Factors Causing Hydrogen Embrittlement of Cold-Drawn Pearlitic Steel Fractured Under Elastic/Plastic Region

In-Vessel Retention (IVR) is one of the most important severe accident mitigation strategies of the third generation passive Nuclear Power Plants (NPP). It is intended to demonstrate that in the case of a core melt, the structural integrity of the Reactor Pressure Vessel (RPV) is assured such that there is no leakage of radioactive debris from the RPV. This paper studied the IVR issue using Finite Element Analyses (FEA). Firstly, the tension and creep testing for the SA-508 Gr.3 Cl.1 material in the temperature range of 25°C to 1000°C were performed. Secondly, a FEA model of the RPV lower head was built. Based on the assumption of ideally elastic-plastic material properties derived from the tension testing data, limit analyses were performed under both the thermal and the thermal plus pressure loading conditions where the load bearing capacity was investigated by tracking the propagation of plastic region as a function of pressure increment. Finally, the ideal elastic-plastic material properties incorporating the creep effect are developed from the 100hr isochronous stress-strain curves, limit analyses are carried out as the second step above. The allowable pressures at 0 hr and 100 hr are obtained. This research provides an alternative approach for the structural integrity evaluation for RPV under IVR condition.

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Repeated alternating loading of a elastoplastic three-layer plate in a temperature field

Izvestiya of Saratov University New Series Series Mathematics Mechanics Informatics ◽

10.18500/1816-9791-2021-21-1-60-75 ◽

2021 ◽

Vol 21 (1) ◽

pp. 60-75

Author(s):

Eduard I. Starovoitov ◽

◽

Denis V. Leonenko ◽

Keyword(s):

Temperature Field ◽

Differential Equations ◽

Boundary Value Problem ◽

Boundary Conditions ◽

Nonlinear Differential Equations ◽

Boundary Value ◽

Plastic Region ◽

Local Load ◽

Natural State ◽

Elastic Plastic

Axisymmetric deformation of a three-layer circular plate under repeated alternating loading from the plastic region by a local load is considered. To describe kinematics of asymmetrical on the thickness of the plate pack is adopted the hypothesis of a broken line. In a thin elastic-plastic load-bearing layers are used the hypothesis of Kirchhoff. A non-linearly elastic relatively thick filler is incompressible in thickness. It is taken to be a hypothesis of Tymoshenko regarding the straightness and the incompressibility of the deformed normals with linear approximation of the displacements through the thickness layer. The work of the filler in the tangential direction is taken into account. The physical relations of stress-strain relations correspond to the theory of small elastic-plastic deformations. The effect of heat flow is taken into account. The temperature field in the plate was calculated by the formula obtained by averaging the thermophysical parameters over the thickness of the package. The system of differential equations of equilibrium under loading of the plate from the natural state is obtained by the Lagrange variational method. Boundary conditions on the plate contour are formulated. The solution of the corresponding boundary value problem is reduced to finding the three desired functions: deflection, shear and radial displacement of the shear surface of the filler. A non-uniform system of ordinary nonlinear differential equations is written for these functions. Its analytical iterative solution is obtained in Bessel functions by the method of elastic solutions of Ilyushin. In case of repeated alternating loading of the plate, the solution of the boundary value problem is constructed using the theory of variable loading of Moskvitin. In this case, the hypothesis of similarity of plasticity functions at each loading step is used. Their analytical form is taken independent of the point of unloading. However, the material constants included in the approximation formulas will be different. The cyclic hardening of the material of the bearing layers is taken into account. The parametric analysis of the obtained solutions under different boundary conditions in the case of a local load distributed in a circle is carried out. The influence of temperature and nonlinearity of layer materials on the displacements in the plate is numerically investigated.

