A Numerical and Experimental Study of the Cleavage Fracture Behaviour of Non-Sharp Defects

2008 ◽  
Author(s):  
Anthony J. Horn ◽  
Andrew H. Sherry
Keyword(s):  
Experimental Study ◽  
Stress Field ◽  
Tensile Stress ◽  
Cleavage Fracture ◽  
Fracture Behaviour ◽  
Numerical Study ◽  
Notch Root ◽  
Experimental Studies ◽  
Stress Criterion ◽  
Edge Notch

Structures containing non-sharp defects exhibit a higher apparent resistance to cleavage fracture than sharp cracks. This paper presents a numerical and experimental study of the cleavage fracture behaviour of single edge notch bend SE(B) specimens with cracks and notches with varying notch root radii. The experimental study demonstrates the increasing resistance to fracture that occurs with increasing notch root radius. This is complemented by a numerical study that quantifies the elastic-plastic stress field ahead of the crack or notch tip. The results of the numerical and experimental studies are used together to show that the cleavage initiation sites, identified using scanning electron microscopy, are located close to the peak tensile stress field occurring ahead of the notch. This implies that a tensile stress criterion is the main controlling factor for cleavage fracture in the notched specimens analysed.

A Numerical and Experimental Study of the Factors Influencing the Differences in Cleavage Fracture Behaviour Between CVN and SENB Specimens

2012 ◽  
Author(s):  
Robin J. Smith ◽  
Anthony J. Horn ◽  
Andrew H. Sherry
Keyword(s):  
Finite Element ◽  
Cleavage Fracture ◽  
Fracture Behaviour ◽  
Numerical Study ◽  
Notch Root ◽  
Notch Depth ◽  
Root Radius ◽  
Element Analysis ◽  
Notch Root Radius ◽  
The Individual

The cleavage fracture behaviour of Charpy V-notch (CVN) and Single Edge Notch Bend (SENB) specimens differ due to the effects of notch root radius, notch depth, notch flank angle and loading rate. This paper presents an experimental and numerical study of the cleavage fracture behaviour of CVN, SENB and a range of non-standard intermediate specimen geometries. The intermediate geometries were selected to provide a basis for quantifying the differences in cleavage fracture behaviour between the CVN and SENB specimens by isolating the individual effects of notch-root radius, notch flank angle and notch depth. Finite element analyses were used to quantify crack and notch-tip stress fields. The study also includes a comprehensive experimental programme covering the range of notch geometries modelled using finite element analysis. The overall aim of the project is to establish links between Wallin’s Master Curve for fracture toughness and the common temperature dependence of Charpy energy observed by EricksonKirk et al.

scholarly journals Experimental Study on Notched Directional Blasting in Tensile Stress Field

2020 ◽  
Vol 13 (1) ◽  
pp. 106-113
Author(s):  
Liyun Yang ◽  
Huanzhen Xie ◽  
Chen Huang ◽  
Dongbin Zhang ◽  
Yuh J. Chao
Keyword(s):  
Experimental Study ◽  
Stress Field ◽  
Tensile Stress ◽  
Tensile Stress Field

scholarly journals Mesoscale Modelling of Concretes Subjected to Triaxial Loadings: Mechanical Properties and Fracture Behaviour

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1099
Author(s):  
Qingqing Chen ◽  
Yuhang Zhang ◽  
Tingting Zhao ◽  
Zhiyong Wang ◽  
Zhihua Wang
Keyword(s):  
Mechanical Properties ◽  
Tensile Stress ◽  
Failure Criterion ◽  
Mesoscale Model ◽  
Fracture Behaviour ◽  
Descent Method ◽  
Triaxial Stress ◽  
Gradient Descent Method ◽  
Stress States ◽  
Shear Failures

The mechanical properties and fracture behaviour of concretes under different triaxial stress states were investigated based on a 3D mesoscale model. The quasistatic triaxial loadings, namely, compression–compression–compression (C–C–C), compression–tension–tension (C–T–T) and compression–compression–tension (C–C–T), were simulated using an implicit solver. The mesoscopic modelling with good robustness gave reliable and detailed damage evolution processes under different triaxial stress states. The lateral tensile stress significantly influenced the multiaxial mechanical behaviour of the concretes, accelerating the concrete failure. With low lateral pressures or tensile stress, axial cleavage was the main failure mode of the specimens. Furthermore, the concretes presented shear failures under medium lateral pressures. The concretes experienced a transition from brittle fracture to plastic failure under high lateral pressures. The Ottosen parameters were modified by the gradient descent method and then the failure criterion of the concretes in the principal stress space was given. The failure criterion could describe the strength characteristics of concrete materials well by being fitted with experimental data under different triaxial stress states.

