FATIGUE PERFORMANCE OF CLAY-EPOXY NANOCOMPOSITES

2005 ◽  
Vol 04 (04) ◽  
pp. 501-507 ◽  
Author(s):  
ARIADNE JUWONO ◽  
GRAHAM EDWARD
Keyword(s):  
Fatigue Life ◽  
Epoxy Resin ◽  
Failure Mechanism ◽  
Strain Amplitude ◽  
Polymer Matrix ◽  
Critical Strain ◽  
Layered Silicates ◽  
Fatigue Properties ◽  
Curing Agent ◽  
Xrd And Tem

This paper presents an investigation of the possibility of improving the fatigue properties of an epoxy resin through dispersion of modified layered silicates within the polymer matrix. Montmorillonite-epoxy nancocomposites were successfully synthesized with a commercially available 1-Methylimidazole curing agent. The morphology of these materials was investigated by XRD and TEM. The findings demonstrated a pattern of clay morphology typically found in nanocomposite systems. Four point loading measurements showed an increase in modulus for 2.5 wt% and 10 wt% clay contents when compared to the unfilled epoxy, whereas the moduli showed a decrease for 5 wt% and 7.5 wt% clay contents. This behavior is typical for most particulate-filled systems. Fracture surfaces were examined using an E-SEM. The failure mechanism of the nanocomposites varied from that of the unfilled epoxy. Below a critical strain amplitude, the fatigue life of the filled epoxy improved significantly compared to that of the unfilled epoxy. In conclusions, the addition of silicates changes the fatigue failure mechanism and improves significantly the fatigue life.

Fatigue Behavior of Ferritic-Pearlitic-Bainitic Steel – Effect of Positive Mean Stress

2009 ◽  
Vol 417-418 ◽  
pp. 577-580
Author(s):  
Jaroslav Polák ◽  
Martin Petrenec
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Strain Amplitude ◽  
Fatigue Behavior ◽  
Cyclic Creep ◽  
Plastic Strain Amplitude ◽  
Fatigue Properties ◽  
Mean Stress ◽  
Bainitic Steel ◽  
The Mean

The fatigue properties of ferritic-pearlitic-bainitic steel using specimens produced from massive forging were measured in stress controlled regime with positive mean stress. The cyclic creep curves and cyclic hardening/softening curves were evaluated. The fatigue life was plotted in dependence on the mean stress and on the plastic strain amplitude. The principal contribution to the drop of the fatigue life with the mean stress is due to the increase of the plastic strain amplitude in cycling with mean stress.

Effect of Gd and Y on the Low Cycle Fatigue Properties of AZ91D-0.4Ca-0.3Sr

2011 ◽  
Vol 197-198 ◽  
pp. 1536-1539
Author(s):  
Yong Chang Zhu ◽  
Shou Fan Rong ◽  
S. N. Shukayev ◽  
Jun Wang
Keyword(s):  
Fatigue Life ◽  
Magnesium Alloy ◽  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
Total Strain ◽  
Fatigue Properties ◽  
Total Strain Amplitude ◽  
Cycle Fatigue ◽  
Gravity Casting

The properties of gravity casting AZ91D-0.4Ca-0.3Sr alloy with Gd and Y in metal mould were studied by controlling the total strain amplitude ranged from 0.05mm to 0.25mm.under the conditions of the stress of ratio R equal to –1. In addition, the microstructure, phases, chemical constitute, fracture and low cycle fatigue behaviors of the magnesium alloy were primarily researched by means of SEM, EDAX and XRD and so on. The results showed that 3.0wt%Gd and 3.0wt%Y introduced the AZ91D-0.4Ca-0.3Sr alloy can refine α-Mg, and that Gd cooperating with Y can significantly improve the low cycle fatigue life. The low cycle fatigue times can be up to approximately 9874.

scholarly journals Effects of Pore Size on Fatigue Deformation Mechanism of Open-Cell Copper Foam at Low Stress Amplitude

