Experimental investigation of the fatigue behavior of glass/epoxy composites evaluated by the stiffness degradation and damage accumulation

2018 ◽  
Vol 53 (6) ◽  
pp. 731-740 ◽  
Author(s):  
Walid Roundi ◽  
Abderrahim El Mahi ◽  
Abdellah El Gharad ◽  
Jean-Luc Rebiere
Keyword(s):  
Composite Laminates ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Matrix Cracking ◽  
Stiffness Degradation ◽  
Cyclic Behavior ◽  
Loading Level ◽  
Applied Loading ◽  
Number Of Cycles ◽  
Core Characteristics

The present paper deals with the mechanical behavior of glass/epoxy composite materials under static and cyclic tensile loading. The tested specimens have been made with different stacking sequences ([02/902]s; [902/02]s; [03/90]s; [903/0]s) according to the vacuum infusion procedure. The results of this investigation show the static behavior of the tested laminated composites characterized by the strain to failure, Young's modulus and tensile strength. Wöhler curves corresponding to each stacking sequence were plotted in order to observe the evolution of the maximum stress Smax according to the number of cycles. Fatigue Tests were performed under various applied loading levels ( r), and these values were chosen to evaluate the effect of loading level on the stiffness degradation and damage growth in the tested specimens. Afterward the evolution of the global damage factor ( D) according to the number of cycles was calculated in function of the core characteristics, applied loading level ( r) and type of loading. The cyclic behavior of the composite laminates mainly depends on the progressive developments of damage mechanisms such as matrix cracking, delamination, and fiber breakage.

Effect of Roller-Working on Fatigue Strength Improvement of Notched Structural Stainless Steel

2006 ◽  
Vol 306-308 ◽  
pp. 151-156
Author(s):  
Priyo Tri Iswanto ◽  
Shinichi Nishida ◽  
Nobusuke Hattori ◽  
Yuji Kawakami
Keyword(s):  
Plastic Deformation ◽  
Stainless Steel ◽  
Fatigue Limit ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Increase With Increase ◽  
Fatigue Strength Improvement ◽  
Rolled Specimen ◽  
Number Of Cycles

In order to study the effect of plastic deformation on fatigue behaviors of plastically deformed specimen, bending fatigue tests had been performed on notched deformed stainless steel specimens. Also pulsating fatigue tests were done on notched non-deformed specimens to evaluate the influence of mean stress on fatigue behavior of notched non-deformed specimens. The result showed that according to increase of deformation value, the fatigue limits of these specimens also significantly increase. Fatigue limit of rolled specimen does not linearly increase with increase in plastic deformation value. Based on fatigue limit diagram, the effect of compressive residual stress on fatigue limit improvement of stainless steel is higher than that of work-hardening. In case of non-deformed specimen, when the compressive mean stress increases, the fatigue limit and the number of cycles to failure increase. In case of tensile mean stress, this kind of mean stress decreases the fatigue limit.

A Multi-Station Rolling/Sliding Tribotester for Knee Bearing Materials

2004 ◽  
Vol 126 (2) ◽  
pp. 380-385 ◽  
Author(s):  
Douglas W. Van Citters ◽  
Francis E. Kennedy ◽  
John H. Currier ◽  
John P. Collier ◽  
Thomas D. Nichols
Keyword(s):  
Material Properties ◽  
Normal Load ◽  
Fatigue Behavior ◽  
Water Environment ◽  
Fatigue Tests ◽  
Test Environment ◽  
Normal Contact ◽  
Bearing Materials ◽  
Number Of Cycles

Total joint replacements traditionally employ ultra high molecular weight polyethylene (UHMWPE) as a bearing material due to its desirable material properties and biocompatibility. Failure of these polyethylene bearings can lead to expensive and risky revision surgery, necessitating a better understanding of UHMWPE’s tribological properties. A six-station rolling/sliding machine was developed to study the behavior of accelerated-aged UHMWPE in cylinder-on-cylinder contact. The normal load and sliding/rolling ratio in the oscillatory contacts can be controlled separately for each test station, as can the liquid test environment. Fatigue tests were run on the machine with UHMWPE versus cobalt-chrome cylinders in a distilled water environment at normal contact pressures of approximately 20 MPa. All specimens failed by subsurface cracking during tribotesting on the machine, and the failures were similar to those that occur in-vivo. The fatigue behavior of the polymer was analyzed to determine its relationship to oxidation and stress state in the rolling/sliding cylinder. At the 20 MPa test load, the number of cycles to fatigue failure by subsurface cracking was inversely proportional to the oxidation level. Analysis of the stress levels through the bulk of the polyethylene specimens and their relationship to the material properties provide insight as to why cracks initiate and propagate subsurface.

