scholarly journals Study on the Influence of Different Prophase Stress Levels on the Fatigue Damage Characteristics of Granite

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Tianzuo Wang ◽  
Mengya Xue ◽  
Peng Sha ◽  
Fei Xue ◽  
Linxiang Wang
Keyword(s):  
Fatigue Damage ◽  
Stress Level ◽  
Development Trend ◽  
Cyclic Stress ◽  
Tangent Modulus ◽  
Dissipated Energy ◽  
Upper Limit ◽  
Stress Levels ◽  
Number Of Cycles ◽  
The Development Trend

In order to reveal the influence of prophase stress levels on the fatigue damage characteristics of granite, uniaxial fatigue tests of granite with different prophase stress levels were carried out on the basis of the MTS 815.04 rock mechanics test system. The results show that, under the same number of cycles, the failure degree increases with the increase of the prophase stress level. Under the low upper limit of cyclic stress, the tangent modulus and dissipated energy increase significantly with the increase of prophase stress level at the early stage of the cycle loading, while the increasing trend is not obvious with the increase of prophase stress level at the late stage. Under the high upper limit of cyclic stress, the tangent modulus and dissipated energy are less affected by the prophase stress level. The development trend of elastic release energy is not obvious with the increase of prophase stress level, which is less affected by the number of cycles. From the damage parameters defined by dissipative energy, under the low upper limit of cyclic stress, the initial damage is less affected by the prophase stress level. With the increase of the number of cycles, the influence of the prophase stress level on the development trend of the damage variable increases gradually. And the development trend of damage variables shows “C-shaped” damage.

The Reliability of a Component Under Several Distributed Cyclic Numbers at the Corresponding Constant Cyclic Stress Levels

2017 ◽  
Vol 4 (2) ◽  
Author(s):  
Xiaobin Le
Keyword(s):  
Cyclic Loading ◽  
Fatigue Damage ◽  
Cyclic Stress ◽  
New Method ◽  
Reliability Calculation ◽  
Stress Levels ◽  
Relative Errors ◽  
Number Of Cycles ◽  
Unsolved Issue ◽  
Loading Spectrum

The probabilistic stress-number of cycles curve (P-S-N curve) approach is widely accepted for describing the fatigue strengths of materials. It is also a widely accepted fatigue theory for determining the reliability of a component under fatigue loadings. However, it is an unsolved issue in the P-S-N curve approach that the calculation of reliability of a component under several distributed cyclic numbers at the corresponding constant cyclic stress levels. Based on the commonly accepted concept of the equivalent fatigue damage, this paper proposes a new method to determine the reliability of the component under several distributed cyclic numbers at the corresponding constant cyclic stress levels. Four examples including two validation examples will be provided to demonstrate how to implement the proposed method for reliability calculation under such fatigue cyclic loading spectrum. The relative errors in validation examples are very small. So, the proposed method can be used to evaluate the reliability of a component under several distributed cyclic number at different stress levels.

Fatigue Characteristics of Open-End Thick-Walled Cylinders Under Cyclic Internal Pressure

1963 ◽  
Vol 85 (4) ◽  
pp. 555-565 ◽  
Author(s):  
T. E. Davidson ◽  
R. Eisenstadt ◽  
A. N. Reiner
Keyword(s):  
Fatigue Crack ◽  
Internal Pressure ◽  
Stress Level ◽  
Cyclic Stress ◽  
Diameter Ratio ◽  
Tensile Fatigue ◽  
Stress Levels ◽  
Fatigue Characteristics ◽  
Using Data ◽  
Rate Of Improvement

Thick-walled cylinder fatigue data due to cyclic internal pressure for open-end cylinders in the range of 103 to 105 cycles to failure and having a diameter ratio of 1.4 to 2.0 at a nominal yield strength of 160,000 pounds per square inch is presented. Discussed and also presented are the effects of autofrettage on the fatigue characteristics of thick-walled cylinders. Autofrettage substantially enhances fatigue characteristics at stress levels below the corresponding overstrain pressure, the degree of improvement increasing the decreasing stress levels. The rate of improvement in fatigue characteristics increases significantly with diameter ratio in autofrettaged cylinders up to a diameter ratio of 1.8–2.0 and to a much smaller degree in the nonautofrettaged condition. The rate of improvement of fatigue characteristics above 2.0 is the same for both the autofrettaged and nonautofrettaged cases. It is shown that thermal treatment of 675 F for 6 hours after autofrettage does not affect fatigue characteristics and that there is a correlation between the cyclic-stress level and the area and depth of the fatigue crack to the point of ductile rupture. The depth of the fatigue crack decreases with increasing cyclic-stress level. A means for using data from a unidirectional tensile fatigue test to predict the fatigue characteristics of thick-walled cylinders is discussed.

