Fatigue of Unidirectional Cord-Rubber Composites

1999 ◽  
Vol 27 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Y. Liu ◽  
Z. Wan ◽  
Z. Tian ◽  
X. Du ◽  
J. Jiang ◽  
...  
Keyword(s):  
Damage Accumulation ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Constant Load ◽  
Testing System ◽  
Rubber Composites ◽  
Cycle Frequency ◽  
Periodic Loading ◽  
Fatigue Damage Accumulation ◽  
Rubber Composite

Abstract A fatigue testing system is established with which the real-time recording of stress, strain, temperature, and hysteresis loss of rubbers or cord-rubber composite specimens subjected to periodic loading or extension can be successfully carried out. Several problems are connected with the experimental study of the fatigue of rubber composites. In constant extension cycling, the specimen becomes relaxed because of the viscoelasticity of rubber composites, and the imposed tension-tension deformation becomes complex. In this method, the specimen is unlikely to fail unless the imposed extensions are very large. Constant load cycling can avoid the shortcomings of constant extension cycling. The specially designed clamps ensure that the specimen does not slip when the load retains a constant value. The Deformation and fatigue damage accumulation processes of rubber composites under periodic loading are also examined. Obviously, the effect of cycle frequency on the fatigue life of rubber composites can not be ignored because of the viscoelasticity of constituent materials. The increase of specimen surface temperature is relatively small in the case of 1 Hz, but the temperature can easily reach 100°C at the 8 Hz frequency. A method for evaluating the fatigue behavior of tires is proposed.

Characterization of the Fatigue Behavior of the Medial Collateral Ligament Utilizing Traditional and Novel Mechanical Variables for the Assessment of Damage Accumulation

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Michelle L. Zec ◽  
Paul Thistlethwaite ◽  
Cyril B. Frank ◽  
Nigel G. Shrive
Keyword(s):  
Damage Accumulation ◽  
Fatigue Behavior ◽  
Displacement Curve ◽  
Second Derivative ◽  
Collateral Ligaments ◽  
Linear Region ◽  
Fatigue Damage Accumulation ◽  
Repetitive Loading ◽  
Recruitment Patterns ◽  
Force Displacement

Ligaments are regularly subjected to repetitive loading in vivo. Typically, mechanical studies focus on repetitive loading protocols of short duration, while those characterizing damage accumulation over a longer duration (i.e., fatigue studies) are lacking. The aims of this study were as follows: (a) to demonstrate that damage does accumulate in ligament tissue subjected to repetitive loading and (b) to evaluate existing and new methods for characterizing fatigue damage accumulation. It was hypothesized that ligaments would accumulate damage with repetitive loading as evidenced by failure at stresses well below ultimate tensile strength, creep curve discontinuities, and by reductions in stiffness during loading. Eight normal medial collateral ligaments from female New Zealand white rabbits were cycled in tension, between 0 MPa and 28 MPa, to failure or until 259,200 cycles, whichever came first. Medial collateral ligaments that did not fail were subsequently loaded to failure. Displacement rates (dlmax/dt) as well as primary, secondary, and tertiary creeps were monitored as indices of damage accumulation and impending mechanical failure. Additionally, the relative utilities of tangent, secant, and chord stiffness parameters were critically evaluated. Finally, new uses for the second derivative of force-displacement data were explored. Three out of eight ligaments failed during testing, demonstrating that ligaments can fail in fatigue under moderate tensile stress in vitro. The evaluation of displacement rates (dlmax/dt), as well as primary through tertiary creep patterns, were not well suited to predicting failure in normal ligaments until rupture was all but imminent. Tangent stiffness, which was calculated from a mathematically defined start of the “linear region,” was surprisingly constant throughout testing. Secant stiffness dropped in a predictable fashion, providing a global indicator of tissue stiffness, but did not provide any insight into fiber mechanics. Chord stiffness, on the other hand, appeared to be sensitive to fiber recruitment patterns. The second derivative of force-displacement data proved to be a useful means of (a) objectively defining the start of the linear region and (b) inferring changes in fiber recruitment patterns within ligament tissue. Tangent, secant, and chord stiffnesses highlight different attributes of ligament responses to loading; hence these parameters cannot be used interchangeably. Additionally, the second derivative of the force-displacement curve was introduced as a useful descriptive and analytical tool.

