Influence Of Stress Distribution Research Articles

Influence of stress distribution in coal seams of non-uniform extremely thick key stratum and disaster-causing mechanisms

This paper analyzes the influence of the overlying extremely thick primary key stratum on the strong mine pressure hazard at the large mining face in Gaojiapu coal mine. The analysis of the distribution characteristics of the primary key stratum in the Gaojiapu coal mine reveals the bow-shaped structural characteristics of the overlying thick primary key stratum. An elastodynamic model was developed using the variational method to calculate and analyze the influence of the movement of the primary key stratum on the stress and energy of the underlying weak rock. The results show that the arch structure of the overlying extremely thick primary key stratum can significantly affect the distribution pattern of stress and strain energy in the coal body, and the stress and strain energy in the coal body are transferred to the middle of the coal column, and the middle region of the coal column enters a high stress state. These results suggest that the change in thickness of the overlying primary key stratum at Gaojiapu in the coal column area is a major factor in the frequent occurrence of impact ground pressure events at the mine. This study explains the causes of frequent impact ground pressure in the lower coal rock mass of the extremely thick primary key stratum, and provides a reference for the prevention and control of impact hazards in the extremely thick primary key stratum.

Stress Distribution and Optimum Spacing Determination of Double-Withdrawal-Channel Surrounding Rocks: A Case Study of Chinese Coal Mine

In this study, the 31113 fully mechanised working face in the Lijiahao Coal Mine was selected as the project background. The failure characteristics and optimum spacing of a double-withdrawal-channel surrounding rock were extensively investigated through field measurements, theoretical analysis, and numerical simulations. The following results were obtained. The loading influence range of the working face was fixed. Under the influence of mining, the stress distribution variation in the double-withdrawal channels with spacing and the influence of stress distribution on the surrounding rock stability of the withdrawal channels were determined. The optimum distance between the double-withdrawal channels to achieve the stability of the surrounding rock was at least 25 m, and engineering measures are required to limit the mining height in the final mining stage. The rationality of the main and auxiliary withdrawal channel spacing of 25 m and measures to limit the mining height in the final stage were demonstrated. The findings of this study provide a valuable reference for constructing the layout of withdrawal channels in the adjacent working faces of the same mining area.

Influence of Stress Distribution on the Ionic Conductivity of a Sulfide All-Solid-State Lithium-Ion Battery

