Papers by Keyword: Hoop Stress

Abstract: An algorithm for determining the stress state of plates of different shapes with holes due to residual deformations was suggested. The residual stresses in the plates were determined using the calculation and experimental method. The algorithm for determining the stresses the near the holes in the plates due to residual deformations is based on the method of integral equations. The residual stresses and stresses near the holes were investigated. Stresses near circular holes with different distributions of plastic deformations were investigated. Cases were established, where at the boundary of holes, depending on their location, high compression or tensile stresses may arise. Particular, that high compression stresses appear at the point of intersection of the center of the weld with holes or outer boundary, which high compression stresses are approximately the same for all radii of the holes. In case of the radii of the holes that are smaller than the zone of plasticity, high tensile stresses appear, which decrease, when the size of the holes increases. In case of the radii of holes that are larger than the zone of plasticity, the maximum tensile stresses arise at points close to the boundary of the zone of plasticity.

Abstract: Present investigation pertains to establish the bulging characteristics of sintered steel preforms under cold upsetting. Cylindrical preforms of Fe-0.8%C and with 1%Mo and 2%Mo of 86% initial theoretical density and 0.4 initial aspect ratio have been produced through conventional powder metallurgy techniques. These preforms were further subjected to secondary deformation, that is, cold upsetting under nil and zinc stearate lubricant conditions. The results obtained from this experiment were used to study the bulging characteristics with densification and hoop stress. An empirical equation is determined between these parameters and is found to follow a power law relationship.

Abstract: This study intended to investigate the longitudinal crack on the tungsten carbide alloy die core that caused by the influence of receiving the hoop tensile stress in the process of inverse extrusion. Therefore, the shrink fit is adopted to design the die core and stress ring, and assemble the die case, in order to yield the hoop compressive stress in advance, which can be used to resist the tensile hoop stress yielded from the forging process. It also applied the FEM simulation software and Taguchi Method L₉(3⁴) in this study to simulate various combinations of different shrink fits, in order to obtain the best combination of die. Moreover, it focused on the compressive strength of material characteristics for the tungsten carbide alloy steel die core, and properly adjusted the shrink fit to prevent an early crack on the die core that caused by the hoop compressive stress in advance, in order to achieve the best result.

Abstract: The decrease of strength leads to damage of worn casing under non-uniform loading, affects the subsequent well testing and completion. In order to verify the finite element model of hoop stress of eccentric worn casing, unworn and worn casings are crushed under the concentrated force, while the critical concentration force and hoop stress are measured. Under the concentrated force, The difference between the numerical solution of hoop stress of eccentric worn casing and the experimental value is from 3.5% to 5% at outer surface of worn position. The established finite element analysis model of casing hoop stress and derived formula can be used to calculate the hoop stress of unworn casing. It is feasible that the finite element method is adopted to analyze the eccentric worn casing hoop stress.

Abstract: The yield strength of liner material affecting the performance of CNG-II composite cylinder was studied by finite element method (FEM) analysis. The yield strength of liner material 30CrMo was changed from 730MPa to 850MPa with seven strength. The tensile strength of liner material, structural parameters of CNG-II composite cylinder and winding parameters were fixed as the yield strength of liner material changing. The auto-frettage effects of CNG-II composite cylinder became worse and the fatigue life of CNG-II composite cylinder lowered with the increasing of liner yield strength. The yield strength of liner should be lowered to some extent for improving the performance of CNG-II composite cylinder in the production of CNG-II composite cylinder.

Abstract: To research the mechanical regularity of steel frame in tunnel, Steel frame and Sprayed concrete Combination Model is applied and the large-section loess tunnel of highway is taken as an example. The hoop stress of flange and the radial stress of web were analyzed, the research results show that:The most areas of hoop stress of flange is in press, the compress value which most areas of flank edge is larger than the outer flank flange in the same area of steel frame. The hoop and radial stress of web is in press. The hoop stress value which most areas of flank edge are larger than the radial stress in the same area of steel frame.

Abstract: Based on unified strength theory, the mechanical behavior of core-concrete of concrete-filled square steel tubular stub columns was analyzed. Through controlling the constraint effect between square steel tube and core-concrete by width-thickness ratio, the ultimate bearing capacity formula for concrete-filled square steel tubular stub columns under axial compression was proposed, and the influencing factors of which was also discussed. The rationality of proposed formula was proved from the comparison of the analytical results obtained in this paper and experimental data.

Abstract: Inner support design criteria is put forward and systematic cornering theory model is established. Displacement differential equation is deduced, and then the radial stress and hoop stress expressions of inner support under the condition of high speed are proposed on the basis of assumption of axisymmetric problem, which makes sure that the inner support is safe under normal pressure and high speed condition. Research results are helpful for inner support structure design of run-flat tire system.

Abstract: The prevention of fatigue failure is an important consideration in the design of aeroengine shafts. In this paper, based on the elastic and elstic-plastic finite element analyses, for a series of small-scale hollow shafts with transverse holes, the maximum princple stress and von Mises stresss around the hole have been obtained. Hence, using McDiarmid and Von Mises criteria, the fatigue crack initiation site and life can be determined. The hoop stress, which is the driving force for the Mode I growth of short cracks initiated around the hole, has been characterised as well.

Abstract: The distribution of hoop stress calculated and simulated by Finite Element Method and theoretical calculation in this paper, when the hydrostatic pressure was carried out on the line pipe of Φ 762mm×31.8 mm API SPEC 5L[1] X70 longitudinal seams submerged arc welding(LSAW). The results of simulated by Finite Element Method were accord well with that of theoretical calculation, both of them shown that the hoop stress deviation between pipe inside surface and outside surface was nearly 40MPa, which was about 9% of the hoop stress of outside surface. Besides, the influence of the D/t(diameter-thickness ratio)on the hoop stress were also researched, which shown that the larger the value of D/t was , the fewer that influence on the hoop stress, when D/t=200, the deviation was less than 1%; Or else, the D/t may cause a great stress gradient in the direction of the thickness, even when the D/t=42, the deviation was up to 5%. So that, the effect of the d/t should be taken into account when calculating the hoop stress of pipe with D/t≤42. In other word, a new hydrostatic pressure formula for the heavy wall thickness pipe( D/t≤42) was put forward and adopted when calculating its hydrostatic pressure, that was P =c* Sh (Do² - Di²) / (Do² + Di²), where, c, specification coefficient; Sh, hoop stress; Do, outside diameter; Di, inner diameter.