Experimental investigation of fatigue crack initiation from notch for 2024 T351 Al-alloy (original) (raw)
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Experimental investigation of fatigue crack initiation from notches in 2024 T351 Al-alloy
https://www.academia.edu/login, 2020
In this investigation, fatigue crack initiation criterion was established from notches in aged hardening aluminum alloy. This criterion was used to predict the residual lifetime in aeronautical structures subjected to constant amplitude loading using concept of local stress at notch. Charpy V-notch specimens were taken from sheet plate and the notch radius accurately machined at value of 0.2mm. The local stresses were determined numerically and validated analytically. In experimental investigation, the V-notched specimens were loaded in four point bending fatigue with a stress ratio R=0.1 and variation in amplitude loading.
Stress Ratio And Notch Effect On Fatigue Crack Initiation And Propagation In 2024 Al-Alloy
2011
This study reports an empirical investigation of fatigue crack initiation and propagation in 2024 T351 aluminium alloy using constant amplitude loading. In initiation stage, local strain approach at the notch was used and in stable propagation stage NASGRO model was applied. In this investigation, the flat plate of double through crack at hole is used. Based on experimental results (AFGROW Database), effect of stress ratio, R, is highlights on fatigue initiation life (FIL) and fatigue crack growth rate (FCGR). The increasing of dimension of hole characterizing the notch effect decrease the fatigue life.
Study On Fatigue Crack Growth Behavior Of Aluminum Alloy In The Presence Of Notch: An FEA Approach
Motivated with the functioning of pressure cylinders and their failures due to the presence of initial flaws, an arc shaped specimen with inner surface notch is used as the theme of the present fatigue crack growth study. Stress intensity factor (SIF) values obtained by the numerical simulation for the single edge notch bend (SENB) specimen show a good agreement with the results obtained by photo elastic technique and hence using the same numerical simulation based finite element analysis (FEA) technique, an influence of presence of notch on the fatigue life of aluminum specimen was investigated by the numerical simulation and compared with experimental results. Test samples and testing methods utilized for the present study are in accordance with American Society for Testing and Materials (ASTM) standards. Outcome of the study shows the dependency of crack propagation on the stress intensity range.
Fatigue strength analysis of notched aluminium specimens using the highly stressed volume method
Fatigue & Fracture of Engineering Materials & Structures, 2012
A B S T R A C T This paper describes a methodology to analyse the fatigue strength of notched aluminium 7075 T7531 specimens using the highly stressed volume method. A straightforward test setup was developed to load test samples with different stress concentrations in repeated bending at high frequency. The highly stressed volumes are precisely determined using static finite element analysis in combination with Matlab for post-processing. Mean values of the local endurable stress amplitudes are calculated by means of the staircase method.
Frattura ed Integrità Strutturale, 2019
A series of strain controlled multiaxial low cycle fatigue (LCF) tests under proportional and non-proportional loading conditions have been conducted on notched specimens. Cylindrical bars of Al 6061 aluminum alloy and AISI 316L stainless steel with four values of stress concentration factors referred to the net section Kt,n were employed. The experimental results evidenced a reduction of fatigue life due to non-proportional loading. Furthermore, the crack initiation site has been detected to be moved from the notch tip in the case of steel for high values of notch radius under non-proportional loading. Stress concentration factor evaluated in the elastic field K t,n has been included in the Itoh-Sakane parameter to evaluate the fatigue life, returning a general underestimation of fatigue life especially for high values of Kt,n. Material notch sensitivity and crack initiation position have been taken into account to further modify the model, improving the original results and showing a better assessment.
Influence of notch (TIP) radius on fatigue crack growth rate
JOURNAL …, 2006
The paper deals with the problem of fatigue crack propagation from notches in plates made of FeP04 steel and AA356-T6 aluminium alloy. The tests were performed under different stress ranges by keeping the nominal load ratio (R= 0. 1) constant. The specimens were ...
Fatigue Failure of Notched Specimen—A Strain-Life Approach
Materials Sciences and Applications, 2011
Failure cycles of notched round specimens under strain controlled cyclic loading are predicted using strain-life relations obtained from experiment for plain fatigue round specimens. For notched specimens, maximum strain occurs at notch root and is different from applied controlled strain. The maximum strain is computed by appropriate Finite element analysis using the FE software ABAQUS. FE model and material parameters are validated by comparing the FE results and experimental results of LCF tests of round specimens. This value of maximum strain is used for prediction of failure cycles. Prediction is compared with the experimental results. The results show good matching.
Notched multiaxial fatigue of Al7050-T7451 on the need for an equivalent proce.PDF
The aim of this work is to investigate stress gradient effects on the fatigue life estimation of notched Al 7050-T7451 specimens under combined torsion and push-pull loading conditions. Initially, simple push-pull and torsion fatigue tests in plain and notched specimens were independently conducted not only to obtain the material properties necessary to calibrate a standard multiaxial critical plane based model, but also to raise the critical distance versus life curves in tension (L -N f ) and in torsion (L -N f ). This latter step also required a Finite Element Elastic Stress Analysis of the notched specimens tested in the medium high-cycle fatigue regime. Then, proportional multiaxial fatigue tests were carried out using this same notched geometry. The combination of a multiaxial model with the theory of critical distance (TCD) was applied to estimate fatigue lives. For this aluminium alloy, neither the use of the L -N f nor L -N f combined with the predictive multiaxial model was able to estimate lives in an accurate way.
Procedia Structural Integrity, 2019
The paper summarizes several approaches on implementing the notch effect into the fatigue life estimate in high-cycle fatigue region in case of uniaxial fatigue experiments on notched bar specimens. Results of own experiments on specimens prepared from 2124-T851 aluminum alloy (five different notch geometries) are used for the subsequent analyses. The nominal solution derived from the stress concentration factors is compared with the stress gradient approach and the critical distance approach.