Fatigue Behavior of a Nanocomposite under a Fighter Aircraft Spectrum Load Sequence

2013 ◽  
Vol 24 ◽  
pp. 58-66 ◽  
Author(s):  
C.M. Manjunatha ◽  
Ramesh Bojja ◽  
N. Jagannathan
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Epoxy Matrix ◽  
Fatigue Behavior ◽  
Crack Density ◽  
Load Spectrum ◽  
Fighter Aircraft ◽  
Matrix Cracks ◽  
The Matrix ◽  
Load Sequence

Two different E-glass fiber reinforced plastic (GFRP) composite laminates having quasi isotropic [(+45/-45/0/90)2]S layup sequence were fabricated viz., GFRP with neat epoxy matrix (GFRP-neat) and GFRP with modified epoxy matrix (GFRP-nano) containing 9 wt. % of CTBN rubber micro-particles and 10 wt.% of silica nanoparticles. Standard fatigue test specimens were machined from the laminates and end-tabbed. Spectrum fatigue tests under a standard fighter aircraft load spectrum, mini-FALSTAFF, were conducted on both the composites at various reference stress levels and the experimental fatigue life expressed as number of blocks to fail, were determined. The stiffness of the specimen was determined from the load-displacement data acquired at regular intervals during the fatigue test. The matrix cracks development in the test specimens with fatigue cycling was determined through optical photographic images. The fatigue life of GFRP-nanocomposite under mini-FALSTAFF load sequence was observed to be enhanced by about four times when compared to that of GFRP-neat composite due to presence of micro-and nanoparticles in the matrix. The stiffness degradation rate and matrix crack density was considerably lower in GFRP-nanocomposite when compared to that of GFRP-neat composite. The underlying mechanisms for improved fatigue performance of GFRP-nanocomposite are discussed.

scholarly journals Improved numerical model for fatigue cumulative damage of mechanical structure considering load sequence and interaction

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199530
Author(s):  
Bixiong Huang ◽  
Shuci Wang ◽  
Shuanglong Geng ◽  
Xintian Liu
Keyword(s):  
Fatigue Life ◽  
Theoretical Basis ◽  
Life Prediction ◽  
Damage Model ◽  
Cumulative Damage ◽  
Load Spectrum ◽  
Random Load ◽  
Mechanical Parts ◽  
Proposed Model ◽  
Load Sequence

To more accurately predict the fatigue life of components under the action of random loads, it is necessary to explore the influence of the interaction between the load sequence and the load on the life prediction. Based on the Manson-Halford method and Corten-Dolan model, this paper establishes a fatigue cumulative damage model that takes into account both the load order and the interaction between loads, and also takes into account the loads near the fatigue limit. The fatigue life of mechanical parts under random load can be calculated through this model, which provides a theoretical basis for life prediction under random load spectrum. The fatigue life of mechanical parts under random load can be calculated through this model, which provides a theoretical basis for life prediction under random load spectrum. Comparing the calculation results of the proposed model with the results of Palmgren Miner, Manson-Halford method, and Corten-Dolan model, it is found that the fatigue damage model established can reasonably predict the fatigue life of parts. Comparison and verification of examples further prove the accuracy and reliability of the proposed model.

Improvement of Fatigue Strength and Impact Properties of Plain-Woven CFRP Modified with Micro Fibrillated Cellulose

2008 ◽  
Vol 47-50 ◽  
pp. 133-136 ◽  
Author(s):  
Norifumi Takagaki ◽  
Kazuya Okubo ◽  
Toru Fujii
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Carbon Fiber ◽  
Impact Load ◽  
Static Fatigue ◽  
Test Results ◽  
Static Properties ◽  
Impact Properties ◽  
Matrix Cracks ◽  
The Matrix

This study investigated the effect of the enhancement by addition of Micro Fibrillated Cellulose (MFC) on the static, fatigue and impact properties of plain-woven CFRP. Test results showed that the addition of MFC little contributed to the improvement of static properties. However, the initiation of matrix cracks between woven carbon fiber cloths was prevented under cyclic loading so that the fatigue life of the CFRP was improved by the modification with MFC. The ductility of plain-woven CFRP was also acquired under impact load by the addition of the MFC to the matrix.

