Vol.23, No.3, 2023, pp. 251–256
UDC:

Polycarbonate based thermoplastics are frequently used in several engineering applications as a consequence of their relatively low price to mechanical toughness ratio, making these materials a perfect choice for various products which, during their lifetime, are subjected to different kinds of external loads. This study is meant to investigate the static fracture toughness and Charpy impact strength of three polycarbonate grades: Makrolon 2405 (unreinforced polycarbonate), Makrolon 9415 (reinforced polycarbonate with 10 % glass fibre), and Makrolon 8035 (polycarbonate with 30 % fibre volume fraction). Static fracture toughness measurements of the three polycarbonate grades are performed by conducting three-point bending tests, using pre-cracked specimens on a universal tensile test machine. Based on the mathematical relations, with maximal force obtained during the tests and with geometry factors (a/W), the critical stress intensity factor has been calculated and compared between the unreinforced and reinforced grades.

Charpy impact strength investigations, using standard notched specimens, were conducted on an Instron CEAST 9050 instrumented Charpy impact pendulum system, following the ISO 179-2 standard. During the measurements one could observe that the reinforced material grades suffered brittle failures, whereas ductile/brittle damage has been observed for the unreinforced grade. After the experimental tests, dynamic fracture toughness investigations have been numerically modelled, showing a relatively good correlation of the results.

Keywords: Makrolon^®, Charpy impact strength, fracture toughness, finite element analysis