MODEL ESTABLISHMENT AND LOAD TRANSFER OF SEMI ARTICULATED FLEXIBLE DRILLING TOOL1)

半铰接柔性钻具的载荷传递规律直接影响超短半径水平井钻进的成功率。为此,首先推导出半铰接柔性钻杆的单元刚度方程并揭示了半铰接柔性钻杆的弯矩传递规律;然后,采用理论分析与数值模拟相结合的方法,验证了半铰接柔性钻杆有限元模型的正确性;最后,建立造斜段半铰接柔性钻具力学模型,对不同井眼曲率半径下半铰接柔性钻具的载荷传递规律进行研究。结果表明：井深位置相同时,井底扭矩值随曲率半径的增加而增大;半铰接柔性钻杆未锁死时,柔性钻杆不传递弯矩且井底扭矩波动较大,相关研究成果为柔性钻具的设计提供理论依据。     

Influence of Drilling Parameters on the Accuracy of Hole-drilling Residual Stress Measurements

Multiple measurements using the hole drilling method were made in samples with a “known” state of residual stress. Drilling parameters were independently varied (bit rotation speed, bit diameter, and hole depth) to determine the effect on accuracy and repeatability. The study showed that accurate results can be achieved without ultra-high drill rotation speeds and that, in aluminum and stainless steel, speeds over 5 krpm and 10 krpm (respectively) were sufficient. Inaccuracies were evident in the stainless steel at speeds below 10 krpm and were attributed to non-circular holes, which may have been the result of bit vibration. There were no significant trends associated with altering the hole depth and only a slight trend associated with bit diameter variation.     

PROGRESS IN MEASUREMENT TECHNOLOGY FOR DRILL STRING VIBRATION

随着深井、超深井数量的快速增加, 钻柱振动导致的钻具失效问题更加突出. 针对钻柱振动的研究可分为理论与数值模拟、测量分析两种方法. 由于钻柱振动具有复杂的非线性特征, 使得理论与数值模拟研究受到了很大限制, 因此井下振动测量技术的研究显得尤为重要. 本文比较全面和系统地介绍了国内外钻柱振动测量技术研究现状和进展情况, 并对几个应用较为成熟的国外测量系统的工作原理、分析方法及应用技术进行了详细的综述. 所得结论可为我国井下振动测量技术的发展提供重要参考.     

Experimental investigation of penetration performance of shaped charge into concrete targets

In order to develop a tandem warhead that can effectively destroy concrete targets, this paper explores the penetration performance of shaped charges with different cone angles and liner materials into concrete targets by means of experiments. The penetration process and the destruction mechanism of concrete targets by shaped charges and kinetic energy projectiles are analyzed and compared. Experimental results suggest that both kinetic energetic projectile and shaped charge are capable of destroying concrete targets, but the magnitudes of damage are different. Compared with a kinetic energy projectile, a shaped charge has more significant effect of penetration into the target, and causes very large spalling area. Hence, a shaped charge is quite suitable for first-stage charge of tandem warhead. It is also found that, with the increase of shaped charge liner cone angle, the depth of penetration decreases gradually while the hole diameter becomes larger. Penetration depth with copper liner is larger than of aluminum liner but hole diameter is relatively smaller, and the shaped charge with steel liner is between the above two cases. The shaped charge with a cone angle of 100° can form a jet projectile charge （JPC）. With JPC, a hole with optimum depth and diameter on concrete targets can be formed, which guarantees that the second-stage warhead smoothly penetrates into the hole and explodes at the optimum depth to achieve the desired level of destruction in concrete targets.     

弯曲波在含非圆孔洞无限压电薄板中的散射

基于线性压电动力学理论,采用波函数展开法、保角映射以及复变函数,对含非圆孔洞无限大压电薄板弹性波的散射及动应力集中问题进行了分析,给出了其动弯矩集中系数(DMCF)的解析表达式.为说明问题,以PZT-4为例,讨论了外加电场、椭圆孔长短半轴比、椭圆孔倾角以及入射波频率对含圆孔和椭圆孔无限大压电薄板弹性波散射的影响,并分别...     

