0719 Failure Criterion Applicable to Large Strain Finite Element Analysis Results to Predict Limit Bending Load of Wall Thinned Pipes (Effect of the Axial Length)

2012 ◽  
Vol 2012.49 (0) ◽  
pp. 071901-071902
Author(s):  
Yoshiaki ITO ◽  
Toshiyuki MESHII
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Failure Criterion ◽  
Axial Length ◽  
Large Strain ◽  
Element Analysis ◽  
Bending Load

Displacement Based Failure Criterion Applicable to Finite Element Analysis Results for Wall-Thinned Pipes Under Pressure Load

2013 ◽  
Author(s):  
Toshiyuki Meshii ◽  
Kan Yoshii
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Failure Criterion ◽  
Large Strain ◽  
True Strain ◽  
Burst Pressure ◽  
Pipe Material ◽  
Element Analysis ◽  
Hardening Material ◽  
Displacement Based

In this work, a failure criterion applicable to large strain elastic-plastic Finite Element Analysis (EP FEA) results was proposed in order to predict the burst pressure of wall-thinned straight pipes. The key finding was that, though the pipe material was strain-hardening material, and though the pipe was locally wall-thinned, the outer surface radial displacement at the flaw center obtained from the EP FEA tended to diverge with the increase in pressure, even though the strain was very low compared to the true strain of fracture. This tendency was validated by the image processing displacement measurement results from the systematic burst tests of wall-thinned pipes. By comparing the EP-FEA results with the test results, the proposed criterion predicted the burst pressure within a maximum 10% difference. Advantage of the criterion is that it uses the true stress and strain relationship below the true tensile strength, and the ambiguous near fracture relationship is not necessary.

Improving Prediction of Limit Bending Load for Wall-Thinned Pipes by Reconsidering the Effect of Biaxiality

2015 ◽  
Author(s):  
Kosuke Mori ◽  
Toshiyuki Meshii
Keyword(s):  
Finite Element Analysis ◽  
Large Strain ◽  
Axial Stress ◽  
Plastic Instability ◽  
Failure Criteria ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Crack Penetration ◽  
Bending Load ◽  
Von Mises

In this paper, a failure criterion applicable to large-strain finite element analysis (FEA) results was studied to predict the limit bending load Mc of the groove shaped wall-thinned pipes, under combined internal pressure and bending load, that experienced cracking. In our previous studies, Meshii and Ito [1] considered cracking of pipes with groove shaped flaw (small axial length δz in Fig. 1) was due to the plastic instability at the wall-thinned section and proposed the Domain Collapse Criterion (DCC). The DCC predicted Mc of cracking for small δz by comparing the von Mises stress σMises with the true tensile strength σB. However, it was indicated that the predictability of Mc was not necessarily sufficient. Thus, in this work, attempts were made to improve the accuracy of Mc prediction with a perspective that multi-axial stress state might affect this plastic instability. As a result of examination of the various failure criteria based on multi-axial stress, it was confirmed that the limit bending load of the groove flawed pipe that experienced cracking could be predicted within 5 % accuracy by applying Hill’s plastic instability onset criterion [2] to the outer surface of the crack penetration section. The accuracy of the predicted limit bending load was improved from DCC’s error of 15% to 5%.

Development of Material Constants for Nonlinear Finite-Element Analysis

1988 ◽  
Vol 61 (5) ◽  
pp. 879-891 ◽  
Author(s):  
Robert H. Finney ◽  
Alok Kumar
Keyword(s):  
Experimental Data ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Large Strain ◽  
Strain Range ◽  
Nonlinear Finite Element ◽  
Element Analysis ◽  
Material Models ◽  
Tensile Data

Abstract The determination of the material coefficients for Ogden, Mooney-Rivlin, Peng, and Peng-Landel material models using simple ASTM D 412 tensile data is shown to be a manageable task. The application of the various material models are shown to be subject to the type and level of deformation expected, with Ogden showing the best correlation with experimental data over a large strain range for the three types of strain investigated. At low strains, all of the models showed reasonable correlation.

Finite element analysis of calibration factors for the modified incremental strain method

2003 ◽  
Vol 38 (1) ◽  
pp. 45-51 ◽  
Author(s):  
B-W Hwang ◽  
C-M Suh ◽  
S-H Kim
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Boundary Conditions ◽  
Reference Model ◽  
Strain Relaxation ◽  
Hole Drilling ◽  
Element Analysis ◽  
Bending Load ◽  
Incremental Strain ◽  
Strain Method

To modify the incremental strain method used to evaluate non-uniform residual stress, a finite element analysis (FEA) of the reference model used to describe a hole-drilling test was conducted. The calibration factors for the x and y directions were obtained from the analysis and then their differences were compared under various loading conditions. A hole-drilling test using a steel plate as the reference specimen was introduced, and under the pure bending load, strain relaxation was measured at each hole-drilling step to determine the calibration factors. Although the calibration factors in the x and y directions varied with the boundary conditions used in the FEA, their differences were reduced to zero for all depths when the prescribed loads as the boundary conditions in the x and y directions became the same. In addition, it was analytically and experimentally confirmed that the calibration factors did not vary with the direction. Accordingly, by making the calibration factors equal in the x and y directions in the modified equation for the incremental strain method, no singularity is produced in the stress calculations.

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