polymeric materials. In order to extract ancillary information concerning fracture proper-ties in addition to the total fracture energy, an instrumented version of this test is examined. Oscillations in the load signal, which severely degraded the utility of the data for materials fracturing in a brittle manner, are determined to be the result of specimen vibration caused by the impact of the hammer. Placement of a felt cushion on the face of the hammer is shown to eliminate these oscillations and the effects of the felt on the load-time information are shown to be minimal. Finally, peak load data extracted from instrumented Izod tests employing felt padding, is used to determine the stress-intensity factor for several plastics of commercial interest. (C) 1993 John Wiley & Sons, Inc.