scholarly journals Generation of Reverse Meniscus Flow by Applying An Electromagnetic Brake

2021 ◽  
Author(s):  
Alexander Vakhrushev ◽  
Abdellah Kharicha ◽  
Ebrahim Karimi-Sibaki ◽  
Menghuai Wu ◽  
Andreas Ludwig ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Lorentz Force ◽  
Applied Magnetic Field ◽  
Numerical Study ◽  
Flow Direction ◽  
Experimental Studies ◽  
Submerged Entry Nozzle ◽  
Mean Flow ◽  
Slab Caster ◽  
The Mean

AbstractA numerical study is presented that deals with the flow in the mold of a continuous slab caster under the influence of a DC magnetic field (electromagnetic brakes (EMBrs)). The arrangement and geometry investigated here is based on a series of previous experimental studies carried out at the mini-LIMMCAST facility at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The magnetic field models a ruler-type EMBr and is installed in the region of the ports of the submerged entry nozzle (SEN). The current article considers magnet field strengths up to 441 mT, corresponding to a Hartmann number of about 600, and takes the electrical conductivity of the solidified shell into account. The numerical model of the turbulent flow under the applied magnetic field is implemented using the open-source CFD package OpenFOAM®. Our numerical results reveal that a growing magnitude of the applied magnetic field may cause a reversal of the flow direction at the meniscus surface, which is related the formation of a “multiroll” flow pattern in the mold. This phenomenon can be explained as a classical magnetohydrodynamics (MHD) effect: (1) the closure of the induced electric current results not primarily in a braking Lorentz force inside the jet but in an acceleration in regions of previously weak velocities, which initiates the formation of an opposite vortex (OV) close to the mean jet; (2) this vortex develops in size at the expense of the main vortex until it reaches the meniscus surface, where it becomes clearly visible. We also show that an acceleration of the meniscus flow must be expected when the applied magnetic field is smaller than a critical value. This acceleration is due to the transfer of kinetic energy from smaller turbulent structures into the mean flow. A further increase in the EMBr intensity leads to the expected damping of the mean flow and, consequently, to a reduction in the size of the upper roll. These investigations show that the Lorentz force cannot be reduced to a simple damping effect; depending on the field strength, its action is found to be topologically complex.

scholarly journals Thermoelastic analysis of FGM hollow cylinder for variable parameters and temperature distributions using FEM

2020 ◽  
Vol 9 (1) ◽  
pp. 256-264
Author(s):  
Dinkar Sharma ◽  
Ramandeep Kaur
Keyword(s):  
Stress Field ◽  
Hollow Cylinder ◽  
Numerical Study ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Functionally Graded ◽  
Gradient Index ◽  
Variable Parameters ◽  
Graded Material ◽  
Governing Differential Equation

AbstractThis paper presents, numerical study of stress field in functionally graded material (FGM) hollow cylinder by using finite element method (FEM). The FGM cylinder is subjected to internal pressure and uniform heat generation. Thermoelastic material properties of FGM cylinder are assumed to vary along radius of cylinder as an exponential function of radius. The governing differential equation is solved numerically by FEM for isotropic and anistropic hollow cylinder. Additionally, the effect of material gradient index (β) on normalized radial stresses, normalized circumferential stress and normalized axial stress are evaluated and shown graphically. The behaviour of stress versus normalized radius of cylinder is plotted for different values of Poisson’s ratio and temperature. The graphical results shown that stress field in FGM cylinder is influenced by some of above mentioned parameters.

Experimental and Numerical Study of Methanol-Water Mixture Single-Phase Heat Transfer in a Micro-Channel Heat Sink

2012 ◽  
Author(s):  
Chun K. Kwok ◽  
Matthew M. Asada ◽  
Jonathan R. Mita ◽  
Weilin Qu
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Sink ◽  
Single Phase ◽  
Numerical Study ◽  
Pure Water ◽  
Molar Fraction ◽  
Water Mixture ◽  
Micro Channel ◽  
Numerical Predictions

This paper presents an experimental study of single-phase heat transfer characteristics of binary methanol-water mixtures in a micro-channel heat sink containing an array of 22 microchannels with 240μm × 630μm cross-section. Pure water, pure methanol, and five methanol-water mixtures with methanol molar fraction of 16%, 36%, 50%, 63% and 82% were tested. Key parametric trends were identified and discussed. The experimental study was complemented by a three-dimensional numerical simulation. Numerical predictions and experimental data are in good agreement with a mean absolute error (MAE) of 0.87%.

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