Determination of Full Range Stress-Strain Behavior of Pipeline Steels Using Tensile Characteristics

2010 ◽  
Author(s):  
Stijn Hertele´ ◽  
Wim De Waele ◽  
Rudi Denys
Keyword(s):  
Full Range ◽  
Tensile Tests ◽  
Proof Stress ◽  
Stress Strain ◽  
Pipeline Steels ◽  
Strain Behavior ◽  
Parameter Values ◽  
Near Future ◽  
Strain Model

It is standard practice to approximate the post-yield behavior of pipeline steels by means of the Ramberg-Osgood equation. However, the Ramberg-Osgood equation is often unable to accurately describe the stress-strain behavior of contemporary pipeline steels with a high Y/T ratio. This is due to the occurrence of two distinct, independent stages of strain hardening. To address this problem, the authors recently developed a new ‘UGent’ stress-strain model which provides a better description of those steels. This paper elaborates a methodology to estimate suited parameter values for the UGent model, starting from a set of tensile characteristics. Using the proposed methodology, good approximations have been obtained for a preliminary series of eight investigated stress-strain curves. Next to all common tensile characteristics, the 1% proof stress is needed. The authors therefore encourage the future acquisition of this stress level during tensile tests. Currently, the authors perform a further in-depth validation which will be reported in the near future.

Expression of a Generic Full-Range True Stress-True Strain Model for Pipeline Steels Using the Product-Log (Omega) Function

2017 ◽  
Author(s):  
Onyekachi Ndubuaku ◽  
Michael Martens ◽  
J. J. Roger Cheng ◽  
Samer Adeeb
Keyword(s):  
True Strain ◽  
Full Range ◽  
True Stress ◽  
Stress Strain ◽  
Pipeline Steels ◽  
Strain Behavior ◽  
Proposed Model ◽  
Strain Relationship ◽  
Strain Model

Steel pipelines are subjected to a variety of complex, and sometimes difficult to predict, loading schemes during the fabrication, installation and operation phases of their lifecycles. Consequently, the mechanical behavior of steel pipelines is not only influenced by the steel grade but also by the loading history of the pipe segments. Due to the resultant intricacies of the nonlinear load-deformation behavior of pipelines, adequate numerical analysis techniques are usually required for simulation of pipelines under different loading schemes. The validity of such numerical simulations is largely influenced by the accuracy of the true stress-true strain characterization of the pipeline steels. However, existing stress-strain mathematical expressions, developed for the characterization of metallic materials over the full-range of the stress-strain relationship, have been observed to either loose predictive accuracy beyond a limited strain range or, for the more accurate full-range models, are cumbersome due to their requirement of a large number of constituent parameters. This paper presents a relatively accurate and simple true stress-true strain model which is capable of accurately predicting the stress-strain behavior of pipeline steels over the full range of strains. The proposed stress-strain model is characteristically unlike existing stress-strain models as it is essentially defined by a Product-Log function using two proposed parameters, and is capable of capturing a reasonable approximation of the yield plateau in the stress-strain curve. To validate the proposed model, curve-fitting techniques are employed for comparison to experimental data of the stress-strain behavior of different pipeline steel grades (X52 – X100). Excellent agreements are observed between the proposed model and the different pipeline steels over the full-range of the true stress-true strain relationship. Furthermore, the applicability of the proposed model is validated by means of a proposed parametric procedure for predicting the ultimate compressive strength of shell elements.

Full-range stress-strain model for stainless steel alloys

2020 ◽  
Vol 173 ◽  
pp. 106266
Author(s):  
D. Fernando ◽  
J.G. Teng ◽  
W.M. Quach ◽  
L. De Waal
Keyword(s):  
Stainless Steel ◽  
Full Range ◽  
Stress Strain ◽  
Steel Alloys ◽  
Strain Model

Three-Stage Full-Range Stress-Strain Model for Stainless Steels

2008 ◽  
Vol 134 (9) ◽  
pp. 1518-1527 ◽  
Author(s):  
W. M. Quach ◽  
J. G. Teng ◽  
K. F. Chung
Keyword(s):  
Stainless Steels ◽  
Full Range ◽  
Stress Strain ◽  
Strain Model

Determination of the Strain Source in Mo/Ni Multilayers

1990 ◽  
Vol 187 ◽  
Author(s):  
L.J. Chyung ◽  
B.M. Clemens ◽  
S. Brennan
Keyword(s):  
Structural Difference ◽  
Grazing Incidence ◽  
Growth Direction ◽  
Coherency Strain ◽  
X Ray Diffraction ◽  
Strain Behavior ◽  
Dependent Strain ◽  
Strain Model ◽  
Modulation Wavelength

AbstractStructural characterization and strain measurements were conducted on Mo/Ni multilayers, with bilayer periods between 10 Å and 200 Å, utilizing symmetric, asymmetrin, and grazing incidence x-ray diffraction techniques. The structural difference between the 15 Å and 20 Å modulation wavelength samples, evident in the symmetric high angle diffraction spectra, is attributed to the absence of crystalline registry in the early stages of sputter deposition, yielding crystalline order only when the bilayer deposition thickness exceeded 15 Å. The dominant mechanism for the observed modulation wavelength dependent strain behavior, both in the growth direction and in the plane of the film, is consistent with a coherency strain model. The orientation relationship predicted for the Mo/Ni system, based on their atomic radii ratio is the Nishiyama-Wasserman relationship, (110)BCC//(111)FCCand[001]BCC//[101]FCC. This relationship would provide the source for the observed coherency strain.

Studies on the Stress-Strain Relationship Bovine Cortical Bone Based on Ramberg–Osgood Equation

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
N. K. Sharma ◽  
M. D. Sarker ◽  
Saman Naghieh ◽  
Daniel X. B. Chen
Keyword(s):  
Cortical Bone ◽  
Linear Regression Analysis ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Loading Conditions ◽  
Stress Strain ◽  
Strain Behavior ◽  
Nonlinear Stress ◽  
Strain Relationship ◽  
Relationship Of

Bone is a complex material that exhibits an amount of plasticity before bone fracture takes place, where the nonlinear relationship between stress and strain is of importance to understand the mechanism behind the fracture. This brief presents our study on the examination of the stress–strain relationship of bovine femoral cortical bone and the relationship representation by employing the Ramberg–Osgood (R–O) equation. Samples were taken and prepared from different locations (upper, middle, and lower) of bone diaphysis and were then subjected to the uniaxial tensile tests under longitudinal and transverse loading conditions, respectively. The stress–strain curves obtained from tests were analyzed via linear regression analysis based on the R–O equation. Our results illustrated that the R–O equation is appropriate to describe the nonlinear stress–strain behavior of cortical bone, while the values of equation parameters vary with the sample locations (upper, middle, and lower) and loading conditions (longitudinal and transverse).

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