Fatigue life of a carbon fiber composite T-joint under a standard fighter aircraft spectrum load sequence

2015 ◽  
Vol 127 ◽  
pp. 260-266 ◽  
Author(s):  
M.M. Thawre ◽  
K.N. Pandey ◽  
A. Dubey ◽  
K.K. Verma ◽  
D.R. Peshwe ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Carbon Fiber ◽  
Fiber Composite ◽  
Carbon Fiber Composite ◽  
Fighter Aircraft ◽  
Load Sequence

scholarly journals Experimental and theoretical evidence for the load sequence effect in the compressive fatigue behavior of concrete

2021 ◽  
Vol 54 (2) ◽  
Author(s):  
Abedulgader Baktheer ◽  
Rostislav Chudoba
Keyword(s):  
Fatigue Life ◽  
Energy Dissipation ◽  
Cyclic Loading ◽  
Fatigue Behavior ◽  
Fatigue Loading ◽  
Theoretical Explanation ◽  
Life Assessment ◽  
Efficient Design ◽  
Sequence Effect ◽  
Load Sequence

AbstractA realistic prediction of the concrete fatigue life exposed to high-cycle loading scenarios with variable amplitudes is of utmost importance for a reliable and economically efficient design of civil engineering infrastructure for transport and energy supply. Current design codes estimate the fatigue life under variable amplitudes using the Palmgren–Miner rule, which assumes a linear scaling between lifetimes measured for uniform cyclic loading scenarios. Several experimental series conducted in the past, however, indicate that this assumption is not valid and that it may lead to unsafe design. In this paper, an experimental and theoretical investigations of the fatigue loading sequence effect in normal- and high-strength concrete behavior are presented, which confirm this observation. In particular, a test campaign with 135 cylinder specimens, including three concrete grades and six different loading scenarios has been conducted. Several response characteristics of the fatigue behavior including Wöhler curves, fatigue creep curves and evolving shapes of hysteretic loops have been evaluated. To substantiate the experimental results, a theoretical explanation of the observed sequence effect is formulated based on the assumption, that energy is dissipated uniformly within the volume of a test specimen during subcritical, compressive cyclic loading. Then, superposition of energy dissipation profiles along the lifetime measured for constant amplitudes becomes possible and a theoretical justification of the experimentally observed sequence effect can be provided. Moreover, a reverse sequence effect reported in the literature for bending fatigue of concrete can then be explained by an unevenly distributed energy dissipation over a cracked specimen. Supported by the theoretical consideration, the processed experimental data is used to validate existing fatigue life assessment rules by testing their ability to reflect the load sequence effect.

PREDICTION OF NUMBER OF CYCLES FROM FATIGUE TEST CONDITIONS AND TRANSVERSE CRACK DENSITY OF CFRP CROSS-PLY LAMINATES

2021 ◽  
Author(s):  
YOUZOU KITAGAWA ◽  
KOTARO HIRAIWA ◽  
MASAHIRO ARAI ◽  
AKINORI YOSHIMURA ◽  
KEITZ GOTO
Keyword(s):  
Fatigue Test ◽  
Transverse Crack ◽  
Crack Density ◽  
Stiffness Degradation ◽  
Remaining Life ◽  
Transverse Cracks ◽  
Cfrp Laminates ◽  
Matrix Cracks ◽  
Test Conditions ◽  
Number Of Cycles

In the present paper, we proposed a methodology that can predict the number of applied load cycles in tension-tension fatigue test of CFRP laminates from microscopic damages and test conditions. It is difficult to predict the fracture of CFRP laminates and to estimate the remaining life of CFRP laminates for ensuring the long-term reliability of the CFRP components because the fracture process of CFRP laminates is quite complex. The damage process of CFRP consists of various microscopic damage such as matrix cracks, fiber/matrix interfacial debondings, delamination and so on. In order to quantitatively estimate the remaining life of CFRPs, we focused on the degree of the microscopic damages and relate that to the remaining life of them. The tension-tension fatigue tests of CFRP cross-ply laminates were carried out, and we suspended the tests at arbitrary cycles. When the tests were suspended, we counted the number of transverse cracks occurred on the specimens by a replica method, and measured the stiffness degradation of the specimens. We formulated an equation that can predict the stiffness degradation using fatigue test conditions. The predicted stiffness degradation to the number of cycles using the formula agreed well with the experimental results. The result demonstrated that the formula can predict the number of subjected cycles from fatigue test conditions and transverse crack density.

