High Temperature Inelastic Deformation of the B1900 + Hf Alloy Under Multiaxial Loading: Theory and Experiment

1990 ◽  
Vol 112 (1) ◽  
pp. 7-14 ◽  
Author(s):  
K. S. Chan ◽  
U. S. Lindholm ◽  
S. R. Bodner ◽  
A. Nagy
Keyword(s):  
Elevated Temperatures ◽  
Cyclic Hardening ◽  
Thin Wall ◽  
Multiaxial Loading ◽  
Biaxial Strain ◽  
Cyclic Tests ◽  
Comparable Magnitude ◽  
Tubular Specimens ◽  
Strain Cycling ◽  
Theory And Experiment

The multiaxial deformation behavior of the Ni-based alloy B1900 + Hf has been studied at elevated temperatures in the range of 649–982°C. Combined tension/ torsion cyclic tests were performed on thin-wall tubular specimens under both in-phase and out-of-phase strain-controlled loading cycles. Both straining conditions resulted in stress loci of comparable magnitude, exhibiting no difference in cyclic hardening response. A phase angle was observed between the deviatoric stress and the incremental plastic strain vectors during 90° out-of-phase strain cycling, and nonproportional stress relaxation occurred under biaxial strain hold. The overall results have been used to assess the flow law, the hardening equations, and the applicability of the J2-based, elastic-viscoplastic model of Bodner-Partom for multiaxial loading conditions. The overall agreement between theory and experiment is good and discrepancies are discussed in relation to micromechanical considerations.

Compressive Fatigue of a Plasma Sprayed Zr02-8 wt%Y203 and Zr02-10wt%NiCrAlCoY TTBC

1995 ◽  
Vol 117 (3) ◽  
pp. 305-310 ◽  
Author(s):  
B. P. Johnsen ◽  
T. A. Cruse ◽  
R. A. Miller ◽  
W. J. Brindley
Keyword(s):  
Compressive Strength ◽  
Fatigue Life ◽  
Elevated Temperatures ◽  
Cyclic Hardening ◽  
Cyclic Stress ◽  
Free Standing ◽  
Initial Portion ◽  
Base Materials ◽  
Plasma Sprayed ◽  
Tubular Specimens

High cycle (>106 cycles) fatigue (HCF) behavior of thick thermal barrier coatings (TTBC’s) was examined for applied stresses near the compressive strength of the material. Test data were obtained on four coating systems: two base materials in the unsealed and CrO2 dip sealed conditions. Free standing tubular specimens were evaluated. The data show that compressive fatigue limits exist for the four coating systems at room temperature (RT) and sealing with CrO2 improves RT fatigue life. Test results also show the ratio of the peak cyclic stress, at 105 cycles, to ultimate compressive strength (UCS) of the Yttria Stabilized Zirconia (YSZ) tubular specimens approaches 0.90 at R = 0.6 (R = minimum/maximum compressive stress). Residual UCS increases were observed after fatigue run-outs at elevated temperatures (5 at 700°C and 1 at 400°C) for both YSZ and the cermet. Ratchetting with cyclic hardening was observed during fatigue with deformation occurring primarily in the initial portion of the high cycle fatigue life of the specimens.

Investigation of the One-Dimensional Endochronic Constitutive Equation for Metals by the Rivlin Test

1984 ◽  
Vol 106 (3) ◽  
pp. 264-270 ◽  
Author(s):  
Han C. Wu ◽  
C. C. Yang
Keyword(s):  
Constitutive Equation ◽  
Strain Path ◽  
Small Strain ◽  
One Dimensional ◽  
Good For ◽  
The One ◽  
Cyclic Straining ◽  
Strain Cycling ◽  
Theory And Experiment

Two sets of experiments with and without strain cycling have been carried out to test the validity of an equation derived from the improved theory of endochronic plasticity. It has been found that for strain path not involving cyclic straining the agreement between theory and experiment is quite good. In the test with strain cycling, the agreement is not good for small strain amplitudes of cycling but the discrepancy diminishes with the increasing amplitude of the strain cycling.

Fatigue responses of cracked Ti/APC-2 nanocomposite laminates at elevated temperature

2019 ◽  
Vol 54 (13) ◽  
pp. 1705-1715
Author(s):  
MHR Jen ◽  
GT Kuo ◽  
YH Wu ◽  
YJ Chen
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Composite Laminates ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Cyclic Tests ◽  
Constant Length ◽  
Nano Powder ◽  
Strength And Stiffness ◽  
Inclined Angle

The mechanical properties and fatigue responses of Ti/APC-2 neat and nanocomposites with inclined single-edged cracks due to tensile and cyclic tests at elevated temperature were investigated. Two types of composite laminates [Ti/(0/90)s/Ti] were fabricated with and without (W/WO) nanoparticles SiO2 of optimal 1 wt.%. The geometry and dimensions of specimens were L × W × t = 240 × 25 × 1.55 mm3. The cracks were of constant length 3 mm and width 0.3 mm. The inclined angles were 0°, 45°, and 60°. Both the tensile and cyclic tests were conducted at elevated temperatures 25℃ (RT), 100℃, 125℃, and 150℃. From the tensile tests we obtained the load vs. displacement curves for both types of laminates with varied inclinations at elevated temperatures. Next, we received the applied load vs. cycles curves for the same laminates with inclined cracks at the corresponding temperature due to cyclic tests. According to the experimental data of both tensile and cyclic tests the mechanical properties, such as strength, stiffness, and life, decreased as the temperature rises. The greater the inclined angles were, the greater the strength and stiffness were. Similarly, the fatigue life was in the same trend. However, the effect of inclined angle on mechanical properties was more strong than those of temperature. The mechanical properties of nanocomposite laminates were higher than those of neat composite laminates, but not significant. The main reason was that the enhancement of spreading nano-powder silica on the laminate interfaces did not effectively eliminate the stress intensity at the crack tip locally.

Development of Noninteraction Material Models With Cyclic Hardening

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Thomas Bouchenot ◽  
Bassem Felemban ◽  
Cristian Mejia ◽  
Ali P. Gordon
Keyword(s):  
Elevated Temperatures ◽  
Kinematic Hardening ◽  
Critical Role ◽  
Constitutive Models ◽  
Cyclic Hardening ◽  
Material Model ◽  
General Purpose ◽  
Pressure Vessels ◽  
Single Element ◽  
Critical Components

Simulation plays a critical role in the development and evaluation of critical components that are regularly subjected to mechanical loads at elevated temperatures. The cost, applicability, and accuracy of either numerical or analytical simulations are largely dependent on the material model chosen for the application. A noninteraction (NI) model derived from individual elastic, plastic, and creep components is developed in this study. The candidate material under examination for this application is 2.25Cr–1Mo, a low-alloy ferritic steel commonly used in chemical processing, nuclear reactors, pressure vessels, and power generation. Data acquired from prior research over a range of temperatures up to 650 °C are used to calibrate the creep and plastic components described using constitutive models generally native to general-purpose fea. Traditional methods invoked to generate constitutive modeling coefficients employ numerical fittings of hysteresis data, which result in values that are neither repeatable nor display reasonable temperature dependence. By extrapolating simplifications commonly used for reduced-order model approximations, an extension utilizing only the cyclic Ramberg–Osgood (RO) coefficients has been developed. This method is used to identify the nonlinear kinematic hardening (NLKH) constants needed at each temperature. Single-element simulations are conducted to verify the accuracy of the approach. Results are compared with isothermal and nonisothermal literature data.

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