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1639 ◽  
Author(s):  
Jian Chen ◽  
Shuowei Dai ◽  
Cong Li ◽  
Wei Li ◽  
Yanjie Ren
Keyword(s):  
Fatigue Life ◽  
Pore Size ◽  
Strain Amplitude ◽  
Stress Amplitude ◽  
Fatigue Behavior ◽  
Optical Microscope ◽  
Fatigue Properties ◽  
Exponential Relationship ◽  
Open Cell ◽  
Copper Foam

Axial compression-compression fatigue experiments on open-cell copper foams with different pore size were investigated in this paper. The effects of the strain amplitude on the fatigue properties were studied and found that there is an exponential relationship between the fatigue life and strain amplitude. The experimental results indicate that a smaller pore size is related to a lower fatigue life. The microstructures of failed copper foam tested at low stress amplitude were observed by optical microscope and scanning electron microscopy (SEM), suggests that different pore size related to different fatigue behavior. The fatigue failure mechanism of the open-cell copper foams were compared by experimental research.

scholarly journals Experimental Study of Low Cycle Fatigue Properties for Epoxy Resins with Dibutyl Phthalate (Dbp)

2018 ◽  
Vol 64 (2) ◽  
pp. 147-159 ◽  
Author(s):  
Zhi Wang ◽  
Jiajia Zhou ◽  
Linjian Song ◽  
Long Li
Keyword(s):  
Fatigue Life ◽  
Epoxy Resin ◽  
Stress Ratio ◽  
Dibutyl Phthalate ◽  
Mechanical Performance ◽  
Low Cycle Fatigue ◽  
Fatigue Properties ◽  
Test Results ◽  
Cycle Fatigue ◽  
Loop Area

AbstractIn order to improve the toughness of traditional epoxy resin, dibutyl phthalate (DBP) was introduced into the epoxy resin. The static mechanical performance of plasticized and unplasticized epoxy resin was evaluated. The test results showed that the DBP modified epoxy resin can obtain a higher toughness than conventional epoxy resin, but the elastic modulus and the tensile strength were slightly reduced. The low cycle fatigue test results indicated that the stress ratio and the stress level were two critical factors of fatigue life, which was increased with the growth of stress ratio. It was also found that the fatigue life of plasticized specimen was much less than that of the unplasticized specimen because of the plastic deformation. A logarithmic linear relationship was then established to predict the fatigue life for plasticized epoxy resin. The strain energy density was also applied to demonstrate the accumulation of energy loss. In addition, the fatigue toughness can be obtained by the hysteresis loop area method.

Preparation and analysis of a flexible curing agent for epoxy resin

2009 ◽  
Vol 114 (5) ◽  
pp. 2706-2710 ◽  
Author(s):  
Y. Yang ◽  
Gong Chen ◽  
K. M. Liew
Keyword(s):  
Epoxy Resin ◽  
Curing Agent

scholarly journals Investigation of Changes in Fatigue Damage Caused by Mean Load under Block Loading Conditions

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2738
Author(s):  
Roland Pawliczek ◽  
Tadeusz Lagoda
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Strain Curve ◽  
Mean Value ◽  
Fatigue Properties ◽  
Stress Strain ◽  
Reference Case ◽  
Block Loading ◽  
The Mean ◽  
Mean Strain

The literature in the area of material fatigue indicates that the fatigue properties may change with the number of cycles. Researchers recommend taking this into account in fatigue life calculation algorithms. The results of simulation research presented in this paper relate to an algorithm for estimating the fatigue life of specimens subjected to block loading with a nonzero mean value. The problem of block loads using a novel calculation model is presented in this paper. The model takes into account the change in stress–strain curve parameters caused by mean strain. Simulation tests were performed for generated triangular waveforms of strains, where load blocks with changed mean strain values were applied. During the analysis, the degree of fatigue damage was compared. The results of calculations obtained for standard values of stress–strain parameters (for symmetric loads) and those determined, taking into account changes in the curve parameters, are compared and presented in this paper. It is shown that by neglecting the effect of the mean strain value on the K′ and n′ parameters and by considering only the parameters of the cyclic deformation curve for εm = 0 (symmetric loads), the ratio of the total degree of fatigue damage varies from 10% for εa = 0.2% to 3.5% for εa = 0.6%. The largest differences in the calculation for ratios of the partial degrees of fatigue damage were observed in relation to the reference case for the sequence of block n3, where εm = 0.4%. The simulation results show that higher mean strains change the properties of the material, and in such cases, it is necessary to take into account the influence of the mean value on the material response under block loads.

