Computed Dependence of Rubber'S Fatigue Behavior on Strain Crystallization

2009 ◽  
Vol 82 (1) ◽  
pp. 51-61 ◽  
Author(s):  
W. V. Mars
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Behavior ◽  
Operating Conditions ◽  
Fatigue Threshold ◽  
Crack Growth Behavior ◽  
Fatigue Crack Nucleation ◽  
Nucleation Behavior ◽  
Wide Range

Abstract This work explores the consequences of strain crystallization on rubber's fatigue crack nucleation behavior over an extensive space of operating conditions, including tension and compression loading states, and relaxing and non-relaxing cycles. The study considers, via computation, how the nonlinear elastic stress-strain behavior, the fatigue crack growth characteristics, and the damage accumulation law combine to produce the Haigh diagram and the Cadwell diagram. Four hypothetical materials are studied, which differ in their crystallization and associated fatigue crack growth behavior. The calculations demonstrate that a relatively simple idealization can credibly predict the unique shape and sensitivities of observed fatigue behavior over a wide range of conditions. They also clarify how features of the Haigh and Cadwell diagrams are linked to the occurrence of crystallization and to parameters such as the power-law slope and the fatigue threshold.

Near-Threshold Fatigue Crack Growth Behavior of ECAPed Ultrafine-Grained Copper

2021 ◽  
Vol 1016 ◽  
pp. 1193-1198
Author(s):  
Shou Dao Qu ◽  
Ze Sheng You
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Threshold ◽  
Coarse Grained ◽  
Crack Growth Behavior ◽  
Fatigue Crack Growth Resistance ◽  
Ultrafine Grained ◽  
Stress Ratios ◽  
Near Threshold

Fatigue crack growth resistance of ultrafine grained Cu processed by equal channel angular pressing (ECAP) was investigated. Particular emphasis was devoted to the effects of microstructure evolution on fatigue crack growth in the near-threshold regime. The ultrafine grained Cu exhibits a lower fatigue threshold than coarse-grained Cu at stress ratios of 0.1 and 0.7. Fatigue induced coarsening of the UFG structure near the fatigue crack and intergranular fatigue crack growth are observed.

FINITELY SCOPED, HIGH RELIABILITY FATIGUE CRACK GROWTH MEASUREMENTS

2018 ◽  
Vol 91 (4) ◽  
pp. 644-650
Author(s):  
Joshua R. Goossens ◽  
William V. Mars
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
High Reliability ◽  
Time Budget ◽  
Rest Period ◽  
Operating Conditions ◽  
Test Time ◽  
Crack Growth Behavior ◽  
Strain Peak

ABSTRACT Classical procedures for characterizing fatigue crack growth behavior often suffer from uncertainties that make it difficult to plan for productive use of test instrument time, and that can result ultimately in too noisy measurements. An enhanced procedure has been implemented that is based on a fixed test time budget, and that establishes operating conditions that produce crack growth rates down to minimum measurable rates. The procedure features (1) a haversine pulse deformation test cycle followed by a rest period, (2) a strain peak that ramps linearly over time, (3) minimum and maximum limits on the strain peak chosen to avoid unproductive test time, and (4) a stress–strain probe cycle for purposes of observing strain energy density. A set of replicates of a carbon black filled, natural rubber bushing compound has been characterized via both procedures, and a statistical analysis is made to compare both. The new procedure significantly improves the quality of crack growth rate curve measurements.

scholarly journals Fatigue Crack Growth Behavior Evaluation of Grainex Mar-M 247 for NASA’s High Temperature, High Speed Turbine Seal Test Rig

2007 ◽  
Author(s):  
Irebert R. Delgado ◽  
Bruce M. Steinetz ◽  
Clare M. Rimnac ◽  
John J. Lewandowski
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Depth ◽  
Growth Behavior ◽  
Operating Conditions ◽  
Crack Growth Behavior ◽  
Fatigue Crack Growth Behavior ◽  
Inspection Interval ◽  
Bolt Holes

