Cyclic Stress-Strain and Fatigue Properties of Sheet Steel as Affected by Load Spectra

1983 ◽  
Vol 11 (1) ◽  
pp. 66 ◽  
Author(s):  
R Horstman ◽  
KA Peters ◽  
RL Meltzer ◽  
M Bruce Vieth ◽  
JF Martin
Keyword(s):  
Sheet Steel ◽  
Cyclic Stress ◽  
Fatigue Properties ◽  
Stress Strain ◽  
Load Spectra

The Influences of Cutting Speed on the Fatigue of Titanium Alloy

2007 ◽  
Vol 10-12 ◽  
pp. 742-746
Author(s):  
Guo Sheng Geng ◽  
Jiu Hua Xu
Keyword(s):  
Titanium Alloy ◽  
Electron Microscope ◽  
High Speed ◽  
Cutting Speed ◽  
Cyclic Stress ◽  
Fatigue Properties ◽  
Stress Strain ◽  
Ta15 Titanium Alloy ◽  
Cutting Speeds ◽  
Scanning Electron

This research is concerned with the influences of cutting speed on the fatigue properties of high speed milled Ti-6.5Al-2Zr-1Mo-1V (TA15) titanium alloy. Four different cutting speeds ranging from 50 to 200m/min were used to mill the specimens for fatigue test, and the fatigue properties of them were studied at two stress levels: 80—800MPa and 90—900MPa. The fatigue lives of the specimens milled under different cutting speeds were compared. The fracture surfaces were analyzed using scanning electron microscope (SEM), and cyclic stress-strain properties of TA15 titanium alloy were investigated with a stress-strain gauge. The results showed that increasing cutting speed can help to improve the fatigue properties of titanium alloy, especially at a relatively low cyclic stress level.

Characterization of High Temperature Thermomechanical Fatigue Properties for Particle Reinforced Composites

2005 ◽  
Vol 297-300 ◽  
pp. 1495-1502
Author(s):  
Hui Ji Shi ◽  
Ya-Xiong Zheng ◽  
Ran Guo ◽  
Gerard Mesmacque
Keyword(s):  
Finite Element ◽  
Fatigue Behavior ◽  
Voronoi Cell ◽  
Thermomechanical Fatigue ◽  
Cyclic Stress ◽  
Fatigue Properties ◽  
Reinforced Composites ◽  
Interfacial Damage ◽  
Stress Strain ◽  
Particle Reinforced Composites

Voronoi cell finite element method (VCFEM) is introduced in this paper to describe the elastic-plastic-creep behavior of particle reinforced composites. The interfacial damage is simulated by partly debonding between Matrix and inclusion. A validation of the nonlinear behavior of the cell element has been carry out by comparing VCFEM results with those calculated by the general finite element package MARC and ABAQUS, and good agreements are found. A microstructure with five inclusions is taken as an example to describe the cyclic stress-strain behavior under different particulate orientation condition, and it shows the influence of the topological microstructure of inclusions. Thermomechanical fatigue properties are also investigated and the loops of stress-strain show the great differences of fatigue behavior between the in-phase case and out-of-case.

Critical Entropy Threshold: An Irreversible Thermodynamic Theory of Fatigue

2012 ◽  
Author(s):  
P. W. Whaley
Keyword(s):  
Fatigue Damage ◽  
Fatigue Testing ◽  
Tensile Tests ◽  
Cyclic Stress ◽  
Irreversible Thermodynamic ◽  
Fatigue Properties ◽  
Microplastic Deformation ◽  
Polycrystalline Materials ◽  
Model Parameters ◽  
Stress Strain

A theoretical model for material fatigue is described using irreversible thermodynamics to quantify fatigue damage by the generation of microplastic entropy. The microplastic entropy generated quantifies the microplastic deformation, commonly accepted as the mechanism of fatigue damage in polycrystalline materials. A stochastic model for microplastic deformation is utilized to calculate the expected values of tensile stress–strain, cyclic stress–strain, microplastic strain energy density and the microplastic entropy generated. When the cumulative microplastic entropy generated in cyclic loading exceeds the critical microplastic entropy threshold calculated from tensile tests, failure occurs. Calculated fatigue life with 99% tolerance limits (99% confidence) compares favorably to data for 6061-T6 aluminum rod and sheet specimens. Model parameters are determined from tensile tests and simple cyclic tests, decreasing the high cost of fatigue testing for parameter identification. This new theory has the potential to significantly decrease the cost of characterizing the fatigue properties of new materials.

Mechanical Properties of Aircraft Materials Subjected to Long Periods of Service Usage

1997 ◽  
Vol 119 (4) ◽  
pp. 380-386 ◽  
Author(s):  
J. N. Scheuring ◽  
A. F. Grandt
Keyword(s):  
Tensile Stress ◽  
Crack Growth ◽  
Cyclic Stress ◽  
Primary Objective ◽  
Material Behavior ◽  
Fatigue Properties ◽  
Virgin Material ◽  
Service Usage ◽  
Stress Strain ◽  
Effects Of Aging

This paper evaluates changes in the behavior of aircraft materials which result from aging and/or corrosion that occurs during long periods of service usage. The primary objective was to determine whether damage tolerant analyses for older aircraft should employ updated properties that more accurately represent the current state of the material, or if the virgin material properties continue to properly characterize the aged/corroded alloy. Specifically, tensile stress-strain curves, cyclic stress life (SN) tests, and fatigue crack growth tests were used to characterize the “aged aircraft” material. These properties were compared with handbook properties for virgin material of the same pedigree. The aluminum alloys tested were obtained from fuselage and wing panels of retired KC-135 aircraft. Computer controlled tests were conducted using specimens machined from the retired aircraft components. Different configurations were used to observe the effects of aging and/or corrosion on material behavior. In the crack growth specimens, various levels of corrosion were observed, thus the crack growth rates could be categorized as a function of the level of corrosion present. The SN and da/dN-ΔK curves for the “aged” only materials were compared with the fatigue properties of virgin material of the same alloy. Similar comparisons were performed for the tensile stress-strain properties.

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.

Cyclic stress-strain response of porous aluminum

1990 ◽  
Vol 6 (2) ◽  
pp. 207-230 ◽  
Author(s):  
Han C. Wu ◽  
Paul T. Wang ◽  
W.F. Pan ◽  
Z.Y. Xu
Keyword(s):  
Cyclic Stress ◽  
Strain Response ◽  
Stress Strain ◽  
Porous Aluminum
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