Low Tension-Tension Cycle Fatigue Properties of 301 Stainless Steel Thin Sheets

2013 ◽  
Vol 351-352 ◽  
pp. 887-891
Author(s):  
Shi Ming Cui ◽  
Rui Dong Wang ◽  
Yong Jie Liu ◽  
Tao Long ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Stress Ratio ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Fatigue Properties ◽  
Testing System ◽  
Loading Frequency ◽  
Thin Sheets ◽  
Cycle Fatigue ◽  
Low Tension

By using of a micro mechanical fatigue testing system, low tension-tension cycle fatigue properties of 301 stainless steel thin sheets with a thickness of 0.1 mm were studied. The effects of loading frequency and stress ratio were considered in the tests. The results show the S-N curves descend continuously in the low cycle regime. Cyclic σ-N curve was obtained according to the traditional fatigue theory. It agrees well with the experimental data, showing that the traditional fatigue research methods are also suitable to describe thin sheets in a certain extent. With the increase of loading stress ratio, the fatigue strength of thin sheets is increased. There is an evident effect of frequency on the fatigue behavior of the thin sheets.

Deformation Based Fatigue Damage Accumulation Model

2015 ◽  
Vol 240 ◽  
pp. 128-133
Author(s):  
Grzegorz Socha ◽  
Lech Dietrich
Keyword(s):  
Fatigue Damage ◽  
Damage Accumulation ◽  
Fatigue Testing ◽  
Damage Parameter ◽  
Damage Indicator ◽  
Fatigue Damage Accumulation ◽  
Relative Damage ◽  
Damage Accumulation Model ◽  
Definition Of ◽  
Life Fraction

This paper reports results of fatigue testing performed under fully reversible, load controlled uniaxial tension-compression. For this scheme of loading definition of relative damage indicator and cumulative damage indicator parameter was given and changes of such parameters during the life of the material were shown for two grades of steel. Simple damage criterion proposed by Johnson [6] was modified to define damage indicator parameter. Definitions of damage parameters based on proposed damage indicator and damage indicator parameter were also given. Damage curves showing changes of damage parameter as the function of the life fraction were shown to illustrate progress of damage during the life of the material.

Cyclic and Fatigue Behavior of the P355NL1 Steel Under Block Loading

2007 ◽  
Author(s):  
He´lder F. S. G. Pereira ◽  
Abi´lio M. P. De Jesus ◽  
Anto´nio A. Fernandes ◽  
Alfredo S. Ribeiro
Keyword(s):  
Fatigue Damage ◽  
Damage Accumulation ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Pressure Vessels ◽  
Cumulative Damage ◽  
Sequential Effects ◽  
Block Loading ◽  
Fatigue Damage Accumulation ◽  
Life Predictions

Current fatigue analyses of metallic structures undergoing variable amplitude loading, including pressure vessels, are mostly based on linear cumulative damage concepts, as proposed by Palmgren and Miner. This type of analysis neglects any sequential effects of the loading history. Several studies have shown that linear cumulative damage theories can produce inconsistent fatigue life predictions. In this paper, both fatigue damage accumulation and cyclic elastoplastic behaviors of the P355NL1 steel are characterized, using block loading fatigue tests. The loading is composed by blocks of constant strain-controlled amplitudes, applied according to two and multiple alternate blocks sequences. Also, loading composed by blocks of variable strain-controlled amplitudes are investigated. The block loading illustrates that fatigue damage evolves nonlinearly with the number of load cycles, as a function of the block strain amplitudes. These observations suggest a nonlinear damage accumulation rule with load sequential effects for the P355NL1 steel. However, the damage accumulation nonlinearity and load sequential effects are more evident for the two block loading rather than for multiple alternate block sequences, which suggests that the linear Palmgren-Miner’s rule tend to produce better results for more irregular loading histories. Some phenomenological interpretations for the observed trends are discussed under a fracture mechanics framework.

