Fatigue and Fretting of Mixed Metal Self-Piercing Riveted Joint

2014 ◽  
Author(s):  
Li Huang ◽  
John Lasecki ◽  
Haiding Guo ◽  
Xuming Su
Keyword(s):  
Crack Initiation ◽  
Failure Mode ◽  
Early Stage ◽  
Fatigue Behavior ◽  
Fretting Wear ◽  
Cyclic Tension ◽  
Micro Cracks ◽  
Riveted Joint ◽  
Crack Initiation Life ◽  
Tension Loading

The fatigue behavior of self-piercing riveting (SPR) joint, joining aluminum alloy 6111T4 and steel HSLA340 sheets with lapshear geometry was investigated in this paper. Sheet crack was the dominant failure mode, while unexpected rivet shank failure tended to occur under high loading level. Fretting wear was observed at interface of aluminum and steel layers, as well as at rivet and sheets under sinusoidal cyclic tension-tension loading. An energy dispersive X-ray (EDX) analysis of fretting debris revealed the presence of oxide of aluminum and zinc. Fretting was shown to be critical as crack initiation spot. In sheet failure mode, micro cracks were found to initiate at early stage, and crack initiation life was much shorter than crack growth life.

Fatigue Behavior of Circumferentially Notched Round Bars of Austenitic Stainless Steel Under Torsional and Axial Loads

2010 ◽  
Author(s):  
Masao Itatani ◽  
Keisuke Tanaka ◽  
Isao Ohkawa ◽  
Takehisa Yamada ◽  
Toshiyuki Saito
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Static Tension ◽  
Cyclic Torsion ◽  
Cyclic Tension ◽  
Crack Initiation Life

Fatigue tests of smooth and notched round bars of austenitic stainless steels SUS316NG and SUS316L were conducted under cyclic tension and cyclic torsion with and without static tension. Fatigue strength under fully reversed (R=−1) cyclic tension once increased with increasing stress concentration factor up to Kt=1.5, but it decreased from Kt=1.5 to 2.5. Fatigue life increased with increasing stress concentration under pure cyclic torsion, while it decreased with increasing stress concentration under cyclic torsion with static tension. From the measurement of fatigue crack initiation and propagation lives using electric potential drop method, it was found that the crack initiation life decreased with increasing stress concentration and the crack propagation life increased with increasing stress concentration under pure cyclic torsion. Under cyclic torsion with static tension, the crack initiation life also decreased with increasing stress concentration but the crack propagation life decreased or not changed with increasing stress concentration then the total fatigue life of sharper notched specimen decreased. It was also found that the fatigue life of smooth specimen under cyclic torsion with static tension was longer than that under pure cyclic torsion. This behavior could be explained based on the cyclic strain hardening under non-proportional loading and the difference in crack path with and without static tension.

scholarly journals Probabilistic Modeling of Slip System-Based Shear Stresses and Fatigue Behavior of Coarse-Grained Ni-Base Superalloy Considering Local Grain Anisotropy and Grain Orientation

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 813 ◽  
Author(s):  
Engel ◽  
Mäde ◽  
Lion ◽  
Moch ◽  
Gottschalk ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Test Data ◽  
Grain Orientation ◽  
Fatigue Behavior ◽  
Coarse Grained ◽  
Shear Stresses ◽  
Grain Sizes ◽  
Crack Initiation Life ◽  
Base Superalloy

