Fatigue Evaluation of 8630 Cast Steel Subjected to Post-Weld Heat Treatment and Stress Relieving

2014 ◽  
Author(s):  
Alireza Shirazi ◽  
Ihab Ragai
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Behavior ◽  
Cast Steel ◽  
Fatigue Tests ◽  
Filler Materials ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Stress Relieving ◽  
Weld Heat

The effect of post weld heat treating and stress relieving on the fatigue strength of AISI 8630 cast steel, weld repaired with different filler materials, is the primary objective of the study. To determine the material properties, experiments included monotonic tensile tests, load-controlled fatigue tests as well as hardness tests. Moreover, specimens were micro-etched to examine the morphology of the fracture surface. The results of the fatigue tests are presented in the form of S-N charts. The test findings are then employed in a generalized numerical solution to predict the fatigue behavior of similar components. Finite element models are used to calculate stresses in tested samples, stress concentrations, and in fatigue life comparisons. Stress-life predictions were performed using the modified Goodman criterion to account for the mean stress effects caused by the stress ratio R = 0.1 loading. Predictions based off of finite element analysis and analytical solution for fatigue life provided reasonable estimates which are confirmed by the experimental results.

Progressive fatigue behavior of single-lap bolted laminates under different tightening torque magnitudes

2020 ◽  
Vol 234 (10) ◽  
pp. 1303-1312
Author(s):  
M Feyzi ◽  
S Hassanifard ◽  
A Varvani-Farahani
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Behavior ◽  
Damage Model ◽  
Three Dimensional ◽  
Bolted Joints ◽  
Element Analysis ◽  
Damage And Failure ◽  
Experienced Fatigue ◽  
Three Dimensional Finite Element

The present paper studies fatigue damage and life of single-lap bolted joints tightened with different torque magnitudes subjected to uniaxial load cycles. The adherends were constructed from E-glass/epoxy layers using a hand layup technique and assembled by 1.5, 3, and 8 N m of applied torques. Increasing the torque magnitude benefitted the final fatigue life of the joints so that the high-cycle fatigue life of the joint sample tightened with 8 N m was as high as 10 times that of the joint tightened with 1.5 N m. In the numerical section of this study, a three-dimensional finite element analysis was employed, and the impacts of applied torques were included in the progressive damage model to assess damage and failure in the bolted joints. For the joints tightened with higher torque levels, numerical results revealed higher fatigue lives but at the cost of more delamination at the vicinity of the hole. Laminate fracture surface was investigated through scanning electron microscopy and more cracking/damage progress was evidenced in matrix, fiber, and matrix–fiber interface as composite joints experienced fatigue cycles. Experimental life data of tested joints agreed with those anticipated through the use of finite element analyses indicating the developed model as an appropriate tool in evaluating the effects of applied torques on the fatigue fracture behavior of bolted laminates.

Effect of different temperatures on the fatigue behavior of interference fitted plates of Al-alloy 7075-T6

2017 ◽  
Vol 233 (7) ◽  
pp. 1324-1335
Author(s):  
H Taghizadeh ◽  
TN Chakherlou
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Thermal Cycle ◽  
Fatigue Behavior ◽  
Three Dimensional ◽  
Fatigue Tests ◽  
Al Alloy ◽  
Interference Fit ◽  
Short Period ◽  
Different Temperatures

The effect of short time exposure to thermal cycle on the fatigue life of interference fitted fastener holes was evaluated by experimental and numerical method in Al-alloy 7075-T6. When interference fitted holes are subjected to temperature, the pre-stresses produced by interference fit may be considerably redistributed. To investigate the pre-stresses redistribution and its effect on the fatigue life of interference fitted specimens, two different temperatures (i.e. 60 ℃ and 120 ℃), apart from room temperature, were selected. The fatigue tests were performed to obtain S–N curves. Tangential pre-stress distribution was analyzed by the finite element method. Three-dimensional stress distributions of interference fit process have been determined around the hole at three temperatures: 25 ℃, 60 ℃, and 120 ℃. The finite element analyses justify the experimentally observed fatigue test behavior. The results show that the short period thermal cycle could improve the fatigue life of the prepared samples.

