Numerical analysis on the influence of rock specimen size on crack stress field

This manuscript presents an experimental and numerical analysis of the mechanical structural behavior of Nylstrong GF-PA6, a plastic material manufactured using FDM (fused deposition modeling) technology for a compression uniaxial stress field. Firstly, an experimental test using several test specimens fabricated in the Z and X-axis allows characterizing the elastic behavior of the reinforced GF-PA6 according to the ISO 604 standard for uniaxial compression stress environments in both Z and X manufacturing orientations. In a second stage, an experimental test analyzes the structural behavior of an industrial part manufactured under the same conditions as the test specimens. The experimental results for the test specimens manufactured in the Z and X-axis present differences in the stress-strain curve. Z-axis printed elements present a purely linear elastic behavior and lower structural integrity, while X-axis printed elements present a nonlinear elastic behavior typical of plastic and foam materials. In order to validate the experimental results, numerical analysis for an industrial part is carried out, defining the material GF-PA6 as elastic and isotropic with constant Young’s compression modulus according to ISO standard 604. Simulations and experimental tests show good accuracy, obtaining errors of 0.91% on the Z axis and 0.56% on the X-axis between virtual and physical models.

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ENPOWER: Investigations by Neutron Diffraction and Finite Element Analyses on Residual Stress Formation in Repair Welds Applied to Ferritic Steel Plates

Volume 6: Materials and Fabrication ◽

10.1115/pvp2005-71786 ◽

2005 ◽

Cited By ~ 1

Author(s):

Carsten Ohms ◽

Robert C. Wimpory ◽

Dimitar Neov ◽

Didier Lawrjaniec ◽

Anastasius G. Youtsos

Keyword(s):

Experimental Data ◽

Residual Stress ◽

Numerical Analysis ◽

Neutron Diffraction ◽

Stress Field ◽

Ferritic Steel ◽

Maximum Stress ◽

Steel Plates ◽

Residual Stress Field ◽

Welding Procedure

The European collaborative research project ENPOWER (Management of Nuclear Plant Operation by Optimizing Weld Repairs) has as one of its main objectives the development of guidelines for the application of repair welds to safety critical components in nuclear power plants. In this context letter box repair welds applied to thin ferritic steel plates to simulate repair of postulated shallow cracks have been manufactured for the purpose of experimental and numerical analysis of welding residual stresses. Two specimens have been procured, one of them prepared in accordance with a standard welding procedure, while in the second case a different procedure was followed in order to obtain extended martensite formation in the heat affected zone. Residual stresses have been determined in both specimens by neutron diffraction at the High Flux Reactor of the Joint Research Centre in Petten, The Netherlands. In parallel Institut de Soudure in France has performed a full 3-d analysis of the residual stress field for the standard welding case taking into account the materials and phase transformations. The experimental data obtained for both specimens clearly suggest that the non-conventional welding procedure rendered higher maximum stress values. In the case of the standard welding procedure numerical and experimental data show a reasonable qualitative agreement. The maximum stress value was in both cases found in the same region of the material — in the base metal just underneath the weld pool — and in both cases found to be of similar magnitude (∼800 MPa found in neutron diffraction and ∼700 MPa found in numerical analysis). In this paper the experimental and numerical approaches are outlined and the obtained results are presented. In addition an outlook is given to future work to be performed on this part of the ENPOWER project. A main issue pending is the application of an optimized advanced post weld heat treatment in one of the two cases and the subsequent numerical and experimental determination of its impact on the residual stress field. At the same time further evaluation of the materials transformations due to welding is pursued.

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Numerical Analysis of Stress Field for Simulating Pressure Vessel Nozzles

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.314-316.1146 ◽

2011 ◽

Vol 314-316 ◽

pp. 1146-1149

Author(s):

Jian Hua Cui

Keyword(s):

Finite Element ◽

Numerical Analysis ◽

Stress Field ◽

Pressure Vessel ◽

High Strain ◽

Special Shape ◽

Equilibrium Conditions ◽

Strain Gradients ◽

Stress Equilibrium ◽

Calculation Results

According to high strain gradients characteristic at the junction between pressure vessel and nozzle, based on simulating shape plate of pressure vessel nozzle, weak-conforming element models are established for two types of special shape plates, which satisfied weak continuous conditions between elements. The weak-conforming element methods do not need satisfy stress equilibrium conditions. It can solve the conventional finite element difficult to adapt to the singularity of the field. The stresses are obtained by means of weak-conforming element method. The calculation results are in accordance with those of experiment results. This paper provides the foundation for the design of special shape plates and analysis of extending crack.

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