Effects of different load schemes on the fatigue crack growth rate
2006 (English)In: Journal of Testing and Evaluation, ISSN 0090-3973, E-ISSN 1945-7553, Vol. 34, no 4, 333-341 p.Article in journal (Refereed) Published
An experimental study was conducted on a nickel-based super alloy, Inconel 718, at an elevated temperature of +400 degrees C. The basic question was how to conduct the experiments in order to obtain fatigue crack growth data as free from load history effects as possible in the stage II region. This was investigated by use of four different load sequences. An important question was to investigate if the so called constant K-I,K-max-method provides an upper bound of the fatigue crack growth rate in the stage II region. The results indicate that the constant K-I,K-max-method gives an upper bound in fatigue crack growth rate in the current measuring range but also gives a statistically significant lower exponent of the crack growth equation. A more reliable method to establish the fatigue crack growth parameters is to propagate the crack under constant stress-intensity factor range. This should be done at two different stress-intensity factor ranges for a few millimetres at each range. Also, Delta K-reducing procedure should not be used, when performing fatigue crack growth testing in the stage II region, in order to minimize the risk of transient crack closure effects.
Place, publisher, year, edition, pages
West Conshohocken, PA: American Society for Testing and Materials , 2006. Vol. 34, no 4, 333-341 p.
fatigue crack growth, crack closure, load scheme, constant KImax-method, experiments
Applied Mechanics Metallurgy and Metallic Materials
IdentifiersURN: urn:nbn:se:kth:diva-15865DOI: 10.1520/JTE14097ISI: 000239197400010ScopusID: 2-s2.0-33845245634OAI: oai:DiVA.org:kth-15865DiVA: diva2:333907
ProjectsKonsortium Materialteknik för demonstration och utveckling av termiska energiprocesser: KME-101
FunderSwedish Energy Agency
QC 201005252010-08-052010-08-052016-05-02Bibliographically approved