The effect of the behaviour of the air springs used in the axle systems of the trucks at different temperatures and frequencies on the fatigue life of the product was investigated by focusing on the crack initiation and propagation. The air spring is designed with a plastic piston to reduce the weight of the system and optimize friction on the rolling surface where the rubber part contacts. The air spring was mounted on the test rig at the design height and tested as a closed-loop at 7 Bar operating pressure and ±50 mm constant amplitude sinusoidal loading condition. The tests were carried out at -40, -25 and +75 °C at frequencies of 1,3,5 Hz. Prototype air springs samples were experimentally tested at different operating temperatures and frequencies under constant internal pressure; their cycles until failure were determined, and the test results were compared within themselves and with the data obtained from the literature. Fatigue life results can be seen more frequently at plus temperatures, while at minus temperatures, it is less. The results showed that the crack initiation and propagation observed in the operating region at -40 and -25 °C significantly differed from the observed crack initiation and propagation at 75 °C. It has been observed that the temperature increase in the working area of the air springs operating at 5 Hz frequency is +4 °C more than the air spring operating at 1 Hz and 1 °C more than that at 3 Hz. This situation showed similar behaviour at minus and post temperatures. Thus, an approach is introduced to predict the fatigue life behaviour of air springs due to crack propagation at different operating temperatures and frequency excitations.
Anahtar Kelimeler: Air springs, Fatigue Life, Minor and plus Temperature, Frequency, Crack propogation
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