Finite Element Analysis of Aluminum Alloy Pitting Stress Concentration

2012 ◽  
Vol 538-541 ◽  
pp. 1664-1669
Author(s):  
Li Hui ◽  
Ying Ying Zhang ◽  
Liang Xu ◽  
Song Zhou ◽  
Yan Wang
Keyword(s):  
Finite Element ◽  
Aluminum Alloy ◽  
Stress Concentration ◽  
Fatigue Crack Initiation ◽  
Measurement Data ◽  
Local Stress ◽  
Element Analysis ◽  
Corrosion Pit ◽  
Corrosion Pits ◽  
Corrosion Time

Based on measurement data and the specific morphology of corrosion pit, three-dimensional finite element model of the corrosion damage specimen is established. Then the local stress condition of corrosion pits is given making use of finite element method, the results of stress concentration due to corrosion pits are also obtained, we can compare the stress concentration arised from the corrosion pit on aluminum alloy specimens in different corrosion time. Results show that the corrosion pits produce stress concentration and become the source of fatigue crack initiation and propagation. With the increasing of corrosion time, the pits get deeper and deeper, and the stress concentration gets more serious near the pits.

scholarly journals Fatigue behaviour of corrosion pits in X65 steel pipelines

2018 ◽  
Vol 233 (5) ◽  
pp. 1771-1782 ◽  
Author(s):  
Farnoosh Farhad ◽  
Xiang Zhang ◽  
David Smyth-Boyle
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Stress Ratio ◽  
Fatigue Crack Initiation ◽  
Local Stress ◽  
Fatigue Behaviour ◽  
Stress And Strain ◽  
Element Analysis ◽  
X65 Steel ◽  
Corrosion Pits

Corrosion pits are a form of geometrical discontinuity that lead to stress and strain concentration in engineering components, resulting in crack initiation under service loading conditions and ultimately fracture and failure. Initiation and propagation of cracks in offshore pipelines can lead to loss of containment and environmental and commercial impacts. In order to prevent such failures, tools to predict the structural integrity of pipelines need to be improved. This work investigates the fatigue behaviour of corrosion pits in API-5L X65 grade steel pipeline utilising numerical and analytical methods. Firstly, load-controlled fatigue tests were carried out on smooth X65 steel samples to establish S–N data. Secondly, local stress–strain behaviour at corrosion pits and its effect on fatigue crack initiation were investigated using elastic-plastic finite element analysis of samples containing a single corrosion pit under cyclic loading. Analysis of stabilised stress–strain hysteresis loops at corrosion pits showed that the local stress ratio at the pit changes from 0.1 to −0.4 while the applied stress amplitude increases with the same stress ratio of 0.1. Analytical methods were also used to predict the local maximum stress and strain at the pit, which showed a similar local stress ratio to the finite element analysis result but lower stress and strain ranges. Finally, fatigue crack initiation life was predicted using the combination of finite element stress and strain analysis and the Smith–Watson–Topper strain–life approach. An advantage of this method for life estimation is that this approach considers the local stress and strains at corrosion pits rather than applied stress.

Finite Element Analysis on Stress Concentration of Well Casing With Corrosion Pits

2010 ◽  
Author(s):  
Jing Zhang ◽  
Jianchun Fan ◽  
Laibin Zhang ◽  
Dong Wen ◽  
Yumei Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Spherical Cavity ◽  
High Stress ◽  
Orifice Diameter ◽  
Element Analysis ◽  
Corrosion Pits

Corrosion-induced pits will disturb the original stress distribution of casing and appear local high stress area. Through 3-D finite element analysis on casing with spherical and cylindrical corrosion cavity, the stress concentration degree and the influences of cavity shape, size and orifice diameter on stress concentration factor are determined and analyzed. The results show that the depth and shape of corrosion cavities are major factors impacting the stress concentration factor. For the casing with corrosion pits, the smaller orifice diameter, the more obvious influence of hemisphere effect on stress concentration factor. With the transition from shallow-spherical cavity to exact hemispherical cavity or from exact hemispherical cavity to deep-spherical cavity or from exact hemispherical cavity to cylindrical cavity, the changes of stress concentration factor show different characteristics.

Investigating the effect of cold expansion process on the fatigue behavior of aluminum alloy 7075-T6 in double-lap shear joints

2018 ◽  
Vol 233 (8) ◽  
pp. 1645-1660 ◽  
Author(s):  
Z Emami Geiglou ◽  
TN Chakherlou
Keyword(s):  
Finite Element ◽  
Aluminum Alloy ◽  
Crack Initiation ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Angular Position ◽  
Expansion Process ◽  
Element Analysis ◽  
Cold Expansion ◽  
Lap Shear