New probabilistic lifetime approaches for coarse grained Ni-base superalloys supplement current deterministic gas turbine component design philosophies; in order to reduce safety factors and push design limits. The models are based on statistical distributions of parameters, which determine the fatigue behavior under high temperature conditions. In the following paper, Low Cycle Fatigue (LCF) test data of several material batches of polycrystalline Ni-base superalloy René80 with different grain sizes and orientation distribution (random and textured) is presented and evaluated. The textured batch, i.e., with preferential grain orientation, showed higher LCF life. Three approaches to probabilistic crack initiation life modeling are presented. One is based on Weibull distributed crack initiation life while the other two approaches are based on probabilistic Schmid factors. In order to create a realistic Schmid factor distribution, polycrystalline finite element models of the specimens were generated using Voronoi tessellations and the local mechanical behavior investigated in dependence of different grain sizes and statistically distributed grain orientations. All models were first calibrated with test data of the material with random grain orientation and then used to predict the LCF life of the material with preferential grain orientation. By considering the local multiaxiality and resulting inhomogeneous shear stress distributions, as well as grain interaction through polycrystalline Finite Element Analysis (FEA) simulation, the best consistencies between predicted and observed crack initiation lives could be achieved.

Fatigue and Fracture Behavior of MMC in the HCF- and VHCF-Regime

2014 ◽  
Vol 783-786 ◽  
pp. 1597-1602 ◽  
Author(s):  
Matthias Wolf ◽  
Guntram Wagner ◽  
Dietmar Eifler
Keyword(s):  
Crack Initiation ◽  
Base Alloy ◽  
Early Stage ◽  
Fatigue Behavior ◽  
Aluminum Matrix ◽  
Matrix Alloy ◽  
Dissipated Energy ◽  
Aluminum Matrix Composites ◽  
Initiation Point ◽  
The Matrix

Aluminum matrix composites (AMCs) are characterized by improved mechanical properties in comparison to their unreinforced matrix alloys. But the knowledge about the fatigue behavior of AMCs in the HCF-and in the VHCF-regime is limited until now. Due to this AMC225xe and AMC xfine225 with an average SiC particle content of 25 vol.-% and particle sizes of 2.5 μm and 0.7 μm, respectively, as well as the base alloy AA2124 were fatigued up to 1010 cycles using the ultrasonic testing facility of the type "UltraFast-WKK-Kaiserslautern".To describe the fatigue behavior of the specimens several measuring devices were used to monitor and record the central process parameters. A very sensitive value to detect specimen failure at an early stage is the dissipated energy which can be determined as the integral of the generator power depending on the ultrasonic pulse time.In comparison to AA2124 the investigated AMCs have shown a considerably enhanced fatigue performance for stress amplitudes higher than 140 MPa. But below this stress amplitude for the matrix alloy run outs at 1010 cycles were realized whereas the AMCs failed at lower number of cycles still at lower stress amplitudes. Moreover, while crack initiation of the matrix alloy in all cases started at the surface for the AMCs the crack initiation point changes from surface to subsurface for more than 107 cycles. The subsurface failures of the composites were caused by microstructural inhomogeneities which could be identified with EDX and micro-CT as particle clusters and copper-iron-rich inclusions.

Thermomechanical Fatigue Behavior of a Directionally Solidified Ni-Base Superalloy

2005 ◽  
Vol 127 (3) ◽  
pp. 325-336 ◽  
Author(s):  
M. M. Shenoy ◽  
A. P. Gordon ◽  
D. L. McDowell ◽  
R. W. Neu
Keyword(s):  
Crack Initiation ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Material Behavior ◽  
Directionally Solidified ◽  
Creep Tests ◽  
Physically Based ◽  
Estimation Scheme ◽  
Crack Initiation Life ◽  
Base Superalloy

A continuum crystal plasticity model is used to simulate the material behavior of a directionally solidified Ni-base superalloy, DS GTD-111, in the longitudinal and transverse orientations. Isothermal uniaxial fatigue tests with hold times and creep tests are conducted at temperatures ranging from room temperature (RT) to 1038°C to characterize the deformation response. The constitutive model is implemented as a User MATerial subroutine (UMAT) in ABAQUS (2003, Hibbitt, Karlsson, and Sorensen, Inc., Providence, RI, v6.3) and a parameter estimation scheme is developed to obtain the material constants. Both in-phase and out-of-phase thermo-mechanical fatigue tests are conducted. A physically based model is developed for correlating crack initiation life based on the experimental life data and predictions are made using the crack initiation model.

