Extension of a Material Model for Pipeline Steels

2012 ◽  
Author(s):  
James D. Hart ◽  
Nasir Zulfiqar ◽  
Joe Zhou ◽  
Keith Adams
Keyword(s):  
Pipe Steel ◽  
Material Behavior ◽  
Matched Pair ◽  
Pipe Material ◽  
Stress Space ◽  
Stress Strain ◽  
Fitting Procedure ◽  
Yield Functions ◽  
Tension And Compression ◽  
Longitudinal Tension

Pipeline steel stress-strain curves obtained from tension and compression testing of longitudinally and circumferentially oriented specimens of the pipe wall can be significantly different e.g., the pipe material is anisotropic. The anisotropic behavior can result from the manufacturing process (e.g., due to cold expansion of UOE pipe) and can also be influenced by strain aging effects (e.g., due to heated application of pipe coating materials). As described in previous work, the Mroz multilinear kinematic hardening plasticity theory has the ability to accurately model different types of anisotropic pipe material behavior including relatively “sharp” uniaxial circumferential tension response and relatively well-rounded uniaxial longitudinal tension and compression response. The stress-strain curve fitting is accomplished by essentially selecting the sizes and initial positions of elliptical von Mises yield functions in stress-space. A previously developed and published 8-parameter model is well-suited for fitting a matched pair of longitudinal tension (LT) and hoop tension (HT) stress-strain curves as might typically be available from a strain-based pipeline design project. Fitting a pair of “target” LT-HT stress-strain curves is accomplished using a “2-root” fitting procedure where the roots correspond to locations where the yield functions intercept the stress axes in two-dimensional (longitudinal-hoop) stress space. In this paper, the previously described 8-parameter/2-root fitting procedure is extended to a 10-parameter/3-root fitting procedure for situations where a matched “triple” of pipe steel stress-strain curves are available (e.g., LT, HT and longitudinal compression or LC). This extension allows for analysis of strain-based design conditions using an analytical pipe steel, which provides an accurate representation of the uniaxial longitudinal and circumferential stress-strain response of the pipeline material. This paper reviews the 8-parameter/2-root fitting procedure and outlines the extension to the 10-parameter/3-root fitting approach including example application.

Analysis of Layer Waviness in Flat Compression-Loaded Thermoplastic Composite Laminates

1996 ◽  
Vol 118 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Daniel O’Hare Adams ◽  
Michael W. Hyer
Keyword(s):  
Shear Stress ◽  
Compression Strength ◽  
Composite Laminates ◽  
Strength Reduction ◽  
Material Nonlinearity ◽  
Material Behavior ◽  
Thermoplastic Composite ◽  
Stress Strain ◽  
Strain Behavior ◽  
Tension And Compression

A finite element analysis was used to investigate layer waviness effects in flat compression-loaded composite laminates. Stress distributions in the vicinity of the layer waves as well as the locations and modes of failure were investigated. Two layer wave geometries were considered, each modeled within an otherwise wave-free thermoplastic composite laminate. These two wave geometries, classified as moderate and severe, corresponded to layer waves fabricated in actual laminates and tested under uniaxial compression loading. Material nonlinearities obtained from intralaminar shear and 0 and 90 deg tension and compression testing were incorporated into the analysis. The nonlinearity observed in the intralaminar shear stress-strain behavior was assumed to be valid for interlaminar shear stress-strain behavior, and the nonlinearity observed in the 90 deg tension and compression stress-strain behavior was assumed to be valid for interlaminar normal stress-strain behavior. Failure was predicted using a maximum stress failure theory. An interlaminar tension failure was predicted for the severe layer wave geometry, producing a large compression strength reduction in comparison to the wave-free laminate. Fiber compression failure was predicted for the moderate layer wave, producing only a slight compression strength reduction. Although significant material nonlinearity was present in the interlaminar compression and shear response of the material, the inclusion of material nonlinearity produced only slight decreases in predicted compression strengths relative to predictions based on linear material behavior.

Dynamic Properties of Filled Rubber — Part I: Simple Model, Experimental Data and Simulated Results

2008 ◽  
Vol 81 (1) ◽  
pp. 1-18 ◽  
Author(s):  
H. R. Ahmadi ◽  
J. G. R. Kingston ◽  
A. H. Muhr
Keyword(s):  
Dynamic Properties ◽  
Cyclic Stress ◽  
Material Behavior ◽  
Stress Strain ◽  
Viscoplastic Model ◽  
Strain Behavior ◽  
Fitting Procedure ◽  
Filled Rubber ◽  
Constant Rate ◽  
Rubber Part

Abstract A simple “viscoplastic” model is used to capture the stress-strain behavior of a filled SBR vulcanizate; a key objective is to predict dynamic properties, in particular the Fletcher-Gent or Payne effect, from non-cyclic stress-strain data. A simple fitting procedure is described to obtain the parameters of the viscoplastic model from the stress relaxation data and stress-strain loading curves at constant rate. Special attention is given to keeping the numbers of parameters and of characterization tests small. Elastic models are incapable of representing several aspects of the material behavior whereas it is confirmed that the proposed “viscoplastic” approach captures the essence of the behavior.