3D numerical simulation of drilling residual stresses

Drilling can affect the integrity of the surface of a mechanical component and reduce its fatigue life. Thus, drilling parameters such as lubrication or drilling velocity must be optimized to ensure a satisfactory residual mechanical state of the hole surfaces. Unfortunately, experimental tests are time consuming and it is not easy to observe the cutting process because of the confinement of the drill zone. The literature does not exhibit any numerical simulation capable of simulating 3D thermomechanical phenomena in the drill zone for large depth holes. Therefore, residual stresses cannot be easily simulated by means of the sole drilling parameters. The aim of this article is to propose a new numerical approach to compute drilling residual stresses for large-depth holes. A first simulation is developed to simulate heat transfer by means of a 3D thermoviscoplastic simulation in a new Rigid-ALE framework allowing the use of large calculation time steps. Then, a time interpolation and a spatial projection are implemented to rebuild the Lagrangian thermal history of the machined component. Finally, a thermo-elastoplastic simulation is carried out to compute residual stresses in the final workpiece. In this paper, the method is applied to a 316L austenitic stainless steel in the case of an unlubricated hole. The computed residual stresses are compared to experimental measurements.     

井下多股淹没射流水力清岩能力分析

研究石油钻井井下射流的水力清岩能力对钻井业有重要意义。本文借助于预处理方法和多块网格对接技术由计算机数值模拟了形状复杂的钻井PDC钻头井底下的多股淹没射流流场。为体现井底有岩屑时射流场对其的清洗作用。文中借助河流泥沙运动理论，分析了岩屑在井下的受力与运动以考虑固相的作用。因岩屑主要为推移运动。在井底除环空外的大部分地方可简化视为二维运动。提出了钻头井底水力清岩能力的体现参数-水力挟岩力。并通过数值模拟显示了井下流场，描述了转速，射流流量，喷嘴面积，射流雷诺数及井下过流空间等流场控制参数对井底水力清岩能力的不同影响，指出相关水力参数在射流时的优化方向。为复杂的井底流场控制和钻头的合理设计做探索基础。     

Non-linear least-squares solution to the moiré hole method problem in orthotropic materials. Part II: Material elastic constants

This is the second of two papers dealing with inverse problems arising from the hole method problem in orthotropic materials. Two inverse problems are of interest in this second paper: one relates to the use of the hole method as a means of separation of stresses; the other deals with using it for orthotropic material elastic constant identification. The problem of separation of stresses is posed and briefly discussed, but the orthotropic material identification problem is addressed, fully showing how to obtain the five orthotropic elastic constants, four of which are independent, when knowing the applied stresses and examining the isothetics or moiré fringes around a through hole in a biaxially loaded thin wood plate.     

聚能装药对混凝土靶板的侵彻研究

系统开展了不同药型罩材料、不同锥角、不同壁厚的聚能装药在不同炸高下侵彻混凝土试验, 研究了罩材料、锥角、壁厚、炸高等结构参数对漏斗坑直径、侵彻孔洞直径、漏斗坑深度以及侵彻深度等参数的影响规律;应用空腔膨胀理论计算了混凝土靶体阻力, 采用改进的伯努利方程和两阶段空腔膨胀理论获得了混凝土靶板在侵彻体作用下的侵彻深度和孔洞直径, 理论结果与试验结果基本吻合;基于AUTODYN 软件平台, 采用与试验一致的聚能装药结构, 开展了57 种工况下侵彻体成形过程的数值模拟研究, 并对其中典型工况的侵彻混凝土过程进行了数值模拟, 计算所得孔洞直径和侵彻深度与试验结果吻合较好, 在此基础上深入探讨了聚能装药作用下混凝土漏斗坑的形成机理, 分析表明, 铝药型罩的开坑机理不同于钢和铜药型罩.      