The fatigue crack growth behavior of Grainex Mar-M 247 is evaluated for NASA’s Turbine Seal Test Facility. The facility is used to test air-to-air seals for use primarily in advanced jet engine applications. Because of extreme seal test conditions of temperature, pressure, and surface speeds, surface cracks may develop over time in the disk bolt holes. An inspection interval is developed to preclude catastrophic disk failure by using experimental fatigue crack growth data. By combining current fatigue crack growth results with previous fatigue strain-life experimental work an inspection interval is determined for the test disk. The fatigue crack growth life of the NASA disk bolt holes is found to be 367 cycles at a crack depth of 0.501 mm using a factor of 2 on life at maximum operating conditions. Combining this result with previous fatigue strain-life experimental work gives a total fatigue life of 1032 cycles at a crack depth of 0.501 mm. Eddy-current inspections are suggested starting at 665 cycles since eddy current thresholds are currently at 0.381 mm. Inspection intervals are recommended every 50 cycles at maximum operating conditions.

Fatigue Crack Growth Behavior in Girth Weld of Natural Gas Transmission Pipelines

2007 ◽  
Vol 345-346 ◽  
pp. 303-306
Author(s):  
Young Pyo Kim ◽  
Cheol Man Kim ◽  
Woo Sik Kim ◽  
Kwang Seon Shin
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Natural Gas ◽  
Crack Growth ◽  
Arc Welding ◽  
Pipeline Steel ◽  
Crack Growth Behavior ◽  
Clear Understanding ◽  
Wide Range ◽  
Natural Gas Transmission

A clear understanding of fatigue properties for the pipeline steel and its weld is important to provide information for pipeline design during pipeline construction and predict pipeline fatigue life during pipeline operation. The materials used in this study are API 5L X65 pipeline steel generally used for natural gas transmission. This pipeline was welded by gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) with V-groove configuration. The fatigue crack growth behaviors of pipeline steel and its girth weld according to crack growth directions and stress ratios were investigated over a wide range of stress intensities in laboratory air.

Fatigue Crack Growth Behavior of High Manganese Austenitic TWIP Steels

2015 ◽  
Vol 833 ◽  
pp. 7-10
Author(s):  
Peng Hui Ma ◽  
Li He Qian ◽  
Jiang Ying Meng ◽  
Shuai Liu ◽  
Fu Cheng Zhang
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Deformation Mode ◽  
Fatigue Threshold ◽  
Stress Intensity Factor Range ◽  
Crack Growth Behavior ◽  
High Manganese ◽  
Three Point Bending ◽  
Twip Steels

Fatigue crack growth (FCG) behavior of three high manganese austenitic twin-induced plasticity (TWIP) steels with different stacking fault energy (SFE) was investigated, aiming at studying the correlation between the FCG resistance and the SFE of the steels. FCG tests were performed using three-point bending specimens at room temperature at stress ratio of 0.1 under the control of stress intensity factor range. Test results showed that the fatigue threshold values of these steels decrease with increasing the SFE. However, in the Paris regime, the crack growth rates of the steels do not appear to correlate directly with SFE. These results are discussed according to the degree of fatigue crack closure and the deformation mode of crack tip zone.

Fatigue Behavior of Notched Aluminum Plates Repaired by Smart and Composite Patches

2010 ◽  
Author(s):  
S. Mohammad Reza Khalili ◽  
Reza Eslami Farsani ◽  
Pasha Mojahedi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Behavior ◽  
Laminated Composite ◽  
Fatigue Loading ◽  
Experimental Results ◽  
Crack Growth Behavior ◽  
Mode I ◽  
Aluminum Plates

In this study, mode I fatigue crack growth behavior of single edge notched thin aluminum plates repaired with single side composite patches is investigated experimentally. Three patches are investigated in this analysis, 1- three layers carbon/epoxy laminated composite patch, 2- smart patches contained shape memory alloy (SMA) wires without pre-strain embedded in between the carbon/epoxy layers, and 3- smart patches contained SMA wires with pre-strain embedded in between the carbon/epoxy layers. The results are compared with the results obtained for un-repaired notched plate and the influence of SMA wires is also studied. The experimental results show a significant increase in crack growth life in all repaired plates compared with un-repaired plate. The repaired plates with smart pre-strained SMA patches show greater life as compared to other plates repaired by other patches. The three layers carbon/epoxy patches show better results compared to smart SMA un-strained patches. Also, numerical modeling is done by ANSYS software to obtain the stress intensity factor in mode I fatigue loading and then applied to Paris law for prediction of the fatigue crack growth life. The results are compared with the experimental results and a good agreement is obtained.