In this paper, the effect of cold expansion process on the fatigue behavior of 7075-T6 aluminum alloy has been investigated both by numerical modeling and conducting experimental tests. In the experimental part, one batch of the specimens without cold expansion and two other batches after being subjected to cold expansions of 1.5% and 4.7% were subjected to cyclic loading in a double-lap shear joint. In the numerical part, finite element simulations of the cold expansion process and loading of the joint were performed and the effect of this process on the stress distribution and the location of the critical zone of the fatigue crack initiation were surveyed. Tangential stresses at different angles around the hole were extracted from the finite element analysis, and after determining the angular position of the surfaces with maximum stresses, crack initiation location in the thickness direction is predicted with an acceptable approximation. The S–N diagrams obtained from the experiments show that the cold expansion process increases fatigue life, and this increase is much more pronounced in lower loads. Also by increasing the percentage of cold expansion from 1.5% to 4.7%, this increase is more appreciable.

scholarly journals The Reliability Life of 7B04 Aluminum Alloy under Alternate Action of Corrosion and Fatigue

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Changfan Li ◽  
Yuting He ◽  
Yu Feng ◽  
Liming Wu ◽  
Sheng Zhang
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Single Side ◽  
Corrosion Pits ◽  
Specimen Number ◽  
Corrosion Time

Experiment of alternate action of corrosion and fatigue on 7B04 aluminum alloy was carried out in this paper and fatigue life was obtained. One of the characteristics about fatigue life is that it is not always decreasing with the increasing of corrosion time. The surface splits caused by the corrosion of intruding and extruding slip steps on the surface and decreasing of stress concentration around corrosion pits were the main reasons. Single side allowance factorkwas proposed to calculate reliability fatigue life with both reliability and confidence. Reliability, confidence, and specimen number had affection on the value ofk. The reliability influences more greatly the reliability fatigue life compared to the confidence. The safe fatigue life is smaller than median life and it was safe to administrate aircraft life using safe fatigue life.

Monitoring of Fatigue Damage Using Ultrasonics and Finite Element Analysis

2012 ◽  
Vol 576 ◽  
pp. 655-658
Author(s):  
Meftah Hrairi ◽  
Masturah Mohammad ◽  
Siti Maisara Ismail
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Aluminum Alloy ◽  
Fatigue Crack Initiation ◽  
Element Analysis ◽  
Ultrasound Technique ◽  
Initiation And Propagation ◽  
Aluminum Alloy 7075 ◽  
Fatigue Failures ◽  
Good Agreement

This study investigated the initiation and propagation of cracks until fracture of aluminum alloy 7075 under cyclic loadings. Tests were conducted to generate fatigue failures from 1×103 to 4×104 cycles at 10 Hz. Nondestructive ultrasound technique was used to detect the presence of any crack as well as its growth. Finite element analysis was conducted in order to assess the ability to predict fatigue crack initiation behavior. The results obtained from the fatigue test were compared to those obtained using ANSYS and a good agreement between the two was observed.

Finite Element Modeling for Steel Cord Analysis in Radial Tires

2013 ◽  
Vol 41 (1) ◽  
pp. 60-79 ◽  
Author(s):  
Wei Yintao ◽  
Luo Yiwen ◽  
Miao Yiming ◽  
Chai Delong ◽  
Feng Xijin
Keyword(s):  
Finite Element ◽  
High Efficiency ◽  
Force Measurement ◽  
Three Dimensional ◽  
Local Stress ◽  
Tension Force ◽  
Center Line ◽  
Element Analysis ◽  
Design Variables ◽  
Steel Cord

ABSTRACT: This article focuses on steel cord deformation and force investigation within heavy-duty radial tires. Typical bending deformation and tension force distributions of steel reinforcement within a truck bus radial (TBR) tire have been obtained, and they provide useful input for the local scale modeling of the steel cord. The three-dimensional carpet plots of the cord force distribution within a TBR tire are presented. The carcass-bending curvature is derived from the deformation of the carcass center line. A high-efficiency modeling approach for layered multistrand cord structures has been developed that uses cord design variables such as lay angle, lay length, and radius of the strand center line as input. Several types of steel cord have been modeled using the developed method as an example. The pure tension for two cords and the combined tension bending under various loading conditions relevant to tire deformation have been simulated by a finite element analysis (FEA). Good agreement has been found between experimental and FEA-determined tension force-displacement curves, and the characteristic structural and plastic deformation phases have been revealed by the FE simulation. Furthermore, some interesting local stress and deformation patterns under combined tension and bending are found that have not been previously reported. In addition, an experimental cord force measurement approach is included in this article.

Stress Analysis and Structure Optimization for the Opening Flat Cover of Pressure Vessels

2012 ◽  
Vol 538-541 ◽  
pp. 3253-3258 ◽  
Author(s):  
Jun Jian Xiao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Stress Analysis ◽  
Structure Optimization ◽  
Pressure Vessels ◽  
Secondary Stress ◽  
Element Analysis ◽  
Primary Stress ◽  
Flat Cover

According to the results of finite element analysis (FEA), when the diameter of opening of the flat cover is no more than 0.5D (d≤0.5D), there is obvious stress concentration at the edge of opening, but only existed within the region of 2d. Increasing the thickness of flat covers could not relieve the stress concentration at the edge of opening. It is recommended that reinforcing element being installed within the region of 2d should be used. When the diameter of openings is larger than 0.5D (d>0.5D), conical or round angle transitions could be employed at connecting location, with which the edge stress decreased remarkably. However, the primary stress plus the secondary stress would be valued by 3[σ].

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