5-1/2 FH钻杆接头极限承载能力研究

随着超深井、定向井、水平井、大位移井及大斜度井在石油钻井工程中的广泛应用,由井下复杂工况引起的钻杆接头过早失效问题日益突出,导致钻井周期增长,成本增加,成为制约钻井工程效益的主要因素之一.近年来,不少学者对钻杆接头进行了大量研究,多数采用二维轴对称模型,少数采用三维力学模型,但并未同时考虑螺纹升角和井眼弯曲作用等因素的影响,而钻杆接头的极限承载能力研究更是鲜见报道.针对上述问题,基于虚功原理、von Mises屈服原则及接触非线性理论,同时考虑螺纹升角和井眼弯曲作用,建立了钻杆接头的三维数值仿真模型与井眼曲率到加载弯矩的转换模型,研究了钻杆接头的上扣特性、井眼曲率对连接强度和密封性能的影响,考虑预紧力、弯曲载荷及动载安全系数,计算了钻杆接头的极限工作拉力和极限工作扭矩.研究结果表明:上扣扭矩使钻杆接头产生一定的初始接触压力,保证钻杆接头井下作业过程中的连接强度与密封性能;井眼曲率对钻杆接头井下作业过程中的连接强度与密封性能影响极大,常见的某些工况会导致钻杆接头的连接强度和密封性能丧失,考虑服役时的随机振动与冲击,常规的超深井、水平井、定向井、大位移井及大斜度井弯曲段钻杆接头的设计和选型应着重考虑井眼曲率的影响;针对设计的每种钻杆接头,都应考虑常见的井眼曲率和轴向拉伸载荷进行极限工作拉力和极限工作扭矩的精细化数值计算,以确保其安全工作.     

Experimental study of the rock-bit interaction

A rock-drilling machine to facilitate full-scale drilling experiments has been built. The machine uses a sixinch tricone roller bit to study the dynamics of the rock-bit interaction. This process is not well understood, and there is a definite need to establish criteria for drill-bit wear and for the directional stability of the drill bit. The research undertaken here is one step towards this goal. Specifically, this paper presents the results of a time-series analysis of forces measured on a drill bit. It is found that there exist no simple relationships between the forces, but some qualitative relationships are found. A strong correlation exists between the vertical force and two of the tangential forces on the drill-bit legs. Some correlation is seen between the other forces, but to a lesser extent. Most of the forces show a dominant frequency at the rate of rotation of the drill bit. This may be due to a hard spot in the formation, hole eccentricity, uneven-bit-roller loading or simply hole deviational effects. Also a frequency which corresponded to three times the rotational rate was dominant. This is interpreted as a result of the three roller cones acting on, for example, a hard spot in the formation. Comparing the observed frequencies to the calculated expected frequencies due to roller-tooth impact, only the lower of the expected frequencies were seen. The higher expected frequencies were apparently attenuated. Some of the intermediate frequencies that were observed cannot be explained in terms of the simple relationships discussed above, and it is concluded that the drill-bit/rock interaction is a very complex process which is not yet fully understood.     

钻柱力学基本方程及其应用

建立了适用于钻柱几何非线性动力分析的钻柱动力学基本方程，在此基础上建立了导向钻具三维小挠度静力分析的数学模型、导向钻具三维大挠度静力分析的数学模型、钻柱稳态拉力－扭矩模型。     

Residual Stress Measurements in Finite-Thickness Materials by Hole-Drilling

Hole-drilling measurements of residual stresses are traditionally made on materials that are either very thick or very thin compared with the hole diameter. The calibration constants needed to evaluate the local residual stresses from the measured strain data are well established for these two extreme cases. However, the calibration constants for a material with finite thickness between the extremes cannot be determined by simple interpolations because of the occurrence of local bending effects not present at either extreme. An analytical model is presented of the bending around a drilled hole in a finite thickness material and a practical procedure is proposed to evaluate the corresponding hole-drilling calibration constants.     

拉压不同弹性模量薄板上圆孔的应力分析

采用弹性理论研究了拉压不同弹性模量薄板上圆孔的孔边应力集中问题．采用广义虎克定律推导出了拉压不同弹性模量薄板上圆孔边的应力平衡方程,并联合利用应力函数及边界条件得到了拉压不同弹性模量薄板上圆孔边的应力表达式．算例分析表明,当薄板材料的拉压弹性模量相差较大时,采用经典弹性理论研究薄板上圆孔的孔边应力是不合适的,当经典弹性理论与拉压不同弹性模量弹性理论的计算结果间的差别超过工程允许误差5%时,应该采用拉压不同弹性模量弹性理论进行计算．     

Equivalent boundary model of lunar soil drilling simulation by DEM

Aiming to solve the computational cost problem in the discrete element simulation for lunar soil drilling sampling, an equivalent boundary method was proposed. A high-accuracy DEM model of lunar soil was established firstly. As the novel alterable constitutive law, the accuracy of the model was verified to meet the performance of real lunar soil very much both in shear strength indices and elastic–plastic behavior. A common drill bit in the geological exploration field for sampling soil was chosen as the simulation object. In preanalysis, it was known that with the increase of drilling depth, the stress concentration area was always near the drill bit, while the affected area of the lunar soil was a cylindrical area around the drill pipe, which extended towards the drilling direction instead of extending around it. Then a big boundary drilling simulation scene was established to investigate the flow direction of lunar soil particles. The motion law of particles and the velocity field information were obtained, and a U-shape chain was described around the drill bit. Finally an equivalent boundary was set near the U-shaped chain, and the size was determined by comparing the soil stress in the fierce collision zone and around the reference boundary. This method could be a reference for other lunar soil drilling researches with other drills of different sizes.     

