High-Cycle Fatigue Resistance of Si-Mo Ductile Cast Iron as Affected by Temperature and Strain Rate

In this article, high-cycle fatigue properties of the EN-GJS700-2 ductile cast iron were experimentally examined, using the four-point rotary-bending fatigue machine. Such material has been widely utilized for manufacturing crankshafts in automotive industries. Therefore, standard specimens were extracted from the crankshaft to consider the manufacturing effect. The other aim of this work is to develop a model, anticipating the probabilistic behavior of the EN-GJS700-2 ductile cast iron. For such objective, the parametric analysis of the most commonly used statistical distributions were performed and compared. Based on the best fitted distribution function on experimental data, fatigue lifetime reliability specifications of the material were analyzed and represented through probabilistic modeling. In addition, the S-N diagram with its scatter-band were conducted at different values of the confidence level. As another investigation, the criterion for designing the crankshaft is the infinite lifetime, or in more practical terms, is the design with allowable stress levels, below the fatigue limit. Based on the staircase test methodology, fatigue endurance limit tests were conducted. Then, statistical trends of the fatigue limit were analyzed by the Dixon-Mood method, based on the maximum likelihood estimation. Obtained results represents that the fatigue limit was 211 MPa for the ductile cast iron.

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A Study on the Role of Grain-Boundary Engineering in Promoting High-Cycle Fatigue Resistance and Improving Reliability in Metallic Alloys for Propulsion Systems

10.21236/ada456825 ◽

2005 ◽

Author(s):

Robert O. Ritchie ◽

Mukul Kumar

Keyword(s):

Grain Boundary ◽

Fatigue Resistance ◽

High Cycle Fatigue ◽

Metallic Alloys ◽

Grain Boundary Engineering ◽

Cycle Fatigue ◽

Propulsion Systems

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Usability of Ultrasonic Frequency Testing for Rapid Generation of High and Very High Cycle Fatigue Data

Materials ◽

10.3390/ma14092245 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2245

Author(s):

Michael Fitzka ◽

Bernd M. Schönbauer ◽

Robert K. Rhein ◽

Niloofar Sanaei ◽

Shahab Zekriardehani ◽

...

Keyword(s):

Strain Rate ◽

High Cycle Fatigue ◽

Fatigue Properties ◽

Ultrasonic Frequency ◽

Cycle Fatigue ◽

Reinforced Polymer ◽

Very High Cycle Fatigue ◽

Ultrasonic Fatigue ◽

Fibre Reinforced Polymer ◽

Very High

Ultrasonic fatigue testing is an increasingly used method to study the high cycle fatigue (HCF) and very high cycle fatigue (VHCF) properties of materials. Specimens are cycled at an ultrasonic frequency, which leads to a drastic reduction of testing times. This work focused on summarising the current understanding, based on literature data and original work, whether and how fatigue properties measured with ultrasonic and conventional equipment are comparable. Aluminium alloys are not strain-rate sensitive. A weaker influence of air humidity at ultrasonic frequencies may lead to prolonged lifetimes in some alloys, and tests in high humidity or distilled water can better approximate environmental conditions at low frequencies. High-strength steels are insensitive to the cycling frequency. Strain rate sensitivity of ferrite causes prolonged lifetimes in those steels that show crack initiation in the ferritic phase. Austenitic stainless steels are less prone to frequency effects. Fatigue properties of titanium alloys and nickel alloys are insensitive to testing frequency. Limited data for magnesium alloys and graphite suggest no frequency influence. Ultrasonic fatigue tests of a glass fibre-reinforced polymer delivered comparable lifetimes to servo-hydraulic tests, suggesting that high-frequency testing is, in principle, applicable to fibre-reinforced polymer composites. The use of equipment with closed-loop control of vibration amplitude and resonance frequency is strongly advised since this guarantees high accuracy and reproducibility of ultrasonic tests. Pulsed loading and appropriate cooling serve to avoid specimen heating.

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