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Application of the Cyclic Strain Approach to the Fatigue Failure of Ship Structural Details

Journal of Ship Research ◽

10.5957/jsr.1987.31.3.177 ◽

1987 ◽

Vol 31 (03) ◽

pp. 177-185

Author(s):

Wolfgang Fricke ◽

Hans Paetzold

Keyword(s):

Fatigue Life ◽

Plastic Region ◽

Steel Structure ◽

Cyclic Strain ◽

Cyclic Stress ◽

Damage Parameter ◽

Elastic Plastic ◽

Strain Behavior ◽

Structural Details ◽

The Relationship

The cyclic strain approach is useful for determining the fatigue life of notches strained in the elastic-plastic region. Examples are the flame-cut edges of cutouts in the ship steel structure. After the description of the cyclic stress-strain behavior of the usual mild steel, the individual elements of the approach are described: the probability distribution of load amplitudes, the relationship between load and local elastic-plastic strain, the relationship between the damage parameter and fatigue life, and finally the damage accumulation law. The approach is illustrated by two examples of longitudinal/transverse web intersections. In the first, the predicted life is confirmed by experimental results. The second example shows the approach for complicated load combinations. It is hoped that this paper will contribute to sound and crack-free ship structural details, particularly if unusual loads are applied to well-tried details or if simplified designs are introduced.

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Effect of Aging Treatment on Hydrogen Embrittlement of Drawn Pearlitic Steel Wire

ISIJ International ◽

10.2355/isijinternational.isijint-2015-735 ◽

2016 ◽

Vol 56 (5) ◽

pp. 893-898 ◽

Cited By ~ 8

Author(s):

Daisuke Hirakami ◽

Toshiyuki Manabe ◽

Kohsaku Ushioda ◽

Kei Noguchi ◽

Kenichi Takai ◽

...

Keyword(s):

Hydrogen Embrittlement ◽

Steel Wire ◽

Aging Treatment ◽

Pearlitic Steel

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Elastic and Plastic Stress Analysis of Composite Beams under Distributed Load

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.232.63 ◽

2012 ◽

Vol 232 ◽

pp. 63-67

Author(s):

Azad Mohammed Ali Saber

Keyword(s):

Stress Analysis ◽

Stress Component ◽

Plastic Region ◽

Composite Layer ◽

Aluminum Matrix ◽

Composite Beams ◽

Elastic Plastic ◽

Distributed Load ◽

Stainless Steel Fiber ◽

Plastic Stress

An analytical elastic-plastic stress analysis is carried out on metal-matrix composite beams of arbitrary orientation, supported from two ends under a transverse uniformly distributed load. The composite layer consists of stainless steel fiber and aluminum matrix. The material is assumed to be perfectly plastic during the elastic–plastic solution. The intensity of the uniform force is chosen at a small value; therefore, the normal stress component is neglected in the elastic-plastic solution. The expansion of the plastic region and plastic stress component of σxare determined for orientation angles of 0, 30, 45, 60 and 90o. Plastic yielding occurs for 0 o and 90 o orientation angles on the lower and upper surfaces of the beam at the same distances from the mid-point. However, it starts first at the lower surface for 30, 45 and 60 o orientation angles.

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Elastic-Plastic Analysis of Pressurized Cylindrical Shells

Journal of Applied Mechanics ◽

10.1115/1.3173075 ◽

1987 ◽

Vol 54 (3) ◽

pp. 597-603 ◽

Cited By ~ 4

Author(s):

G. N. Brooks

Keyword(s):

Shell Theory ◽

Plastic Region ◽

Yield Condition ◽

Elastic Plastic ◽

Tresca Yield Condition ◽

Axisymmetric Shell ◽

Bending Stresses ◽

Principal Directions ◽

The Moment ◽

Thin Shell Theory

Plasticity in shells is often contained near the ends of a segment where the bending stresses are significant. Outside of this local neighborhood the behavior is elastic. Thus, an axisymmetric shell can be divided along its axis into a purely elastic region away from an end and the local region where plasticity is present. The moment-curvature relation in the elastic-plastic region is calculated using the Tresca yield condition. Use of the Tresca yield condition greatly simplifies this derivation because the principal directions are known. This moment-curvature relationship is “exact” in the sense that only the standard assumptions of thin shell theory are made. The solutions of the elastic and plastic regions are matched at their intersection for an efficient numerical solution. The technique is used here to study the semi-infinite clamped cylindrical shell with an internal pressure loading.

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