scholarly journals Giga-Cycle Fatigue Behavior of the Nuclear Structure of 316L Weldments

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhihong Xiong ◽  
Engao Peng ◽  
Lianghua Zeng ◽  
Qirong Xu
Keyword(s):  
Fatigue Strength ◽  
Arc Welding ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Laser Beam Welding ◽  
Fatigue Loading ◽  
Testing System ◽  
Cycle Fatigue ◽  
Gas Tungsten Arc ◽  
Ultrasonic Fatigue

Some components made of 316L stainless steel in nuclear reactors are connected by welding, and these are under giga-cycle fatigue loading. Therefore, the giga-cycle fatigue behavior of 316L weldments, which are fabricated by Laser Beam Welding (LBW) and Gas Tungsten Arc Welding (GTAW), were investigated using an ultrasonic fatigue testing system. The results indicate that the fatigue strength of LBW-made weldments is almost the same as that of GTAW-made weldments even though the microstructure and mechanical properties of the weldments are different. For the LBW-made specimens, the LBW-induced internal pores with a diameter range of about 89–270 μm were observed in the fracture surface. However, an obvious decrease in fatigue life was not observed in such cases. For the GTAW-made specimens, the quality requirement of the weld seam has to be more strict to prevent fatigue strength from decreasing. The fatigue failure mode of the GTAW-made specimens is the same as that of LBW-made specimens in the high-cycle fatigue regime but different in the giga-cycle fatigue regime.

Cyclic and Fatigue Behavior of the P355NL1 Steel Under Block Loading

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Hélder F. S. G. Pereira ◽  
Abílio M. P. De Jesus ◽  
Alfredo S. Ribeiro ◽  
António A. Fernandes
Keyword(s):  
Fatigue Damage ◽  
Damage Accumulation ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Pressure Vessels ◽  
Cumulative Damage ◽  
Sequential Effects ◽  
Block Loading ◽  
Fatigue Damage Accumulation ◽  
Life Predictions

Current fatigue analyses of metallic structures undergoing variable amplitude loading, including pressure vessels, are mostly based on linear cumulative damage concepts, as proposed by Palmgren and Miner. This type of analysis neglects any sequential effects of the loading history. Several studies have shown that linear cumulative damage theories can produce inconsistent fatigue life predictions. In this paper, both fatigue damage accumulation and cyclic elastoplastic behaviors of the P355NL1 steel are characterized using block loading fatigue tests. The loading is composed of blocks of constant strain-controlled amplitudes, applied according to two and multiple alternate blocks sequences. Also, loading composed by blocks of variable strain-controlled amplitudes are investigated. The block loading illustrates that fatigue damage evolves nonlinearly with the number of load cycles, as a function of the block strain amplitudes. These observations suggest a nonlinear damage accumulation rule with load sequential effects for the P355NL1 steel. However, the damage accumulation nonlinearity and load sequential effects are more evident for the two block loading rather than for multiple alternate block sequences, which suggests that the linear Palmgren–Miner rule tends to produce better results for more irregular loading histories. Some phenomenological interpretations for the observed trends are discussed under a fracture mechanics framework.

scholarly journals Effect of Static and Dynamic Aging on Fatigue Behavior of Sn3.0Ag0.5Cu Solder Alloy

2017 ◽  
Author(s):  
Yiran Li ◽  
Yuvraj Singh ◽  
Ganesh Subbarayan
Keyword(s):  
Cell Size ◽  
Solder Alloy ◽  
Damage Accumulation ◽  
Accumulation Rate ◽  
Fatigue Behavior ◽  
Constitutive Models ◽  
Creep Model ◽  
Microstructural Parameters ◽  
Dynamic Aging ◽  
Fatigue Damage Accumulation