Introduction, Objective, MethodsIt is widely known that the ionic conductivity of a sulfide based solid electrolyte (SE) is enhanced with pressurization[1]. In order to take advantage of this property, sulfide all-solid-state lithium-ion battery (SASSLiB) is expected to be pressurized. The electrodes of SASSLiB are composite material constituted by different substances such as SE and active material (AM). Hence, when pressurized, a non-uniform stress distribution forms within the electrodes due to the unique Young’s moduli of the constituting substances[2]. Considering the pressure dependence of ionic conductivity observed in SE, a non-uniform stress distribution is likely to affect the net ionic conductivity of the electrodes.Objective of this study is to elucidate the effect of stress distribution on the ion transportation characteristics of an electrode layer in SASSLiB by combining experiment and numerical calculation. The experiment includes internal visualization by x-ray CT and electrochemical measurement of a simplified electrode consisting SE (Li10GeP2S12)[3] and electrochemically stable zirconia. To separate the effect of stress distribution from morphological factors such as volumetric fraction and tortuosity, structural data collected from x-ray CT was used to quantify the volume of non-SE regions and used to quantify tortuosity by numerical calculation employing random-walk algorithm. Additionally, voxel-finite-element-stress calculation and electric field calculation was combined to perform ion transportation simulation. To elaborate, stress distribution was expressed in two different calculation models: isotropic and anisotropic. The isotropic model assumes that the ionic conductivity at a particular voxel is dependent on the minimum principal stress value in all x, y, z directions. The anisotropic model assumes that the ionic conduction occurs anisotropically with different ionic conductivity corresponding to the voxel’s perpendicular stresses in x, y, z direction. Furthermore, the ion transportation simulation was conducted for cases with SE’s Young’s modulus set to 0.3 GPa and 21.7 GPa. The former value is experimentally measured under low pressure condition, and the latter is the value obtained by first principle calculation[4]. We have assumed that the true value of unknown and pressure dependent Young’s modulus of SE lies in between these two values.Result and DiscussionThe ionic conductivity of a composite made by SE and zirconia was significantly lower than that of SE-only sample. Comparing the ionic conductivities obtained experimentally and numerically, the discrepancy was large when only void ratio and tortuosity were considered. When stress distribution was additionally considered, discrepancy drastically decreased. Fig.1 and Fig.2 show the magnitude of discrepancy between experimental and numerical results when composite was under 100 MPa of pressure, and are results obtained by isotropic model and anisotropic model respectively. The points plotted are relative conductivity with respect to a mixture with 0% zirconia, and the points represented are results from the composite with zirconia fraction varying from 19% to 67% from left to right. The dotted line represents a complete alignment of experimental and numerical results, and closer a value is to this line, smaller the discrepancy. It is apparent from the two figures that in both models that there is a significant offset between the line of complete alignment and the case stress distribution was not considered. On the other hand, the line of complete alignment lies in between the results from numerical models obtained with respective Young’s modulus. This validates our assumption that the true Young’s modulus lies in between the values mentioned earlier. Additionally, this implies that by accounting for the non-linearity of stress-strain relationship of SE, the discrepancy between the line of complete alignment and the numerical results can further be decreased.The discrepancy between the line of complete alignment and the results excluding stress distribution increases as the volumetric fraction of zirconia increases. Additionally, the discrepancy between the numerical results of two different Young’s moduli increases as zirconia fraction increases. These increasing discrepancies with the increased zirconia fraction can be attributed to the decreasing stress in SE, instigating decrease of ionic conductivity, and in turn, widening the discrepancy.ConclusionPresence of a material with different Young’s modulus than that of SE alters the ion transportation characteristics of an electrode layer by forming a non-uniform stress distribution. And the impact of such stress distribution is much greater as the volumetric ratio of materials with high Young’s modulus increase. Therefore, stress distribution is an important factor to consider to accurately evaluate the ion transportation characteristics in the electrode layers of SASSLiB, especially as volume of non-SE materials, such as AM, increases. Figure 1

Effects of crack position on fatigue life of large seamless storage vessels made of 4130X for hydrogen refueling station

Fatigue property of CrMo steel is significantly degraded by hydrogen embrittlement (HE), which probably influences the fatigue life of hydrogen storage vessels made of CrMo steel. In this study, tests of fatigue crack growth rate (FCGR) for specimens extracted from the cylinder, juncture and shoulder of a seamless storage vessel made of 4130X for hydrogen refueling station were performed in 45 MPa hydrogen gas. Based on the test results, a finite element method (FEM) based on adaptive grid technique was applied to calculate fatigue life of the vessel with an initial crack at different positions. 3D laser scanning technology was used to build the model which can well conform to the actual vessel. Results indicate that the FCGR of 4130X in 45 MPa hydrogen is approximately 10–15 times of the FCGR in air. The FCGR of specimens from the shoulder is approximately 1.2–1.5 times of that from the cylinder and juncture. However, as the influence of stress distribution, the fatigue life of a vessel with a crack in the middle of the cylinder is lower than that of the vessel which exists crack with the same size at the juncture and shoulder.

Investigation on Performance of No-Insulation Coil Considering the Influence of Stress Distribution on Radial Characteristic Resistivity

The no-insulation (NI) winding technique is a useful approach in high field magnets. As the operation current can pass through adjacent turns, radial characteristic resistance (including the resistance of stabilizer layer, substrate layer and turn-to-turn contact surface) becomes a decisive factor influencing the NI magnet's thermal stability and excitation delay behavior of NI magnet. Radial characteristic resistivity is mainly affected by the tape material and turn-to-turn contact stress. However, stress distribution in most design examples is scarcely considered, and a mean resistivity obtained through an experimental test is often used. To facilitate the NI magnet's realization of faster charging and lower excitation loss, a nonuniform winding prestress method is proposed to adjust the radial resistivity while maintaining the coil's mechanical stability. This paper investigates the pretightening force, thermal stress, and electromagnetic force in the process of manufacturing, cooling, and excitation of a high-temperature superconducting NI magnet. A distribution of the radial resistivity is obtained considering the varying tendency of radial resistivity under changing stress. An equivalent circuit model and finite element model are applied to analyze the NI coil's excitation characteristics. The results are compared with the mean resistivity value model and provide a theoretical basis for NI magnet design.

