Advanced Materials Research Vols. 602-604

Abstract: Stress analysis was performed for certain connecting rod assembly by the finite element method, exploring the influence of connecting rod strength with the change of interference. After calculation, it was found that the stress in oil hole of connecting rod small end and bottom edge in the inner hole of connecting rod small end was large. Through the comparison of the different scheme, it got that : the change of the interference of connecting rod small end bushing had a great effect on the stress in oil hole and bottom edge. The increasing of interference made the stress of the bottom edge in the inner hole increase gradually and basically linearly; The maximum stress of oil hole decreased at first, and then increased. Without considering interference, maximum stress was 117MPa. When the interference was 0.01mm, maximum stress got the minimum value about 96MPa. After it, with the increasing of interference, maximum stress increased gradually. When the interference is relatively small, the breakout pressure plays a key role in the stress of oil hole of connecting rod small end, and when the interference is relatively large, the interference plays the leading role.

Abstract: Mohr-Coulomb strength theory has been used to analyses the elastic-plastic analytical solution of pressure tunnel in the field of rock engineering for many years. Because it could only solve the problems with one kind of material, the application of the theory was greatly restricted. In order to reflect the effects of stress redistribution, the stress adjustment coefficient is introduced in this paper to develop the elastic-plastic analytical solution of deep buried circle tunnel based on the unified strength theory. The applicability formulas is gained based on the critical pressures, which can be obtained in other situations or strength thoeries simplified by assuming the parameter value in the formula. An example is analyzed, and the yield range versus the inner pressure and stress distribution are presented. The results show that the parameter in unified strength theory has significant effects on the radius of plastic zone and the magnitude of stresses of the wall rock of tunnel, comparing with theory of Mohr-Coulomb.

Abstract: This article adopts Krylov’s functions, getting a general solution of deflection differential equation of short cylindrical shell. Due to the general solution and continuity and smoothness conditions of shell’s deflection, detailed calculating formulas about deformation and stress of large diameter cylindrical shells with cross-section are obtained, whose solving process is realized by programming. Taking a running tank for example, the method deduced in this article calculates its deformation and stress. Compared with the FE (finite element) calculation results and the test data, this method calculates tank wall's stress and deformation accurately, which can be used to check the thickness of tank shell.

Abstract: Based on the fast fourier transform (FFT) and flexibility matrix method, the effects of the FFT and flexibility matrix method on the distribution of oil film pressure, elastic deformation in the steady load and the journal center orbit of the connecting rod big-end bearings in the dynamic load are investigated. The results are shown that when the eccentricity ratio is more than 1, the maximum oil film pressure obtained by FFT method is bigger on both ends of the journal bearing and on its intermediate position is smaller. To the connecting rod big-end bearing, under the dynamic load condition, there is the same trend of the journal center orbit with two methods. However, with FFT method, the journal is largely deviated from bearing center.

Abstract: Simulating motion process of incompact landslip-collapse soil. Monitoring evolution process of average contact force and unbalance force when which are moving. Simulation results indicate that: Process of its motion manifest the macro space position changes, as well as, are the change process about contact stress, unbalance force within the inter particle and single particle movement mechanics etc. Average contact force reflects close degree between particles, fluctuation extent of microscopic parameter and levels of interaction between particles. Microscopic parameters of movement process can be used in the theoretic modeling analysis of complex movement of the incompact soil.

Abstract: Use the mirror method to transform the quarter space to the whole space under the complex coordinate system, and with the help of the boundary conditions around the cylindrical lining to solve the unknown coefficient. To do some numerical calculations of the dynamic stress concentration factor and the electric field intensity concentration factor around the cylindrical lining by using the program. In the numerical calculations stage, by changing the medium’s parameters, the structure’s geometry influence and the frequencies of incident wave to obtain more results on dynamic stress concentration factor (DSCF) and electric field intensity concentration factor (EFICF).The calculating results indicate that, under the action of SH wave the DSCF and EFICF around the cylindrical lining are similar to each other, and regularly distributed along the edge of the cylindrical lining. While the magnitude of DSCF and EFICF are larger than any other situations when the frequency of the incident wave was low. And the results are similar to results of the whole space condition too.

Abstract: After cracks appear in the surface layer, the stress mode of pavement structure transits from infinite continuum to limited size board, and the cracks become stress concentration areas. Based on the practical tire contact pressure and contact area, this paper establishes the C3D8R model by ABAQUS, to calculate and analyse the influence on the surface cracks extension from graded gravel transition layer under half-sinusoid load. Analysis shows that the graded gravel has excellent stress dissipation ability. Whether there are cracks in the surface layer, the graded gravel transition layer between asphalt surface layer and semi-rigid base layer could greatly reduce the tensile stresses in the bottom of semi-rigid base and subbase layers, improve the road bearing level, delay and avoid the cracks extension to deep road and prolong the road service life.

Abstract: After cracks appear in the semi-rigid base layer, the stress mode of pavement structure transits from infinite continuum to limited size board, and the cracks become stress concentration areas. Based on the practical tire contact pressure and contact area, this paper establishes the C3D8R model by ABAQUS, to calculate and analyse the influence on the base cracks extension from graded gravel transition layer under half-sinusoid load. Analysis shows that the graded gravel has excellent stress dissipation ability. Whether there are cracks in the base, the graded gravel transition layer between asphalt surface layer and semi-rigid base layer could greatly reduce the tensile stresses in the bottom of semi-rigid base and subbase layers, improve the road bearing level, delay and avoid the cracks extension to deep road and prolong the road service life.

Abstract: Using coupied variational principle, predicting fatigue crack initiation life of plane stress state plate-like component which leads to large range damage is analysed. The closed form solution about predicting fatigue crack initiation life of plane stress state plate-like component which leads to large range damage is derived. The method adopted in this paper is definite in mechanical concept，it can be widely used in analysis of predicting fatigue crack initiation life of various plate-like component which leads to large range damage. A new thinking and new method is provided for predicting crack initiation life of plate-like component.

Abstract: At the beginning stage of the progressing cavity pump (PCP) operation or working in the oil well with high gas content, the stator and rotor of PCP usually operate under dry sliding. Analyzing the wear morphology of stator rubber and discussing wear mechanism are very important for choosing the best stator rubber for different working conditions, which is directly related to the service life of PCP. Wear behavior of NBR/FKM blend rubber (10:0、3:7、7:3、8:2、0:10) was investigated at room temperature using a MPV-600 ring-on-block tester under dry sliding. The wear morphology of blend was analyzed through the stereomicroscope and the wear mechanism was also discussed. The results show that different blend own different wear mechanism. The wear mechanism of NBR/FKM=8:2 blend rubber is fatigue wear, which is better than the others under dry friction.