Cumulative fatigue damage for 3-D angle-interlock woven composite under three-point bending cyclic loading

2012 ◽  
Vol 22 (1) ◽  
pp. 3-16 ◽  
Author(s):  
Limin Jin ◽  
Baozhong Sun ◽  
Bohong Gu
Keyword(s):  
Cyclic Loading ◽  
Fatigue Damage ◽  
Stress Level ◽  
Three Dimensional ◽  
Woven Composite ◽  
Damage Development ◽  
Static Test ◽  
Three Point Bending ◽  
Cumulative Fatigue Damage ◽  
Number Of Cycles

This article presents the quantitative characterization of cumulative fatigue damage behavior for the three-dimensional angle-interlock woven composite undergoing three-point bending cyclic loading. The S–N curve was obtained to demonstrate the fatigue life of the three-dimensional angle-interlock woven composite under different stress levels. The increment of cycles for each 5% interval of stress level was reported to show the difference of fatigue resistance performances of the three-dimensional angle-interlock woven composite among the high, middle, and low intervals of stress level. In addition, the Cumulative Fatigue Damage versus Number of Cycles (D–N) curve and the Deflection Index versus Number of Cycles (F–N) curve were deduced to characterize the three-stage cumulative fatigue damage. Furthermore, the damage morphologies of the three-dimensional angle-interlock woven composite after fatigue tests were photographed to compare with those in quasi-static test. The cracks initiation and propagation in the three-dimensional angle-interlock woven composite during the process of cyclic loading were summarized to find the mechanisms of fatigue damage development.

Measuring and Defining Fatigue Behavior of Asphalt Binders

2002 ◽  
Vol 1810 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Karen S. Bonnetti ◽  
Kitae Nam ◽  
Hussain U. Bahia
Keyword(s):  
Fatigue Damage ◽  
Fatigue Behavior ◽  
Energy Ratio ◽  
Asphalt Binders ◽  
Dissipated Energy ◽  
Actual Performance ◽  
Testing Conditions ◽  
Testing Frequency ◽  
Number Of Cycles ◽  
Definition Of

Fatigue damage is a distress mechanism observed in asphalt, particularly at moderate to low temperatures. Preliminary studies have shown that unmodified asphalts are sensitive to fatigue and that the use of modifiers in asphalt binders can dramatically improve the binder’s response to fatigue. One of the major challenges encountered has been the lack of a definition of fatigue failure consistent with the actual performance of the material regardless of testing conditions. Superpave® asphalt binder specification has improved the evaluation of modified and neat asphalts, but the definition of failure for fatigue damage is still unclear. A selected set of unmodified and modified binders was chosen and tested under a range of loading modes, stress or strain amplitudes, temperatures, and frequencies. The fatigue data were analyzed using the dissipated energy ratio concept. Np, the number of cycles to crack propagation, was used as the fatigue criterion for the analysis. Using the initial dissipated energy per cycle ( Wi) as the main independent variable for modeling fatigue of binders appears to be a promising technique to normalize some of the testing conditions. The parameter Np20, defined as the number of cycles at which the dissipated energy ratio shows 20% deviation from the no-damage ratio, appears to be a promising parameter to define failure. Using Np20 values, all modification methods used showed improvement in the fatigue behavior of unmodified asphalts. The level of improvement, however, was highly dependent on the modifier type and the testing conditions. Initial dissipated energy, testing frequency, and temperature were found to be important factors. If damage parameters are used in future specifications of binders, testing frequency and testing stress or strain levels should be carefully selected to represent pavement structural conditions and traffic speed.

PROBABILISTIC SPECIMEN PROPERTY-FATIGUE LIFE MAPPING AND P-S-N CURVE FITTING

2013 ◽  
Vol 20 (05) ◽  
pp. 1350020
Author(s):  
LIYANG XIE ◽  
JIANZHONG LIU ◽  
NINGXIANG WU ◽  
WENXUE QIAN
Keyword(s):  
Fatigue Life ◽  
Test Data ◽  
Stress Level ◽  
Curve Fitting ◽  
Cyclic Stress ◽  
Small Sample ◽  
Test Method ◽  
Life Distribution ◽  
Stress Levels ◽  
Curve Fitting Method

Fitting P-S-N curve with small-size sample of fatigue test data is significant in engineering applications. Although several small sample-based P-S-N curve fitting methods have been developed, complexity in mathematics and/or the unrealistic assumption of the methods hinder their application seriously. Based on the principle of probabilistically mapping from the probability distribution of specimen property to that of fatigue life of the specimen, this paper presents a new, easy to apply P-S-N curve fitting method. By collecting the life distribution information dispersed in several small-size samples of fatigue lives tested under different cyclic stress levels, a large-size sample of equivalent fatigue life data can be built based on the mapping mechanism as well as the uniqueness of the relationship between fatigue life standard deviation and cyclic stress level. The basic viewpoint is that the fatigue lives tested at any cyclic stress levels can be equivalently converted to an arbitrary baseline stress level according to the life distribution–stress relationship, and this principle can be applied to determine the P-S-N curves with a limited number of test data. Test results illustrate that the P-S-N curves obtained by such methods with 30, 24 or 20 samples, respectively, are close to those obtained by the conventional test method with 60 or 40 samples.

