Advanced Materials Research Vols. 712-715

Abstract: Surrounding rock system of underground engineering is highly nonlinear, and there is no unified cognition for its stability criteria. Introduces the basic principle of catastrophe theory, focusing on the cusp catastrophic model, build a simplified mechanical model for the surrounding rock, and the instability of surrounding rock of the cusp catastrophic model is obtained. In practical engineering, it is show that catastrophe theory is an effective method to study the instability problem of the tunnel.

Abstract: Based on the plane strain model, a three-dimensional vibration model was setup for soil dynamic response of soil surrounding large diameter pile. An accurate analytical solution was got by considering the couple effect of vertical and horizontal displacement of soil. Through the discussion parameters slenderness ratio (L/d), hysteretic damping ratio (D_s,D_v) and soil Poisson's ratio (ν),it is concluded that they are very important for the vertical vibration propproperties of soil impedance.

Abstract: This paper studies how to eliminate the deformation caused by the earthquake liquefaction for highway foundation. experimental studied two technologies, rubble piles or gravel and cement mixing pile combined. Summary the highway earthquake liquefaction ground treatment technology of Tangshan coastal areas,to eliminate earthquake liquefaction and to Control Settlement.

Abstract: The cracks were found on the surface of DD6 single crystal turbine blade. The blade fracture mode and causing reason were studied by analyzing the fracture surface and the microstructure in the vicinity of the cracks using Optical Microscope (OM) and Scanning Electron Microscope (SEM). The results indicated that the cracks fracture was resulted from the surface recrystallization of the blade. Owing to the presence of cast stress in the blade during the directional solidification process, a later solution treatment resulted in the formation of recrystallization grains. Meanwhile, some white particles with high concentration of W were precipitated at the grain boundary. Under the testing condition, the cracks initiated at the recrystallization boundary and expanded along the white precipitated phases until fatigue fracture.

Abstract: The experimental and numerical simulations of mechanical properties of co-continuous composites SiC_n/Al produced by infiltration of SiC preforms with melted 2024 Al alloy using Solidwork2012 Simulation code were carried out. The results showed that ultimate tensile strengths of SiC_n/Al up to 410 MPa at a failure strain of up to 0.7% without any heat treatment. The compression strength was up to 710 MPa with 2% strain to failure. The composites show an excellent resistance to high cycle fatigue. Fatigue life for specimen was 4.5×10⁵ cycles for 250 MPa while R=-1.0, and 4.9×10⁵ cycles for 164 MPa while R=-0.05. Simulated data shows there is different mechanical behavior between SiC structs and Al matrix, difference of elasticity modulus of two constituents occasion difference of generated deflection, Al has taken place large deformation; Due to structural characteristic of SiC, the force on each rib affects other adjacent rib, Al and SiC restrict each other to prevent from producing the strain.

Abstract: A three-dimensional model of two columns covering hydraulic support was created by Pro/E software. The model was imported into ABAQUS software for finite element analysis. The stresss distribution of the hydraulic support in the conditions of the top beam partial load and the base reversed was got. The result was a reference in the design and structural optimization of the hydraulic support.

Abstract: Methods for anti-fatigue design of the crane and F.E.M. Rules for the Design of Hoisting Appliances were introduced. The structure of Bridge-Type Grab Ship Unloader, the object of this study, has been simulated, by using the finite element analysis software of ANSYS, to conduct the fatigue analysis and to give the calculation results, which can provide solutions to practical engineering.

Abstract: A finite element study was performed to investigate the design method of the casual anchor skeleton at the closure of a PC continuous box girder bridge. Based on a finite element model of a certain four spans PC continuous box girder bridge, we found that the stresses of skeleton calculated with the finite model were 5 percent beyond those with the traditional analytic method. Besides, the tensile stresses increased 19 percent and the compressive ones were 14 percent decreased considered the vertical unbalance temperature and both increased 8 percent for the wind, which were totally ignored in the traditional analytic method. So, the traditional analytic method is inaccurate and unsafe for the casual anchor skeleton design, and the general temperature difference, the vertical unbalance temperature and the wind are better to be considered.

Abstract: The research of impeller dynamic characteristics by modal analysis technology is a kind of practical and effective fault diagnosis method, which has the vital significance to realize the security of machinery. Crack and blade fracture often occur in centrifugal compressor impeller. In order to study the impeller dynamic characteristic with crack and the blade fracture, a three-dimension finite element model (FEM) was built using ANSYS program, and an experimental modal analysis was also carried out. The compared results show that the preceding four orders natural frequencies and vibration models are basically consistent, and those also verified the reliability of the simulation results. In addition, two kinds of failure mode were also simulated, such as crack and blade fracture. It concluded that all orders natural frequencies decrease clearly, compared with the normal impeller. How the severity of crack and blade fracture affects the natural frequency was also discussed.

Abstract: Finite element method is a kind of method with the aid of computer engineering analysis of discretization numerical calculation. In the rotary steering drilling during the process of practical work, there was a great drilling pressure torque, space size limit strictly and requires a high efficiency and reliability .The working conditions are complex when drillings work underground and the working environment is harsh, there may has many unpredictable situations, the drilling tool may encounter the loose soil, or may be a hard rock, and these changes force is transmitted through the variation cardan shaft, so it is very necessary to check the strength of the variation cardan shaft. This article analyze the variation cardan shaft by ANSYS and provide a reference for actual use.