Studies of the Dynamic and Mechanical Properties of Thermoplastics by the Split Hopkinson Pressure Bar Method

摘要

The split Hopkinson pressure bar method is introduced in the investigation of thermoplastics. Compression tests at strain rates of the order of 1000 s(-1) were performed on polypropylene, polyamide 6 and polycarbonate. The materials were studied in both elastic and plastic deformations over a temperature range of -110 (163 K) to +160 C (433 K). The stress-strain curves were determined from the computed measurement data. The yield strength for all materials was approximately 300 N sq mm and the elastic modulus was about 20,000 N sq mm at room temperature. Curves of three types were obtained in the plastic experiments and the differences were explained by means of relaxation theory. The damping factor was determined for all materials from the measurement results. The loss modulus of polycarbonate was calculated from the temperature rise in the specimens. In addition the influence of annealing on the properties of polycarbonate was studied using split Hopkinson pressure bar tests.