两端并圈多股弹簧的冲击响应研究

针对实际工作中的多股簧是两端并圈,且主要用作往复运动中的复进簧来承受冲击载荷的问题,推导了两端并圈多股簧的中心线数学模型,通过CATIA软件生成了两端并圈多股簧的三维几何模型,进一步建立了两端并圈多股簧的有限元冲击模型并利用ABAQUS软件进行冲击响应计算。计算结果表明：多股簧受冲击载荷时,使各簧圈产生振动,弹簧上各质点的运动以纵波的形式向固定端传递,并会在固定端和受力端反射,因此弹簧上各质点的位移和速度不再沿轴向呈线性分布;受力端变形大,固定端基本没有变形,当冲击载荷超过极限值时,就会使多股簧的簧圈产生压并现象;实际设计多股簧时,必须进行冲击响应分析,合理选择多股簧的刚度,避免压并现象的发生。     

60Si2CrVA弹簧断裂原因分析

通过断口分析、金相检验、硬度测试及化学成分分析等方法,对60Si2CrVA弹簧进行断裂原因分析。结果表明：该弹簧断裂失效性质为疲劳断裂;弹簧端圈磨削裂纹是导致弹簧断裂的根本原因;提出了防止磨削裂纹产生的建议．对指导生产有一定参考价值。     

弹簧管压力表传动机构探讨

本文分析弹簧管压力表的传动机构，在理想假定条件下导出弹簧管自由端的运动轨迹方程，求出单圈与多圈螺旋形弹簧管的灵敏度和最佳中心角，给出传动机构非线性最小的条件等。     

客车轴端接地装置弹簧压力试验台研制

客车轴端接地装置弹簧压力试验台用于检测客车轴端接地装置各弹簧的压力及任一个弹簧压力与各弹簧压力平均值之差.本文阐述了利用薄片状压力传感器测量客车轴端接地装置弹簧压力的方式,及测量装置的研制,主要叙述了测量方案的确定及测量的实现手段.经现场使用证明,该设备测量准确、可靠性强、测量速度快,完全满足工艺要求.     

拉伸螺旋弹簧的可靠性研究

对汽车拖拉机上使用的几种拉伸弹簧的断裂位置和断裂方式进行了研究，发现断裂几乎都产生在端圈与钩环弯曲处。计算结果表明，钩环弯曲处承受较大的切应力；弯曲圆弧曲率半径越小，弯曲处承受应力越大，其应变能随之增大，使该部位处于较高的能量状态而不稳定，有向稳定状态转化的趋势。为了降低应变能，出现应力松弛，导致位错滑移产生永久变形，降低了局部区域的屈服强度及其疲劳极限，从而引起疲劳破坏。拉伸弹簧钩环弯曲处是最薄弱的环节和关键部位．改变拉伸弹簧的载荷分布，正确选择材料和工艺可提高拉伸螺旋弹簧的可靠性寿命。     

千分表的拆卸和修理

千分表的拆卸方法及修理顺序，现以杠杆齿轮传动式千分表为例作一介绍，供参考。1拆卸顺序（l）拆下后盖（2）将固定的片状销的螺丝钉旋松，向后拉开片状销，将表圈、刻度盘、表蒙、弹簧一并取出。表圈应从侧面小心取出，以免弄弯表针。（3）刻度盘嵌于表圈内，并有销钉定位，防止表圈与其相对转动。如需修理时可将刻度盘取出。（4）拆下长指针、短指针和小刻度盘。（5）从表的正面取出固定圆座板的3只紧固螺钉，从表体上取下圆座板。（6）由测杆上取下拉力弹簧、档帽、测头、导杆，旋松端块上的紧固螺钉，将测杆抽出。（7）旋出导槽块上的…     

注水阀弹簧断裂原因分析

注水阀弹簧在使用约6个月发生断裂。采用宏、微观检验和化学成分分析等方法对失效件进行了检测。结果表明,该弹簧断裂为腐蚀疲劳断裂。疲劳裂纹的形成是由于消毒氯水在弹簧应力最大的第一与第二圈并圈处产生许多蚀坑,材料中非金属夹杂物加速了腐蚀向基体内延伸,为弹簧的疲劳断裂提供了裂纹源,在工作应力的作用下导致弹簧断裂失效。     

