scholarly journals Ultrasound-assisted creep deformation of metals

2021 ◽  
pp. 265-273
Author(s):  
Andrew Rusinko ◽  
Ali Alhilfi
Keyword(s):  
Experimental Data ◽  
Creep Deformation ◽  
Analytic Solutions ◽  
Ultrasonic Field ◽  
Acoustic Energy ◽  
Secondary Creep ◽  
Synthetic Theory ◽  
Analytical Instrument ◽  
Deformation State ◽  
Ultrasound Assisted

This paper aims to develop a mathematical model to calculate the creep deformation of metals in the ultrasonic field. Experimental data recording that acoustic energy leads to an increase of primary and secondary creep has become the impetus for this research. The model is constructed in terms of the synthetic theory of irrecoverable deformation. To catch the phenomena caused by sonication, we introduce a new term reflecting the nucleation and development of the crystalline grid's defects in the ultrasonic field. By inserting this term into the basic relationships of the synthetic theory that define the deformation state of the material, we have derived the formulae describing the development of time-dependent deformation coupled with ultrasound. As a result, since the analytic solutions fit good the experimental data, we have elaborated an analytical instrument to predict the increase in the creep deformation of metals due to acoustic energy.

scholarly journals An analytic description of the creep deformation of metals in the ultrasonic field

2021 ◽  
Author(s):  
Andrew Rusinko ◽  
Ali H. Alhilfi ◽  
Morika Rusinko
Keyword(s):  
Ultrasonic Vibration ◽  
Creep Deformation ◽  
Ultrasonic Field ◽  
Primary Creep ◽  
Analytic Description ◽  
Flow Rule ◽  
Synthetic Theory ◽  
Ultrasound Assisted

AbstractThe effect of superimposed ultrasonic vibration on the primary creep of metals is modeled in terms of the synthetic theory of irrecoverable deformation. We consider two sonication modes: (i) the ultrasound acts continuously during the deformation, and (ii) the ultrasound is periodically on and off. Whereas both cases show a significant increase in primary creep, the periodical sonication leads to higher deformation values. To catch the phenomenon of ultrasound-assisted creep, we extend the flow rule equation by a term that accounts for the process occurring on the microlevel of material induced by ultrasound.

On the Interrupted Creep Test Under Low Stress Levels for the Power Law Parameter Extraction

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Bin Yang ◽  
Fu-Zhen Xuan ◽  
Wen-Chun Jiang
Keyword(s):  
Creep Strain ◽  
Stress Level ◽  
Creep Test ◽  
Creep Deformation ◽  
Parameter Extraction ◽  
Tertiary Creep ◽  
Secondary Creep ◽  
Creep Stage ◽  
Strain Data

Abstract Low stress interrupted creep test, as an interim compromise, can provide essential data for creep deformation design. However, there are no clear guidelines on the characterization of the terminating time for interrupted low-stress creep test. To obtain a suitable terminating time in terms of economy and effectiveness, long-term creep strain data of 9%Cr steels are collected from literatures and their creep deformation characterization is analyzed. First, the variations of normalized time and strain of each creep stage with the stress level are discussed. Then, the effect of the terminating time on final fitted results of Norton–Bailey equation is estimated. Third, the relationship between demarcation points at different creep stages and minimum/steady-state creep rate is analyzed. The results indicate that when the creep rupture life is considered as an important factor for creep design, the tertiary creep stage is of greatest significance due to the largest life fraction and creep strain fraction at low stress level. However, the primary and secondary creep stages are of great significance for design due to their larger contribution to 1% limited creep strain. And the long-term secondary creep data could be extrapolated by combining the primary creep strain data obtained from interrupted creep tests with the time to onset of tertiary creep derived from a similar Monkman–Grant relationship.

Unsteady 2-D Compressible Flow in Unbounded Domain

1995 ◽  
Vol 117 (1) ◽  
pp. 91-96 ◽  
Author(s):  
Deguan Wang ◽  
E. Benjamin Wylie
Keyword(s):  
Experimental Data ◽  
Open Space ◽  
Flow Model ◽  
Subsonic Flow ◽  
Analytic Solutions ◽  
Two Dimensional ◽  
Closed Region ◽  
Open Domain ◽  
Isentropic Flow ◽  
Two Dimensional Flow

An unsteady isentropic flow model is presented to calculate the two-dimensional flow field in an arbitrarily closed region or in an open fluid domain. In the open domain, a unique boundary condition is implemented to simulate the infinite character of the open space. The characteristics-like method presented herein is shown to be robust over the entire subsonic flow range and, with the implementation of the infinite boundary, provides numerical results in agreement with analytic solutions and experimental data.

