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.

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.

scholarly journals Significance of flow rule for the passive earth pressure problem

2021 ◽  
Author(s):  
Christoph Schmüdderich ◽  
Franz Tschuchnigg ◽  
Helmut F. Schweiger
Keyword(s):  
Finite Element ◽  
Earth Pressure ◽  
Flow Rule ◽  
Passive Earth Pressure ◽  
Element Analysis ◽  
Pressure Coefficients ◽  
Earth Pressures ◽  
Numerical Instabilities ◽  
Associated Flow Rule

AbstractDetermination of earth pressures is one of the fundamental tasks in geotechnical engineering. Although many different methods have been utilized to present passive earth pressure coefficients, the influence of non-associated plasticity on the passive earth pressure problem has not been discussed intensively. In this study, finite-element limit analysis and displacement finite-element analysis are applied for frictional materials. Results are compared with selected data from literature in terms of passive earth pressure coefficients, shape of failure mechanism and robustness of the numerical simulation. The results of this study show that passive earth pressure coefficients determined with an associated flow rule are comparable to the Sokolovski solution. However, comparison with a non-associated flow rule reveals that passive earth pressure coefficients are significantly over predicted when following an associated flow rule. Moreover, this study reveals that computational costs for determination of passive earth pressure are considerably larger following a non-associated flow rule. Additionally, the study shows that numerical instabilities arise and failure surfaces become non-unique. It is shown that this problem may be overcome by applying the approach suggested by Davis (Soil Mech 341–354, 1968).

Finite Element Analysis of Motor Box for EBZ160 Horizontal Roadheader

2015 ◽  
Vol 1090 ◽  
pp. 233-237
Author(s):  
Ji Jun Miao ◽  
Ri Sheng Long
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Optimal Design ◽  
Safety Factor ◽  
Stress And Strain ◽  
Element Analysis

In order to solve the cracking and poor reliability problems of motor box of Horizontal Roadheader, the static structural FEA (Finite Element Analysis) of cutting arm & motor box of the EBH160 Horizontal Roadheader was conducted, and the stress and strain contours of FEA were obtained. By comparing the calculated results, the safety factor of cutting arm & motor box was 1.36, which provides a reference for the optimal design of cutting arm & motor box.

Gradient of Soil Constitutive Model

2010 ◽  
Vol 168-170 ◽  
pp. 1126-1129
Author(s):  
Wen Xu Ma ◽  
Ying Guang Fang
Keyword(s):  
Plastic Strain ◽  
Strain Gradient ◽  
Soil Analysis ◽  
Natural Material ◽  
Flow Rule ◽  
The Finite Element Method ◽  
Gradient Effect ◽  
Non Local ◽  
Associated Flow Rule ◽  
Plastic Strain Gradient

For the soil is a very complex natural material, significant strain gradient effect exist in soil analysis. Based on the "gradient" phenomenon, we add the plastic strain gradient hardening item into the traditional Cambridge yield surface. By using the consistency conditions and associated flow rule, we get the explicit expression of plastic strain gradient stiffness matrix. And the finite element method of plastic strain gradient is also shown in this article. Plastic strain gradient is actually a phenomenological non-local model containing microstructure information of the material. It may overcome the difficulties in simulating the gradient phenomenon by traditional mechanical model.

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