Nanoindentation of hyperelastic polymer layers at finite deformation and parameter re-identification

Thin polymer layers on substrates have a wide range of application in important areas. However, it is impossible to measure the mechanical properties with the traditional testing methods. Recently, nanoindentation became a new but primary testing technique of thin layers. In the present work, based on a finite element model of contact mechanics and hyperelastic materials, nanoindentation of polymer layers is simulated with the finite element code ABAQUS^?. Three often used hyperelastic models, that is, the neo-Hookean, Mooney–Rivlin and Yeoh models are investigated. The behaviour of these three models is compared to each other in different boundary value problems of nanoindentation in order to get some feeling of the different behaviour of various hyperelastic models under nanoindentation. In contrast to the traditional analytical method, the penetration depth is not restrained to avoid the influence of the substrate. A parameter re-identification strategy is employed to extract the parameters of the material models at small and finite deformation based on the principle of biological evolution. Furthermore, it is investigated how large the penetration depth has to be chosen in order to distinguish different models in reference to the load–displacement curves. Finally, the possibility is discussed of describing the data obtained by a non-linear complex model using the relatively simple approach based on the neo-Hookean model.     

梧州市花岗岩风化壳工程地质研究及垂直分带

花岗岩风化壳由表及里有不同的风化等级。认识风化程度的差异，给出各风化层的判别标准，这对于风化壳工程地质性状的研究，评价建筑场地的稳定性极为重要。本文在系统地搜集梧州市花岗岩风化壳的地质资料和已有的土工试验资料的基础上，进行薄片显微照像分析、颗粒分析。结合城市工程地质勘察工作特点，给出了梧州市花岗岩风化壳垂直分带的划分标准。     

Brief investigation of induced drilling stresses in the center-hole method of residual-stress measurement

Results of experiments to measure induced drilling stresses in the center-hole method of residual-stress measurement are described. Five specimens of different metals were specially prepared in an attempt to relieve malerial residual stress. Surface-residual-stress measurements were then performed by the center-hole method with a conventionally used (low-speed) end mill and an ultra-high-speed drill. For each specimen, the relieved strains due to the hole drilling were significantly higher for the low-speed end mill than for the ultra-high-speed drill. Preliminary conclusions are that the ultra-high-speed drill would be much superior to the conventional low-speed end mill in the measurement of residual stress by the center-hole method.     

用能量法分析层状材料弹性接触问题

利用能量法分析了层状材料（薄膜／基体）弹性接触问题，得到了具有一阶精度的闭合解，给出了求解薄膜弹性模量和泊松比的表达式，并与有限元的数值解进行了比较。二者比较结果表明：在工程材料范围内，理论解与数值解相差在6％以内；同时表明单相材料中剪切模量与弹性模量之间的关系也适用层状材料中的薄膜材料。在数值解的基础上，讨论了薄膜厚度与压头半径的比值对求解精度的影响，发现此比值对精度影响不大。通过对层状材料等效泊松比与等效弹性模量的定义，给出了用压痕实验测定薄膜泊松比与弹性模量的方法。     

Determination of residual-stress variation with depth by the hole-drilling method

The hole-drilling method is a residual-stress measurement technique in which a blind hole (usually 1.6 mm or 3.2 mm in diameter) is drilled into a material and the strain perturbances around the hole are measured by surfacemounted strain gages. The conventional hole-drilling-method procedure is to analyze the net strain changes due to the drilling of the full-depth hole (usually about 100 percent of hole diameter) and to interpret the resulting stress calculations insofar as they represent the average stresses through the hole depth. It has been determined that this procedure may lead to significant errors, particularly where there are large stress variations through the hole depth. Such errors may be difficult to detect simply by observing the strain data. This paper describes a finite-element procedure which was used to develop calibration constants to allow measurements of residual-stress variation with depth to be routinely performed by the hole-drilling method.