scholarly journals Theoretical analysis of stress intensity factor for two unequal collinear cracks subjected to internal pressure and compressive stress

2021 ◽  
Vol 37 ◽  
pp. 584-596
Author(s):  
Xianshang Zhang ◽  
Qingming Long ◽  
Tao Zheng ◽  
Zheming Zhu ◽  
Meng Wang ◽  
...  
Keyword(s):  
Stress Intensity ◽  
Internal Pressure ◽  
Compressive Stress ◽  
Elliptic Integral ◽  
Complex Stress ◽  
Integral Function ◽  
Collinear Cracks ◽  
Mode Ii Crack ◽  
The Difference ◽  
Good Agreement

Abstract In this paper, a new solution of the stress intensity factors (SIFs) for two unequal collinear cracks is developed considering internal pressure, friction and compressive stress. The complex stress function and elliptic integral function are used to obtain the analytical solution of the SIFs, and it shows a good agreement with the previous researchers’ solutions and numerical results. The theoretical results show that the difference and interaction of the SIFs at cracks’ tips are caused by crack geometry parameters, and they also indicate that the internal pressure leads to the SIFs of a mode I crack and affects the SIFs of a mode II crack because of friction.

FEM Stress Analysis and Mechanical Characteristics of Bolted Pipe Flange Connections With PTFE Blended Gaskets Subjected to External Bending Moments and Internal Pressure

2017 ◽  
Author(s):  
Koji Sato ◽  
Toshiyuki Sawa ◽  
Riichi Morimoto ◽  
Takashi Kobayashi
Keyword(s):  
Stress Distribution ◽  
Internal Pressure ◽  
Mechanical Characteristics ◽  
Bending Moment ◽  
Leak Rate ◽  
Bending Moments ◽  
Four Point Bending ◽  
Sealing Performance ◽  
The Difference ◽  
Good Agreement

In designing of pipe flange connections with gaskets, it is important to examine the mechanical characteristics of the connections subjected to external bending moments due to earthquake such as the changes in hub stress, axial bolt forces and the contact gasket stress distribution which governs the sealing performance. One of the authors developed the PTFE blended gaskets and the authors examined the mechanical characteristics of the connections with the PTFE blended gaskets under internal pressure. However, no research was done to examine the mechanical characteristics of the connections with the newly developed PTFE blended gasket subjected to external bending moment due to earthquake. The objectives of the present study are to examine the mechanical characteristics of the connection with PTFE blended gasket subjected to external bending moment and internal pressure and to discuss the difference in the load order to the connections between the internal pressure and the external bending moments. The changes in the hub stress, the axial bolt force and the contact gasket stress distribution of the connection are analyzed using FEM. Using the obtained the gasket stress distribution and the fundamental data between the gasket stress and the leak rate for a smaller test gasket, the leak rate of the connection with the gasket is predicted under external bending moment and internal pressure. In the FEM calculations, the effects of the nominal diameter of pipe flanges on the mechanical characteristics are shown. In the experiments, ASME class 300 4 inch flange connection with 2m pipes at both sides is used and the test gasket is chosen as No.GF300 made by Nippon Valqua Industries, ltd. Four point bending moment is applied to the connection. The FEM results of the hub stress and the axial bolt forces are in a fairly good agreement with the experimental results. In addition, the FEM results of the leak rate are fairly coincided with the measured results.

SIF Calculation for Two Cracks Emanating From the Internal Boundary of a Tube

1990 ◽  
Vol 112 (4) ◽  
pp. 374-377
Author(s):  
Y. H. Wang ◽  
C. Z. Li
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Internal Pressure ◽  
Crack Length ◽  
Collocation Method ◽  
Outer Boundary ◽  
Internal Boundary ◽  
Collinear Cracks ◽  
Boundary Collocation Method

The stress intensity factor (SIF) corresponding to two collinear cracks emanating from the internal boundary of a tube is calculated by boundary collocation method (BCM). Uniform internal pressure acts in the cylinder and on the crack surfaces or a uniform external tension on the outer boundary. For different ratios of the internal to the external radius, Ri/Re, and different ratios of the crack length to the cylinder thickness, 1/(Re−Ri), SIF values have been obtained. At the same time, the calculation shows that the convergence of the method is satisfactory.