Evaluation of Fatigue Crack Initiation Life in a Press-Fitted Shaft Considering the Fretting Wear

2009 ◽  
Vol 33 (10) ◽  
pp. 1091-1098 ◽  
Author(s):  
Dong-Hyong Lee ◽  
Seok-Jin Kwon ◽  
Won-Hee You ◽  
Jae-Boong Choi ◽  
Young-Jin Kim
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Fretting Wear ◽  
Crack Initiation Life

Effect of Recrystallization on Low-Cycle Fatigue Behavior of DZ4 Directionally-Solidified Superalloy

2006 ◽  
Vol 306-308 ◽  
pp. 175-180 ◽  
Author(s):  
Hui Ji Shi ◽  
Hai Feng Zhang ◽  
Yan Qing Wu
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Grain Boundaries ◽  
Shot Peening ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Nickel Base Superalloy ◽  
Directionally Solidified ◽  
Crack Initiation Life

Effect of recrystallization on DZ4 directionally-solidified nickel-base superalloy was investigated both at room temperature and high temperature of 673K. In-situ SEM surface observation were performed. Experimental results reveal that the material performance is strongly influenced by surface recrystallization layer. All specimens were prepared under conditions of shot peening and 4h 1220°C high temperature annealing. Different shot peening pressure specimens have different recrystallization states. High shot penning pressure specimens have clear and straight grain boundaries and the grain size appears to be a little bit larger. Recrystallization state seems not only affect the fatigue life, but also the crack initiation pattern and crack initiation life. Low shot peening pressure specimens have much lower fatigue life which is around 8-10% of virgin one, and SEM Real-time observation reveals that channeling cracks initiated at the early stage of fatigue life. High shot peening pressure specimens have higher fatigue life comparing to low shot peening pressure specimens, although it’s almost half lower than the virgin one, and cracks initiated not until middle or latter stage of fatigue life. Crack initiation life is also much longer than those of low shot peening pressure. Low shot peening pressure specimens seems not fully recrystallized, and its grain boundaries are much fragile which is responsible for high density microcracks initiation, and finally leads to the failure. Further nano-indention experiments on surface recrystallized layers show that higher shot peening recrystallized layers have much lower elastic module, which may explain the longer crack initiation life.

Fatigue Life Prediction for Short Dents in Petroleum Pipelines

2002 ◽  
Author(s):  
Adam J. Rinehart ◽  
Peter B. Keating
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Crack Propagation ◽  
External Force ◽  
Life Prediction ◽  
Fatigue Behavior ◽  
Contact Region ◽  
Fatigue Cracking ◽  
Fatigue Life Prediction ◽  
Crack Initiation Life

Pipeline dent fatigue behavior has been shown to be strongly dependent upon dent length and external force dent restraint characteristics. Full-scale laboratory tests have shown that short dents that are unrestrained by an external force typically experience fatigue cracking in the dent periphery outside of the dent contact region. A fatigue life prediction method for short dents is presented here. In order to assess method accuracy, predictions are made for cases in which fatigue life has been measured experimentally. The predictions account for both crack initiation life and crack propagation life. Stress concentration values used in the predictions are determined using finite element modelling on a case-by-case basis for comparison purposes. Appropriate crack initiation life estimates, stress intensity factor predictions, and crack propagation models are taken from existing literature. Predicted and measured fatigue lives are compared for the cases studied.

Assessment Technology of Fatigue Crack Initiation Life of Weld Structures

2017 ◽  
Vol 86 (1) ◽  
pp. 56-58
Author(s):  
Seiichiro TSUTSUMI ◽  
Fincato RICCARDO ◽  
Mitsuru OHATA ◽  
Tomokazu SANO
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Assessment Technology ◽  
Crack Initiation Life
Sign in / Sign up

Export Citation Format

Share Document