Displacement evolution of a creeping landslide stabilized with piles

In order to explore the displacement evolution of a creeping landslide stabilized with piles, an analytical model is proposed in this paper. Mechanical behaviors of the sliding surface and the sliding layer in the model are assumed to be visco-plastic and elastic, respectively. Equilibrium of a soil slice in the sliding layer is applied to establish the differential equation, which can be solved as a non-homogeneous heat equation. The displacement of the soil around stabilizing pile is considered as boundary condition at the bottom of the sliding layer, and the stress applied on the upper boundary of the sliding layer is assumed to be a constant. Therefore, the displacement solution of the sliding layer was obtained by solving the non-homogeneous heat equation with the mixed boundary conditions. Subsequently, the analytical model is validated against the monitoring data from Hongyan landslide in China. A good agreement between the measured displacement and the calculated displacement by the proposed model is obtained. Finally, the pile-stabilized region with respect to time, influences of stress distribution in the sliding layer, and the water table on the proposed model are discussed in this paper.

The influence of stress distribution in four different fixation systems used in treatment of mandibular angle fractures – a three‐dimensional finite element analysis

AbstractAimTo study and compare the stress distribution fields in four fixative materials used commonly in the treatment of angle of the mandible fractures using finite element analysis (FEA).Materials and methodsUsing commercially available FEA software, four three‐dimensional models of the mandibular angle region were created by graphical representation, and an oblique unfavourable fracture was simulated. A conventional titanium miniplate, a three‐dimensional titanium miniplates, a locking titanium miniplates and a bioresorbable plate were modelled three‐dimensionally and applied to the mandibular angle region of the model, and stress distribution fields of each were analysed under similar loading conditions.ResultsThe locking titanium plate and the three‐dimensional titanium plate had favourable stress distribution when compared with the conventional titanium miniplating system and the bioresorbable plating system, showing that they were superior to the latter in terms of post‐fixation stability.ConclusionThe locking titanium miniplate and the three‐dimensional titanium miniplate would offer better fixation stability in the post‐fixation period when compared with the conventional titanium miniplate and the bioresorbable plating system.

Research on the Influence of Hole Arrangement on Ring Die Strength

Ring die is the critical component of pellet mill, its working performance and service life directly affect the pellet quality and production cost. This work analyzed the stress distribution of ring dies with two different hole arrangements and studied the influence of stress distribution on ring die strength. It is shown that there is stress concentration at the hole edge and the stress concentration distributes along the width of ring die at the feed side, the die hole arrangement have influence on ring die strength and the effect of hole wall thickness on ring die strength increased with the wear of die hole, finally a better pattern of hole arrangement was obtained.

1137 表面置換型人工骨頭における設置角度の有限要素解析による検討(S11-3 計測と力学-生体への応用(3),S11 計測と力学-生体への応用)

Femoral resurfacing implantation is alternative option to total hip replacement for the surgery of femoral head osteonecrosis. Although it was developed first in the 1970s, it did not come into wide use because postoperative stability was not sufficient for a long period. Femoral resurfacing implantation has been attracted the attention of orthopedic surgeon again, since material and design technology has been recently progressed. In this study, finite-element models of femoral head replacement with the resurfacing implantation were created based on a clinical CT images, and stress analyses were carried out considering inhomogeneous property of bone. Furthermore, influence of stress distribution around die femoral head with arrangement of the resurfacing implantation was investigated by changing position of the implantation. Validity of implant angle in usual surgery was discussed by the analyses.

Influence of stress distribution on adhesion strength of sputtered hard coatings

Today’s research activities in improving the properties of cutting tools are concentrated on optimizing manufacturing technologies and tool geometry, on alloying of special cutting materials and on coating of tools. As a result of the poor machinability of new cutting tool materials, the surface properties are influenced by the grinding process used during tool manufacturing. In spite of optimized coating-parameters, deposited PVD-coatings fail because of insufficient surface properties of the substrates. In this contribution, influences of residual stress distribution in subsurface layers on interface strength of PVD-coated cemented carbides were investigated. Considered topics are the influence of grinding, micro blasting, and water peening of carbides on surface topography and surface integrity. Dependencies between stress distribution in subsurface layers and interface strength of (Ti,Al)N-coatings as well as effects on wear behavior in dry machining are highlighted. Surface properties of the tools are characterized by SEM and X-ray residual stress measurements (XRD). The X-ray measurement of the depth profile of the residual stress distribution is done by using different lattice planes which correspond to different penetration depths. Due to increased interface strength of micro blasted tools a superior wear behavior in dry machining is observed.