An Evaluation of Fatigue Damage in Low-Cycle Range for Sn-3.5Ag, Sn-0.7Cu Lead-Free Solders and Sn-Pb Eutectic Solder Using Image Processing to Surface Feature

2005 ◽  
Author(s):  
Takehiko Takahashi ◽  
Susumu Hioki ◽  
Ikuo Shohji ◽  
Osamu Kamiya
Keyword(s):  
Image Processing ◽  
Fatigue Life ◽  
Fatigue Test ◽  
Surface Deformation ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Lead Free ◽  
Cycle Fatigue ◽  
Surface Features ◽  
Lead Free Solders

The low-cycle fatigue behavior of Sn-3.5mass%Ag, Sn-0.7mass%Cu lead-free solders and Sn-37mass%Pb solder were investigated at strain rate of 0.1%/s with a non-contact extensometer at room temperature (22 ± 3 °C). In addition, the relationship between the surface features in the low-cycle fatigue test and the fatigue life of those solders were investigated by image processing. The fatigue lives of Sn-3.5mass%Ag and Sn-0.7mass%Cu were better than that of Sn-37mass%Pb. The low-cycle fatigue behavior on each solder followed Coffin-Manson equation. The surface deformation in fine wrinkles was observed in the low-cycle fatigue test at each solder. The surface features for each solder were evaluated by image processing from the surface deformation. The surface features in the low-cycle fatigue test did not appear until under 10% of the fatigue life for Sn-3.5mass%Ag, until 10% of the fatigue life for Sn-0.7mass%Cu, and until 20% of the fatigue life for Sn-37mass%Pb.

Study on Weld Fatigue Evaluation Under Sour Service Environment Using Battelle Structural Stress Method

2013 ◽  
Author(s):  
Jeong K. Hong ◽  
Thomas P. Forte
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Fatigue Behavior ◽  
Structural Stress ◽  
Loading Conditions ◽  
Test Results ◽  
Knock Down ◽  
Weld Toe ◽  
Weld Fatigue ◽  
Sour Service

Risers, pipelines and flowlines for deep water applications are subject to corrosive environments. Especially, in the presence of hydrogen sulfide which makes the field sour, their fatigue performance becomes significantly degraded. In order to quantify the sour degradation effect, a knock-down factor has been introduced. This factor is defined as the fatigue life reduction relative to the in-air fatigue life. Several sets of fatigue test results in sour service environments have been published. These include strip specimens of different sizes, e.g., diameters, wall thicknesses, and arc lengths. Naturally, the knock-down factor must be based upon a statistically valid number of fatigue test results obtained from the same specimen geometry and the same loading conditions tested in air and in sour conditions. Currently, the database available in the open literature is too limited to properly define a knock-down factor. Moreover, there is a great deal of scatter within the database and each test in a sour environment is costly and time consuming. Thus, it is difficult to establish a statistically valid database upon which to base the knock-down factor. A mesh-insensitive structural stress method has been developed by Battelle researchers and has been proven to be highly effective in correlating the fatigue behavior of welded joints. In 2007, the Battelle structural stress based weld fatigue master S-N curve was included in ASME Section VIII Div. 2 because it successfully consolidated more than 800 fatigue test results for weld toe failures onto a single master S-N curve with very little scatter, regardless of specimen shape, size, loading type, and steel alloy [1–2]. A knock-down factor is derived by applying the Battelle structural stress method to the existing database for sour environment tests and by using the current in-air database as the reference condition. This approach will reduce the uncertainty in the knock-down factor because it allows a wider range of sour environment data from specimens of different sizes, types, and loading conditions to be combined, while simultaneously reducing scatter. As such, a unified knock-down factor can be determined with greater statistical validity and wider applicability for design recommendations in sour conditions.

