ENHANCING SINGLE-LAP COMPOSITE JOINTS LIFE ESTIMATION BY GRAPHENE ADDITION: AN HYBRID APPROACH ANALYSIS

2021 ◽  
Author(s):  
MILVIA O. REIS ◽  
LIDIANNE DE P. P. MAPA ◽  
UCHILLA G. LEÃO ◽  
THAIANE O. T. XIMENES, ◽  
ELVIS C. MONTEIRO ◽  
...  
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Hybrid Approach ◽  
Lap Joints ◽  
Uv Exposure ◽  
Cycle Fatigue ◽  
Life Estimation ◽  
Single Lap Joints ◽  
Finite Element Procedure

The hybrid formulation based on experimental data and the finite element procedure seems to be able to predict crack initiation under fatigue conditions for single lap joints aged by UV exposure. The UV exposure decreased stiffness and strength. The addition of graphene seems to postpone such ageing. However, by considering that cracks initiates when the (TS/σVM)~1. “Soft” adhesives can reach longer fatigue life at low loadings, while “stiff” adhesives have its fatigue life drastically decreased but at higher loadings. Stiff adhesives are more suitable for low cycle fatigue conditions, while for high cycle fatigue the option is a soft adhesive.

Low Cycle Fatigue Life of Type 316 Stainless Steel Notched Specimen Under Proportional and Non-Proportional Multiaxial Loadings

2010 ◽  
Author(s):  
Takamoto Itoh
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Strain Path ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Notched Specimen ◽  
Life Estimation ◽  
316 Stainless Steel ◽  
Strain Parameter ◽  
Strain Paths

This study discusses multiaxial low cycle fatigue life of notched specimen under proportional and non-proportional loadings at room temperature. Strain controlled multiaxial low cycle fatigue tests were carried out using smooth and circumferentially notched round-bar specimens of type 316 stainless steel. Four kinds of notched specimens were employed of which elastic stress concentration factors, Kt, are 1.5, 2.5, 4.2 and 6.0. The strain paths include proportional and non-proportional loadings. The former employed a push-pull straining or a reversed torsion straining. The latter was achieved by strain path where axial and shear strains has 90 degree phase difference but their amplitudes is the same based on von Mises’ criterion. The notch dependency of multiaxial low cycle fatigue life and the life estimation are discussed. The lives depend on both Kt and strain path. The strain parameter for the life estimation is also discussed with the non-proportional strain parameter proposed by the author with introducing Kt. The proposed parameter gives a satisfactory correlation with multiaxial low cycle fatigue life of notched specimen of type 316 stainless steel under proportional and non-proportional loadings.

scholarly journals Fatigue life time modelling of Cu and Au fine wires

2018 ◽  
Vol 165 ◽  
pp. 06002
Author(s):  
Golta Khatibi ◽  
Ali Mazloum-Nejadari ◽  
Martin Lederer ◽  
Mitra Delshadmanesh ◽  
Bernhard Czerny
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Load Ratio ◽  
Life Time ◽  
Material Model ◽  
Cycle Fatigue ◽  
Rate Dependency

In this study, the influence of microstructure on the cyclic behaviour and lifetime of Cu and Au wires with diameters of 25μm in the low and high cycle fatigue regimes was investigated. Low cycle fatigue (LCF) tests were conducted with a load ratio of 0.1 and a strain rate of ~2e-4. An ultrasonic resonance fatigue testing system working at 20 kHz was used to obtain lifetime curves under symmetrical loading conditions up to very high cycle regime (VHCF). In order to obtain a total fatigue life model covering the low to high cycle regime of the thin wires by considering the effects of mean stress, a four parameter lifetime model is proposed. The effect of testing frequency on high cycle fatigue data of Cu is discussed based on analysis of strain rate dependency of the tensile properties with the help of the material model proposed by Johnson and Cook.

Transition From Low Cycle to High Cycle in Uniaxial Fatigue

2013 ◽  
Author(s):  
Mohamed E. M. El-Sayed
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Uniaxial Stress ◽  
Life Assessment ◽  
Elastic Behavior ◽  
Cycle Fatigue ◽  
Fatigue Life Assessment ◽  
Component Development

Fatigue is the most critical failure mode of many mechanical component. Therefore, fatigue life assessment under fluctuating loads during component development is essential. The most important requirement for any fatigue life assessment is knowledge of the relationships between stresses, strains, and fatigue life for the material under consideration. These relationships, for any given material, are mostly unique and dependent on its fatigue behavior. Since the work of Wöhler in the 1850’s, the uniaxial stress versus cycles to fatigue failure, which is known as the S-N curve, is typically utilized for high-cycle fatigue. In general, high cycle fatigue implies linear elastic behavior and causes failure after more than 104 or 105 cycles. However. the transition from low cycle fatigue to high cycle fatigue, which is unique for each material based on its properties, has not been well examined. In this paper, this transition is studied and a material dependent number of cycles for the transition is derived based on the material properties. Some implications of this derivation, on assessing and approximating the crack initiation fatigue life, are also discussed.