涡旋机械的涡圈始端型线研究

涡旋机械中涡圈的始端型线不但影响排气角或压缩过程，而且与涡旋机械的整机性能主涡圈始端部分的强度有密切联系。目前关于涡圈始端型线的修正方法有几种，本文则在分析这几种修正方法的基础上提一种改进方法并且予以图解论证。     

弹簧压力试验机示值超差的原因及排除方法

(1)弦线在弦线轮上绕的多少对示值影响最大。实践得出规律：试验机弦线轮绕线多少，对试验机示值的影响最大可达±10%以上。在弦线轮绕不足一圈，即从弦线点至弦线与弦线轮相切点的夹角在200°～300°之间最为合适。而且在指示度盘上指针的回转角应不大于1.2圈。其次，需要更换弦线轮的弹簧时要特别注意，因为弦线轮直径的大小与弹簧伸长有一定的比例关系。从技术要求中我们可知，当试验机某量程加到最大载荷时，弹簧均应伸长92～97mm之间。生产中要求弹簧伸长与弦线轮直径之比应近似为0.445。如：弹簧伸长94.7mm，则轮直径应为42.12mm，若…     

气动压边在铝盖模具中的设计应用研究

铝盖生产首先需要将铝板进行圆筒拉伸，是属于带压边圈的拉伸方式。目前铝盖行业普遍采用的压边方式是橡胶圈或弹簧压缩提供压边力，由于橡胶圈和弹簧的压缩特性，在压缩过程，提供的压边力存在一个变化的过程，即先小后大，从而导致拉伸后的铝筒侧部壁厚存在不均的情况。而且橡胶圈和弹簧的经反复压缩后容易失效，压边力提供不均，影响产品质量。本文主要研究气动压边的方式，在铝筒拉伸的整个过程提供均匀可靠的压边力，确保铝筒质量。     

Mutual Inductance and Force Calculations Between Coaxial Bitter Coils and Superconducting Coils with Rectangular Cross Section

Mutual inductance and force calculations between coaxial Bitter coils and superconducting coils with rectangular cross section in a hybrid magnet system using derived semi-analytical expressions based on two integrations were performed. The mutual inductance and force calculations are based on the assumption of the uniform current density distribution in superconducting coils. The current density distribution of a Bitter coil in radial direction, however, is inversely proportional to the radius of the Bitter coil. The influence of the current density redistribution caused by a cooling hole and an inhomogeneous temperature distribution of Bitter coil of a water-cooled magnet was not considered. The obtained expressions can be implemented by Simpson’s integration with FORTRAN programming. We confirm the validity of mutual inductance calculation by comparing it with a filament method, and give the accuracy of two methods. The mutual inductance values computed by two methods are in excellent agreement. The derived semi-analytical expressions of mutual inductance allow a low computational time compared with filament method to a specific accuracy. The force is derived by multiplying the currents of the two coils by their mutual inductance gradient.     

电磁悬浮熔炼系统的结构及其悬浮力的研究

电磁悬浮熔炼技术是伴随着对特种纯净材料的需求以及航天等高新技术中对微重力研究等而产生和发展起来的，因其重要的科学技术地位而受到关注。本文从电磁基本理论从发，对轴对称螺线锥管电磁悬浮熔炼系统的结构进行分析，得到悬浮系统几何参数与悬浮力的关系；对悬浮系统中平衡线圈的结构进行改进，计算结果表明，改进结构具有较大的悬浮力。据此研制的试验系统实现了电磁全悬浮。     

足尺磁流变液耗能器的性能与试验研究

磁流变液耗能器是新一代智能型耗能器,是实现半主动振动控制的理想元件。设计制作了基于土木结构振动控制的最大阻尼力约为180kN的足尺磁流变液耗能器,并试验研究了其阻尼力性能。试验表明,对于具有多励磁线圈的磁流变液耗能器,相邻线圈的电流异向时其最大电流下的阻尼力,远大于同向的情况。试验还表明,多线圈共同工作下耗能器所产生的最大阻尼力,远小于各线圈单独工作时阻尼器所产生的最大阻尼力的简单叠加,且线圈越多,减小的程度也越大。     

Electromagnetic Forces of High-T c Superconducting Coated Conductor Coils Subjected to Sinusoidal Traveling Magnetic Fields

In order to optimize the structure of high temperature superconducting coils for linear motor applications, three separate coils with different shapes made of Re-BCO coated conductor were studied: circular shaped single pancake, circular shaped double-pancake and racetrack shaped single-pancake. The thrust and vertical forces of the three coils above a conventional flat linear three-phases winding were investigated experimentally. With the aid of the experimentally obtained values, it was found that single-pancake coil in the shape of a racetrack was the best selection for a flat single-sided linear motor system. Studies were also made on the frequency characteristics of the vertical force of the racetrack shaped single-pancake coil.     

