Applied Mechanics and Materials Vols. 395-396

Abstract: Here individual anchored strength of prestressed end with local area under pressure was studied, the damaged mechanism of local area under pressure was discussed. The ferrule effect of peripheral concrete upon the concrete under local pressure loading is not obvious. For prestressed concrete members, especially scattered end anchorage of prestressed concrete member, the standard formula is not applicable.

Abstract: According to the specification given, the theoretical calculation formula of the theoretical value is higher than the measured load values. Specifications given by the bureau of compressive bearing capacity formula is suitable for ordinary reinforced concrete member. For prestressed concrete members, especially scattered end anchorage of prestressed concrete member, the standard formula is not applicable.

Abstract: In this paper, the distribution of different critical stresses, which were used in previous correlation articles for the assessment of subsurface rolling contact fatigue damage, was analyzed. The rationality of orthogonal shear stress was selected as the key stress controlling the subsurface rolling contact fatigue damage was clarified. Base on the linear fatigue damage accumulative theory and the modification equation for the range of asymmetrical stress, the influence of friction on subsurface rolling contact fatigue damage was studied. The results show that the subsurface orthogonal shear stress is a completely symmetrical stress when the friction coefficient is zero, while it is an asymmetrical stress with considering the friction. The stress ratio of subsurface orthogonal shear stress and subsurface rolling contact fatigue damage is increased with the increasing of friction.

Abstract: In view of the low pressure tight gas reservoir in Songnan block, the comprehensive experiment of in-situ stress is carried out. Firstly, the tuffaceous breccia of Longshen 301 and 307 has been cored and the flag line is depicted. Through the viscous remanence experiment, the secondary viscous remanence component at 0°C~200°C is gradually separated, and the average direction of the two groups core flag line are obtained, which are 92.0° and 114.7°. Then to mark the flag line as the baseline, using the wave velocity anisotropy experiment to measure the acoustic wave velocity under different phase angle, the minimum wave velocity phase angle of the two groups core are achieved, which are 23° and 44° . And combined with the direction of the flag line, the direction of maximum horizontal principal stress are determined for N69o E and N70.7o E. Finally, using DSA (differential strain) experiment, the strain recovery of 9 direction under hydrostatic pressure are measured, and the three principal strain, the magnitude and direction of the principal stress are obtained through the inversion, the maximum principal stress direction of which are N70.8o E and N71.7o E. Compared the wave velocity anisotropy experiments and DSA experimental results, both close, the direction of the regional maximum horizontal in-situ stress is determined for N70.5° E ± 1.5°. According to the above research results, the basis for the engineering design of Songnan block such as oil and gas exploration, development, drilling and production is provided.

Abstract: The turbine generator rotor and the wedge is an important part of the turbogenerator. In order to ensure the stability and reliability of the steam turbine during operation, it needs to calculate and analyze the strength of the generator rotor and the wedge. In this paper, we did the study of the turbine generator rotor and the strength of the wedge by finite element analysis. by using ANSYS software, when in operating speed and speeding, we compared to the results of the calculation of plane and solid elements, and found that the safety factor of the plane was lower. Based on the results of two calculations, we got the generator rotor structure modification and optimization of the structural design, which improve the strength of the generator rotor tooth head and wedge.

Abstract: To get a way of calculating the reliability of fatigue life of torsion spring, the paper discussed the optimal design of fatigue reliability for cylindrical helical torsional spring with Monte-Carlo method, and tried to build a new method to analyze the fatigue reliability of cylindrical helical torsional spring. The new method could test different values of parameters of a spring, and it could calculate the fatigue reliability of the spring in every parameter value with about 100 thousand test points with Monte-Carlo method, which can be set to get a better result, and it gave the comparison and selection to designers finally. The method was run with the software-MATLAB. The paper gave an example at last, and it compared the new methods results with ones of traditional design and discussed the differences.

Abstract: Shock wave parameters of cabins for shipboard defensive structure are studied based on shock wave theory. The destroy of defensive structure can be estimated by impulse of shock wave. In the process of air shock wave propagating, isentropic suction wave is reflected from void cabin into defense structure. The solution of shock wave attenuation of void cabin can be reached by using isentropic line to replace the shock adiabatic of the reflected shock. It can be seen from the example that the multi-layers defense structure system of warship is very important to decrease the damage from explosive shock wave. The method can be used to predict the extent of damage of naval vessel.

Abstract: To analyze the stability of stepped telescopic booms accurately, using vertical and horizontal bending theory, this paper established the deflection differential equations of stepped column model of arbitrary sectioned telescopic boom, the stability were analyzed, and obtained the precise expression of the buckling characteristic equation; Took certain seven-sectioned telescopic booms as example, by comparing the results with ANSYS, the accuracy of the equations deduced in this paper was verified. Presented the equivalent component method for the stability analysis of multi-stepped column, the equivalent cross-sectional moment of inertia was deduced by energy method, thus the stability of stepped column equivalent to that of constant section component. By comparing the results with exact value, the precision of equivalent component method was verified which was convenient for stability analysis of telescopic boom.

Abstract: Finite Element Method (FEM) and strain gage technique are used for analysing strain and stresses values on a jib cranes according to the standards. API and SAE J987 standards describe the test procedure and state the stress limits for cranes. The crane is constructed on a petroleum platform on the Caspian Sea. FEM was used to determine the critical points, which have high stress on the structure. Strain gages applied on these points are used to measure the strain and then stresses were calculated for each point. FEM and experiments’ results were compered to determine the differences and errors.

Abstract: In this study, three-dimensional mechanical model of the perforated casing was simplified as flat plate mechanical model. The theoretical equation for the calculation of collapsing strength factor for a perforated casing under squeeze was derived as per elasticity theory. Three-dimensional FEM model of a perforated casing was built using ANSYS and analysis was performed. The stress concentration factor (SCF) was discussed for perforated casing in this paper and the effects of aperture on SCFs were analyzed in detail.