Brittle Fracture Under a Complex State of Stress

1976 ◽  
Vol 98 (1) ◽  
pp. 206-210 ◽  
Author(s):  
M. C. Shaw
Keyword(s):  
Brittle Fracture ◽  
Hydrostatic Stress ◽  
Tensile Tests ◽  
Maximum Tensile Stress ◽  
Complex Stress ◽  
Uniaxial Tensile ◽  
State Of Stress ◽  
Maximum Tensile Strain ◽  
The Difference ◽  
Good Agreement

A hydrostatic stress modified maximum tensile strain theory of fracture previously shown to be in good agreement with results on tungsten carbide specimens loaded to fracture under a variety of complex states of stress is discussed. This theory is applied to tests on marble involving two states of complex stress. The results suggest that the size effect in brittle fracture is smaller than usually assumed. The theory explains the difference in maximum tensile stress at fracture for torsion and uniaxial tensile tests.

Explaining the magnetism of gold

2017 ◽  
Author(s):  
Robson de Farias
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Formation Enthalpy ◽  
Gold Atom ◽  
Orbital Energy ◽  
Knudsen Effusion ◽  
Energy Diagram ◽  
Unpaired Electrons ◽  
The Difference ◽  
Good Agreement

<p>In the present work, a computational study is performed in order to clarify the possible magnetic nature of gold. For such purpose, gas phase Au<sub>2</sub> (zero charge) is modelled, in order to calculate its gas phase formation enthalpy. The calculated values were compared with the experimental value obtained by means of Knudsen effusion mass spectrometric studies [5]. Based on the obtained formation enthalpy values for Au<sub>2</sub>, the compound with two unpaired electrons is the most probable one. The calculated ionization energy of modelled Au<sub>2</sub> with two unpaired electrons is 8.94 eV and with zero unpaired electrons, 11.42 eV. The difference (11.42-8.94 = 2.48 eV = 239.29 kJmol<sup>-1</sup>), is in very good agreement with the experimental value of 226.2 ± 0.5 kJmol<sup>-1</sup> to the Au-Au bond<sup>7</sup>. So, as expected, in the specie with none unpaired electrons, the two 6s<sup>1</sup> (one of each gold atom) are paired, forming a chemical bond with bond order 1. On the other hand, in Au<sub>2</sub> with two unpaired electrons, the s-d hybridization prevails, because the relativistic contributions. A molecular orbital energy diagram for gas phase Au<sub>2</sub> is proposed, explaining its paramagnetism (and, by extension, the paramagnetism of gold clusters and nanoparticles).</p>

Effect of leakage and blockage on the acoustic behavior of particle filters

2019 ◽  
Vol 67 (6) ◽  
pp. 483-492
Author(s):  
Seonghyeon Baek ◽  
Iljae Lee
Keyword(s):  
Transfer Matrix ◽  
Particle Filters ◽  
Acoustic Analysis ◽  
Transmission Loss ◽  
One Dimensional ◽  
Filter System ◽  
The Difference ◽  
The One ◽  
Analytical Approaches ◽  
Good Agreement

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

Effect of design parameters on stresses occurring at the tooth root in a spur gear pressed on a shaft

2021 ◽  
pp. 095440892199529
Author(s):  
Fatih Güven
Keyword(s):  
Internal Pressure ◽  
Tangential Stress ◽  
Spur Gear ◽  
Design Parameters ◽  
Interference Fit ◽  
Gear Design ◽  
Compact Design ◽  
Fit Tolerance ◽  
Moderate Stress ◽  
Good Agreement

Gears are commonly used in transmission systems to adjust velocity and torque. An integral gear or an interference fit could be used in a gearbox. Integral gears are mostly preferred as driving gear for a compact design to reduce the weight of the system. Interference fit makes the replacement of damaged gear possible and re-use of the shaft compared to the integral shaft. However, internal pressure occurs between mating surfaces of the components mated. This internal pressure affects the stress distribution at the root and bottom land of the gear. In this case, gear parameters should be re-considered to assure gear life while reducing the size of the gear. In this study, interference fitted gear-shaft assembly was examined numerically. The effects of rim thickness, profile shifting, module and fit tolerance on bending stress occurring at the root of the gear were investigated to optimize gear design parameters. Finite element models were in good agreement with analytical solutions. Results showed that the rim thickness of the gear is the main parameter in terms of tangential stress occurring at the bottom land of the gear. Positive profile shifting reduces the tangential stress while the pitch diameter of the gear remains constant. Also, lower tolerance class could be selected to moderate stress for small rim thickness.