A Study on the Fatigue Life Prediction and Evaluation of the Natural Rubber Components for Automobile Vehicles

2006 ◽  
Vol 326-328 ◽  
pp. 589-592
Author(s):  
Chang Su Woo ◽  
Wan Doo Kim ◽  
Jae Do Kwon
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Natural Rubber ◽  
Fatigue Damage ◽  
Damage Parameter ◽  
Fatigue Tests ◽  
Element Analysis ◽  
Engine Mount ◽  
Lagrange Strain

The fatigue analysis and lifetime evaluation are very important in design procedure to assure the safety and reliability of the rubber components. The interest of the fatigue life of rubber components such as the engine mount is increasing according to the extension of warranty period of the automotive components. In this study, the fatigue lifetime prediction methodology of the vulcanized natural rubber was proposed by incorporating the finite element analysis and fatigue damage parameter determined from fatigue tests. Finite element analysis of 3D dumbbell specimen of natural rubber was performed based on a hyper-elastic material model determined from the tension, compression and shear tests. The Green-Lagrange strain at the critical location determined from the finite element analysis was used for evaluating the fatigue damage parameter of the natural rubber. Fatigue tests were performed using the 3D dumbbell specimens with different levels of maximum strain and various load. The basic mechanical properties test and the fatigue test of rubber specimens under the normal and elevated temperature were conducted. Fatigue life curves can be effectively represented by a following single function using the maximum Green-Lagrange strain. Fatigue lives of the natural rubber are predicted by using the fatigue damage parameters at the critical location. Predicted fatigue lives of the engine mount agreed fairly with the experimental fatigue lives a factor of two.

Fatigue Life Evaluation of Automotive Engine Mount Insulator

2008 ◽  
Vol 385-387 ◽  
pp. 649-652
Author(s):  
Chang Su Woo ◽  
Wan Doo Kim ◽  
Shin Hur
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Biaxial Tension ◽  
Material Model ◽  
Damage Parameter ◽  
Fatigue Tests ◽  
Element Analysis ◽  
Automotive Engine ◽  
Engine Mount ◽  
Lagrange Strain

Fatigue life of automotive engine mount insulator made of natural rubber was evaluated. In order to develop an appropriate fatigue damage parameter of the rubber material, a series of displacement controlled fatigue tests was conducted using 3-dimensional dumbbell specimens with different levels of mean displacement. It was shown that the maximum Green-Lagrange strain was a proper damage parameter, taking the mean displacement effects into account. Nonlinear finite element analyses of the rubber engine mount insulator and 3D dumbbell specimen were performed based on a hyper-elastic material model determined from the simple and equi-biaxial tension tests. Fatigue life prediction of the engine mount insulator was made by incorporating the maximum Green-Lagrange strain values, which was evaluated from the finite element analysis and fatigue tests, respectively. Predicted fatigue lives of the engine mount insulator showed a fairly good agreement with the experimental fatigue lives.

scholarly journals Retrofit Fatigue Cracked Diaphragm Cutouts Using Improved Geometry in Orthotropic Steel Decks

2020 ◽  
Vol 10 (11) ◽  
pp. 3983 ◽  
Author(s):  
Zhuo-Yi Chen ◽  
Chuan-Xi Li ◽  
Jun He ◽  
Hao-Hui Xin
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Cracks ◽  
Suspension Bridge ◽  
Geometrical Parameters ◽  
Stress Concentrations ◽  
Wheel Load ◽  
Element Analysis ◽  
Orthotropic Steel Decks ◽  
Stress Flow