Large versus Small Grain Sizes on Fatigue Life of Aluminum Aircraft Wheels

2019 ◽  
Vol 391 ◽  
pp. 174-194 ◽  
Author(s):  
Fahad Alzubi ◽  
Mark Timko ◽  
Yong Jun Li ◽  
Ray Toal ◽  
Kelly Tovalin ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Microstructural Analysis ◽  
Cycle Fatigue ◽  
Sem Images ◽  
Stress Levels ◽  
Bending Fatigue Test ◽  
Rotating Bending Fatigue

The high cycle fatigue behavior of an aluminum alloy of small and large grains was investigated. Samples of small and large grains were provided as rotating bending fatigue test specimens. The samples were tested at eight different stress levels from 103 MPa (15 ksi) to 345 MPa (50 ksi) with a 34 MPa (5 ksi) increase at each level. As-received samples were evaluated for optical microstructural analysis. Scanning electron microscopy (SEM) images were used to evaluate the fractured surface of several samples. High cycle fatigue S-N curves were generated. The fatigue test results showed that grain size has a strong influence on the fatigue life. The high cycle fatigue S-N curves of small grains showed better fatigue life as compared to large grains in the lower stress levels. At higher stresses, the situation was reversed.

scholarly journals LEVERAGE OF CIGARETTE ASH POWDER CONCENTRATIONS ON THE ALTERNATING BENDING FATIGUE OF UNSATURATED POLYESTER RESIN

2020 ◽  
Vol 8 (11) ◽  
pp. 675-682
Author(s):  
Edrees E. Al-Obeidi ◽  
◽  
Mohammed Mahmoud Uonis ◽  
Mohammed A. Al-Jubouri ◽  
◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Behavior ◽  
Unsaturated Polyester ◽  
Natural Fibers ◽  
Weight Fraction ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Powder Concentration ◽  
The Matrix ◽  
Cigarette Ash

The present work, describes an attempt was made to study the effect of cigarette ash powder concentration,on the micro hardness and alternative bending fatigue behavior of unsaturatedpolyester resin reinforced with various weight fractions of cigarette ash powder (1.25, 3.7, 4.9 Wt. %), which is natural fibers form. The preparation of the composites was achieved using hand lay-up process. During the test, fatigue tests were used by applying a stress ratio sinusoidal wave (R= -1), which is believed to give a marginal increase in temperature. The effects of the fatigue life of the test composites are determined using the stress curves (S) number of cycles (N) (S − N).The results showed that the fatigue life of the composite being produced depends on the percentage of fractions of weight. This findings also shows an increase in fatigue age by four times longer for the weight fraction of (1.25 wt. %) and more than two for cigarette ash powder (3.7 wt. %). The higher weight fraction (4.9 wt. %) of cigarette ash powder, reduced the fatigue life lower than the matrix behavior. Increasing percentage weights of cigarette ash powder increases the toughness measured by hardness for all composites.

scholarly journals Fatigue Behavior of an Al-12.7Si-0.7Mg Alloy Processed by Extrusion and Heat Treatment

2021 ◽  
Vol 8 ◽  
Author(s):  
Fang Liu ◽  
Fuxiao Yu ◽  
Dazhi Zhao ◽  
Li Gao
Keyword(s):  
Heat Treatment ◽  
Fatigue Life ◽  
Tensile Properties ◽  
Fatigue Test ◽  
Fatigue Behavior ◽  
Fatigue Property ◽  
Hot Extrusion ◽  
Refined Microstructure ◽  
Equiaxed Grains ◽  
Al Matrix

The fatigue life of a hot extruded Al-12.7Si-0.7Mg alloy under T1, T4, and T6 conditions was studied. The microstructure and tensile properties of the alloy were investigated in order to analyze the fatigue behavior. The results of the fatigue test showed that an extruded Al-12.7Si-0.7Mg alloy provided greater fatigue life compared to a cast Al-Si alloy, which was explained by the refined microstructure characterized by fine Si particles uniformly distributed in the Al matrix of fine equiaxed grains promoted by hot extrusion. The fatigue property of the alloy in T6 treatment was higher than that in the T4 and T1 conditions due to strengthening precipitation.

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