In this paper, the effect of pretest isothermal aging and in-test aging on the fatigue behavior of Sn3.0Ag0.5Cu alloy are examined using the microstructurally adaptive creep model (MACM) and the maximum entropy fracture model (MEFM). Compared to traditional constitutive models, the MACM considers the effect of thermal history. Two microstructural parameters, the average Ag3Sn particle size and the average primary-Sn cell size, are identified as critical to capturing the aging behavior of SnAgCu alloys and are incorporated into a modified Dorn creep form. The MEFM is next utilized to characterize the damage accumulation rate in the Sn3.0Ag0.5Cu solder alloy. The MEFM uses a single damage accumulation parameter, which connects the accumulated damage to the accumulated in-elastic dissipation. This parameter is independent of sample geometry, test temperature and strain rate. The concepts of static aging and dynamic aging are utilized to describe pretest aging and in-test aging. In 25° C tests, with longer static aging, a faster fatigue damage accumulation results. Through the relationship between the damage accumulation rate and the average primary-Sn cell size, the influence of microstructural evolution introduced by static aging on fatigue behavior is confirmed. In 100° C tests, the dynamic aging causes further rapid damage accumulation relative to the 25° C tests.

Microscopic Analysis of Fatigue Damage Accumulation in TiAl Intermetallics

2014 ◽  
Author(s):  
Luca Patriarca ◽  
Can Içöz ◽  
Mauro Filippini ◽  
Stefano Beretta
Keyword(s):  
Fatigue Damage ◽  
Titanium Aluminide ◽  
Damage Accumulation ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Image Correlation ◽  
Gamma Titanium Aluminide ◽  
Full Field ◽  
Fatigue Damage Accumulation ◽  
Residual Strains

In order to design efficient and light components for the aircraft industry preserving the safety of the design, more sophisticated design criteria are required for the application of new materials. In particular, the usage of novel manufacturing processes to produce advanced materials such as the gamma titanium aluminide alloys (γ-TiAl) requires the investigation of the microstructure influence in the fatigue damage accumulation processes. In this work we examine a Ti-48Al-2Cr-2Nb alloy obtained with an additive manufacturing technique by Electron Beam Melting (EBM) by conducting monotonic and fatigue experiments both on tension and compression samples. The full-field residual strain maps corresponding to different applied stress levels and number of cycles are obtained through the use of high-resolution Digital Image Correlation (DIC). The strain maps were overlaid with the images of the microstructure and detailed analyses were performed to investigate the features of the microstructure where high local strain heterogeneities arise. High local residual plastic shear strains were measured inside lamellar colonies, which are detected as the precursor to fatigue crack initiation. The measure of the residual strains also provides further information on the role of the intermetallic phases on the fatigue behavior of γ-TiAl alloys.

scholarly journals Very High Cycle Fatigue Behavior of Carbon Manganese Steels

2010 ◽  
Vol 146-147 ◽  
pp. 1780-1783
Author(s):  
Hong Qian Xue ◽  
Danièle Wagner
Keyword(s):  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Effect Of Temperature ◽  
Testing System ◽  
Loading Frequency ◽  
Ultrasonic Fatigue ◽  
Carbon Manganese Steels ◽  
Temperature Scanning ◽  
Initial Results ◽  
Manganese Steels

An ultrasonic fatigue testing system capable of operating at temperatures at 250 has been introduce to study the fatigue behavior of carbon manganese steels (A42 and A48) and loading frequency of approximately 20 kHz. Endurance limit results were comparable to those generated at room temperature to determine the effect of temperature. Scanning electron microscopy was then used to determine the initiation sites and the failure mechanisms. Initial results indicate that fatigue strength decrease a little at 250 , interior inclusions were the major microstructural feature responsible for crack initiation in the alloy.

Sign in / Sign up

Export Citation Format

Share Document