Mechanical characterization and finite element modeling of polylactic acid BCC-Z cellular lattice structures fabricated by fused deposition modeling

2016 ◽  
Vol 231 (11) ◽  
pp. 1995-2004 ◽  
Author(s):  
R Rezaei ◽  
MR Karamooz Ravari ◽  
M Badrossamay ◽  
M Kadkhodaei
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Polylactic Acid ◽  
Fused Deposition Modeling ◽  
Material Behavior ◽  
Lattice Structures ◽  
Stress Strain ◽  
Fused Deposition ◽  
Tension And Compression ◽  
Deposition Modeling

In recent years, cellular lattice structures are of interest due to their high strength in combination with low weight. They may be used in various areas such as aerospace and automotive industries. Accordingly, assessment of their manufacturability, repeatability and mechanical properties is very important. In this paper, these issues are investigated for Polylactic Acid cellular lattice structures fabricated by fused deposition modeling. To do so, some benchmarks are designed and fabricated to find suitable processing parameters as well as the structural dimensions. In addition, to evaluate the mechanical properties of the lattice’s material, a number of tension and compression specimens are fabricated and tested. The material’s stress–strain curves reveal non-linear behaviors. These curves are not coincided in tension and compression which shows an asymmetric material behavior. To characterize the fabricated cellular lattices, they are tested in compression, and the deformation mechanisms of the structures are analyzed. To investigate the correlation between the bulk material and the material of the ligaments, a solid finite element model is developed to predict the stress–strain response of the lattice. The obtained result shows a reasonably good correlation between the model and experiments.

Strength Hypothesis Applied to Hard Foams

2011 ◽  
Vol 70 ◽  
pp. 99-104 ◽  
Author(s):  
Vladimir A. Kolupaev ◽  
Alexandre Bolchoun ◽  
Holm Altenbach
Keyword(s):  
Experimental Data ◽  
Closed Surface ◽  
Material Behavior ◽  
Optimal Solutions ◽  
Objective Functions ◽  
Stress Space ◽  
Hydrostatic Tension ◽  
Special Cases ◽  
Tension And Compression ◽  
Principal Stress Space

The analysis of well-known strength hypotheses leads to the derivation of a generalized model, which contains a number of known hypotheses as special cases and could be used for the description of the 3D-failure of hard foams. This model in the case of the strength hypothesis for hard foams is characterized by a closed surface in the principal stress space. In order to fit the model to the experimental data certain objective functions are formulated. The optimization results are shown in the Pareto-diagram (optimal solutions for several targets). The results of the fitting are plotted in the Burzyński-plane. It can be seen that reliable modeling requires the knowledge of the material behavior under hydrostatic tension and compression.

scholarly journals A General Temperature-Dependent Stress–Strain Constitutive Model for Polymer-Bonded Composite Materials

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1393
Author(s):  
Xiaochang Duan ◽  
Hongwei Yuan ◽  
Wei Tang ◽  
Jingjing He ◽  
Xuefei Guan
Keyword(s):  
Composite Materials ◽  
Constitutive Model ◽  
Model Parameters ◽  
Temperature Dependent ◽  
Stress Strain ◽  
Proposed Model ◽  
Single Temperature ◽  
Testing Data ◽  
Bonded Composite ◽  
Tension And Compression

This study develops a general temperature-dependent stress–strain constitutive model for polymer-bonded composite materials, allowing for the prediction of deformation behaviors under tension and compression in the testing temperature range. Laboratory testing of the material specimens in uniaxial tension and compression at multiple temperatures ranging from −40 ∘C to 75 ∘C is performed. The testing data reveal that the stress–strain response can be divided into two general regimes, namely, a short elastic part followed by the plastic part; therefore, the Ramberg–Osgood relationship is proposed to build the stress–strain constitutive model at a single temperature. By correlating the model parameters with the corresponding temperature using a response surface, a general temperature-dependent stress–strain constitutive model is established. The effectiveness and accuracy of the proposed model are validated using several independent sets of testing data and third-party data. The performance of the proposed model is compared with an existing reference model. The validation and comparison results show that the proposed model has a lower number of parameters and yields smaller relative errors. The proposed constitutive model is further implemented as a user material routine in a finite element package. A simple structural example using the developed user material is presented and its accuracy is verified.

Semi-inverse method for predicting stress–strain relationship from cone indentations

2003 ◽  
Vol 18 (9) ◽  
pp. 2068-2078 ◽  
Author(s):  
A. DiCarlo ◽  
H. T. Y. Yang ◽  
S. Chandrasekar
Keyword(s):  
A Priori ◽  
Model Material ◽  
Material Behavior ◽  
The Finite Element Method ◽  
Stress Strain ◽  
Indentation Tests ◽  
Strain Relationship ◽  
Initial Force ◽  
Relationship Of ◽  
Force Displacement

A method for determining the stress–strain relationship of a material from hardness values H obtained from cone indentation tests with various apical angles is presented. The materials studied were assumed to exhibit power-law hardening. As a result, the properties of importance are the Young's modulus E, yield strength Y, and the work-hardening exponent n. Previous work [W.C. Oliver and G.M. Pharr, J. Mater. Res. 7, 1564 (1992)] showed that E can be determined from initial force–displacement data collected while unloading the indenter from the material. Consequently, the properties that need to be determined are Y and n. Dimensional analysis was used to generalize H/E so that it was a function of Y/E and n [Y-T. Cheng and C-M. Cheng, J. Appl. Phys. 84, 1284 (1999); Philos. Mag. Lett. 77, 39 (1998)]. A parametric study of Y/E and n was conducted using the finite element method to model material behavior. Regression analysis was used to correlate the H/E findings from the simulations to Y/E and n. With the a priori knowledge of E, this correlation was used to estimate Y and n.