Effect of Magnetic Fields on the Resistance and Microstructure of Al-Cu Alloy during Solidification Processing

2011 ◽  
Vol 287-290 ◽  
pp. 2916-2920
Author(s):  
Chun Yan Ban ◽  
Peng Qian ◽  
Xu Zhang ◽  
Qi Xian Ba ◽  
Jian Zhong Cui
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Turning Points ◽  
Probe Method ◽  
Solidification Processing ◽  
Ac Magnetic Field ◽  
Dc Magnetic Field ◽  
Cu Alloy ◽  
The Difference ◽  
Good Agreement

The resistance of Al-21%Cu alloy under no magnetic field, DC magnetic field and AC magnetic field from liquid to solid was measured by a four-probe method. The difference of resistance versus temperature curves (R-T curves) was analyzed. It is found that the R-T curves of Al-21%Cu alloy are monotone decreasing and have two obvious turning points. Under DC magnetic field, the liquidus and solidus temperatures of the alloy both decrease, while under AC magnetic field, the liquidus and solidus temperatures both increase. There is a good agreement between the microstructure of quenching sample and R-T curves. The mechanism of the effect of magnetic fields was discussed.

Local atomic structure in tetragonal pure ZrO2nanopowders

2010 ◽  
Vol 43 (2) ◽  
pp. 227-236 ◽  
Author(s):  
Leandro M. Acuña ◽  
Diego G. Lamas ◽  
Rodolfo O. Fuentes ◽  
Ismael O. Fábregas ◽  
Márcia C. A. Fantini ◽  
...  
Keyword(s):  
Tetragonal Phase ◽  
Local Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Structures ◽  
Crystallite Sizes ◽  
Exafs Study ◽  
The Difference ◽  
X Ray Absorption ◽  
Good Agreement

The local atomic structures around the Zr atom of pure (undoped) ZrO2nanopowders with different average crystallite sizes, ranging from 7 to 40 nm, have been investigated. The nanopowders were synthesized by different wet-chemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO2nanopowders can be described by a model consisting of two oxygen subshells (4 + 4 atoms) with different Zr—O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye–Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to thezdirection; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4 + 2 + 2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments.

On Thick-Walled Cylinder Under Internal Pressure

2003 ◽  
Vol 125 (3) ◽  
pp. 267-273 ◽  
Author(s):  
W. Zhao ◽  
R. Seshadri ◽  
R. N. Dubey
Keyword(s):  
Internal Pressure ◽  
Strain Curve ◽  
Stress Strain ◽  
Piecewise Linearization ◽  
Elastic Plastic ◽  
Plastic Cylinder ◽  
Parametric Functions ◽  
The Difference ◽  
New Formulation ◽  
Walled Cylinder

A technique for elastic-plastic analysis of a thick-walled elastic-plastic cylinder under internal pressure is proposed. It involves two parametric functions and piecewise linearization of the stress-strain curve. A deformation type of relationship is combined with Hooke’s law in such a way that stress-strain law has the same form in all linear segments, but each segment involves different material parameters. Elastic values are used to describe elastic part of deformation during loading and also during unloading. The technique involves the use of deformed geometry to satisfy the boundary and other relevant conditions. The value of strain energy required for deformation is found to depend on whether initial or final geometry is used to satisfy the boundary conditions. In the case of low work-hardening solid, the difference is significant and cannot be ignored. As well, it is shown that the new formulation is appropriate for elastic-plastic fracture calculations.

The derivation of the rotational potential function from atom–atom potentials. III. Borohydride compounds

1988 ◽  
Vol 66 (4) ◽  
pp. 791-793 ◽  
Author(s):  
David Smith
Keyword(s):  
Transition Temperature ◽  
Experimental Method ◽  
Potential Function ◽  
Ground Level ◽  
Potential Functions ◽  
The Difference ◽  
Level Degeneracy ◽  
Entropy Of Transition ◽  
Good Agreement

The rotational potential functions for the borohydride ion embedded in potassium and rubidium halides are derived from atom–atom potentials of the Buckingham (exp-6) type. The librational frequencies computed from the potential functions are in good agreement with the observed frequencies. The potential functions for rubidium and potassium borohydrides derived from the atom–atom potentials yield librational frequencies that are about 10% higher than the observed values. Since the entropy of transition for potassium and rubidium borohydrides is less than expected, there is a possibility that there is some ordering of the borohydride ions above the transition temperature. An experimental method is presented for studying the ordering of the borohydride ions based on the difference in the ground level degeneracy of a tetrahedral ion in ordered and disordered states.

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