Modeling the Temperature-Dependence of Tertiary Creep Damage of a Directionally Solidified Ni-Base Superalloy

2009 ◽  
Author(s):  
Calvin M. Stewart ◽  
Erik A. Hogan ◽  
Ali P. Gordon
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Creep Damage ◽  
Time Estimation ◽  
General Purpose ◽  
Tertiary Creep ◽  
Secondary Creep ◽  
Directionally Solidified ◽  
Estimation Model ◽  
Element Analysis

Directionally solidified (DS) Ni-base superalloys have become a commonly used material in gas turbine components. Controlled solidification during the material manufacturing process leads to a special alignment of the grain boundaries within the material. This alignment results in different material properties dependent on the orientation of the material. When used in gas turbine applications the direction of the first principle stress experienced by a component is aligned with the enhanced grain orientation leading to enhanced impact strength, high temperature creep and fatigue resistance, and improve corrosion resistance compared to off axis orientations. Of particular importance is the creep response of these DS materials. In the current study, the classical Kachanov-Rabotnov model for tertiary creep damage is implemented in a general-purpose finite element analysis (FEA) software. Creep deformation and rupture experiments are conducted on samples from a representative DS Ni-base superalloys tested at temperatures between 649 and 982°C and two orientations (longitudinally- and transversely-oriented). The secondary creep constants are analytically determined from available experimental data in literature. The simulated annealing optimization routine is utilized to determine the tertiary creep constants. Using regression analysis the creep constants are characterized for temperature and stress-dependence. A rupture time estimation model derived from the Kachanov-Rabotnov model is then parametrically exercised and compared with available experimental data.

Cavitation in lubrication. Part 2. Analysis of wavy interfaces

1977 ◽  
Vol 80 (4) ◽  
pp. 757-767 ◽  
Author(s):  
M. D. Savage
Keyword(s):  
Experimental Data ◽  
Small Amplitude ◽  
Reynolds Equation ◽  
Pressure Field ◽  
Harmonic Wave ◽  
Fluid Flows ◽  
Rotating Cylinder ◽  
Analytic Solutions ◽  
Fluid Interface ◽  
Theory And Experiment

The steady and unifrom flow of a viscous fluid past a unifrom cavity in a gemoetry with small, yet arbitrary, film thickness is considered. A mathematical model for describing steady perturbations to such a flow is presented in which the perturbation to the cavity-fluid interface is represented by a small amplitude harmonic wave of wavenumber n. A linearized perturbation analysis then permits the formulation of a boundary-value problem involving the homogeneous Reynolds equation, the solution to which determines both n and the perturbed pressure field.Numerical and approximate analytic solutions are determined for the cylinderplane geometry in which fluid flows between a rotating cylinder and a Perspex block. Whilst these compare well with experimental data over the whole range \[ 0.1 < \eta U/T < 3, \] closest agreement between theory and experiment is attained for small values of both ηU/T and n.

Creep Parameters Determination by Omega Model to Norton Bailey Law by Regression Analysis for Austenitic Steel SS-304

2021 ◽  
Vol 324 ◽  
pp. 188-197
Author(s):  
Mohsin Sattar ◽  
A. Rahim Othman ◽  
Shahrul Kamaruddin ◽  
Mohammad Azad Alam ◽  
Mohammad Azeem
Keyword(s):  
Regression Analysis ◽  
Creep Behavior ◽  
Creep Deformation ◽  
Complete Analysis ◽  
Mechanical Equipment ◽  
Strain Rates ◽  
Secondary Creep ◽  
Creep Data ◽  
Ss 304 ◽  
Omega Model

