Česká společnost pro mechaniku – odborná skupina Počítačová mechanika a Ústav termomechaniky AV ČR, v.v.i. a si Vás dovolují pozvat na přednášku, kterou prosloví

Matjaž Šraml
University of Maribor,
Smetanova 17, 2000 Maribor, Slovenia

Anotace:
Disc brakes, not only for railway applications but generally in all vehicle applications count as in-constructed safety components. Therefore, their reliability during service is essential. The aim of this study is to make a procedure for the determination of the expected fatigue life of brake disc while operating on a particular route.

First objective of the research is to evaluate the fatigue life of modular cast iron EN-GJS-500-7, used for railway brake discs. Tension and low-cycle fatigue properties were examined at room temperature (RT), 300 °C and 400 °C. Tensile stress-strain curves, cyclic hardening/softening curves, cyclic stress-strain curves, stress-strain hysteresis loops and fatigue life curves were obtained for all temperatures. Young’s modulus remained quite temperature stable, while proof stress and ultimate tensile strength decreased with increasing temperature. Fatigue life decreased for around 50 % at 300 °C, while at 400 °C samples endured to only 10% of strain reversals of those at RT.

Second part of the study is numerical analysis using FEM. Axle mounted railway brake disc, made of ductile cast iron EN-GJS-500-7 has been analyzed. A comparison is made between the experimentally measured temperature on the friction surface of the brake disc during dynamometer tests and the results by finite element analysis in two load cases. Estimated fatigue life has been calculated taking mean stress into account and using several multiaxial fatigue criteria.