Diaphragm cutouts are set to release redundant constraints and hence reduce weld fatigue at the connection of U-ribs to diaphragms in orthotropic steel decks. However, most fatigue cracks which originate from the edge of cutouts are in fact detected in the diaphragms. Therefore, a retrofit technology on cracked cutouts at the diaphragm is proposed and applied to the orthotropic steel box girder of a suspension bridge. Firstly, the stress concentration on the cutout is analyzed through refined finite element analyses. Furthermore, the fatigue cracked cutouts are retrofitted by changing their geometrical parameters. Thereafter, an optimized geometry and the size of diaphragm cutouts were confirmed and applied in the rehabilitation of a suspension bridge. On-site wheel load tests were carried out before and after retrofitting of the diaphragm cutout. The stress distributions along the edges of the cutouts and at the side of a diaphragm were measured under a moving vehicle. The stress spectra at two critical locations on the edge of a cutout was obtained under longitudinally and laterally moving vehicles. Finally, the fatigue life of the cutouts is assessed by the modified nominal stress method. The analytical and test results indicate that the wheel loads on the deck transmit stress to the diaphragms through the U-ribs, during the load transmission process, the stress flow is obstructed by diaphragm cutouts, resulting in local stress concentrations around the cutouts. In addition, the overall size of the cutouts should be small, but the radius of the transition arc should be large, thus the stress flow will not be obviously obstructed. After the retrofitting of the cutouts by improved geometry, the maximum stress decreases by 87.6 MPa, which is about 40% of the original stress. The equivalent constant amplitude stress is reduced by 55.2% when the lateral position of the wheel loads is taken into consideration. Based on the stresses obtained by finite element analysis (FEA) and experimental tests, the fatigue lives of the original cutouts are 1.7 and 4.9 years, respectively, which increase to 78.1 and 155.5 years, respectively, after the cutouts were retrofitted, which indicates that the improved geometry and retrofit technology can enhance the fatigue performance and extend the fatigue life of diaphragm cutouts with fatigue cracks.

Testing of In-Plane Shear Properties under Fatigue Loading

1995 ◽  
Vol 14 (9) ◽  
pp. 965-987 ◽  
Author(s):  
Larry B. Lessard ◽  
Olivia P. Eilers ◽  
Mahmood M. Shokrieh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
High Stress ◽  
Fatigue Loading ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Plane Shear ◽  
Shear Properties ◽  
Notched Specimens

A two-dimensional finite element analysis is performed in order to analyze and improve the performance of the three-rail shear test specimen as prescribed by the ASTM Standard Guide for testing of in-plane shear properties of composite laminates [1]. Of main interest is the location of high-magnitude stresses in the matrix direction that affect the fatigue life of the specimen. Through finite element analysis, the optimal specimen configuration is determined by inserting slots in the positions at which there are stress concentrations. This has the effect of transferring the location of high stress away from critical areas, thus increasing the fatigue life of the specimen. The results are verified by three-rail shear tests performed for both standard un-notched and new notched specimens. The notched specimens show great improvement in both static strength and fatigue life.

Analysis of Fatigue Life of SPR (Self-Piercing Riveting) Jointed Various Specimens Using FEM

2008 ◽  
Vol 580-582 ◽  
pp. 617-620 ◽  
Author(s):  
Bok Kyu Lim
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Behavior ◽  
Pure Shear ◽  
Automotive Application ◽  
Finite Element Models ◽  
Tensile Shear ◽  
Element Analysis ◽  
Shear Specimen ◽  
Cross Tension

Self-Piercing Riveting(SPR) is becoming an important joining technique for various material sheets and shapes, of automotive application. Fatigue behavior of SPR connections needs to be investigated experimentally and numerically to predict SPR fatigue lives. The simulations of various SPR specimens (Coach-Peel specimen, Cross-Tension specimen, Tensile-Shear specimen, Pure-Shear specimen) are performed to predict the fatigue life of SPR connections under different shape combinations. Finite element models of various SPR specimens are developed using a FEMFAT SPOT SPR pre-processor. The fatigue lives of SPR specimens are predicted using a FEMFAT 4.4e based on the linear finite element analysis.

Fatigue behavior of interference fitted Al-alloy 7075-T651 specimens subjected to bolt tightening

2018 ◽  
Vol 233 (9) ◽  
pp. 1879-1893
Author(s):  
H Taghizadeh ◽  
TN Chakherlou
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Test ◽  
Failure Modes ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Al Alloy ◽  
Clamping Force ◽  
Interference Fit ◽  
Test Behavior