scholarly journals Fatigue Crack Growth Behavior Evaluation of Grainex Mar-M 247 for NASA’s High Temperature High Speed Turbine Seal Test Rig

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Irebert R. Delgado ◽  
Bruce M. Steinetz ◽  
Clare M. Rimnac ◽  
John J. Lewandowski
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Depth ◽  
Growth Behavior ◽  
Operating Conditions ◽  
Crack Growth Behavior ◽  
Fatigue Crack Growth Behavior ◽  
Inspection Interval ◽  
Bolt Holes

The fatigue crack growth behavior of Grainex Mar-M 247 is evaluated for NASA’s turbine seal test facility. The facility is used to test air-to-air seals primarily for use in advanced jet engine applications. Because of extreme seal test conditions of temperature, pressure, and surface speeds, surface cracks may develop over time in the disk bolt holes. An inspection interval is developed to preclude catastrophic disk failure by using experimental fatigue crack growth data. By combining current fatigue crack growth results with previous fatigue strain-life experimental work, an inspection interval is determined for the test disk. The fatigue crack growth life of NASA disk bolt holes is found to be 367cycles at a crack depth of 0.501mm using a factor of 2 on life at maximum operating conditions. Combining this result with previous fatigue strain-life experimental work gives a total fatigue life of 1032cycles at a crack depth of 0.501mm. Eddy-current inspections are suggested starting at 665cycles since eddy current detection thresholds are currently at 0.381mm. Inspection intervals are recommended every 50cycles when operated at maximum operating conditions.

Evaluation of the Fatigue Crack Growth Behavior by Experiments and Numerical Simulations on Full-Size Pipeline Steels

2018 ◽  
Author(s):  
Siham Hjiej ◽  
Nikolay Osipov ◽  
Adrien Lebrun ◽  
Clement Soret ◽  
Yazid Madi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Pipeline Steel ◽  
Fatigue Behavior ◽  
Crack Growth Behavior ◽  
Numerical Comparison ◽  
Pipeline Steels ◽  
Full Size

The safety of gas transportation pipelines under fatigue loading remains an important issue. The purpose of the present study is to better evaluate the fatigue crack growth (FCG) behavior by carrying out analysis/predictions and experiments in full-size pipeline steels. A full characterization was made using several samples of an X42 grade pipeline steel, to characterize the monotonic and the fatigue behavior. Fatigue tests on full-scale pipeline steels under pressure loading were performed. The potential drop (PD) method applied to pressurized pipes makes it possible to monitor and quantify both crack initiation and crack propagation. These tests served as a basis for numerical comparison. Crack propagation of the full-size pipeline steel was simulated by finit element analysis (FEA) using an adaptive re-meshing approach implemented as part of the Z-set/Zebulon software. Simulation allows predicting fatigue crack growth life on pipes using results of tests on specimens as an input.

Fatigue Crack Growth Behavior of Alloy 800H at Elevated Temperature

1991 ◽  
Vol 113 (3) ◽  
pp. 271-279 ◽  
Author(s):  
K. Y. Hour ◽  
J. F. Stubbins
Keyword(s):  
Fatigue Crack ◽  
High Temperature ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Alloy 800H ◽  
Low Frequencies ◽  
R Ratio ◽  
Wide Range

High temperature crack growth behavior is investigated over a wide range of R-ratios, frequencies, and temperatures in Alloy 800H. It is found that high R-ratio, low frequency, or high temperature can enhance creep damage and thus induce an intergranular crack growth mode. At low frequencies, the nonlinear fracture mechanics parameter, C*, is found to correlate time-dependent fatigue crack growth rate well if the applied mean stress is used in calculating C*. On the other hand, the Paris crack growth law using Keff is proven to be an adequate expression to use when fatigue (time-independent) damage dominates. These conclusions correlate well with damage mechanisms observed from sample fracture surfaces.

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