scholarly journals True Stress-True Strain Models for Structural Steel Elements

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
P. Arasaratnam ◽  
K. S. Sivakumaran ◽  
M. J. Tait
Keyword(s):  
Numerical Analysis ◽  
Tensile Test ◽  
Structural Steel ◽  
Deformation Behavior ◽  
True Strain ◽  
True Stress ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Strain Relationship ◽  
Strain Model

A standard uniaxial tensile test, which establishes the engineering stress-strain relationship, in general, provides the basic mechanical properties of steel required by a structural designer. Modern numerical analysis techniques used for analysis of large strain problems such as failure analysis of steel structures and elements metal forming, metal cutting, and so forth, will require implementation and use of true stress-true strain material characterization. This paper establishes a five stage true stress-strain model for A992 and 350W steel grades, which can capture the behavior of structural steel, including the postultimate behavior of steel, until fracture. The proposed model uses a power law in strain hardening range and a weighted power law in the postultimate range. The true stress-true strain model parameters were established through matching of numerical analysis results with the corresponding standard uniaxial tensile test experimental results. The material constitutive relationship so derived was then applied to predict the load-deformation behavior of coupons with a hole in the middle region subjected to direct tension loading. The predicted load-deformation behavior of perforated tension coupons agreed well with the corresponding test results validating the proposed characterization of the true stress-true strain relationship for structural steel.

Investigation on Elastic Behaviour of DP800 Dual Phase Steel

2015 ◽  
Vol 1134 ◽  
pp. 109-115
Author(s):  
Noraishah Mohamad Noor ◽  
Haryanti Samekto ◽  
Ahmad Razlan Yusoff ◽  
Rasool Mohideen ◽  
Nazrul Idzham Kasim ◽  
...  
Keyword(s):  
Tensile Test ◽  
Power Law ◽  
Dual Phase Steel ◽  
Piecewise Linear ◽  
True Strain ◽  
True Stress ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Dual Phase ◽  
Plasticity Model

The elastic relaxation behavior of dual phase steel DP800 is studied in this investigation, based on experimental and numerical methods the true stress-true strain curve obtained from a standard uniaxial tensile test differs according to angular rolling direction The relationship between true stress and true strain are presented in the form of power law equation. This form of material constitutive model shows that the strength coefficient and strain hardening exponent vary significantly in describing the nonlinear true stress-true strain relationship of the material. Finite Element (FE) calculations with Belytschko-Lin-Tsay shell element formulation are performed using the non-linear FE code Ls-Dyna to predict the plastic deformation of the material. Power Law Isotropic Plasticity criterion is adopted for these numerical analyses. The local strains in plastic deformations zone and true stress-strains characteristics obtained by experiment are compared. Using the same parameter the simulation was applied in different modes which are known as Isotropic Elastic-Plastic Model and Piecewise Linear Isotropic Plasticity Model providd in Ls-Dyna simulation for comparison. In general, good agreement in results is obtained between Power Law Isotropic Plasticity Model is obtained compared to Isotropic Elastic-Plastic Model and Piecewise Linear Isotropic Plasticity Model. It is demonstratedthat the behavior of the strain and the Power law criterion can be determined from uniaxial tensile test with the aid of non-linear FE analyses.

Study on Constitutive Modeling for Large Deformation Behavior of Polyethylene Considering Strain Rate Effect

2013 ◽  
Author(s):  
Sijia Zhong ◽  
Jianfeng Shi ◽  
Jinyang Zheng
Keyword(s):  
Strain Rate ◽  
Large Deformation ◽  
Constitutive Modeling ◽  
Deformation Behavior ◽  
True Strain ◽  
True Stress ◽  
Uniaxial Tensile ◽  
Pipeline System ◽  
Composite Effect ◽  
Time Deformation

Polyethylene (PE) pipes have been applied in transportation of key energy medium such as natural gas in the past decades. The mechanical property of PE is of great importance for better design and safer application of PE pipeline system. The large deformation behavior is a key character of PE, not only for its significant strain rate sensitivity, but also for localized necking process after yielding. In this paper, a new constitutive modeling method was proposed to charaterize the rate-denpendent large deformation behavior of PE, in which the true stress is regarded as a function of true stain and true strain rate alone. Uniaxial tensile tests of PE were conducted under various cross-head speeds, and a digital camera was used to record the real-time deformation of specimens. By separating the composite effect into respective effect of local true strain and strain rate on the local true stress in the necking region, a phenomenological model for describing the rate-dependent deformation behavior under uniaxial tension was ealstablished. Model results were validated and found in good agreement with experimental data.

Miniature Test Technique for Acquiring True Stress–Strain Curves for a Large Range of Strains Using a Tensile Test and Inverse Finite Element Method

2011 ◽  
Vol 110-116 ◽  
pp. 4204-4211 ◽  
Author(s):  
Hafeez Farrukh ◽  
M.N. Desmukh ◽  
Husain Asif ◽  
D.K. Sehgal
Keyword(s):  
Finite Element ◽  
Tensile Test ◽  
True Strain ◽  
Element Model ◽  
Conventional Technique ◽  
True Stress ◽  
Constitutive Behavior ◽  
Test Technique ◽  
Miniature Specimen ◽  
Strain Relationship

The paper presents a non conventional technique to predict the constitutive behavior of materials by assessing the true stress–true strain relationship through miniature specimen tests. The miniature test was conducted on two different types of steel ring specimens (outer diameter14mm, inner diameter 8mm, thickeness 0.5mm) with V-notch (1mm depth) added diametrically to it. A finite element model was developed and validated to calculate the load–deflection curve obtained from the miniature specimen experiment. The constitutive behavior assigned to the specimen for the calculations was determined from the standard tensile test. Using an inverse methodology, it was possible to show that the constitutive behavior from the miniature tests using inverse FE procedure, and that from the conventional standard ASTM test bears close resemblance.

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.

Sign in / Sign up

Export Citation Format

Share Document