石油钻机管柱移运装置设计与动力学仿真

为解决石油钻机传动系统抗压能力较弱的问题,设计一种新型石油钻机管柱移运装置,并针对其动力学特性展开研究。将油管上翻机构、伸缩臂、猫道翻转机构连接在石油钻机管柱的既定位置处,完成移运装置的主要部件结构设计,再分别从负荷重心、负荷量、顶升区域三方面,分析所设计石油钻机管柱移运装置的动力学特性。实验结果表明,新型石油钻机管柱移运装置可以在快速向下钻进的同时,保证动力传导设备轴压力载荷量、回旋扭矩载荷量始终处于较高的数值水平,对于增强石油钻机传动系统的抗压能力能起到一定的促进作用。

Load spectrum analysis for combined frame of closed high-speed press

Based on the basic theory of mechanics,kinematic and dynamic analysis for a slider-crank mechanism with a balance mechanism is performed.The theoretical formula of the load spectrum for the interaction between the crank shaft and the bearing seat of the upper beam is achieved by approximately simplifying the mechanical model of the crank shaft.The simulation for the load spectrum data of combined frame under the operating conditions of blanking or piling is performed using Matlab and the law of the load spectrum curves under these two conditions is analyzed.The simulation results show that under a no-load condition,the load spectrum curves of the interaction between the crank shaft and the bearing seat of the upper beam present a form of periodic sine wave and under the piling condition,the load spectrum curves of the interaction between the crank shaft and the bearing seat of the upper beam present a form of periodic pulse wave.The simulation results can provide a theoretical foundation for the load determination during the process of analyzing the dynamic characteristics on the combined frame of a closed high-speed press through the finite element method.

Axial compression physical testing of traditional and bird beak SHS T-joints

The static tests of nine traditional and bird beak square hollow structure(SHS) T-joints with different β values and connection types under axial compression at brace end were carried out. Experimental test schemes, failure modes of specimens, jack load-vertical displacement curves, jack load-deformation of chord and strain intensity distribution curves of joints were presented. The effects of β and connection types on axial compression property of joints were studied. The results show that the ultimate axial compression capacity of common bird beak SHS T-joints and diamond bird beak SHS T-joints is larger than that of traditional SHS T-joint specimens with big values of β. The ultimate axial compression capacity of diamond bird beak SHS T-joints is larger than that of common bird beak SHS T-joints. As β increases, the increase of the ultimate axial compression capacity of diamond bird beak SHS T-joints over that of common bird beak joints grows. The ultimate axial compression capacity and the initial axial stiffness of all kinds of joints increase as β increases, and the initial axial stiffness of the diamond bird beak SHS T-joints is the largest. The ductilities of common bird beak and diamond bird beak SHS T-joints increase as β increases, but the ductility of the traditional SHS T-joints decreases as β increases.

The effects of Haversian fluid pressure and harmonic axial loading on the poroelastic behaviors of a single osteon

In order to well understand the mechanism of the mechanotransduction in bone, we propose a new model of transverse iso- tropic and poroelastic osteon cylinder considering Haversian fluid pressure. The analytical pore pressure and velocity solutions are obtained to examine the fluid transport behavior and pressure distribution in a loaded osteon on two different exterior sur- face cases. Case I is stress free and fully permeable and case I1 is impermeable. The following are the results obtained. （i） The Haversian fluid may not be ignored because it can enlarge the whole osteonal fluid pressure field, and it bears the external loads together with the solid skeleton. （ii） The increase of both axial strain amplitude and frequency can result in the increase of fluid pressure and velocity amplitudes, while in case II, the frequency has little effect on the fluid pressure amplitude. （iii） Under the same loading conditions, the pressure amplitude in case II is larger than that in case I, while the velocity amplitude is smaller than that in case I. This model permits the linking of the external loads to the osteonal fluid pressure and velocity, which may be a stimulus to the mechanotransduction of bone remodeling signals.

Analysis of Aerodynamic Load on Straight-bladed Vertical Axis Wind Turbine

This paper presents a wind tunnel experiment for the evaluation of energy performance and aerodynamic forces acting on a small straight-bladed vertical axis wind turbine(VAWT) depending on several values of tip speed ratio. In the present study, the wind turbine is a four-bladed VAWT. The test airfoil of blade is symmetry airfoil(NACA0021) with 32 pressure ports used for the pressure measurements on blade surface. Based on the pressure distributions which are acted on the surface of rotor blade measured during rotation by multiport pressure-scanner mounted on a hub, the power, tangential force, lift and drag coefficients which are obtained by pressure distribution are discussed as a function of azimuthally position. And then, the loads which are applied to the entire wind turbine are compared with the experiment data of pressure distribution. As a result, it is clarified that aerodynamic forces take maximum value when the blade is moving to upstream side, and become small and smooth at downstream side. The power and torque coefficients which are based on the pressure distribution are larger than that by torque meter.