scholarly journals Fatigue Modeling and Numerical Analysis of Re-Filling Probe Hole of Friction Stir Spot Welded Joints in Aluminum Alloys

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2171
Author(s):  
Armin Yousefi ◽  
Ahmad Serjouei ◽  
Reza Hedayati ◽  
Mahdi Bodaghi
Keyword(s):  
Experimental Data ◽  
Tensile Strength ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Behavior ◽  
Element Model ◽  
Plastic Strain Amplitude ◽  
Friction Stir ◽  
Probe Hole ◽  
Good Agreement

In the present study, the fatigue behavior and tensile strength of A6061-T4 aluminum alloy, joined by friction stir spot welding (FSSW), are numerically investigated. The 3D finite element model (FEM) is used to analyze the FSSW joint by means of Abaqus software. The tensile strength is determined for FSSW joints with both a probe hole and a refilled probe hole. In order to calculate the fatigue life of FSSW joints, the hysteresis loop is first determined, and then the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted. The results were verified against available experimental data from other literature, and a good agreement was observed between the FEM results and experimental data. The results showed that the joint’s tensile strength without a probe hole (refilled hole) is higher than the joint with a probe hole. Therefore, re-filling the probe hole is an effective method for structures jointed by FSSW subjected to a static load. The fatigue strength of the joint with a re-filled probe hole was nearly the same as the structure with a probe hole at low applied loads. Additionally, at a high applied load, the fatigue strength of joints with a refilled probe hole was slightly lower than the joint with a probe hole.

Evaluation of Fatigue Strength of Similar and Dissimilar Welded Joints of Modified 9Cr–1Mo Steel

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Shigeru Takaya
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Welded Joints ◽  
Strain Distribution ◽  
Evaluation Method ◽  
Welded Joint ◽  
Element Model ◽  
Fast Breeder Reactor ◽  
Good Agreement

This paper presents an evaluation method for the fatigue strength of similar and dissimilar welded joints of modified 9Cr–1Mo steel, which is a candidate structural material for demonstration of fast-breeder reactor being developed in Japan. The discontinuity of the mechanical properties across a welded joint causes a nonhomogeneous strain distribution, and this effect should be considered in the evaluation of the fatigue strength of welded joints. In this study, a “two-element model,” which comprises base metal and welded metal, was employed. First, the strain ranges of each element are calculated, and second, the fatigue lives of each element are evaluated. Finally, the shorter fatigue life is selected as the fatigue life of the welded joint. The failure position can be also estimated by this model. The evaluation results were compared with experimental data obtained at elevated temperature, and the results were in good agreement.

Fatigue Behavior and Deformation of Aluminum and Steel HVOF Sprayed with WC-Co Coatings

1997 ◽  
Author(s):  
A. Ibrahim ◽  
C.C. Berndt
Keyword(s):  
Fatigue Life ◽  
Room Temperature ◽  
Fatigue Behavior ◽  
Three Dimensional ◽  
Element Model ◽  
Fatigue Tests ◽  
Dimensional Finite Element ◽  
Life Distributions ◽  
Three Dimensional Finite Element ◽  
Good Agreement

Abstract The effect of WC-Co coating on the high cycle fatigue (HCF) behavior of SAE 12L14 steel and 2024-T4 aluminum was investigated. The fatigue tests were performed at room temperature and 370°C. The fatigue life distributions of specimens in the polished, grit blasted, peened, and coated conditions are presented as a function of the probability of failure. HVOF sprayed WC-Co coating has influenced the fatigue life of aluminum and steel. Factors contributing to this influence, which include grit blasting, elastic modulus, and residual stress, are discussed. A three-dimensional finite-element model (FEM) of the coated specimen was used to calculate the stress distribution across the coating and the substrate. The results of the analytical model are in good agreement with fatigue lives observed experimentally.

An energetic method to evaluate the macro and micro high-cycle fatigue behavior of the aluminum alloy

2017 ◽  
Vol 232 (8) ◽  
pp. 1456-1469 ◽  
Author(s):  
Junling Fan ◽  
Xinglin Guo ◽  
Yanguang Zhao
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Energy Dissipation ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Thermal Signal ◽  
Dissipation Mechanism ◽  
Good Agreement

An energetic method is proposed to rapidly evaluate the macro- and microfatigue behavior of aluminum alloy in high-cycle fatigue. The theoretical correlation between the thermal signal and the energy dissipation during the fatigue process is established for the irreversible dissipation mechanism description. The energetic method is applied to predict the fatigue strength and the entire fatigue life of the aluminum alloy. Moreover, the energy dissipation is properly used to evaluate the microplastic behavior at the grain scale, which is responsible for the progressive movements of the internal microstructures. Experiments were carried out to validate the current energetic method, and good agreement was obtained between the predicted results and the traditional results. Thus, the current energetic method is confirmed to be promising for the macro and micro high-cycle fatigue behavior assessment.

