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1 Journal of Achievements in Materials and Manufacturing Engineering

1 2006

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Fatigue behaviour and energy dissipation of a nodular cast iron in ultrasonic fatigue loading

Xue H. Q., Bayraktar E., Bathias C.

Journal of Achievements in Materials and Manufacturing Engineering

2006

Vol. 18, nr 1-2

251--254

Purpose: In the current research, fatigue tests of cast iron (GS51) have been conducted using the ultrasonic fatigue system and monitored by an advanced infrared imaging system in real time. Fatigue damage processes has been observed and analyzed. Furthermore, heat condition effect has been to analyze. Design/methodology/approach: Fatigue behaviour in the very high cycle regime of 1010 cycles were investigated with a cast iron (GS51) under ultrasonic fatigue test system in ambient air at room temperaturę with a stress ratio R=-1. The influence of frequency was examined by comparing similar data generated on conventional servo hydraulic test systems. An infrared camera was also used to record specimen temperatures at various load levels caused by internal damping due to cycling at a very high frequency. Findings: The S-N curves obtained show that fatigue failure occurred beyond 10 9 cycles, fatigue limit does not exist for the cast iron and there is no evidence of frequency effect on the test results. A detailed study on fatigue specimens subjected to ultrasonic frequency shows that the temperature evolution of the cast iron specimen is very evident, the temperature increased just at the beginning of the test, the temperature increased depending on the maximum stress amplitude. Research limitations/implications: Ultrasonic fatigue test methodology had been applied extensively in exploring fatigue lives at very high cycle regime. However, it is a predominant problem that the thermal Energy dissipation results in increasing of temperature of specimen at very high frequency fatigue experiment. In order to investigate the heat dissipation of ultrasonic fatigue specimen and understand the influence of temperaturę evolution on the fatigue properties, it is necessary to obtain the temperature response of vibratory specimen. Originality/value: Early stage of damage of the cast iron which lead to crack initiation and micro crack growth are characterized by local microstructure temperature evolution, so as to understand the relationship between heat dissipation and fatigue state of material.