发电机用磁性槽楔对电磁参数与性能的影响

以一台1MW隐极同步发电机为例建立数学模型,通过理论计算与有限元软件分析该电机采用不同相对磁导率的磁性槽楔时,对发电机的电磁参数与电机性能的影响。结果表明装有磁性槽楔的电机要比非磁性槽楔的电机气隙系数减小,气隙磁密波形更平滑,输出电压波形质量更好,励磁电流降低,但短路比减小,以及磁导率越大磁性槽楔所受电磁力越大。综合确定磁性槽楔选用相对磁导率为5的更为合理。     

基于ANSYS的氧传感器夹紧套模具设计

针对汽车氧传感器夹紧套的质量问题,对氧传感器及夹紧套的结构特点进行了研究,设计出了一套能将氧传感器的敏感元件与夹紧套通过冲压成形固定在一起的夹紧套冲压模具。先利用夹紧套的径向塑性变形特点,确定夹紧套周向压缩加工的工艺方式;再由模具要将压力机的竖直运动转变为夹紧套径向塑性变形所需的水平运动,从而设计出了压盖式斜楔结构的模具结构;再对模具进行了冲压载荷校核,符合模具冲压载荷不超过冲压设备公称压力这一设计规范;选择模具中压块与连接螺杆做ANSYS应力分析,以施加载荷及约束并求解,获得了应力与应变等值线图。研究结果表明,压块与连接螺杆的强度及刚度均满足使用条件且具有较高的安全裕度。     

某水电站进水口右岸楔形体边坡稳定性分析

针对西藏地区水电工程前期设计阶段受地质资料限制,对楔形体边坡稳定性分析往往需要大量试算验算,设计工作效率低的问题,以某水电站坝址楔形体XT2为分析对象,采用数值计算软件ABAQUS对初始地应力场进行反演,并将反演出的地应力场应用于大型有限差分分析软件FLAC3d,进行楔形体边坡稳定性计算与分析。结果表明,该方法既保证了计算结果的可靠性,又大大缩短了计算时间。     

一种新型级进模具结构设计和工作过程分析

通过对导轨锁定器零件的级进模设计的介绍,阐述了一种新型级进模具结构设计及工作的全过程。具体从制件的冲压工艺出发,进而设计排样方案,确定模具结构,论述了模具的设计过程及冲裁模具结构和运作原理。介绍了该种模具关键部位的结构设计,浮动抬料块、杠杆结构、抽芯式弯曲结构、斜楔驱动滑动式弯曲成形机构。实践证明,此种模具结构设计新颖、模具后期维修快捷,生产操作方便,效率高,冲制的产品质量精度高。     

承受k/r型剪应力作用楔形体问题的应力解

对非对称楔形体在楔面承受各种不同荷载作用下的弹性应力解进行了比较系统的研究．首先利用应力函数及其导数在楔形体边界上的力学意义和海维赛（Ｈｅａｖｉｓｉｄｅ）函数，求出了在楔面下部承受ｋ／ｒ型剪应力作用下非对称楔形体问题的弹性应力的一般解，然后，令楔面角α和β取不同的值，可以得到各种不同问题的弹性应力解，如边坡问题和１／４平面问题的弹性应力解．其结果可为实际工程问题提供理论依据．     

A Conservative Integral for Determining Stress Intensity Factors of a Bimaterial Strip

Both conservative line and area integrals are derived from the Betti reciprocal principle to determine the stress intensity factor for a bimaterial strip. Numerical results are presented to demonstrate the accuracy of the methods. Several mesh types have been exploited to examine the effect of meshing on the results. Stress intensity factors obtained by means of the line integral vary somewhat between paths. Those found by means of the area integral have the same value on different paths. This revised version was published online in August 2006 with corrections to the Cover Date.     

回转窑砌砖设计图

为配合我国GB／T17912－1999《回转窑用耐火砖形状尺寸》的贯彻执行，导出了双楔形环形砌砖的计算式为直线方程，介绍了计算图的绘制方法及其在砖衬厚度为160mm等大端尺寸回转窑砌砖中的应用。     

Behaviour of shotcrete supported rock wedges subjected to blast-induced vibrations

The static state of stress at the brow in a sub-level caving mine is, due to stress re-distribution, almost uniaxial (major principal stress perpendicular to the cross cut). Since large amounts of explosives are detonated in each production round, the impact of stress waves on the brow can be significant. An extensive failure mapping programme in the Kiirunavaara mine showed that many of the failures close to the brow were structurally controlled. Furthermore, the area of damaged shotcrete was extensive when plain shotcrete was used. At brows supported by fibre reinforced shotcrete, damage in the roof was observed within a horizontal distance of about 3 m from the drawpoint. To study the behaviour of roof wedges supported by shotcrete and subjected to blast-induced vibrations a single-degree-of-freedom (SDOF) model was developed. The model consists of a shotcrete layer and a rock wedge.Vibration measurements showed that maximum particle velocity was approximately 1.2 m/s. The acceleration record showing the largest magnitude was used as the load in the dynamic analyses.The analyses showed that a wedge can be ejected by a dynamic load even if the static safety factor was >10. Furthermore, the non-linear response of the wedges was in most of the cases greater when the wedge was supported both by the joints and the shotcrete layer compared to the case when the wedge was only supported by shotcrete. A conclusion from the analyses is that it is difficult to predict the dynamic response from static calculations.To provide a safe working environment close to the drawpoint, the rock support must sustain the impact of stress waves from production blasting. To support rock wedges subjected to dynamic load the support must be able to consume the energy imposed on the wedges from blasting. The non-linear numerical analyses showed that reinforced shotcrete has the necessary bearing capacity to support the wedges formed in the roof of the cross cut close to the brow. This was in fair agreement with the failure mapping.The single-degree-of-freedom (SDOF) model can be used to study the response of an arbitrarily shaped rock wedge supported by shotcrete as long as the movement of the wedge can be idealised by a pure translation and the dimensions of the wedge are small compared to the length of the incident wave. Analyses showed that 2D wedges can be used to judge whether symmetric or non-symmetric 3D wedges in a uniaxial stress field (which occurs close to the brow) are stable or not when they are subjected to waves induced by blasting.     

台阶爆破岩石破碎楔块理论及数值模拟研究

在逐排或齐发爆破情况下,一般没有考虑岩石在单个炮孔爆破后产生的空间破碎形态问题。岩石在爆炸作用下产生的空间破碎形态主要受岩石性质,自由面状况、炸药性能等因素影响。逐孔起爆改变了岩石的自由面状况,进而对爆破效果产生了较大的影响。根据露天台阶爆破逐孔起爆条件下岩石动态破碎特征,提出了露天台阶爆破岩石破碎楔块理论,分析了逐孔起爆条件下,体积公式计算炮孔装药量的局限。采用有限元软件ABAQUS/EXPLICT中的CEL方式加载爆炸载荷,并结合混凝土塑性损伤本构(CDP)建立了双坡面三维台阶爆破模型,得到了不同时刻岩体内应力分布云图和裂纹扩展以及损伤演化情况。模拟结果表明:岩石爆破破碎楔块理论更加接近逐孔起爆条件岩石破碎状况,并有利于炮孔装药量计算。