Effect of flow rules and elastic strains on pressuremeter test results in dense sand

2009 ◽  
Vol 46 (2) ◽  
pp. 160-167 ◽  
Author(s):  
Vincenzo Silvestri ◽  
Ghassan Abou-Samra ◽  
Christian Bravo-Jonard
Keyword(s):  
Flow Rule ◽  
Stress And Strain ◽  
Test Results ◽  
Pressuremeter Test ◽  
Dense Sand ◽  
Strain Components ◽  
Strain Paths ◽  
Calibration Chamber ◽  
Elastic Strains ◽  
Cam Clay

Simple numerical methods that allow to obtain stress and strain paths in sand during self-boring pressuremeter tests are presented in this paper. The material is considered to undergo deformation in drained and plane-strain conditions. The flow rules of Rowe, Cambridge-type (Cam clay and Nova) model, and the sawtooth model are used in the analysis. Elastic strains are also considered in relation with the flow rule of Rowe. The proposed approach has been evaluated using a reference pressuremeter test performed on Ticino sand in a calibration chamber. The results indicate that the stress–strain–volume change responses of the sand predicted by the various models are quite similar, with and without consideration of the elastic strain components.

A Constitutive Model for Estimating Multiaxial Notch Strains

1995 ◽  
Vol 117 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Yung-Li Lee ◽  
Yung J. Chiang ◽  
Hang-Hong Wong
Keyword(s):  
Surface Model ◽  
Flow Rule ◽  
Stress And Strain ◽  
Element Analysis ◽  
Strain Calculation ◽  
Notch Stress ◽  
Strain Components ◽  
Geometrical Constraints ◽  
Life Predictions ◽  
Associated Flow Rule

True stress and strain components at a notch are the essential parameters for fatigue life predictions. Nonlinear finite element analysis (FEA) could be the perfect solution to the notch stress and strain calculation, but its usage may be very limited due to intensive CPU time consumption. Estimation techniques for the multiaxial notch stresses and strains from linear FEA results are important and needed. The existing approach—the Hoffmann and Seeger theory—is limited for monotonic loading cases. It appears difficult to extend its application to nonproportional and variable amplitude loading cases. A generalized method for estimating multiaxial notch stresses and strains on the basis of elastic stress solutions is presented here. This method utilizes a two-surface model with the Mroz hardening equation and the associated flow rule to simulate the local notch stress and strain responses for any geometrical constraints of specimens under monotonic, in-phase and out-of-phase loading. The uniaxial material properties associated with the two-surface model are determined by: the Neuber rule, the Glinka rule and FEA results. Comparisons are made with the notch strains calculated by nonlinear FEA and those obtained from strain gages. Reasonable correlations between the measured and predicted notch strains are observed for SAE 1045 material.

scholarly journals A Consistent Relationship between the Stress and Plastic Strain Components and Its Application in Deep Drawing Process

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Yong Zhang ◽  
Qing Zhang ◽  
Xianrong Qin ◽  
Yuantao Sun
Keyword(s):  
Plastic Strain ◽  
Deep Drawing ◽  
Metal Forming ◽  
Yield Criterion ◽  
Flow Rule ◽  
Drawing Process ◽  
Deep Drawing Process ◽  
Dimensional Changes ◽  
Consistent Relationship ◽  
Strain Components

As von Mises yield criterion and associated flow rule (AFR) are widely applied in metal forming field, a semitotal deformation consistent relationship between the stress and plastic strain components and the rule of dimensional changes of metal forming processes in a plane-stress state are obtained on the basis of them in this paper. The deduced consistent relationship may be easily used in forming interval of the workpiece. And the rule of dimensional changes can be understood through three plastic strain incremental circles on which the critical points can be easily determined on the same basis. Analysis of stress and plastic strain evolution of aluminum warm deep drawing process is conducted, and the advantage of nonisothermal warm forming process is revealed, indicating that this method has the potential in practical large deformation applications.

Modification of Pre-Cracked Charpy Specimens for Surveillance Specimen Programs

2009 ◽  
Author(s):  
Boris Margolin ◽  
Vladimir Nikolaev ◽  
Valentin Fomenko ◽  
Lev Ryadkov
Keyword(s):  
Experimental Data ◽  
Finite Element Method ◽  
Fracture Toughness ◽  
Finite Element ◽  
Brittle Fracture ◽  
Stress And Strain ◽  
Test Results ◽  
Deep Side ◽  
Strain Fields ◽  
Calculation Analysis

Application of pre-cracked Charpy specimens with various depth of side-grooves is considered for fracture toughness prediction. Recommendations for prediction of temperature dependence of fracture toughness are given when using small-sized specimens with deep side-grooves. Test results of about 500 specimens, cut from materials with various degrees of embrittlement are presented. On the basis of 3D calculations by finite element method the procedure used in standard ASTM E 1921 for calculation of Ke and J, is developed for bending specimens with deep side-grooves. An attempt is undertaken to explain the obtained experimental data from the standpoints of the available criteria of brittle fracture based on calculation analysis of stress and strain fields (SSF) of SE(B)-10 specimens with various depths of side-grooves.