Numerical Modeling of Macroscopic Behavior of Particulate Composite with Crosslinked Polymer Matrix

2011 ◽  
Vol 465 ◽  
pp. 129-132
Author(s):  
Luboš Náhlík ◽  
Bohuslav Máša ◽  
Pavel Hutař
Keyword(s):  
Young’S Modulus ◽  
Polymer Matrix ◽  
Young's Modulus ◽  
Numerical Models ◽  
Strain Curve ◽  
Particulate Composite ◽  
Material Behavior ◽  
Particulate Composites ◽  
Stress Strain ◽  
Crosslinked Polymer

Particulate composites with crosslinked polymer matrix and solid fillers are one of important classes of materials such as construction materials, high-performance engineering materials, sealants, protective organic coatings, dental materials, or solid explosives. The main focus of a present paper is an estimation of the macroscopic Young’s modulus and stress-strain behavior of a particulate composite with polymer matrix. The particulate composite with a crosslinked polymer matrix in a rubbery state filled by an alumina-based mineral filler is investigated by means of the finite element method. A hyperelastic material behavior of the matrix was modeled by the Mooney-Rivlin material model. Numerical models on the base of unit cell were developed. The numerical results obtained were compared with experimental stress-strain curve and value of initial Young’s modulus. The paper can contribute to a better understanding of the behavior and failure of particulate composites with a crosslinked polymer matrix.

scholarly journals Studying the effect of elastic-plastic strain and hydrogen sulphide on the magnetic behaviour of pipe steels as applied to their testing

2018 ◽  
Vol 145 ◽  
pp. 05003
Author(s):  
Anna Povolotskaya ◽  
Eduard Gorkunov ◽  
Sergey Zadvorkin ◽  
Igor Veselov
Keyword(s):  
Plastic Strain ◽  
Initial Stress ◽  
Elastic Deformation ◽  
Hydrogen Sulphide ◽  
Strain State ◽  
Pipe Steel ◽  
Magnetic Behaviour ◽  
Pipe Steels ◽  
Stress Strain ◽  
Stress Strain State

The paper reports results of magnetic measurements made on samples of the 12GB pipe steel (strength group X42SS) designed for producing pipes to be used in media with high hydrogen sulphide content, both in the initial state and after exposure to hydrogen sulphide, for 96, 192 and 384 hours under uniaxial elastic-plastic tension. At the stage of elastic deformation there is a unique correlation between the coercive force measured on a minor hysteresis loop in weak fields and tensile stress, which enables this parameter to be used for the evaluation of elastic stresses in pipes made of the 12 GB pipe steel under different conditions, including a hydrogen sulphide containing medium. The effect of the value of preliminary plastic strain, viewed as the initial stress-strain state, on the magnetic behaviour of X70 pipe steels under elastic tension and compression is studied. Plastic strain history affects the magnetic behaviour of the material during subsequent elastic deformation since plastic strain induces various residual stresses, and this necessitates taking into account the initial stress-strain state of products when developing magnetic techniques for the determination of their stress-strain parameters during operation.

Hyperelastic Muscle Simulation

2007 ◽  
Vol 345-346 ◽  
pp. 1241-1244 ◽  
Author(s):  
Mohd. Zahid Ansari ◽  
Sang Kyo Lee ◽  
Chong Du Cho
Keyword(s):  
Skeletal Muscle ◽  
Silicone Rubber ◽  
Soft Tissues ◽  
Material Model ◽  
Incompressible Material ◽  
Material Behavior ◽  
Rubber Tube ◽  
Stress Strain ◽  
Element Analysis ◽  
Strain Behavior

Biological soft tissues like muscles and cartilages are anisotropic, inhomogeneous, and nearly incompressible. The incompressible material behavior may lead to some difficulties in numerical simulation, such as volumetric locking and solution divergence. Mixed u-P formulations can be used to overcome incompressible material problems. The hyperelastic materials can be used to describe the biological skeletal muscle behavior. In this study, experiments are conducted to obtain the stress-strain behavior of a solid silicone rubber tube. It is used to emulate the skeletal muscle tensile behavior. The stress-strain behavior of silicone is compared with that of muscles. A commercial finite element analysis package ABAQUS is used to simulate the stress-strain behavior of silicone rubber. Results show that mixed u-P formulations with hyperelastic material model can be used to successfully simulate the muscle material behavior. Such an analysis can be used to simulate and analyze other soft tissues that show similar behavior.

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