scholarly journals APPLICATION OF ACOUSTIC PULSE ECHO-METHOD FOR THE INVESTIGATION OF DYNAMIC AND STRUCTURAL DYSLOCATION CHARACTERISTICS OF CRYSTALS

2021 ◽  
pp. 142-148
Author(s):  
О.M. Petchenko ◽  
G.О. Petchenko ◽  
A.V. Bezugly ◽  
S.M. Boiko
Keyword(s):  
Plastic Strain ◽  
Acoustic Pulse ◽  
Strain Range ◽  
Mechanical Relaxation ◽  
Frequency Range ◽  
Dislocation Interaction ◽  
Plastic Strain Range ◽  
Elastic Loading ◽  
Pulse Echo ◽  
Pulse Echo Method

The multifunctional pulse equipment allowіng to use the method of amplitude-independent internal friction in the frequency range 7.5 to 232.5 MHz is described. Equipment gjves the possibility to investigate the peculiarities of the process of phonon-dislocation interaction in crystals, to carry out thermoactivation analysis of the process of dislocation of the dislocations about the stoppers under the action of temperature and elastic loading, to study processes of dislocation and mechanical relaxation in loaded samples in the quasi-elastic and plastic strain range.

Pulse-echo method of investigating plastic strain

1974 ◽  
Vol 6 (2) ◽  
pp. 248-251
Author(s):  
E. V. Korovkin ◽  
Ya. M. Soifer
Keyword(s):  
Plastic Strain ◽  
Pulse Echo ◽  
Pulse Echo Method

Low-Cycle Fatigue of AISI 1010 Steel at Temperatures up to 1200°F (649°C)

1977 ◽  
Vol 99 (3) ◽  
pp. 432-443 ◽  
Author(s):  
C. E. Jaske
Keyword(s):  
Plastic Strain ◽  
Fatigue Resistance ◽  
Stress Amplitude ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Cyclic Stress ◽  
Cyclic Life ◽  
Stress Strain ◽  
Plastic Strain Range ◽  
Tensile Hold

This program was undertaken to develop isothermal low-cycle fatigue information for AISI 1010 steel in air. Such information is needed to help predict acceptable conditions for equipment and structures operating at elevated temperatures. Tensile properties and cyclic stress-strain behavior were also developed. For lives between 103 and 106 cycles to failure, fatigue curves were developed at 70, 400, 600, 800, 1000, and 1200°F (21, 204, 316, 427,538, and 649°C). Data for these curves were obtained from constant-amplitude, fully reversed strain-cycling tests of axially loaded specimens. Results from the same experiments were used to define cyclic stress-strain curves at each of the above temperatures. Dynamic strain aging caused a maximum amount of cyclic hardening at 600°F (316°C). In terms of stress amplitude, the maximum fatigue strength was at 600°F (316°C). In terms of either total strain range or plastic strain range, the maximum fatigue resistance was at 400°F (204°C). At temperaures above 600°F (316°C), fatigue resistance decreased as temperature increased. Tensile hold periods caused a significant reduction in cyclic life at 800 and 1000°F (427 and 538°C) but had no noticeable effect on cyclic life at 600°F (316°C). Fatigue resistance was quantified in terms of power functions relating fatigue life to both plastic strain range and stress amplitude, and cyclic stress-strain response was quantified in terms of a power function relating stress amplitude to plastic strain amplitude. The method of strain-range partitioning provided good cyclic life predictions for the limited number of tensile hold-time experiments, although other types of hold periods were not evaluated.

scholarly journals Isothermal Fatigue Behavior of Sn-Pb Solder Joints

1990 ◽  
Vol 112 (2) ◽  
pp. 94-99 ◽  
Author(s):  
T. S. E. Summers ◽  
J. W. Morris
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Strain Rate ◽  
Fatigue Behavior ◽  
Strain Range ◽  
Load Drop ◽  
Plastic Strain Range ◽  
Double Shear ◽  
Isothermal Fatigue ◽  
Fatigue Data

Isothermal fatigue data were collected for the compositions 5Sn-95Pb, 20Sn-80Pb, 40Sn-60Pb, 50Sn-50Pb and 63Sn-37Pb within the binary Sn-Pb system. All of these compositions are commercially available and include those most commonly used. Because Sn-rich solders are rarely used, they were not investigated here. The fatigue life was defined by a 30 percent load drop. The solders were tested in a double shear configuration joined to copper at 75° C. The displacement rate chosen was 0.01 mm/min, which corresponds to a strain rate of 1.5 × 10−4s−1 for our specimen configuration, over a 10 percent plastic strain range. Additionally, the microstructural changes during fatigue are presented. The various solder compositions studied exhibit strikingly different as-solidified microstructures. These differences are discussed in terms of their effect on the isothermal joint failure mechanism and joint isothermal fatigue life.

A Two Surface Model for Transient Nonproportional Cyclic Plasticity, Part 1: Development of Appropriate Equations

1985 ◽  
Vol 52 (2) ◽  
pp. 298-302 ◽  
Author(s):  
D. L. McDowell
Keyword(s):  
Plastic Strain ◽  
Kinematic Hardening ◽  
Strain Range ◽  
Cyclic Plasticity ◽  
Plastic Strain Rate ◽  
Internal Variables ◽  
Surface Model ◽  
Fading Memory ◽  
Plastic Strain Range ◽  
Hardening Modulus

A two surface stress space model is introduced with internal state variable repositories for fading memory of maximum plastic strain range and non-proportionality of loading. Evolution equations for isotropic hardening variables are prescribed as a function of these internal variables and accumulated plastic strain, and reflect dislocation interactions that occur in real materials. The hardening modulus is made a function of prior plastic deformation and the distance of the current stress point from the limit surface. The kinematic hardening rules of Mroz and Prager are used for the yield and limit surfaces, respectively. The structure of the model is capable of representing essential aspects of complex nonproportional deformation behavior, including direction of the plastic strain rate vector, memory of plastic strain range, cross-hardening effects, variation of hardening modulus, cyclic hardening or softening, cyclic racheting, and mean stress relaxation.

scholarly journals Thermal-Stress and Low-Cycle Fatigue Data on Typical Materials

1965 ◽  
Author(s):  
K. E. Horton ◽  
J. M. Hallander ◽  
D. D. Foley
Keyword(s):  
Plastic Strain ◽  
Low Cycle Fatigue ◽  
Mechanical Strain ◽  
Thermal Strain ◽  
Strain Range ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Ferrous Alloys ◽  
Plastic Strain Range ◽  
Analysis Of Results

This paper presents the results of low-cycle-fatigue tests wherein either thermal strain or mechanical strain was the independent variable. The materials investigated were primarily ferrous alloys for use in nuclear reactors. The analysis of results was based on plastic-strain-range measurements which could be made reproducibly in the 2 × 10−5 range. Graphs of plastic strain range versus cycles to failure were often found to be independent of large variations in temperature and cycle time. The results from thermal-fatigue and constant-temperature-fatigue tests were usually indistinguishable on these graphs, suggesting that identical metallurgical phenomena occurred in each type of test.

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