scholarly journals Synthesis of antibacterial polyether biguanide curing agent and its cured antibacterial epoxy resin

2021 ◽  
Vol 24 (1) ◽  
pp. 63-72
Author(s):  
Rui Li ◽  
Guoxing Yang ◽  
Yudan Wang ◽  
Lijia Liu ◽  
Qiang Wang ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Curing Agent

Uniaxial Ratcheting and Low-Cycle Fatigue Failure of U75V Rail Steel

2016 ◽  
Vol 853 ◽  
pp. 246-250 ◽  
Author(s):  
Tao Fang ◽  
Qian Hua Kan ◽  
Guo Zheng Kang ◽  
Wen Yi Yan
Keyword(s):  
Fatigue Life ◽  
Strain Amplitude ◽  
Stress Ratio ◽  
Stress Amplitude ◽  
Rail Steel ◽  
Low Cycle Fatigue ◽  
Mean Stress ◽  
Cycle Fatigue ◽  
Ratcheting Strain ◽  
Cyclic Straining

Experiments on U75V rail steel were carried out to investigate the cyclic feature, ratcheting behavior and low-cycle fatigue under both strain- and stress-controlled loadings at room temperature. It was found that U75V rail steel shows strain amplitude dependent cyclic softening feature, i.e., the responded stress amplitude under strain-controlled decreases with the increasing number of cycles and reaches a stable value after about 20th cycle. Ratcheting strain increases with an increasing stress amplitude and mean stress, except for stress ratio, and the ratcheting strain in failure also increases with an increasing stress amplitude, mean stress and stress ratio. The low-cycle fatigue lives under cyclic straining decrease linearly with an increasing strain amplitude, the fatigue lives under cyclic stressing decrease with an increasing mean stress except for zero mean stress, and decrease with an increasing stress amplitude. Ratcheting behavior with a high mean stress reduces fatigue life of rail steel by comparing fatigue lives under stress cycling with those under strain cycling. Research findings are helpful to evaluate fatigue life of U75V rail steel in the railways with passenger and freight traffic.

scholarly journals Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 476 ◽  
Author(s):  
Chao Gu ◽  
Min Wang ◽  
Yanping Bao ◽  
Fuming Wang ◽  
Junhe Lian
Keyword(s):  
Fatigue Life ◽  
Quantitative Analysis ◽  
Critical Size ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Property ◽  
Bearing Steel ◽  
Fatigue Properties ◽  
Bearing Steels ◽  
Inclusion Distribution

The fatigue property is significantly affected by the inner inclusions in steel. Due to the inhomogeneity of inclusion distribution in the micro-scale, it is not straightforward to quantify the effect of inclusions on fatigue behavior. Various investigations have been performed to correlate the inclusion characteristics, such as inclusion fraction, size, and composition, with fatigue life. However, these studies are generally based on vast types of steels and even for a similar steel grade, the alloy concept and microstructure information can still be of non-negligible difference. For a quantitative analysis of the fatigue life improvement with respect to the inclusion engineering, a systematic and carefully designed study is still needed to explore the engineering dimensions of inclusions. Therefore, in this study, three types of bearing steels with inclusions of the same types, but different sizes and amounts, were produced with 50 kg hot state experiments. The following forging and heat treatment procedures were kept consistent to ensure that the only controlled variable is inclusion. The fatigue properties were compared and the inclusions that triggered the fatigue cracks were analyzed to deduce the critical sizes of inclusions in terms of fatigue failure. The results show that the critical sizes of different inclusion types vary in bearing steels. The critical size of the spinel is 8.5 μm and the critical size of the calcium aluminate is 13.5 μm under the fatigue stress of 1200 MPa. In addition, with the increase of the cleanliness of bearing steels, the improvement of fatigue properties will reach saturation. Under this condition, further increasing of the cleanliness of the bearing steel will not contribute to the improvement of fatigue property for the investigated alloy and process design.

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