Applied Mechanics and Materials Vol. 483

Abstract: The vertical steel bar bending forming is a kind of new process of bending method. The bending speed, bending radius and clamping length H which is the parameters of vertical steel bar bending machine , is directly affect the quality of bending forming parts. This paper calculated the length of reinforcement before being incised and the springback angle of bending steel bar which obtained the reasonable cutting length and bending Angle; Then based on rigid-flexible virtual prototype technology to build the dynamics model of vertical steel bar bending system. Through simulation analysis ,it obtained the relationship between bending speed, bending radius , clamping length H and forming quality of bending steel bar. In this paper, the analysis method have reference value to the design of similar steel bar bending machines.

Abstract: The dynamic model of nonlinear stiffness rotor-bearing system with pedestal looseness fault was set up, taking the linearity and cube item as the physics nonlinear factors. The periodic solution of system was analyzed by continuation-shooting algorithm for periodic solution of nonlinear non-autonomous system, and the stability of system periodic motion and unsteady law are discussed by Floquet theory. The unstable form of it is Hopf bifurcation. In the region of critical rotate speed, the main motion of the system is periodic-4; and it of ultra critical rotate speed, the main motion of the system is periodic-3 and chaotic motion. The conclusions provide theoretic basis reference for the fault diagnosis of the rotor-bearing system.

Abstract: Lattice transimission towers are commonly made of angles bolted together directly or through gussets. And angle members are usually subjected to high axial force with eccentricity. Conventional structural analysis softwares solve such problems with the assumption of regarding the bolted connection as a rigid joint connection and ignored the effect of joint eccentricity. Thus the calculated internal forces of the structure members are bigger than those of real measurements, and the calculated structure deformation are smaller than the experimental ones under the same load. The main reasons for the discrepancy between the experimental results and the analytical solutions are bolt slippage and joint eccentricity. In this paper, the displacement-load curves of the bolted connections are introduced into the finite element simulation, revealing the effect of bolt slippage on the static response of lattice structure. The simulation results show that the bolt slippage causes the redistribution of the member internal forces of the lattice structure and increases the displacement of the lattice structure. The proposed algorithm and simulation results would provide good reference for further engineering applications.

Abstract: Based on the finite element analysis of the slip coat in the compulsory lifting system of hyper-thermal snubbing operation injected by steam, the static analysis with regard to the slip coat is undoubtedly employed taking advantage of the finite element software. And then, the failure forms are deduced and the maximum allowable stress is calculated by analyzing the stress distribution.

Abstract: general steel of the original tanker of LPG truck is substitute by high strength steel in order to reduce the weight of tanker. Then strength and stiffness of new tanker is calculated, the result shows that strength and stiffness of new tanker satisfies safety requirement.

Abstract: This paper mainly depends on experiment. Take theory and software analysis as supplement. Using pine and fir as test material, the quantitative analysis, using uniform design method to qualitative pine, fir wood block the relationship between mechanical properties and geometrical parameters in the case of triangle, failure characteristics through experimental phenomenon of different materials and different sizes of wood in the triangle block pressure, finally using finite element analysis software ANSYS/LS-DYNA to simulate and analyze test. By comparing the analysis result of test and software, find out the problems and corresponding correction. The final analysis laid the foundation for the whole static wood structure analysis and dynamic. To provide scientific and technical support for rural residential "seismic safety engineering", thus forming the new wooden structure node and reinforcement for clause.

Abstract: According to the theory of gear geometry, the equations of teeth surface of double pressure angles asymmetric face-gear were conducted. Discrete points were generated in MATLAB according to the surface equations, and then the author established contact finite element models of single-tooth pair in ANSYS. The calculated value of contact pressure of the single tooth contact finite element model and the calculated value of contact pressure which given by the point-contact Hertz theory were compared to verify the effectiveness of the contact finite element method. Several groups of parameters were calculated and the results showed that the use of reasonable asymmetric design can effectively reduce the max surface contact pressure and the max tooth root bending stress.

Abstract: This article presents an analysis on possible ways of utilizing low-temperature waste heat. If well-designed, this could contribute to increasing the efficiency of power plants without introducing many complex changes to the whole system. The main analysis focuses on the location of the regenerative heat exchanger in the facility. This could differ with varying temperatures of working media in the system. The base for investigations was a 800 MW-class power unit operating in off-design conditions and supplied with steam from an BB2400 boiler. Modifications to the model were made using commercially available software and by applying the Stodola equation and the SCC method. It allowed to determine the most suitable position for installing the low-temperature heat exchanger. Calculations for off-design conditions show that, after making some modifications to the system, both heat and electricity generation could be increased through the addition of a low-temperature heat exchanger.

Abstract: A whole machine tool structure is a muti-DOF system, it is usually composed of many parts which are connected with joint interfaces. The structure is complicated that the accuracy of modal test is always in a low level. When doing modal test, equivalent single DOF method can not only improve the efficiency and decrease the difficulty, but also exclude interferences such as random noise. In this paper, the author simplified a two-DOF system into an equivalent single DOF system and derived its frequency response function, then analyzed a testing device for fixed joint by using the equivalent single DOF method, and measured several groups of unit area dynamic characteristic parameters of fixed joint interfaces in different materials and different working conditions. The dynamic characteristic parameters can be used in further study of machine tool joint interfaces.

Abstract: Radio Density of bones is measured in Hounsfield Units (HU) by a technique called as tomography, whereas the Bone Mineral Density (BMD) is measured by Dual-energy X-Ray Absorptiometry (DXA) scan. We aimed at finding correlation between BMD and HU of human bones for their strength evaluation.