Analysis on Torsional Fatigue Life of Turbo-Generator Shafts

2011 ◽  
Vol 467-469 ◽  
pp. 1858-1863 ◽  
Author(s):  
Yu Jiong Gu ◽  
Tie Zheng Jin
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Circuit Simulation ◽  
Short Circuit ◽  
Cycle Fatigue ◽  
Two Phase ◽  
Torsional Fatigue ◽  
Turbo Generator ◽  
The Impact

Both low-cycle fatigue and high-cycle fatigue exist during torsional vibrations, but the impact of high-cycle fatigue has rarely been considered. In this paper, a torsional fatigue life analyzing method used for torsional vibration of turbo-generator shafts has been developed based on Manson-Coffin equation and high-cycle fatigue theory. The method has been used to estimate the torsional fatigue life in the most dangerous section of the shafts in a power plant. The cumulative torsional fatigue damage under two-phase short circuit simulation has been predicted.

scholarly journals Research on the Fatigue Performance of TC6 Compressor Blade under the CCF Effect

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Zhang Yakui ◽  
Guo Shuxiang
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Compressor Blade ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Test Rig ◽  
Source Characteristics ◽  
Fracture Appearance ◽  
Fatigue Life Reduction

This paper studied the influence of high and low combined fatigue (CCF) on compressor blade fatigue performance. We investigated the coupling between low cycle fatigue (LCF) loading from centrifugal force with high cycle fatigue (HCF) loading from vibration and determined the blade disc vibration frequency using static analysis at maximum rotational speed. We designed and constructed a combined fatigue test rig, and CCF tests were performed on a TC6 compressor blade to analyze fatigue life characteristics. Results showed that CCF could significantly shorten blade life compared with pure LCF and that larger HCF caused more significant fatigue life reduction. Fatigue source characteristics and CCF fracture appearance were observed and analyzed using a scanning electron microscope (SEM).

Enhancing Fatigue Properties of Nanostructured Metals and Alloys

2007 ◽  
Vol 29-30 ◽  
pp. 117-122 ◽  
Author(s):  
Terry C. Lowe
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Computational Methods ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Metals And Alloys ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Nanostructured Metals ◽  
Improve Fatigue

Recent research on the fatigue properties of nanostructured metals and alloys has shown that they generally possess superior high cycle fatigue performance due largely to improved resistance to crack initiation. However, this advantage is not consistent for all nanostructured metals, nor does it extend to low cycle fatigue. Since nanostructures are designed and controlled at the approximately the same size scale as the defects that influence crack initiation attention to preexisting nanoscale defects is critical for enhancing fatigue life. This paper builds on the state of knowledge of fatigue in nanostructured metals and proposes an approach to understand and improve fatigue life using existing experimental and computational methods for nanostructure design.

scholarly journals Diesel Engine Crankshaft High Cycle Fatigue Life Estimation and Improvement Through FEA

2016 ◽  
Vol V5 (01) ◽  
Author(s):  
Mr. Suraj K. Kolhe ◽  
Mr. Amit Chaudhari ◽  
Mr. Prafull Ghare ◽  
Dr. J. V. L. Venkatesh ◽  
Keyword(s):  
Fatigue Life ◽  
Diesel Engine ◽  
High Cycle Fatigue ◽  
Cycle Fatigue ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Engine Crankshaft

Fatigue Performance of Low Rigidity Titanium Alloy for Biomedical Applications

2004 ◽  
Vol 449-452 ◽  
pp. 1265-1268
Author(s):  
Toshikazu Akahori ◽  
Mitsuo Niinomi ◽  
Hisao Fukui ◽  
Akihiro Suzuki
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Limit ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Tangential Force ◽  
Solution Treatment ◽  
Beta Phase ◽  
Fretting Fatigue ◽  
Cycle Fatigue

Microstructures of Ti-29Nb-13Ta-4.6Zr (TNTZ) aged at temperatures between 573 and 723 K after solution treatment at 1063 K have super fine omega phase, or􀀂 both super fine alpha and omega phases, respectively in beta phase with an average grain diameter of 20 µm. Plain fatigue strength of TNTZ aged after solution treatment is much greater than that of as-solutionized TNTZ in both low cycle fatigue and high cycle fatigue life regions. This is due to the improvement of the balance of strength and ductility by the precipitation of alpha phase. Fretting fatigue strength of TNTZ conducted with various heat treatments decreases dramatically as compared with their plain fatigue strength in both low cycle fatigue and high cycle fatigue life regions. In this case, the decreasing ratio of fretting fatigue life increases with increasing the small crack propagation area where both the tangential force and frictional force at the contact plane of pad exist. In fretting fatigue in air, the ratio of fretting damage (Pf/Ff), where Pf and Ff stand for plain fatigue limit and fretting fatigue limit, respectively, increases with increasing elastic modulus. In fretting fatigue in Ringer’s solution, the passive film on specimen surface is broken by fretting action in TNTZ, which have excellent corrosion resistance, and, as a result, corrosion pits that lead to decreasing fretting fatigue strength especially in high cycle fatigue life region, are formed on its surface.

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