Papers by Keyword: Yielding

Abstract: In this work, the creep analysis of thick-walled rotating cylinder made of Aluminum Silicon Carbide under internal pressure has been investigated taking some assumptions, viz. no change in the volume of the cylinder, cylinder material is anisotropic, principal axes coincides with the axes of anisotropy, effective stress is dependent upon effective strain rate, and there is zero strain in the axial direction (Z direction in polar coordinate). Sherby’s law has been used to calculate the creep rate. After finding the formulas for radial, tangential and axial stresses for anisotropic cylinder, the findings have been validated by checking the values and comparing the graphs for an isotropic cylinder case with one of the already published research for isotropic cylinders with similar conditions. The graphs plotted in cases of anisotropic cylinder, enables us to conclude that despite large stress values in the radial and tangential directions, the creep rates in such cylinders were found to be approximately zero. This led to deduce that anisotropy is very helpful in designing long-lasting cylinders. In corollary, anisotropy helps in minimizing creep behaviour in radial and tangential directions.

Abstract: Yield-thixotropy is an important time dependent rheological behavior of gelled waxy crude oil. In order to study the yield-thixotropic behavior of gelled waxy crude oil under cyclic shearing of linear increasing and decreasing of shear rate, four different types of waxy crude oil were studied experimentally by using RS150H rheometer. It is found that because the recovery rate of wax crystal structure is slow, study should be focus on the first loop. At a certain temperature, the hysteresis loop moves away from the share rate axis and the area of the loop becomes larger with increased rate of share rate sweep; and vice versa, the loop moves toward the share rate axis and the area of the loop becomes smaller with decreased rate of share rate sweep. And the yield stress is also reduced and the yielding time increased with decreased rate of share rate sweep. In addition, based on the experimental results an empirical correlation is developed to describe the relationship of yielding time and rate of share rate sweep.

Abstract: The steel industry has developed rapidly in recent years. At the same time,steel structure residence also rises gradually.Buckling is the main disadvantage of steel structures,so the strength of steel can't be fully utilized. Steel-timber combined member has both excellent mechanical properties and nice decoration effect, and can be well applied in steel residential building.

Abstract: The prestressing wires of prestressed concrete cylinder pipe (PCCP) provide pipe wall with compressive stress to resist internal pressure. Broken wires may cause yielding of steel cylinder and increase the risk of pipe failure with time. In order to reveal the mechanism of steel-cylinder yielding in PCCP with broken wires, a simplified model is developed and the maximum number of broken wires to preclude exceeding limit stress in steel cylinder can be determined conveniently by the equations derived in this paper. Verification analysis shows that the solution of simplified model agrees well with that of nonlinear finite element analysis. By comparing the calculated maximum number of broken wires with the detected actual number of broken wires, steel-cylinder yielding in prestress loss zone can be predicted, thus aiding condition assessment of PCCP

Abstract: Steel-timber combined member is a new kind of structural member composed of steel core and timber facing with bolt joint.This paper established the finite element analysis models of cantilever beam, and the finite element models were analyzed by the finite element package ANSYS considering the material and geometrically nonlinear.The results were compared with experimental results.Good mechanical properties were verified with comparison between data abtained from the test and calculated results.

Abstract: Yielding of polycrystalline low carbon steel is characterized by a clear yield point followed by unstable Lüders deformation and such a yielding behavior is taken over to fine grained steel with the grain size of 1μm or less. Yield strength of ferritic steel is increased with grain refinement standing on the Hall-Petch relation. The following equation is realized up to 0.2μm grain size in the relation between yield strength y and grain size d: y [MPa]= 100+600×d[μm]-1/2. In low carbon steel, it might be concluded that the Hall-Petch coefficient (ky) is around 600MPa•μm1/2. However, the ky value of interstitial free steels is substantially small as 130-180MPa•μm1/2 and it can be greatly increased by a small amount of solute carbon less than 20ppm. It was also cleared that the disappearance of yield point by purifying is due to the decrease in the ky value. On the other hand, the ky value is changeable depending on heat treatment conditions such as cooling condition from an elevated temperature and aging treatment at 90°C. These results suggest the contribution of carbon segregation at grain boundary in terms of the change in the ky value. On the contrary, substitutional elements such as Cr and Si do not give large influence to the ky value in comparison with the effect by carbon.

Abstract: Within the scope of this paper, the formability of the press hardenable steel 22MnB5 will be investigated with regard to its anisotropic properties at elevated temperatures under the processing conditions of hot stamping. Two different experimental setups have been realized, one at the University of Erlangen-Nuremberg using conductive heating, and the other one at the University of Padova using inductive heating. Both of these equipments enable the characterization of the material anisotropy behavior by performing uniaxial, hot tensile tests in the range of hot stamping temperatures.

Abstract: This study was aimed at evaluating the structural safety of the new bogie frames for Korean-standardized rubber-tired AGT vehicles. The guidance frame and the rotation frame were designed according to Korean-standardized specifications for rubber-tired AGT vehicles, and their stresses were analyzed by using the finite element method. Based on the results of the analysis, dynamic stresses were measured while the train was running under various conditions in the test track. Analytical and experimental results verified the structural safety of the new bogie frames.