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.

Fatigue Behavior and Damage Assessment of Stainless Steel/Aluminum Composites

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Volkan Eskizeybek ◽  
Ahmet Avci ◽  
Ahmet Akdemir ◽  
Ömer Sinan Şahin
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
Fatigue Behavior ◽  
Laminated Composite ◽  
Strain Energy Release ◽  
Fatigue Loading ◽  
304 Stainless Steel

Fatigue crack growth and related damage mechanisms were investigated experimentally in a stainless steel/aluminum laminated composite with middle through thickness crack, and two different fracture mechanics approaches applied to the composite to reveal their differences under fatigue loading. The laminated composite material, which has a unidirectional continuous AISI 304 stainless steel as fibers and Al 1060 as matrix, was produced by using diffusion bonding. Fatigue tests were conducted in accordance with ASTM E 647. The relationships between fatigue crack growth rate (da/dN), stress intensity factor (ΔK), and strain energy release rate (ΔG) were determined; and damage behavior was discussed. Both linear elastic fracture mechanics (LEFM) and compliance method were used, and the results were compared with each other. It is found that as the crack propagates, the LEFM overestimates the ΔG values. Interlaminar and fiber/matrix interface damage were evaluated by fractographic examination.

scholarly journals Investigation of Fatigue Crack Growth in Full-Scale Railway Axles Subjected to Service Load Spectra: Experiments and Predictive Models

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1427
Author(s):  
Amir Pourheidar ◽  
Luca Patriarca ◽  
Stefano Beretta ◽  
Daniele Regazzi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Behavior ◽  
Full Scale ◽  
Experimental Results ◽  
Residual Lifetime ◽  
Crack Growth Behavior ◽  
Load Spectra ◽  
Life Predictions

In this paper, a series of experimental investigations was performed on full-scale railway axles to analyze the fatigue crack growth behavior of EA4T steel under load spectrum derived from real operating conditions. The experimental results were compared to life predictions carried out adopting two models: (i) the conventional Nasgro equation and (ii) the cyclic R-curve concept implemented in the Modified Nasgro equation for describing the crack growth behavior of an arbitrary crack length. The results show that the life predictions performed by means of the Modified Nasgro equation coincide well with the experimental results with an underestimation of the residual lifetime less than 32%, while the traditional Nasgro equation leads to significant overestimation (≈120%) of the residual lifetime for load spectra close to the in service scenario.

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.

scholarly journals Fatigue Crack Growth Behavior of PWA 1484 Single Crystal Superalloy at Elevated Temperatures

1995 ◽  
Author(s):  
Jack Telesman ◽  
Louis J. Ghosn
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Driving Force ◽  
Narrow Band ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Mode I ◽  
Fatigue Crack Growth Behavior ◽  
Crack Driving Force

A study was done to determine the fatigue crack growth behavior of a PWA 1484 single crystal nickel base superalloy in a temperature range of 427°C to 871°C. Two distinctive failure modes were observed which were a function of both temperature and frequency. At lower temperatures and higher frequencies crack growth occured on the {111} octahedral slip planes at an oblique angle to the loading direction. Higher temperatures and decrease in frequencies favored a Mode I type failure process. The failure mode transitions were explained by invoking arguments based on environmental damage mechanisms. The fatigue crack growth rate data were analyzed using three different crack driving force parameters. The parameters investigated consisted of the Mode I stress intensity parameter corrected for the inclined crack trajectory, and two different octahedral Mode II parameters which are based on the calculation of resolved shear stresses on the {111} slip systems. The Mode I ΔK parameter did a fair job in correlating the data but did not collapse it into a single narrow band. The two octahedral crack driving force parameters, ΔKRSS and a newly proposed ΔKOCT, collapsed all the data into a single narrow band. In addition to correlating the fatigue crack growth rates, the two octahedral parameters also predicted the {111} planes on which the crack growth took place.

Fatigue Crack Growth Behavior of PWA 1484 Single Crystal Superalloy at Elevated Temperatures

1996 ◽  
Vol 118 (2) ◽  
pp. 399-405 ◽  
Author(s):  
J. Telesman ◽  
L. J. Ghosn
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Driving Force ◽  
Narrow Band ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Mode I ◽  
Crack Driving Force ◽  
Loading Direction

A study was done to determine the fatigue crack growth behavior of a PWA 1484 single-crystal nickel-base superalloy in a temperature range of 427°C to 871°C. Two distinctive failure modes were observed, which were a function of both temperature and frequency. At lower temperatures and higher frequencies crack growth occurred on the {111} octahedral slip planes at an oblique angle to the loading direction. Higher temperatures and decrease in frequencies favored angle to the loading direction. Higher temperatures and decrease in frequencies favored a Mode I type failure process. The failure mode transitions were explained by invoking arguments based on environmental damage mechanisms. The fatigue crack growth rate data were analyzed using three different crack driving force parameters. The parameters investigated consisted of the Mode I stress intensity parameter corrected for the inclined crack trajectory, and two different octahedral Mode II parameters, which are based on the calculation of resolved shear stresses on the {111} slip systems. The Mode I ΔK parameter did a fair job in correlating the data but did not collapse it into a single narrow band. The two octahedral crack driving force parameters, ΔKRSS and a newly proposed ΔKOCT, collapsed all the data into a single narrow band. In addition to correlating the fatigue crack growth rates, the two octahedral parameters also predicted the {111} planes on which the crack growth took place.

Sign in / Sign up

Export Citation Format

Share Document