The Variation Law of Mechanical Parameters of Type I Fatigue Crack Tip Under High Frequency Resonant Loading
Gao Hong-Li, Zheng Huan-Bin*, Qiu Xin-Guo, Liu Huan, Liu Hui
Identifiers and Pagination:Year: 2015
First Page: 379
Last Page: 387
Publisher Id: TOMEJ-9-379
Article History:Received Date: 23/12/2014
Revision Received Date: 2/2/2015
Acceptance Date: 27/2/2015
Electronic publication date: 26/6/2015
Collection year: 2015
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: (https://creativecommons.org/licenses/by/4.0/legalcode). This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
This work explores the variation law of mechanical parameters at fatigue crack tip of compact tension specimen with type I pre-notch based on dynamic finite element method (FEM) in the high frequency resonant fatigue crack propagation test. The displacement fields, the strain fields and the stress intensity factors (SIF) at CT specimen fatigue crack tip in one stress cycle and at different crack lengths under constant amplitude high frequency sinusoidal alternating loading condition are calculated and the related variation laws of mechanical parameters are analyzed. In order to calculate the dynamic SIF at fatigue crack tip, the static SIF has been calculated first. The compared results of the static finite element analysis with the theoretical calculation show that finite element modeling and calculating method and respective results are accurate. Secondly, the variation law of SIF at crack tip during the process of fatigue crack propagation test is studied by dynamic FEM. Finally, the high frequency resonant fatigue crack propagation test has been performed and the dynamic strain gauge is used to measure the strain at crack tip during one stress cycle. The research results show that during crack stable propagation stage, the displacement, strain and SIF at type I fatigue crack tip are in the same form having high frequency resonant load, and the displacement, strain and SIF amplitude increase with the crack growth. The error of static SIF between the calculated result by FEM and the theoretical result is 2.51%. The maximum error of the strain at crack tip between the FEM calculating result and the experimental result is 2.93%.