Mechanical and radiographic properties of a shape memory polymer composite for intracranial aneurysm coils

An intracranial aneurysm can be a serious condition that can go undetected until the aneurysm ruptures, causing hemorrhaging within the subarachnoid space surrounding the brain. The typical treatment for large aneurysms is by embolization using platinum coils. However, in about 15% of the cases treated by platinum coils, the aneurysm eventually re-opens as a result of the bio-inertness of platinum. One solution to this is to develop suitable materials with increased bio-activity to use as coil implants. In this research, a shape memory polymer (SMP), Calomer™, produced by The Polymer Technology Group, Inc., was investigated as a candidate for aneurysm coils. The SMP was tested to determine its thermo-mechanical properties and the strength of the shape recovery force. Composite SMP specimens containing tantalum filler were produced and tested to determine the mechanical effect of adding this radio-opaque metal. Thermo-mechanical testing showed that the material exhibited a shape recovery force a few degrees above the glass transition temperature, T_g. The effects of the addition were small and included a decrease in T_g and recovery force. SMP coils deployed inside a simulated aneurysm model demonstrate that typical hemodynamic forces do not hinder the shape recovery process. The radio-opacity of the Ta-filled material was characterized with clinical fluoroscopy.     

放电时序对双向加载式管件电磁翻边的影响

目的 研究放电时序对翻边变形的影响规律,提高成形能力.方法 以双向加载式管件电磁翻边系统为研究对象,建立基于电路-磁场-固体力学耦合的仿真模型,针对放电时序的变化,详细分析驱动电流、电磁力和翻边变形受到的影响,揭示其作用机理.结果 与常用的同时放电相比,最佳的时序放电在保证脉冲时间一致性的同时,将径、轴向线圈电流峰值分别提高11.6％和降低12.4％,最终使径、轴向电磁力峰值分别提高18.8％和6.8％,翻边角度提升约30％,显著提升了系统的翻边能力.结论 控制放电系统开关时刻改变放电时序,可以使放电能量在线圈间发生转移,影响线圈中的驱动电流波形,从而提高电磁力大小并改善其径轴向分量的比例关系,显著增强电磁系统的成形能力.     

Flagellar dynamics of a connected chain of active,polar, Brownian particles

We show that active, self-propelled particles that are connected together to form a single chain that is anchored at one end can produce the graceful beating motions of flagella. Changing the boundary condition from a clamp to a pivot at the anchor leads to steadily rotating tight coils. Strong noise in the system disrupts the regularity of the oscillations. We use a combination of detailed numerical simulations, mean-field scaling analysis and first passage time theory to characterize the phase diagram as a function of the filament length, passive elasticity, propulsion force and noise. Our study suggests minimal experimental tests for the onset of oscillations in an active polar chain.     

Optimal realization of arbitrary forces in a magnetic stereotaxissystem

Very small implanted permanent magnets guided by large electromagnetic coils have been proposed previously as a method for delivering hyperthermia to or guiding catheters through brain tissue. This procedure is termed “magnetic stereotaxis”. Early efforts employed a single coil on a movable boom, a design that proved logistically difficult to use on human patients. The present work deals instead with a design where several stationary coils are employed to develop a force on the implanted magnet. The coil current-to-force relationship is developed for this type of machine, and several optimal solutions for realizing an arbitrary static force are presented for various constraints on the orientation of the implanted permanent magnet. Costs of the different solutions are compared in several examples using a mathematical model based on the Magnetic Stereotaxis System (MSS) developed by Stereotaxis, Inc., the University of Virginia, and Wang NMR     

Analysis of a fork-shaped rectangular coil facing moving sheet conductors

The electromagnetic induction method utilising eddy current plays an important role in a non-destructive material test. In testing slab-type material by electromotive force method, there is the fork-shaped coil method, which has two coils placed on both sides of the test piece. In most studies, circular coils have been analysed. However, it has been pointed out quantitatively that a rectangular coil is more useful than a circular coil for a non-destructive test. The authors derive a rigid theoretical formula with a test theory experiment.