About Relation Between Irradiation Hardening of Ferritic Steels and Ductile Fracture Toughness Decrease

2009 ◽  
Author(s):  
Jiri Novak
Keyword(s):  
Fracture Toughness ◽  
Temperature Dependence ◽  
Ductile Fracture ◽  
Stress Level ◽  
Deformation Theory ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Irradiation Hardening ◽  
Ductile Fracture Toughness

We showed recently that temperature dependence of the ductile fracture toughness can be predicted on the base of two assumptions: 1) assumption of constant characteristic length, 2) assumption of proportionality between J-R curve slope and deformation work in unit volume, evaluated from zero to critical strain for initiation of deformation bands determined in plane strain geometry for material modeled by deformation theory of plasticity. Temperature dependence of ductile fracture toughness results simply from temperature dependence of the stress-strain curve. Irradiation hardening changes stress-strain behavior in a qualitatively different way: It is observed that irradiation hardening to certain yield stress level changes the stress-strain curve of the material in the same way as prestraining of the unirradiated material to the same flow stress level does. Equivalence of irradiation and prestraining concerns all key properties of deformation theory; namely the secant modulus should be taken from the stress-strain curve of unirradiated material. With exception of this specific feature, the task of finding relative fracture toughness decrease by irradiation is the same as prediction of relative decrease of fracture toughness by temperature change. In the frame of the corresponding theory, relative decrease of ductile fracture toughness expressed by J-R curve slope can be obtained from the stress-strain curve of unirradiated material and irradiation hardening level. Quantitative results are presented for the weld metals 72W and 73W, studied in the Fifth Irradiation Series in the Heavy-Section Steel Irradiation Program, and compared with experimental data.

A Reassessment of Deformation Theories of Plasticity

1959 ◽  
Vol 26 (2) ◽  
pp. 259-264
Author(s):  
Bernard Budiansky
Keyword(s):  
Strain Hardening ◽  
Deformation Theory ◽  
Strain Curve ◽  
Uniaxial Stress ◽  
Plasticity Theory ◽  
Stress Strain Curve ◽  
Proportional Loading ◽  
Stress Strain ◽  
Simple Deformation ◽  
Strain Hardening Rate

Abstract It is shown that deformation theories of plasticity may be used for a range of loading paths other than proportional loading without violation of general requirements for the physical soundness of a plasticity theory. The extent to which deviations from proportional loading are admissible on this basis is calculated quantitatively for the simple deformation theory of Nadai. It is shown that the lower the strain-hardening rate of the uniaxial stress-strain curve, the greater are the permissible deviations from proportional loading.

A new test for determining the mechanical and fracture behavior of materials in sheet-bulk metal forming

2015 ◽  
Vol 231 (8) ◽  
pp. 693-703 ◽  
Author(s):  
CMA Silva ◽  
MB Silva ◽  
LM Alves ◽  
PAF Martins
Keyword(s):  
Fracture Toughness ◽  
Metal Forming ◽  
Three Dimensional ◽  
Strain Curve ◽  
Shear Zones ◽  
Shear Stresses ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Bulk Metal ◽  
Bulk Metal Forming

This paper presents a new experimental test for determining the stress–strain curve and the fracture toughness of sheets to be used in sheet-bulk metal forming (SBMF) applications. The test is based on the utilization of double-notched specimens loaded in shear and combines the plane stress loading conditions of sheet metal forming with the three-dimensional plastic flow conditions of bulk metal forming, which are commonly found in SBMF processes. The methodology to obtain the stress–strain curve involves calculation of the shear stresses and strains along the two symmetric plastic shear zones of the test specimens up to point where cracks start to propagate along the ligaments that connect each pair of opposite notches. The determination of fracture toughness involves characterization of the evolution of load with displacement for a number of test cases performed with specimens having different ligaments between the two symmetric opposite notches. The work is performed on aluminium alloy EN AW 5754 H111 sheets with 5 mm thickness and the results obtained by means of the new proposed test are compared against those from conventional mechanical and fracture characterization tests.

