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Influence Of Testing Frequency On The Fatigue Behaviour Of Metals And Alloys

Upadhyaya, Y S and Sridhara, B K (2003) Influence Of Testing Frequency On The Fatigue Behaviour Of Metals And Alloys. In: XIII National Conference of Indian Society of Mechanical Engineers, 30-31 December 2003, IIT Roorkee.

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Abstract

Research has shown that testing frequency influences the fatigue behaviour of metals and alloys under certain test conditions. This review paper focuses on the fatigue behaviours like crack growth, life, endurance limit, hysteresis curve etc.. The materials used were steel, cast iron, titanium, tantalum, niobium and alloys of aluminium, nickel, titanium and cobalt. The materials were tested in the wide frequency range of 0.00003-1800 Hz and at ultrasonic frequency of 20 kHz. Ultrasonic frequency (vibratory) fatigue testings were carried out in displacement control under resonance condition. Usually the fatigue behaviour of materials does not vary significantly when tested at conventional and at high or ultrasonic frequencies. Attempts were made to model the influence of testing frequency. Dependency of fatigue crack growth rate on loading frequency, was explained by viscoplasticity of the material. The fatigue behaviour of materials is influenced by frequency when other factors like stress ratio, maximum load, loading waveform, temperature, environment etc. are also varying. The stress ratio varies in the range of -1 to 0.95 and majority of ultrasonic frequency fatigue tests were conducted at a stress ratio of -1. For Ti-6Al-4V and nickel alloy Inconel 718, frequency dependence fatigue behaviour varies with stress ratio. Fatigue tests were conducted at room temperature, but low temperature test at -196oC and the high temperature test in the range of 400-900oC, were also reported. Time dependent, cycle dependent and mixed regime of fatigue behaviours were noted depending upon the frequency range. Generally, the fatigue life increases with increase in frequency and fractography showed transgranular fracture at higher frequency and intergranular fracture at lower frequency.

Item Type: Conference or Workshop Item (Paper)
Subjects: Engineering > MIT Manipal > Mechanical and Manufacturing
Depositing User: MIT Library
Date Deposited: 29 Sep 2012 09:19
Last Modified: 29 Sep 2012 09:19
URI: http://eprints.manipal.edu/id/eprint/77304

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