An Energy-Based Framework to Determine the Fatigue Strength and Fatigue Ductility Parameters for LCF/HCF Life Assessment of Turbine Materials

2014 ◽  
Author(s):  
M.-H. Herman Shen ◽  
Sajedur Akanda
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Weld Metal ◽  
Weld Joint ◽  
Turbine Rotor ◽  
Life Assessment ◽  
Strength Parameters ◽  
First Approximation ◽  
Good Agreement

An energy-based framework is developed to determine the fatigue strength parameters of Basquin equation and the fatigue ductility parameters of Manson-Coffin equation to predict fatigue life of a steam turbine material. The proposed framework is based on assessing the complete energy necessary to cause fatigue failure of a material. This energy is considered as a fundamental material property and is known as fatigue toughness. As a first approximation, the fatigue toughness is equivalent to the monotonic tension energy of a material. This assumption was experimentally verified for weld metal of a weld joint constituent of a turbine rotor and for aluminum 6061-T6. However, in case of base metal of the weld joint constituent, the fatigue toughness was found to be higher than the monotonic energy. From the fatigue toughness and the experimentally determined fatigue life at two different stress levels, the cyclic parameters of Ramberg-Osgood constitutive relation that describes the hysteresis stress-strain loop were calculated. Next, the coefficients and exponents of Basquin and Manson-Coffin equations were expressed as functions of fatigue toughness and cyclic parameters of a material. The predicted fatigue life obtained from the present energy-based framework was found to be in a good agreement with the experimental data.

Evaluation of Fatigue Strength of Similar and Dissimilar Welded Joints of Modified 9Cr-1Mo Steel

2014 ◽  
Author(s):  
Shigeru Takaya
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Welded Joints ◽  
Strain Distribution ◽  
Welded Joint ◽  
Element Model ◽  
Fast Breeder Reactor ◽  
Weld Joints ◽  
Homogeneous Strain

This paper presents evaluation methods of fatigue strength of similar and dissimilar welded joints of modified 9Cr-1Mo steel which is a candidate structural material for a demonstration fast breeder reactor being developed in Japan. The discontinuity of mechanical properties across welded joint causes a non-homogeneous strain distribution, and this effect should be taken into account for evaluation of fatigue strength of weld joints. In this study, ‘2-element model’, which is consisted of base metal and weld metal, was employed. Firstly, strain ranges of each element are calculated, and secondly fatigue lives of each element are evaluated. Finally, shorter fatigue life is chosen as fatigue life of the weld joint. Failure position can be also estimated by this model. Evaluation results were compared with experimental data at elevated temperature, and it was shown that they agree well.

A Study on the Fatigue Behavior of Hot Dip Galvanized Steel Connections

2017 ◽  
Vol 754 ◽  
pp. 241-243 ◽  
Author(s):  
S.M.J. Razavi ◽  
M. Peron ◽  
F. Mutignani ◽  
J. Torgersen ◽  
F. Berto
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Structural Steel ◽  
Fatigue Behavior ◽  
Galvanized Steel ◽  
Central Hole ◽  
Practical Applications ◽  
Steel Connections ◽  
Good Agreement

The effect of a galvanizing coating on the fatigue strength of S355 structural steel is analyzed in detail showing that the decrease of the fatigue life is very limited if compared with that of uncoated joints and the results are in good agreement with Eurocode detail category, without substantial reductions. The procedure for the preparation of the specimens is systematically described in this note providing a useful tool for engineers involved in similar practical applications. The results are compared with previous data from notched galvanized specimens weakened by a central hole and not treated specimens characterized by the same geometry.

scholarly journals Effect of Oil – Corrosion on Tensile and Fatigue S-N Curve Properties of AA6061-T6

2021 ◽  
Vol 39 (3A) ◽  
pp. 407-414
Author(s):  
Hussain J.M. Al-Alkawi ◽  
Ghgada A. Aziz ◽  
Shmoos R. Mazel
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Corrosion Fatigue ◽  
Shot Peening ◽  
Fatigue Behavior ◽  
Surface Layers ◽  
Compressive Residual Stresses ◽  
Behavior Strength

The present study described the effect of shot peening on mechanical properties and rotating corrosion –fatigue behavior (strength and life) of AA6061-T6. Ultimate tensile strength (UTS) and yield stress (YS) were reduced by 4.6% and 1.24% when immersing the tensile samples in crude oil for 60 days. The values of (UTS) and (YS) were raised from 307 to 316 MPa and from 248 to 254 MPa respectively when treated for 10 min. shot peening (SP). Hardness of oil corrosion samples dropped due to pitting corrosion and slightly raised for SP prior to corrosion samples. Oil corrosion reduced the fatigue strength by (-1.25%). This percentage was enhanced due to SP to 2.377%. SP significantly increased the rotating fatigue life by a factor of 1.19 and 1.3 at (UTS) and (Ys) loads respectively. (SP) technique improved corrosion-fatigue resistance due to producing compressive residual stresses at surface layers.

