铝电解槽磁流体稳定性有限元分析

本文采用有限元法求解分层磁流体小扰动方程系统特征值，研究铝电解槽稳定性。研究结果表明，在没有电磁力时，铝液表面波动（内波）是稳定的。存在电磁力时，它会激发铝液表面波动的某些低频长波分量不稳定性，高频短波不受影响。被激发的不稳定波动频率和扰动增长率与电流密度，磁感应强度垂直分量，铝电解槽长宽比，电解质和铝液的密度差，厚度等因素密切相关。减少电流密度，磁感应强度，增加电极距离和铝液厚度可以提高铝电解槽的稳定性。这对铝电解槽优化设计和在线控制有重要意义。     

海洋石油平台水下夹桩器本体结构分析

水下夹桩器是一种广泛应用于海洋石油平台建设的液压夹具。水下夹桩器本体焊接在导管架上，支撑夹桩器液压缸。在水下夹桩器本体设计中，采用有限元法完成了对本体强度和刚度的结构分析；建立了有限元分析模型，用ANSYS软件进行结构分析，得到了分析结果，并将该结果与理论计算结果进行了比较，验证了有限元分析技术的有效性。设计结果满足工程要求，为改进和优化结构提供了理论依据，节省了分析计算时间。     

单桩腿有限元分析

为保证桩腿在冬季冰区海域的安全使用,对桩腿结构进行冰载荷作用下的强度分析。应用ANSYS软件建立桩腿、地基、冰相互作用的仿真计算模型,实现桩腿的力学分析。对桩腿进行了强度校核,计算出冰载荷作用下桩腿的变形及其应力状态。计算结果表明,桩腿在此冰载荷作用下强度满足安全要求。     

潜孔锤冲击作用下土体变形的有限元分析

潜孔锤冲击挤密钻进过程中周围土体的变形机理是一个高度非线性问题。针对潜孔锤在土中的面-面接触问题,运用Drucker-Prager屈服准则为判据,将土体视为DP材料,通过钻具与土之间的接触及施加冲击载荷来模拟钻进过程,从而建立了潜孔锤在土中冲击挤密钻进的有限元模型。利用非线性瞬态动力学有限元分析手段,对钻进过程中冲击力对土的作用加以研究,分析了钻具周围土体的应力、应变以及钻具与土体的摩擦情况。结果表明,在冲击载荷作用下,锥形钻头前端土体应力集中,并形成应力泡,冲击功主要用于竖向压缩土体,而水平方向的挤压作用相对较小,摩擦应力在钻头锥面附近出现峰值,是影响钻进速度的主要原因之一。     

Compact Dipole Antenna for Terrestrial Digital Multimedia Broadcasting Service

A compact dipole antenna for the terrestrial digital multimedia broadcasting (TDMB) application is presented. The length of the antenna is about 0.06λ at the TDMB resonance frequency of 190 MHz. Miniaturization of the antenna is achieved by using meander structures and lumped elements. The proposed antenna has two resonance frequencies and covers the TDMB band from 174 MHz to 216 MHz in Korea. The antenna has good impedance bandwidth and radiation characteristics for the TDMB. The experimental results of the designed dipole antenna are presented and analyzed.     

三维有限元法分析频率对接地电阻的影响

提出了用涡流场的A-V有限元分析方法计算接地系统接地电阻的方法,分析了入地电流频率的变化对接地电阻的影响。计算结果表明,频率对接地体自身电阻的影响较大,但对散流电阻的影响很小。     

Determining stress intensity factors of composites using crack opening displacement

The main purpose of this paper is to find the mixed-mode stress intensity factors of composite materials using the crack opening displacement (COD). First, a series solution of the composite material with a crack was used to evaluate COD values. Then, the least-squares method was used to calculate mixed-mode stress intensity factors. This algorithm can be applied to any method that generates or measures COD values. The major advantage of this method is that COD values very near the crack tip are not necessary. Both finite element simulations and laboratory experiments were applied to validate this least-squares method with acceptable accuracy if the even terms of the series solution are removed.     

Symmetric BEM formulations for 2-D steady-state and transit potential problems

This paper presents a new concept for symmetric boundary element method (SBEM) applicable to 2-D steady-state and transit potential problems. Two kinds of SBEM formulations are derived. Symmetry is obtained simply through matrix manipulation, and no hypersingularity appears. Therefore, SBEM is much easier than the traditional symmetric Galerkin BEM. Compared with the traditional asymmetric BEM, the present SBEM can reduce the computational cost for time domain problems only. However, when applied to BEM/FEM coupling procedure, SBEM can reduce the computational cost for both steady-state and time domain problems. Three numerical examples are included to illustrate the effectiveness and accuracy of the present formulations.     

WSP特殊螺纹接头油井管的研制

介绍了WSP特殊螺纹接头的基本结构和设计思想,运用有限元方法,重点论述了密封设计和连接强度设计的方法和准则,并通过全尺寸试验进行了验证。计算和试验结果表明,该接头具有先进的螺纹形式、合理的扭矩台肩和金属/金属密封结构,有效地克服了API圆螺纹和偏梯形螺纹的不足,螺纹达到了与管体等强度,气密封能力达到了管体的内壁屈服压力。研究结果可以为开发更多适合油气田实际的特殊螺纹接头油井管提供参考。     

An investigation of the relation between the temperature dependences of the initial unbalance and the output signal of resistance strain sensor bridge circuits

The relation between the initial unbalance and the output signal of bridge circuits when acted upon simultaneously by the physical factor being measured and the temperature of the surroundings when the bridge is supplied from a voltage or current source is investigated. Analytic relations are obtained which explain the temperature dependence of the useful output voltage under external physical action. __________ Translated from Izmeritel’naya Tekhnika, No. 1, pp. 48–49, 2007.