Mechanical states encoded by stretch-sensitive neurons in feline joint capsule

1996 ◽  
Vol 76 (1) ◽  
pp. 175-187 ◽  
Author(s):  
P. S. Khalsa ◽  
A. H. Hoffman ◽  
P. Grigg
Keyword(s):  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Neuronal Response ◽  
Neural Response ◽  
Joint Capsule ◽  
Stress And Strain ◽  
Mechanical State ◽  
Simple Correlation ◽  
Strain Components

1. The sensitivity of group II joint afferents innervating cat knee joint capsule to in-plane stretch was studied in vitro. Single afferents were recorded from teased filaments of the posterior articular nerve. The capsule was stretched by applying forces through tabs along the edges of the capsule (3 tabs/edge) with the use of an apparatus that allowed for independent control of each load. The relationships between the neural responses of these afferents and the local continuum mechanical state of the joint capsule have been investigated. By appropriately loading the tissue margins, it was possible to establish states of uniaxial and biaxial tension, including shear. 2. Plane stress was calculated from the loads along the tissue margins. Stress at the location of the mechanoreceptor ending was estimated by interpolation. Strain was calculated from deformations of the capsule measured by tracking markers on its surface. Full characterization of tissue stress and strain made it possible to determine strain energy density and the magnitudes of other coordinate invariant mechanical quantities. 3. Individual afferents (n = 15) exhibited pronounced selectivity to the direction of applied stress and strain. There was no overall preferred orientation across neurons, and simple correlation of individual stress or strain components with the neuronal response revealed no consistent relationship between neuronal response and any single tensor component. However, linear multiple regression of the combined stress and strain components with the neuronal response revealed high correlation (mean R = 0.91), indicating that the measured mechanical states strongly determine the neuronal response. There was a much stronger relationship between neuronal response and stress variables than with strain variables. Simple correlation of the first invariant of the stress tensor with neuronal response had the highest mean correlation of the tensor quantities (R = 0.51). On average, strain energy density was only modestly correlated with the neural response (R = 0.28). 4. These findings indicate that capsule mechanoreceptors are encoding the local continuum mechanical state in the joint capsule. The neural response of these mechanoreceptors is more strongly correlated to local stress than to local strain.

scholarly journals Plastic anisotropy of soft reconstituted clays

2008 ◽  
Vol 45 (3) ◽  
pp. 314-328 ◽  
Author(s):  
Minna Karstunen ◽  
Mirva Koskinen
Keyword(s):  
Stress Ratio ◽  
Plastic Anisotropy ◽  
Stress Path ◽  
Test Results ◽  
Fabric Anisotropy ◽  
Induced Anisotropy ◽  
Modified Cam Clay ◽  
Model Predictions ◽  
Elastoplastic Constitutive Model ◽  
Cam Clay

The aim of the paper is to extend the experimental validation of the S-CLAY1 model, which is a recently proposed elastoplastic constitutive model that accounts for initial and plastic strain-induced anisotropy. Drained stress path controlled tests were performed on reconstituted samples of four Finnish clays to study the effects of anisotropy in the absence of the complexities of structure present in natural undisturbed clays. Each test involved several loading, unloading, and reloading stages with different values of stress ratio and, hence, induced noticeable changes in the fabric anisotropy. Comparisons between test results and model predictions with the S-CLAY1 model and the modified Cam clay model demonstrate that despite its simplicity, the S-CLAY1 model can provide excellent predictions of the behaviour of unstructured soil.

Deriving Plastic Constitutive Equations of the Material in Complex Stress State by Means of Simple Test Results

2011 ◽  
Vol 109 ◽  
pp. 100-104 ◽  
Author(s):  
Xiao Jiu Feng ◽  
Li Fu Liang
Keyword(s):  
Stress State ◽  
Constitutive Equations ◽  
Complex Stress ◽  
Complex Stress State ◽  
One Dimension ◽  
Isotropic Hardening ◽  
Flow Rule ◽  
Test Results ◽  
Loading Function ◽  
Simple Tension

By conducting simple tension and torsion tests to material, constitutive equations of one dimension are obtained. Plastic theories of continuum mechanics are used for analyzing deformation behavior of the material after yielding. Here, material is presumed to have isotropic hardening characteristic. By using Mises loading function and the associative flow rule, the derivations are made to extend the constitutive equations of one dimension in the simple tension and torsion tests to that of multi-dimension and obtain the plastic constitutive equations of the material in complex stress state , respectively.

An Evaluation of Anisotropic Effective Stress-Strain Criteria for the Biaxial Yield and Flow of 2024 Aluminum Tubes

1983 ◽  
Vol 105 (4) ◽  
pp. 242-249 ◽  
Author(s):  
M. G. Stout ◽  
S. S. Hecker ◽  
R. Bourcier
Keyword(s):  
Yield Criterion ◽  
Flow Behavior ◽  
Flow Rule ◽  
Additional Parameter ◽  
Face Centered Cubic ◽  
Aluminum Tubes ◽  
Theoretical Predictions ◽  
Strain Paths ◽  
Face Centered ◽  
Two Parameters

2024 aluminum tubes, heat treated to a T6 and T8 temper, were tested in combinations of tension-internal pressure and tension-torsion loading. Yield loci and flow behavior were determined for both modes of loading and compared to theoretical predictions. Both tempers of 2024 aluminum exhibited crystallographic textures and anisotropic yield and flow. Hill’s quadratic yield criterion and the associated flow rule under-estimate balanced biaxial yield and flow, which is consistent with hydraulic bulge data on other face-centered cubic metals. Hill’s nonquadratic criterion, which adds one additional parameter, and Bassani’s criterion, which adds two parameters, predict the anisotropic yield behavior much more accurately. Predictions of the complete flow behavior, including strain paths, with these anisotropic criteria could be improved markedly by including provisions for planar anisotropy.

Sign in / Sign up

Export Citation Format

Share Document