In the material’s creep failure analysis, the difficulty of assessing the applied thermo-mechanical boundary conditions makes it critically important. Numerous creep laws have been established over the years to predict the creep deformation, damage evolution and rupture of the materials subjected to creep phenomena. The omega model developed by the American Petroleum Institute and Material Properties Council is one of the most commonly used creep material models for numerical analysis over the years. It is good in defining the fitness of mechanical equipment for service engineering evaluation to ensure the reliable service life of the equipment. The Omega model, however, is not readily accessible and specifically incorporated for creep evaluation in FEA software codes and creep data is always scarce for the complete analysis. Therefore, extrapolation of creep behavior was performed by fitting various types of creep models with a limited amount of creep data and then simulating them, beyond the available data points. In conjunction with the Norton Bailey model, based on API-579/ASME FFS-1 standards, a curve fitting technique was employed called regression analysis. From the MPC project omega model, different creep strain rates were obtained based on material, stress and temperature-dependent data. In addition, as the strain rates increased exponentially with the increase in stresses, regression analysis was used for predicting creep parameters, that can curve fit the data into the embedded Norton Bailey model. The uncertainties in extrapolations and material constants has highlighted to necessitate conservative safety factors for design requirement. In this case study, FEA creep assessment was performed on the material SS-304 dog bone specimen, considered as a material coupon to predict time-dependent plastic deformation along with creep behavior at elevated temperatures and under constant stresses. The results indicated that the specimen underwent secondary creep deformation for most of the period.

scholarly journals Analytic Creep Durability of Rotating Uniform Disks

1998 ◽  
Vol 4 (4) ◽  
pp. 249-256
Author(s):  
Yuriy Nyashin ◽  
Victor Shishlyaev
Keyword(s):  
Experimental Data ◽  
Crack Initiation ◽  
Creep Deformation ◽  
Rotating Disk ◽  
Dissipated Energy ◽  
Material Damage ◽  
Aircraft Engines ◽  
Damage Propagation ◽  
Turbine Disks ◽  
Creep Deformations

Turbine disks of aircraft engines in operation are subjected to alternating thermocyclic deformation under high temperatures. Operation gives rise to sufficiently high stresses and subsequent creep damaging effects.In this paper we suggest an approach for describing creep rupture of a simple rotating disk due to the accumulation of creep induced microdefects. The dissipated energy of the creep deformation is considered as the measure of material damage.The lifetime of the disk can be predicted on the basis of this approach. Both crack initiation and damage propagation to complete rupture of a disk are calculated. The analytic results can be compared to known experimental data. The derived algorithm can be applied to estimate the lifetime of real machinery components when creep deformations are dominant.

Application of the Monkman-Grant Relationship for Ultrafine-Grained Metallic Materials

2013 ◽  
Vol 577-578 ◽  
pp. 137-140
Author(s):  
Marie Kvapilová ◽  
Jiří Dvořák ◽  
Petr Král ◽  
Milan Svoboda ◽  
Vàclav Sklenička
Keyword(s):  
Creep Deformation ◽  
Damage Tolerance ◽  
Creep Damage ◽  
Tolerance Factor ◽  
Tertiary Creep ◽  
Secondary Creep ◽  
Metallic Materials ◽  
Ultrafine Grained ◽  
Ultrafine Grained Materials ◽  
The Relationship

The applicability of the Monkman-Grant relationship was analyzed and validated for ultrafine-grained metallic materials under investigation. A special attention has been given to the creep damage tolerance factor which is defined as the ratio of the strain to fracture to the Monkman-Grant ductility and which describes the coupling between creep deformation and damage based on continuum creep damage approach. It was found, that ultrafine-grained materials generally obey the Monkman-Grant relationship, however, the relationship is especially suitable for materials exhibiting short secondary creep and long tertiary creep stages when dislocation-controlled creep is dominant.

Modeling Creep Deformation and Damage Behavior of Tempered Martensitic Steel in the Framework of Additive Creep Rate Formulation

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
J. Christopher ◽  
B. K. Choudhary
Keyword(s):  
Creep Rate ◽  
Internal Stress ◽  
Creep Strain ◽  
Creep Deformation ◽  
Creep Damage ◽  
Tertiary Creep ◽  
Time Behavior ◽  
Secondary Creep ◽  
Modeling Creep ◽  
Applied Stresses

Additive creep rate model has been developed to predict creep strain-time behavior of materials important to engineering creep design of components for high temperature applications. The model has two additive formulations: the first one is related to sine hyperbolic rate equation describing primary and secondary creep deformation based on the evolution of internal stress with strain/time, and the second defines the tertiary creep rate as a function of tertiary creep strain. In order to describe creep data accurately, tertiary creep rate relation based on MPC-Omega methodology has been appropriately modified. The applicability of the model has been demonstrated for tempered martensitic plain 9Cr-1Mo steel for different applied stresses at 873 K. Based on the observations, a power law relationship between internal stress and applied stress has been established for the steel. Further, a higher creep damage accumulation with increasing life fraction has been observed at low stresses than those obtained at high stresses.

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