New Method for Calculation of Impact Strength of Short Glass Fiber Reinforced Plastics.

The tests for determining fracture data which are described in literature often deal with the methods of linear-elastic fracture mechanics (LEFM). The critical stress intensity factor K//I//C can only be determined with unusually large material thicknesses and, in addition to that, is strongly dependent on temperature and time. Therefore, great problems are involved in transferring the LEFM-data to thin-wall moldings. In recent years, the Institut fuer Kunststoffverarbeitung (IKV) have determined material characteristics in special tensile impact tests. These data - the minimum fracture strain and the minimum volume-specific work to fracture - represent real minima, which are not exceeded even in cases of fastest loading and lowest temperatures.