A Probabilistic Fatigue Damage Model for Describing the Entire Set of Fatigue Test Data of the Same Material

2019 ◽  
Author(s):  
Xiaobin Le
Keyword(s):  
Fatigue Test ◽  
Fatigue Damage ◽  
Test Data ◽  
Stress Level ◽  
Damage Model ◽  
Fatigue Tests ◽  
Small Sample ◽  
Test Machine ◽  
Stress Levels ◽  
D Model

Abstract One typical widely-accepted approach for describing the fatigue test data is the P-S-N curve approach. However, the P-S-N curve approach has some issues such as: (1) If there are only a few fatigue test data at a fatigue test stress level, the P-S-N curve approach is not valid due to the small sample size; (2) When the total number of fatigue tests under different stress levels might be larger such as more than 30 even though the number of fatigue tests at the same stress level is small, the P-S-N curve cannot be used to analyze such set of fatigue data; (3) It is difficult to calculate the reliability of a component under a cyclic stress level when the probabilistic distribution function under this stress level is not available in the P-S-N curves. The author has proposed the K-D probabilistic fatigue damage model (K-D model) to overcome those issues. The 6061-T6 10-gauge sheet-type flat fatigue specimen was designed, manufactured, and tested on the Instron 8081 fatigue test machine to verify this K-D model. The fatigue tests were under five different cyclic axial loadings with a total of 195 tests. In this paper, the fatigue test data will be analyzed by the P-S-N curve approach and the K-D model. The systematic comparisons between the P-S-N curve approach and the K-D model have approved and verified that the K-D model can be used to analyze and to describe the fatigue test data under all different fatigue stress levels and can be used to calculate the reliability of a component under any type of cyclic fatigue loading.

Conjectures, Hypotheses, and Theories of Drumlin Formation (In memory of Stanislaw Baranowski)

1981 ◽  
Vol 27 (97) ◽  
pp. 503-505 ◽  
Author(s):  
Ian J. Smalley
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Stress Level ◽  
Critical Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Glacial Till ◽  
Forming Process ◽  
Stress Levels

AbstractRecent investigations have shown that various factors may affect the shear strength of glacial till and that these factors may be involved in the drumlin-forming process. The presence of frozen till in the deforming zone, variation in pore-water pressure in the till, and the occurrence of random patches of dense stony-till texture have been considered. The occurrence of dense stony till may relate to the dilatancy hypothesis and can be considered a likely drumlin-forming factor within the region of critical stress levels. The up-glacier stress level now appears to be the more important, and to provide a sharper division between drumlin-forming and non-drumlin-forming conditions.

scholarly journals Critical Dynamics of Defects and Mechanisms of Damage-Failure Transitions in Fatigue

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2554
Author(s):  
Oleg Naimark ◽  
Vladimir Oborin ◽  
Mikhail Bannikov ◽  
Dmitry Ledon
Keyword(s):  
Fatigue Damage ◽  
Kinetic Equations ◽  
Experimental Methodology ◽  
Preliminary Deformation ◽  
Scaling Properties ◽  
In Situ Data ◽  
Number Of Cycles ◽  
Fish Eye ◽  
Very High

An experimental methodology was developed for estimating a very high cycle fatigue (VHCF) life of the aluminum alloy AMG-6 subjected to preliminary deformation. The analysis of fatigue damage staging is based on the measurement of elastic modulus decrement according to “in situ” data of nonlinear dynamics of free-end specimen vibrations at the VHCF test. The correlation of fatigue damage staging and fracture surface morphology was studied to establish the scaling properties and kinetic equations for damage localization, “fish-eye” nucleation, and transition to the Paris crack kinetics. These equations, based on empirical parameters related to the structure of the material, allows us to estimate the number of cycles for the nucleation and advance of fatigue crack.

scholarly journals The development trend of AC-style PDPs

1998 ◽  
Vol 82 (Appendix) ◽  
pp. 311-311
Author(s):  
Tetsuji Okajima ◽  
Chizuka Tani
Keyword(s):  
Development Trend ◽  
The Development Trend
Sign in / Sign up

Export Citation Format

Share Document