Estimating the dimensions of the radial crack zone formed in a contained explosion of a line charge in a brittle medium

1985 ◽  
Vol 25 (4) ◽  
pp. 619-625 ◽  
Author(s):  
P. A. Martynyuk ◽  
E. N. Sher
Keyword(s):  
Radial Crack ◽  
Line Charge ◽  
Crack Zone

Angular terms in the electron density for the phosphine molecule

1956 ◽  
Vol 52 (4) ◽  
pp. 703-711 ◽  
Author(s):  
R. A. Ballinger ◽  
N. H. March
Keyword(s):  
Variational Method ◽  
Charge Density ◽  
Electron Density ◽  
Legendre Polynomials ◽  
Molecular Axis ◽  
Thomas Fermi ◽  
Line Charge ◽  
Density Map ◽  
Circular Line

ABSTRACTAn attempt is made to calculate the first few angular terms in an expansion of the electron density for the phosphine molecule in Legendre polynomials. Such an expansion is appropriate for a model in which the three hydrogen nuclei are smeared to form a circular line charge. The Thomas–Fermi approximation has been used in conjunction with the variational method. The variational density employed includes p and f angular terms. An approximate charge density map is constructed for a plane containing the molecular axis in order to demonstrate the effect of the angular terms.

Evolution of line charge density of steadily-developing upward positive leaders in triggered lightning

2013 ◽  
Vol 118 (10) ◽  
pp. 4670-4678 ◽  
Author(s):  
Mingli Chen ◽  
Dong Zheng ◽  
Yaping Du ◽  
Yijun Zhang
Keyword(s):  
Charge Density ◽  
Line Charge ◽  
Triggered Lightning

Three-Dimensional Interaction Effects in an Internally Multicracked Pressurized Thick-Walled Cylinder— Part I: Radial Crack Arrays

1996 ◽  
Vol 118 (3) ◽  
pp. 357-363 ◽  
Author(s):  
M. Perl ◽  
C. Levy ◽  
J. Pierola
Keyword(s):  
Radial Crack ◽  
Crack Depth ◽  
Three Dimensional ◽  
Internal Surface ◽  
Interaction Effects ◽  
Life Assessment ◽  
Fatigue Life Assessment ◽  
Dimensional Interaction ◽  
Least Squares Fit ◽  
Wide Range

Under certain conditions, numerous internal surface cracks develop in pressurized thick-walled cylinders, both in the radial and longitudinal directions. For fatigue life assessment of such vessels, the 3-D interaction effects among these cracks on the prevailing stress intensity factors (SIFs) need evaluation. In Part I of this paper, radial crack arrays are considered exclusively. The mode I SIF distribution for a wide range of semi-circular and semi-elliptical cracks are evaluated. The 3-D analysis is performed via the finite element method with the submodeling technique, employing singular elements along the crack front. SIFs are evaluated for arrays of up to n = 180 cracks; for a wide range of crack depth to wall thickness ratios, a/t, from 0.05 to 0.6; and, for various ellipticities of the crack, i.e., the ratio of crack depth to semicrack length, a/c, from 0.2 to 2. Using a least-squares fit, two simple expressions for the most critical (n = 2) SIFs are obtained for sparse and dense crack arrays. The formulas, which are functions of a/t and a/c, are of very good engineering accuracy. The results clearly indicate that the SIFs are considerably affected by the interaction among the cracks in the array as well as the three-dimensionality of the problem. In Part II of this paper, the interaction effects between longitudinal coplanar cracks will be analyzed.

Binding Performance of a Zirconia Framework Material and Veneering Porcelain

2010 ◽  
Vol 177 ◽  
pp. 186-189 ◽  
Author(s):  
Long Quan Shao ◽  
Bin Deng ◽  
Yuan Fu Yi ◽  
Qi Liu ◽  
Wei Wei Zhang ◽  
...  
Keyword(s):  
Bond Strength ◽  
Thermal Shock ◽  
Shear Bond Strength ◽  
Chemical Element ◽  
Radial Crack ◽  
Visual Observation ◽  
Thermal Shock Test ◽  
Cross Sectional ◽  
Shock Test ◽  
Cad Cam

In this study, the binding performance of a Cercon-based zirconia framework material and special Cercon Ceram S zirconia veneering porcelain is discussed. Rectangular 30 mm × 20 mm × 2 mm porcelain blocks were made from zirconia using the CAD/CAM system. The 2 mm veneering porcelain was then sintered onto blocks at a temperature of 850-800°C with a loading speed of l mm/min. The shear bond strength of the interface was tested. Sintering was studied by visual observation, scanning electron microscopy, energy dispersive spectroscopy (EDS), thermal shock test and other methods. Excellent sintering results of the zirconia framework material and veneering porcelain can be achieved. The cross-sectional morphology of the samples, observed by SEM, shows a uniform, fine, and smooth texture for the veneering porcelain, whereas that of the zirconia framework material shows a rough surface with a uniform and compact texture. EDS results indicate that a small amount of A12O3 and SiO2 is present in the zirconia area, and no ZrO2 or Y2O3 is detected in the veneering porcelain area. No interlayer radial crack or flaw is found throughout the entire thermal shock test of the samples at 60-240°C. Thus, the cracking temperature of the samples is pegged at T>240°C. The shear bond strength of the interface is 32.62±5.77 MPa. Chemical element infiltration exists between zirconia and the veneering porcelain, indicating the chemical bond between the two. An excellent match between the Cercon-based zirconia framework and the special veneering porcelain can be achieved, which can satisfy clinical requirements.

scholarly journals Thermal vision of fracture behavior on acrylic composites

2021 ◽  
pp. 4-4
Author(s):  
Vanja Malisic ◽  
Marina Stamenovic ◽  
Slavisa Putic
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Fatty Acid Methyl Esters ◽  
Methyl Esters ◽  
Alpha Phase ◽  
Elongation At Break ◽  
Flax Oil ◽  
Alumina Particles ◽  
Crack Zone ◽  
Thermal Vision

The aim of this work was to investigate thermal properties of acrylate-based composite combined with alumina-based particles. The composites were made of poly (methyl methacrylate) (PMMA) modified with dimethyl itaconate (DMI) as a matrix. As reinforcement were used alumina particles (Al2O3) and alumina doped with iron oxide (Al2O3-Fe) modified with 3-aminopropyl-trimethoxylane (AM) and flax oil fatty acid methyl esters (biodiesel - BD). According to the thermal conductivity measurements, the highest thermal conductivity values had the composite with alumina particles with the highest alpha phase content. With the addition of modified alumina particles to PMMA/DMI matrix mechanical properties were improved (tensile strength, modulus of elasticity and elongation at break). Composite with 3 wt. % Al2O3-Fe-AM particles had the most improved mechanical properties. It was noticed that this composite, compared to PMMA, had the lowest temperature in a crack zone (10.28%) and that is due to the better stiffness and highest thermal conductivity. The results indicated that the Sobel fractured surface area is related to the crack energy, which is reflected by the temperature of sample monitored by thermal vision.

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