A modified version of MATLAB application window for predicting the weld bead profile and stress–strain plot of AA5052 CMT weldment using ER4043

SIMULATION ◽  
2021 ◽  
pp. 003754972110315
Author(s):  
B Girinath ◽  
N Siva Shanmugam
Keyword(s):  
Strain Curve ◽  
Weld Bead ◽  
Welding Parameters ◽  
Bead Geometry ◽  
Hybrid Technique ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Weld Bead Geometry ◽  
Inference System ◽  
Engineering Stress

The present study deals with the extended version of our previous research work. In this article, for predicting the entire weld bead geometry and engineering stress–strain curve of the cold metal transfer (CMT) weldment, a MATLAB based application window (second version) is developed with certain modifications. In the first version, for predicting the entire weld bead geometry, apart from weld bead characteristics, x and y coordinates (24 from each) of the extracted points are considered. Finally, in the first version, 53 output values (five for weld bead characteristics and 48 for x and y coordinates) are predicted using both multiple regression analysis (MRA) and adaptive neuro fuzzy inference system (ANFIS) technique to get an idea related to the complete weld bead geometry without performing the actual welding process. The obtained weld bead shapes using both the techniques are compared with the experimentally obtained bead shapes. Based on the results obtained from the first version and the knowledge acquired from literature, the complete shape of weld bead obtained using ANFIS is in good agreement with the experimentally obtained weld bead shape. This motivated us to adopt a hybrid technique known as ANFIS (combined artificial neural network and fuzzy features) alone in this paper for predicting the weld bead shape and engineering stress–strain curve of the welded joint. In the present study, an attempt is made to evaluate the accuracy of the prediction when the number of trials is reduced to half and increasing the number of data points from the macrograph to twice. Complete weld bead geometry and the engineering stress–strain curves were predicted against the input welding parameters (welding current and welding speed), fed by the user in the MATLAB application window. Finally, the entire weld bead geometries were predicted by both the first and the second version are compared and validated with the experimentally obtained weld bead shapes. The similar procedure was followed for predicting the engineering stress–strain curve to compare with experimental outcomes.

Stress-strain curve of paper revisited

2012 ◽  
Vol 27 (2) ◽  
pp. 318-328 ◽  
Author(s):  
Svetlana Borodulina ◽  
Artem Kulachenko ◽  
Mikael Nygårds ◽  
Sylvain Galland
Keyword(s):  
Three Dimensional ◽  
Strain Curve ◽  
Failure Behavior ◽  
Three Dimensional Model ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Fiber Network ◽  
Bonding Parameters ◽  
Particle Level ◽  
The Impact

Abstract We have investigated a relation between micromechanical processes and the stress-strain curve of a dry fiber network during tensile loading. By using a detailed particle-level simulation tool we investigate, among other things, the impact of “non-traditional” bonding parameters, such as compliance of bonding regions, work of separation and the actual number of effective bonds. This is probably the first three-dimensional model which is capable of simulating the fracture process of paper accounting for nonlinearities at the fiber level and bond failures. The failure behavior of the network considered in the study could be changed significantly by relatively small changes in bond strength, as compared to the scatter in bonding data found in the literature. We have identified that compliance of the bonding regions has a significant impact on network strength. By comparing networks with weak and strong bonds, we concluded that large local strains are the precursors of bond failures and not the other way around.

Definition of the yield point in plasticity and its effect on the shape of the yield locus

1966 ◽  
Vol 1 (4) ◽  
pp. 331-338 ◽  
Author(s):  
T C Hsu
Keyword(s):  
Yield Point ◽  
Experimental Work ◽  
Strain Curve ◽  
Yield Locus ◽  
Experimental Results ◽  
Stress Strain Curve ◽  
Proportional Limit ◽  
Stress Strain ◽  
Small Section ◽  
Definition Of

Three different definitions of the yield point have been used in experimental work on the yield locus: proportional limit, proof strain and the ‘yield point’ by backward extrapolation. The theoretical implications of the ‘yield point’ by backward extrapolation are examined in an analysis of the loading and re-loading stress paths. It is shown, in connection with experimental results by Miastkowski and Szczepinski, that the proportional limit found by inspection is in fact a point located by backward extrapolation based on a small section of the stress-strain curve, near the elastic portion of the curve. The effect of different definitions of the yield point on the shape of the yield locus and some considerations for the choice between them are discussed.

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