scholarly journals Fatigue Life Improvement of Cracked Aluminum 6061-T6 Plates Repaired by Composite Patches

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1421
Author(s):  
Armin Yousefi ◽  
Saman Jolaiy ◽  
Reza Hedayati ◽  
Ahmad Serjouei ◽  
Mahdi Bodaghi
Keyword(s):  
Fatigue Life ◽  
Fatigue Behavior ◽  
Weight Ratio ◽  
High Strength ◽  
Plastic Strain Amplitude ◽  
Composite Patch ◽  
Life Improvement ◽  
Cracked Structures ◽  
Aluminum Plates ◽  
High Flexibility

Bonded patches are widely used in several industry sectors for repairing damaged plates, cracks in metallic structures, and reinforcement of damaged structures. Composite patches have optimal properties such as high strength-to-weight ratio, easiness in being applied, and high flexibility. Due to recent rapid growth in the aerospace industry, analyses of adhesively bonded patches applicable to repairing cracked structures have become of great significance. In the present study, the fatigue behavior of the aluminum alloy, repaired by a double-sided glass/epoxy composite patch, is studied numerically. More specifically, the effect of applying a double-sided composite patch on the fatigue life improvement of a damaged aluminum 6061-T6 is analyzed. 3D finite element numerical modeling is performed to analyze the fatigue performance of both repaired and unrepaired aluminum plates using the Abaqus package. To determine the fatigue life of the aluminum 6061-T6 plate, first, the hysteresis loop is determined, and afterward, the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted and validated against the available experimental data from the literature. Results reveal that composite patches increase the fatigue life of cracked structures significantly, ranging from 55% to 100% for different applied stresses.

Fatigue Characteristics of Composite Antenna Structure

2004 ◽  
Vol 261-263 ◽  
pp. 1109-1114
Author(s):  
Dong Hal Kim ◽  
W. Hwang ◽  
Hyun Chul Park ◽  
W.S. Park
Keyword(s):  
Fatigue Life ◽  
Satellite Communication ◽  
Fatigue Behavior ◽  
Load Level ◽  
Tangent Loss ◽  
Antenna Structure ◽  
Antenna Performance ◽  
Bending Fatigue Test ◽  
Structural Surface ◽  
Good Agreement

The objective of this work was to design Surface Antenna Structure (SAS) and investigate fatigue behavior of SAS that was asymmetric sandwich structure. This term, SAS, indicates that structural surface becomes antenna. Constituent materials were selected considering electrical properties, dielectric constant and tangent loss as well as mechanical properties. For the antenna performance, SSFIP elements inserted into structural layers were designed for satellite communication at a resonant frequency of 12.5 GHz and final demonstration article was 16 x 8 array antenna. In cyclic loading, flexure behavior was investigated by 4-point bending and 4-point bending fatigue test. Fatigue life curve of SAS was obtained. Experimental results were compared with single load level fatigue life prediction equations (SFLPEs) and in good agreement with SFLPEs. SAS concept is the first serious attempt at integration for both antenna and composite engineers.

scholarly journals Microstructural and Fracture Surface Study of Friction Stir Welded AA5082-AA7075 Butt Joints

2020 ◽  
Vol 5 (1) ◽  
pp. 49-56
Author(s):  
Gaurav Kumar ◽  
◽  
Rajeev Kumar ◽  
Ratnesh Kumar
Keyword(s):  
Tensile Strength ◽  
Fatigue Life ◽  
Fracture Surface ◽  
Microstructural Analysis ◽  
Butt Joints ◽  
Friction Stir ◽  
Three Samples ◽  
Mode Of Failure ◽  
Microstructural Behavior ◽  
Scanning Electron

In this study, experiments were performed to analyze the fracture surface and microstructural behavior of friction stir welded (FSW) AA5082-AA7075butt joints. Three samples at varying speeds and constant feed were prepared to identify optimum tool speed to produce FSW AA5082-AA7075 butt joints having maximum tensile strength and fatigue life. A scanning electron microscope (SEM) was used to analyze microstructure and fracture surfaces. The samples prepared exhibited a considerable difference in their fatigue life and tensile strength. Microstructural analysis showed the refinement of grains present in the stir zone (SZ), also known as the weld nugget, and thermo-mechanically affected zone (TMAZ). The study of the fracture surface showed that the mode of failure was ductile in nature

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