Stress Evaluation on Materials Having Non-Linear Lattice Strain Distributions

AbstractThe state of the art of stress evaluation on materials having non-linear lattice strain distributions is presented.New results on heterogeneous materials with measurements conducted on both phases of the material show compensation of the shear stress components σ13 in ground surface layers of (α+β) brass. There is only the compensation of normal components σ11 of (α+γ) steel after plastic straining.The fundamental aspects and the evaluation of macro- and microresidual stresses on materials having preferred orientation are broadened. The use of Mo-Ka-radiation shows linear lattice strain distributions, as a result of minimizing the influence of micro residual stresses causing oscillations. The interplanar distance- or strain-polefigure shows similarities with the intensity polefigure.The knowledge of the theoretical influence of stress distribution with depth from the surface of the material is extended. The experimental procedure should use either different radiations having different penetration depths or a low-penetrating radiation in combination with removal of surface layers.

The influence of stress distribution on the deformation and fracture behaviour of ceramic materials under compression creep conditions

The stress distribution developed in test pieces during compression creep has been determine using the finite element method. The analyses are shown to account precisely for the inhomogeneous distribution of grain-boundary cracks developed during creep of polycrystalline magnesia and indicate that the accommodation of grain-boundary sliding by cavity formation is the rate-controlling process during high temperature creep of reaction-bonded silicon nitride.

Influence of stress distribution in the slope zone on the stability of open workings and dumps

Influence of stress distribution in the slope zone on the stability of open workings and dumps

Influence of Stress Distribution on Rupture of Marble

Influence of Stress Distribution on Rupture of Marble

A discussion on tone sandhi problems in Chinese

The most important tone sandhi is that of tone-3. Each of the two forms of bisyllabic sequences in Chinese, the quasi-iambic and the trochaic, has two types of tone sandhi pattern. As far as the quasi-iambic sequence is concerned, tone-3 followed by other tones (including the neutral tone) except another tone-3 changes to ½ tone-3. Tone-3 followed by another tone-3 changes to tone-2. As far as the trochaic sequence is concerned, tone-3 followed by the neutral tone derived originally from tone-3 changes either to ½ tone-3 as before any other neutral tone, or to tone-2 as before any stressed tone-3. Tone-3 followed by the first type of trochaic sequence changes to tone-2, and that followed by the second type changes to ½ tone-3. Tone sandhi patterns of the sequences formed by three stressed tone-3 syllables, though mostly determined by the IC, are rather inconsistent; they vary from speaker to speaker. There are two types of tone sandhi patterns of the sequences formed by more than three stressed tone-3 syllables. The first type is uttered with a momentary pause which has the function of separating one IC from another. The second type is uttered without the pause. Thus only the tone pattern of the final syllable remains unchanged. Whether a polysyllabic sequence is uttered with a momentary pause or not depends on the speaker. In general, due to the influence of stress distribution, 223-sequences and 2223-sequences may optionally change to 213-sequences and 2123-sequences respectively when they are spoken faster. This confirms that the description of sandhi patterns in the second paragraph of section 1 is correct.

Influence of stress distribution on fatigue strength of adhesive-bonded joints

A study was made of the fatigue behavior of three types of 2024-T3 aluminum-alloy adhesive-bonded joints: single-lap joint, scarf joint and butt joint bonded with two kinds of adhesives, a vinyl-phenolic type, FM-47 and a nitride rubber-phenolic type, Metlbond 4021. Two different modes of fatigue failures of the single-lap joints, i.e., sheet-metal failure and adhesive-bonding failure, were caused by the different stress components in the joint. The influence of the variations of stress distribution caused by the difference in mechanical properties of the adhesive, geometry of the joints, and the type of loading on fatigue strength of the adhesive-bonded joints, were analyzed.