Experimental fatigue behavior of carbon/flax hybrid composites under tensile loading

2020 ◽  
pp. 002199832095490
Author(s):  
Mariem Ben Ameur ◽  
Abderrahim El Mahi ◽  
Jean-Luc Rebiere ◽  
Moez Beyaoui ◽  
Moez Abdennadher ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Hybrid Composites ◽  
Fatigue Behavior ◽  
Damping Ratio ◽  
Hysteresis Loops ◽  
Tensile Loading ◽  
Fatigue Tests ◽  
Dissipated Energy ◽  
Fiber Volume ◽  
Number Of Cycles

The aim of the present study is to investigate the mechanical behavior of carbon/flax hybrid composites under static and fatigue tensile loading. The failure characteristics and parameters used in the fatigue tests were deduced from the static ones. The effect of the applied stress level, hybridization and stacking sequences on the stiffness, hysteresis loops, dissipated energy and damping, were studied for a various number of cycles during fatigue tests. The Wohler S-N curves were constructed to investigate the effect of hybridization on the fatigue behavior. The results obtained show that the fatigue performance as well as the fatigue resistance increase with the increase of the volume fraction of carbon fiber. Nevertheless, the damping ratio and the fatigue life increase with the increase of the flax fiber volume fraction.

An Experimental Study on Low Cycle Fatigue of Inconel 617 Super Alloy

2006 ◽  
Vol 306-308 ◽  
pp. 163-168 ◽  
Author(s):  
Jae Hoon Kim ◽  
Duck Hoi Kim ◽  
Young Shin Lee ◽  
Young Jin Choi ◽  
Hyun Soo Kim ◽  
...  
Keyword(s):  
Strain Energy ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Fatigue Tests ◽  
Cyclic Behavior ◽  
Cycle Fatigue ◽  
Inconel 617 ◽  
Number Of Cycles ◽  
Cycles To Failure ◽  
Super Alloy

Low cycle fatigue tests are performed on the Inconel 617 super alloy that be used for structural material of hot gas casing for gas turbine. The relations between strain energy density and number of cycles to failure are examined in order to predict the low cycle fatigue life of Inconel 617 super alloy. The lives predicted by strain energy methods are found to coincide with experimental data and results obtained from the Coffin-Manson method. And, the cyclic behavior of the Inconel 617 super alloy is characterized by cyclic hardening with increasing number of cycles.

The Effect of Proof Loading on the Fatigue Behavior of Open Link Chain

1992 ◽  
Vol 114 (1) ◽  
pp. 27-33 ◽  
Author(s):  
S. M. Tipton ◽  
G. J. Shoup
Keyword(s):  
Fatigue Life ◽  
Residual Stresses ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Strain Gages ◽  
Applied Loading ◽  
Heat Treated ◽  
Strength Tests ◽  
Neuber's Rule ◽  
Failure Site

Open link lifting chain is routinely proof loaded during manufacture. However, the effect of residual stresses imposed by this operation on the fatigue strength of the chain has not been quantitatively investigated. This paper discusses the results of constant amplitude fatigue tests on open link chain segments which have received proof loading at various levels. The chain was initially heat treated to relieve manufacturing residual stresses and then proof loaded at levels ranging from 0 to 82 percent of its break strength. Tests were performed at two different mean loads and four different load amplitudes. Failure site trends are noted as a function of applied loading and are correlated with results of a finite element stress analysis. Residual stresses are estimated using strains measured from strain gages placed at critical locations on individual links during the proof load operation. Residual stress estimates are used with standard fatigue damage parameters to estimate the fatigue life of the chain and predictions are compared to data. Proof loading was shown to substantially increase the fatigue life of the chain. Residual stresses can explain the increase in fatigue life. Neuber’s rule demonstrated the ability to model the data trends.

scholarly journals Fatigue Behavior of Al 7075-T6 Plates Repaired with Composite Patch under the Effect of Overload

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2025
Author(s):  
Bel Abbes Bachir Bouiadjra ◽  
S. M. A. K. Mohammed ◽  
Faycal Benyahia ◽  
Abdulmohsen Albedah
Keyword(s):  
Crack Growth ◽  
Fatigue Behavior ◽  
Adhesive Layer ◽  
Fatigue Tests ◽  
Thin Plates ◽  
Composite Patch ◽  
Al 7075 ◽  
Number Of Cycles ◽  
Aluminum Alloy 7075 ◽  
Cycles To Failure

Repair of aeronautical structures by composite patch bonding has shown its effectiveness in several studies during the last few decades. This repair technique leads to a retardation in the propagation of repaired cracks via load bridging across the patch throughout the adhesive layer, interfacing it with the repaired structure. The purpose of this study is to analyze the behavior of patch-repaired cracks present in thin plates made of aluminum alloy 7075-T6 and subjected to a single tensile overload. The sequence of application of overload on the fatigue behavior was also studied. Fatigue tests were conducted on Al 7075-T6 notched specimens where crack growth and number of cycles to failure were monitored for different patching/overload scenarios. A detailed fractographic study was performed on failed specimens to analyze the micromechanical behavior of the crack growth related to each scenario. The obtained results showed that the application of the overload before bonding the patch leads to an almost infinite fatigue life of the repaired plates.

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