Interference fit process is extensively used in bolted and pined joints having different fatigue behavior compared to plain hole specimens. In the present research, fatigue behavior of interference fitted specimens subjected to bolt clamping force has been investigated. The objective of the present study is to extend the present knowledge about the fatigue behavior of interference fitted holes by investigating the subsequent bolt clamping force effect based on the experimental and numerical results in Al-alloy 7075-T651 plates. To investigate the effect of bolt tightening on the fatigue life of interference fitted specimens two tightening torque levels were employed. Fatigue tests were performed to obtain S–N curves and failure modes of interference fitted bolt clamped specimens. Circumferential pre-stress distribution created by interference fit and bolt clamping has been analyzed by finite element method. The finite element analyses justify the experimentally observed fatigue test behavior. The fatigue test results demonstrate that bolt clamping force applied on interference fit plays a positive effect on fatigue behavior and prolongs the fatigue life.

Fatigue Assessment of “Corroded” Mooring Chain

2019 ◽  
Author(s):  
David A. Baker ◽  
Zhen Li ◽  
Sue Wang ◽  
Xiying Zhang ◽  
Yunliang Shao ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Test ◽  
Best Practice ◽  
Fatigue Testing ◽  
Fatigue Tests ◽  
Element Analysis ◽  
Cycle Count ◽  
Remaining Fatigue Life ◽  
Mooring Chain

Abstract Assessment of corroded mooring chain for continued service is a challenging task faced by industry. Current best practice relies heavily on qualitative inspection information collected during inspection campaign. There has been little investigation into this practice and whether it is an appropriate technique or can be improved. To address this issue, the Fatigue of Corroded Mooring Chains (FoCCs) Joint Industry Project (JIP), initiated in 2016 with fifteen (15) participating organizations, including oil majors, chain manufactures, consulting firms, and classification societies, to examine assessment methods for evaluating remaining fatigue life. JIP teams were formed to progress fatigue testing and finite element objectives. One such team, comprised of ExxonMobil, ABS and Asian Star Anchor Chain, has performed an additional series of fatigue tests beyond the core JIP work effort. A fatigue test was conducted to 1) demonstrate the utility of finite element analysis in the assessment of fatigue life and 2) demonstrate performance of simulated damage. This unique fatigue test program was conducted on mooring chain with manufactured “corrosion pits” of different dimensions. All chain surface features were digitally recorded and converted into finite element models. These models were subsequently analyzed to compare with test results — both cycle count and failure location. This paper presents the findings from these fatigue tests and finite element analyses and how they can be utilized for assessment of remaining fatigue life.

Effects of Shot-Peening on Fretting-Fatigue Behavior of Ti-6Al-4V

2002 ◽  
Vol 124 (2) ◽  
pp. 222-228 ◽  
Author(s):  
S. A. Namjoshi ◽  
V. K. Jain ◽  
S. Mall
Keyword(s):  
Fatigue Life ◽  
Shot Peening ◽  
Fatigue Behavior ◽  
Contact Region ◽  
Fretting Fatigue ◽  
Initiation Site ◽  
Fatigue Tests ◽  
Residual Tensile Stress ◽  
X Ray Diffraction ◽  
Element Analysis

The effects of shot-peening on the fretting fatigue behavior of titanium alloy, Ti-6Al-4V were investigated. Specimens were shot-peened as per AMS 2432 standard. X-ray diffraction analysis measured a maximum compressive stress of 800 MPa at the specimen surface, which reduced to zero at a depth of 188 μm. The compensatory residual tensile stress in the specimen was estimated using a curve fitting technique, the maximum value of which was found to be 260 MPa at a depth of 255 μm. Fretting fatigue tests were conducted at room temperature at a cyclic frequency of 200 Hz. Scanning electron microscopy of the shot-peened fretting fatigue specimens showed that the crack initiated at a point below the contact surface, the depth of which was in the range of 200–300 μm. Finite element analysis of the fretting fatigue specimens was also conducted. Fatigue life diagrams were established for the fretting fatigue specimens with and without shot-peening, and were compared to those under the plain fatigue condition, i.e. without fretting. Shot-peening improved the fretting fatigue life of Ti-6Al-4V; furthermore, it moved the crack initiation site from the fretting contact region to a region inside the specimen. Moreover, stress analysis showed that the fatigue failure of shot-peened specimens was caused by the compensatory tensile residual stress.

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